PDA

View Full Version : School Pjoject - Ben Hur Hydroplane



Seanj85
09-12-2019, 10:16 AM
School started last week and we have begun our major project this year in Advanced Materials Processing. As a class we are building a 60's style hydroplane called a Ben Hur made famous by Hal Kelly. I chose this design because it is wider than your average hydro, also more stable and buoyant. We are not looking to race but rather just have some fun testing on the water. The plans are also more affordable and can be built with locally attainable materials (we are on a budget).

Rock was nice enough to donate a whole bunch of outboard parts including a late 70s's 70hp 3 cyl merc. We have stripped down the motor rebuilt carbs and fixed up whatever electrical components that were deteriorating. We anticipate the weight of the motor to be about 120 lbs (stripped down). We could probably drop it another 5-10 lbs or so if we delete the starter. Cold compression appears to be good and after some simple adjustments the motor popped off and actually idled. We slapped a 15" leg and lower from a merc 402 on and it bolted right up. We are in the process of adding a low water pickup so we can run the lower nice and high. By no means is this a race motor, but it it should make some decent power to weight and i think it will work if propped right and setup with proper weight distribution.

As far as building the boat goes, we are in the process of gathering materials and setting up templates for the ribs. Since we are not looking to race the boat, ribs will be built either out of true 3/4 mahogany or mahogany surfaced down to true 1/2" instead of spruce lined 1/4" marine ply.

I have experience with outboards, woodworking and some fiber-glassing but do not consider myself a pro as some of you are. Please feel free to make recommendations.

Attached are some pictures of the start. Ill be sure to document future progress, looking forward to the build. Forgive me if these pics dont work, im learning here.&nbsp;&nbsp;<br><br>https://i.imgur.com/Wz4yFZd.jpg<br>https://i.imgur.com/yriCCey.jpg<br>https://i.imgur.com/DwQI9Lt.jpg<br>https://i.imgur.com/rnjpCzM.jpg<br>https://i.imgur.com/Gje2NJP.jpg

Seanj85
09-12-2019, 10:22 AM
448677448678448679448680

rock
09-12-2019, 11:03 AM
Thanks for posting this. Excited to watch the progress.

Rock

tnelsmn
09-12-2019, 02:35 PM
Can't wait to see this come together. Shop class was my saving grace in high school. Never built anything this cool though.

Seanj85
09-20-2019, 01:07 PM
Well this past week went quick. We got templates made up and started cutting out ribs. We are using one by 6 mahogany, which looks more like sapele. Either way it should have good holding ability for fasteners. Hope to have ribs done next week and maybe even begin laying out girders.

449187449185449186449184449188

Seanj85
10-04-2019, 01:57 PM
Ribs are officially complete, getting them to the perfect size was a little bit of a struggle as we broke some and ate up some (expensive) material in the process. Getting each one the perfect opening size for girders was difficult as well. We wound up finding the center of each rib and marking 9 1/4" out from each center to give us a perfect opening of 18 1/2" for the driver. We are almost ready to build Girders and beams for the sponsons and anticipate starting them next week.
Templates for each are being built out of foam core, which is challenging. Students have been learning how to read a scaled drawing and transferring measurements with an architects scale on to the templates. We have had a couple problems and are moving a little slower than I had hoped, but the kids are still excited about the build and have been really receptive to the challenges. I feel like they are getting a lot out of it. Attached are a few pics I took today.450150450152450153

89LASER
10-07-2019, 06:23 AM
I wish all schools brought back shop classes. Your progress looks great, keep up the quality work. You'll always have some breakage along the way, part of the learning curve.

LakeFever
10-07-2019, 09:01 AM
Cool school :cool:

Seanj85
10-07-2019, 02:41 PM
I wish all schools brought back shop classes. Your progress looks great, keep up the quality work. You'll always have some breakage along the way, part of the learning curve.


I think it's one of the most important classes, not everyone is made for school. Thanks for the comment! Started cutting girders today, progress pics to come.

rock
10-07-2019, 06:36 PM
Almost all the schools in our area have abandoned industrial arts classes. Teachers are saying nobody wants to sign up for anything that does not concern computers. In my opinion this is where the school board needs to step in and make it mandatory. As great as all this tech stuff is we are still going to need carpenters, electricians, mechanics, and people that can read a tape or maybe even add without a machine. The mindset of the teaching profession needs a overhaul about as bad as our government. My hat is off to you Sean as you are teaching skills they will soon have no other way to acquire. Good job.

Rock

Seanj85
10-11-2019, 01:31 PM
We spent the 4 day week laying out girders. They were layed out to scale from a pretty small picture where 1/8" = 1'. Templates were derived from foam core and transferred to 1/4" marine ply. We stapled the two girders together so they would be identical when cutting them out. Not sure how accurate we are but I have a feeling we are close. Today it all came together and was the first day it started looking like a boat, students were excited as they were all taking pics to show their friends. Progress is slow, but there is only so much that we can do in a 40 minute time slot each day. Next week my goal is to get ribs attached to girders and start getting cutting sponson beams and battens.
450530450531450532450533450534

tnelsmn
10-13-2019, 10:12 PM
Good progress! Will the students get a chance to drive it when finished?

Seanj85
10-14-2019, 03:26 PM
Good progress! Will the students get a chance to drive it when finished?

Well, the school doesn't want to me to let anyone drive it. Buttttt exceptions can always be made. I want to see how it performs first before putting anyone's child behind the wheel. If it seems safe enough and kids have taken a safe boaters course I would like to give them a spin. About half the kids working on it are seniors, so they will no longer be associated with the school once the summer rolls around, so that shouldnt be an issue.

tnelsmn
10-15-2019, 02:19 PM
Thats good to hear, once they graduate not much the school can do about it. Plus you'll be coming into summer after graduation, so that's perfect timing. Built myself a nice dresser and TV stand in wood shop, but never a boat. So cool!

wogi
10-24-2019, 08:33 PM
Just a quick question, transom Height? Cant tell by the instructions posted, but what is the transom height in the plans? Neat to see this happening and maybe some younger folks will get interested in this stuff

Instigator
10-26-2019, 07:37 AM
Great stuff!

The Ben Hur was a famous and popular design of the era.

Great progress so far.
I built and raced many similar boats for yrs, when I was 40 lbs lighter.

One early trick I learned in building them was to mount the structure to a flat, square, level, straight jig.
Built on saw horses or a unlevel surface, you will build in a “twist” to the hull which will greatly affect speed and performance.

You are building a “stressed skin” hull which mean the frame has no strength until the skin (plywood) is installed. You will glue up a pretzel and not even know it.

Love your power plant and outside the box thinking to get the short mid the hull needs.
Those Motors make great power and w/some set up and testing you should have a rocket on your hands.

The construction is a huge, fun part of the process but a well sorted, 100 lb hydro should be even more fun.
Ive been 120 in a 19’ boat and 65 in a 100 lb, 10’ hydro and for pure fun and sensation of speed...., can’t beat the hydro.

Once you learn how much you can change attitude of boat by shifting body weight/position it all changes.

Way cool and thanks for interjecting this thought process to the youngins.

Well done sir!

Gary

Instigator
10-26-2019, 10:35 AM
PS, not sure if you’ve already decided how to attach skin (besides glue) but in my mind, the only way to do it is w/a narrow crown staple gun.
To weak to hammer nails and most places would bounce as well.

Seanj85
10-26-2019, 03:04 PM
Just a quick question, transom Height? Cant tell by the instructions posted, but what is the transom height in the plans? Neat to see this happening and maybe some younger folks will get interested in this stuff
Good question, we just started working on the transom, plans say to run a 17" transom for a standard fishing motor. We want to run a surfacing prop w low water pickup so we are going to start with 18 1/2" and can always cut it down if we need to.

Seanj85
10-26-2019, 03:13 PM
Instigator, thank you so much for tips and the reply. We would love to mount it to a permanent jig but unfortunetly we dont have a lot of room in the shop. We are building it behind the table saw, and whenever we need to slice up an 8 foot board, the boat has to be moved. What we have been doing is shimming the saw horses level before fastening ribs and battens. I hope it stays straight, so far it seems to be working. I really hope we dont wind up with a pretzel. Thank you for the tips on using a pneumatic stapler, we will do that when attaching the skin.

Seanj85
10-26-2019, 03:26 PM
Haven"t posted progress in a while so I figured I'd share some news. I keep telling myself to take more pics, but I wind up getting distracted easily as I'm running the hydro build (advanced materials processing) during the same period as a standard materials processing class. We are having a lot of fun, ribs are all attached to girders, center battens are now down, and sponsons are in the process of being cut. The sponsons need a little tweaking to fit perfect but with a little love we will get it right. Before attaching anything else on the bottom we are going to cut the transom out and get it attached, as everything sort of attaches it's way back there.

451503451504

rock
10-26-2019, 03:53 PM
Lookin good. I'll bet those kids are having a blast.

Rock

Seanj85
10-31-2019, 02:57 PM
So we hit a little bit of a snag today. We glued up a ridiculously strong transom and when installing it we noticed the last rib was attached 3/16" sideways. I remember the notch in this girder was the only one widened to accommodate the larger rib. Apparently the students widened it a bit too much and glued the last rib crooked as a politician. After some measuring and leveling we determined that the other ribs were straight. Our solution: glue the transom in square.. which looks a bit off but is not. Hopefully this is the only setback we are dealt, it should not effect performance as the girders are still square to the ribs and identical to stbd and port sides. It's just a little disappointing as everything was coming out so nice. 451823451824
451825

Seanj85
11-20-2019, 03:00 PM
It has been a while since I posted, as the whole process has sort of slowed down. We are at a point where we are shaping different parts of the boat to fit perfectly and preparing girders, ribs and battens for the plywood skin. I know it does not look like we have made a lot of progress but with each step we have had to troubleshoot and overcome some small problems. There are gaps in the plans where we have had to sort of make the best guess we can to move forward and have had several small victories as well as setbacks. Shaping of battens, rub rail and sponsons has been done with belt sander and block planes. This takes time as getting students setup for the period can sometimes take 20 minutes leaving us with 15 minutes to work and 5 mins for cleanup.

453093

453094

453095

rock
11-20-2019, 06:12 PM
Rome wasn't built in a day. Slow, steady progress is what these kids need to see. Teaches patience in an instant world.

Rock

Instigator
11-20-2019, 07:37 PM
Good stuff Sean.

I think, every boat I’ve built from plans, including the one I finished a yr ago, had gaps in the plans.
Not that big of deal if your used to it and or have shop space for it but, a teacher/instructor/mentor w/a class to teach and schedule dictated to you..., good luck.

Based on the above, make the parts fit, project progress, class advance and finish your boat.

Good stuff and please continue on.

You rock.

tnelsmn
11-20-2019, 08:12 PM
Rome wasn't built in a day. Slow, steady progress is what these kids need to see. Teaches patience in an instant world.

Rock

This is so true! Great to see progress on the project.

Seanj85
01-10-2020, 03:26 PM
Sorry I havent posted in a while, things have been a bit crazy on my end. My wife gave birth to a beautiful baby boy in December (our first). After having him home for a few days he developed a little cough, which turned into an inability to breathe. We brought him into a hospital and the doctors informed us he had gotten the RSV virus, and had an oxygen saturation in the low 80s. 13 exhausting days in the hospital later and we are finally home. Unfortunately I had to take some time off work and the boat build got put on hold for a bit.

So as far as the boat goes, we are almost done applying the meranti ply on the bottom, we are shooting it in with galvanized crown staples and titebond 3, then going over spots with countersunk stainless screws. We are looking pretty level overall and am I happy with the progress so far. If you look, you can see the air trap on the bottom which looks like an S -curve. It's supposed to generate lift and reduce drag in the water. Some spots need additional sanding/ filling/ fairing but we are looking pretty good and plan on running a couple strips of fiberglass over the important plywood seams.

456083
456084
456085
456086
456087

Instigator
01-10-2020, 04:08 PM
Wow!
Thank god your baby is healthy.
Yikes.

Boat looks great.

home made tunnel
01-10-2020, 04:53 PM
Congrats on being a Daddy! That's Huge! I'm a new dad as well, and love seeing little wooden boat projects like this.
Sure is a neat little vessel.

Prior replies were correct about the stressed skin style boats - you can see in my pictures that I had made a jig to hold my tunnel sides straight and level when I was building my boat. This is what they were talking about.
I don't think it's necessary in your case, being a smaller fun vessel, but regardless it's still coming out great!



456093456094456095456096

rock
01-10-2020, 07:05 PM
Wow. That is beautiful. Nice boat too. Congrats Dad.

Rock

Seanj85
01-10-2020, 08:08 PM
Congrats on being a Daddy! That's Huge! I'm a new dad as well, and love seeing little wooden boat projects like this.
Sure is a neat little vessel.

Prior replies were correct about the stressed skin style boats - you can see in my pictures that I had made a jig to hold my tunnel sides straight and level when I was building my boat. This is what they were talking about.
I don't think it's necessary in your case, being a smaller fun vessel, but regardless it's still coming out great!



456093456094456095456096
I saw your build thread, awesome stuff! What kinda performance are you getting out of that thing!??

Seanj85
01-14-2020, 05:27 PM
Flipped the hydro over today, sat her on level ground and it looks good. No twists, sponson afterplanes are both touching ground along with the pad on the transom. Next the plans call for some shoring before we add 3 layers of spar varnish over the interior. Once that is done we can add top battons and 1/8" meranti ply decking on top sides. We finished up nose cone on the frankenmerc, dont look too hard, it's not beautiful as the kids faired it. Just have to finish up a little electrical stuff on it. Project is moving along nicely.
456453456454456455456456

wogi
01-14-2020, 05:44 PM
A+ for workmanship :thumbsup:

tnelsmn
01-14-2020, 07:51 PM
Looks great, proud group of kids there! Glad youngsters these days are still able to get their hands dirty and build a project like this.

rock
01-14-2020, 07:58 PM
Lookin good. Can't hardly wait to see the finished product. Are you going to paint it or just clear it?

Rock

Seanj85
01-14-2020, 08:57 PM
Lookin good. Can't hardly wait to see the finished product. Are you going to paint it or just clear it?

Rock

Hard to say, I love the clear coat look, but I dont know if our work will be good enough for a clear. I have a student who works at a place that does decal wraps, we may try to wrap it. If that doesnt work then paint.

Dave S
01-15-2020, 12:52 AM
2 things I will add....If ya can tie in the bulkheads in front of the dashboard.....and if ya want I have a 15 inch mid...that looks like a 20 inch......Great work.....Allways wanted to build one.....Me WOOD BUTCHER.......so I never tried.......

Seanj85
01-15-2020, 04:33 PM
2 things I will add....If ya can tie in the bulkheads in front of the dashboard.....and if ya want I have a 15 inch mid...that looks like a 20 inch......Great work.....Allways wanted to build one.....Me WOOD BUTCHER.......so I never tried.......
Hahahaha
Not sure what you mean by tieing in bulkheads in the front. We are going to add some structure when we do the steering and whatnot up in the bow, still a ways away from there though.
I know it doesnt look like it but the motor is already a 15 inch shaft. We put it on the boat temporarily just to be sure as we made the transom 19 inches for a surfacing prop and low water pickup. Maybe you guys could give me your thoughts on motor height, we can still come up a bit with some shims, I'll try and include some pics.

456543456542456544

home made tunnel
01-15-2020, 05:10 PM
I saw your build thread, awesome stuff! What kinda performance are you getting out of that thing!??
I've come close to 70, but I have way too much weight in the rear still. I relocated the battery to the front, but the fuel tank has to go up there also. The bare hull weighed 505 lbs, and the motor is just under 400 lbs. Plus hydraulic steering setup. Plus the jack plate. I probably have close to 450 lbs hanging on the transom.
I say I need more weight forward because it still porpoises around 60mph. I've messed with all sorts of props and engine heights. Too high, and I cant even get on plane. Too low, and she's slow. I'm sure I have the right height and prop, now I just need to work on the balance.


2 things I will add....If ya can tie in the bulkheads in front of the dashboard.....and if ya want I have a 15 inch mid...that looks like a 20 inch......Great work.....Allways wanted to build one.....Me WOOD BUTCHER.......so I never tried.......

Wood Butcher. I love it. I think that may be the name of my tunnel hull that I haven't named yet... GENIOUS, DAVE!!!


Hahahaha
Not sure what you mean by tieing in bulkheads in the front. We are going to add some structure when we do the steering and whatnot up in the bow, still a ways away from there though.
I know it doesnt look like it but the motor is already a 15 inch shaft. We put it on the boat temporarily just to be sure as we made the transom 19 inches for a surfacing prop and low water pickup. Maybe you guys could give me your thoughts on motor height, we can still come up a bit with some shims, I'll try and include some pics.



2" below the pad is usually a good starting point. Many members have good luck with that as a rule of thumb to start with. If you have cavitation issues getting on plane... drop it a bit. If not.. just monitor water pressure.

Dave S
01-15-2020, 06:25 PM
I see the lower unit is a 15..... sorry my bad.....Most 3 clys I have seen were 20 inchers.....

RONNIE
01-21-2020, 07:36 PM
Great to see theres still a school on Long Island that still has a shop program. best of luck with the project. what else is need to complete the project that we all can help with?? parts we all have in the shop and shed??

wogi
01-21-2020, 07:47 PM
Who gets to do the testin ?

Instigator
01-21-2020, 08:36 PM
Try some stain before painting it.
You might be surprised how good it looks.
You can come up w/some stripes to hide boo boo’s if you need to.

As light as that boat is, you should be able to run the propshaft even and it will still jump in plane.
If the motor will pump water that high.

Start watching e-bay for props. You’ll want as much ouch as you can find.
Watch gas tank size, weight and placement. It will have a huge effect on attitude and performance.
Keep it aft if you can.
The hull will build lift and try to carry the bow at speed.

We Used to run real small, 2 or 3 gal tanks mounted right against the transom.
We also had some tanks that hung on the back of the motor.

Make sure and wire a kill switch and run a dead mans throttle that returns to idle/close if let go of.

That thing should be wicked fast w/that motor.
Be careful.

Seanj85
01-21-2020, 09:40 PM
Great to see theres still a school on Long Island that still has a shop program. best of luck with the project. what else is need to complete the project that we all can help with?? parts we all have in the shop and shed??

Ronnie, we are going to need cable steering. I am looking around online and am having trouble locating something. I could probably rig up some redneck home made stuff but I want the steering to be legit as possible. There is a lot of power on the back of this boat. I have been keeping an eye on local stuff via craigslist put pickings are slim.

Seanj85
01-21-2020, 09:45 PM
Who gets to do the testin ?

I am going to to test it with another member of my department first. If it is safe we will then let students test it (so long as they have their boaters safety course). I will have my boat out as the mothership and command center of the operation. Some detuneing may be in order.

Seanj85
01-21-2020, 09:51 PM
Poured in a little 2 lb 2 part closed cell foam today. Just in case. We are going to add a little more to the transom area and sponsons.

We also started adding topside battens. We noticed our ribs were not perfect on the top sides. We had to add a few shims for a smooth transition.
457005457006
457007

Instigator
01-22-2020, 06:42 AM
Here is what we used for steering in the race boats.
Cheap, easy, light and safe.

This is the steering drum and the wheel bolts right to it.
Go to Home Depot and buy some plastic coated, 1/4” beaded cable for steering cable.
Two coaming pullies, on opposite sides, cable from drum through pullies, turns 90* and heads for motor.
You then mount a steering bar to motor, normally on back, at top of mid section, and bottom of Powerhead.
Mount one additional pulley to each end, then run cable through them.
Can run either direct which means the tail of cable loops around steering bar pulley and clamps to itself.
In direct would have cable tail secured back to coaming just forward of transom. Indirect gives better leverage for s heavy/powerful motor line your running.
Go to hydroracer.com for pics.

On set up, once correct, the back of the sponsons should be 2” - 3” off the water.
You will control this but moving your body fore and aft on the floorboard, while driving in your knees.
Youll want knee pads.
By moving the C. of G. and flying the bow is what makes 3 point hydros so fast.
I have photos but don’t know how to load from my phone.

BTW, the steering drums are very easy to make if you have access to a fab shop.


Ronnie, we are going to need cable steering. I am looking around online and am having trouble locating something. I could probably rig up some redneck home made stuff but I want the steering to be legit as possible. There is a lot of power on the back of this boat. I have been keeping an eye on local stuff via craigslist put pickings are slim.

Seanj85
01-22-2020, 09:52 AM
Here is what we used for steering in the race boats.
Cheap, easy, light and safe.

This is the steering drum and the wheel bolts right to it.
Go to Home Depot and buy some plastic coated, 1/4Ē beaded cable for steering cable.
Two coaming pullies, on opposite sides, cable from drum through pullies, turns 90* and heads for motor.
You then mount a steering bar to motor, normally on back, at top of mid section, and bottom of Powerhead.
Mount one additional pulley to each end, then run cable through them.
Can run either direct which means the tail of cable loops around steering bar pulley and clamps to itself.
In direct would have cable tail secured back to coaming just forward of transom. Indirect gives better leverage for s heavy/powerful motor line your running.
Go to hydroracer.com for pics.

Great stuff, thank you. I do not have access to a metal shop to make a drum outside of my woodshop here, I am assuming it has some sort of bearing inside of it. Where can I buy a decent one?

Instigator
01-22-2020, 05:00 PM
Yes they have a bearing in them.

I just bought the one in the pic I posted.

PM me your address and when it arrives, I’ll forward it to you and the kids.
I have 9 yrs exp racing that type of boat, as well as design/build.
Happy to help you w/set up if you like.

Seanj85
01-23-2020, 11:26 AM
Thought I would post a few progress pics. It is midterm week and a few students have come in to work in-between tests.

457069
457070

Seanj85
01-27-2020, 11:50 AM
Yes they have a bearing in them.

I just bought the one in the pic I posted.

PM me your address and when it arrives, I’ll forward it to you and the kids.
I have 9 yrs exp racing that type of boat, as well as design/build.
Happy to help you w/set up if you like.

PM Sent, thank you for the help

Instigator
01-27-2020, 05:11 PM
Just got the steering drum.
Packed so well I’ll just change labels and send it your way Sean.

Should go out tomorrow.


PM Sent, thank you for the help

Seanj85
01-29-2020, 05:24 PM
Started buttoning up her top sides today. Sponsons are finally done and top battens are finally added. We were originally going to staple down the top sides with staples from the air gun, but the pos harbor freight gun decided to quit on us 3 staples in. So we made a quick switch to using an old school spring loaded staple gun. The top sides are only 1/8 inch thick so nails would have pulled right thru. We pulled the boat out into the hallway to staple down the piece of ply, this way we know we were on some solid level ground. I am very happy with how she sits on land, with 4 points of contact. I took a few measurements and the two sides are nice and even. Attached are a few pics from the past week or so.

457481457482457483457484457485457486

home made tunnel
01-29-2020, 07:58 PM
eXCITING! Should be ready to go for spring time !!

Instigator
01-30-2020, 09:51 AM
Looks great Sean.

Stapling is the only way to skin one of those.
A hammer will bounce off the deck/battens before you drive a single nail.
Done right, nails/staples are only clamps until the glue dries anyhow.

BTW, your steering drum went out yesterday.

Seanj85
01-30-2020, 03:37 PM
BTW, your steering drum went out yesterday.

Thank you Gary. It came in today.
You are the best!

Instigator
01-30-2020, 07:46 PM
Glad you got it.

Youll still need a set of coaming pullies and steering bar pullies.
The bar pullies are easy to come up with.

Coaming pullies you’ll have to watch for.

rock
01-30-2020, 07:51 PM
Done right, nails/staples are only clamps until the glue dries anyhow.

Very true.

wogi
01-31-2020, 09:45 AM
Hull drain's? Not to take away from a great job, but wondering if you are putting hull drain plugs in and if the form placement would cause problems in draining any water the hull may take on in the sponsions, as that's the lowest point and it is foamed now

Seanj85
01-31-2020, 06:48 PM
Hull drain's? Not to take away from a great job, but wondering if you are putting hull drain plugs in and if the form placement would cause problems in draining any water the hull may take on in the sponsions, as that's the lowest point and it is foamed now

Oh shoot. I forgot about drains. I guess we will have to drill them in on sponsons and transom, but I didnt think about the foam getting in the way. I was planning on drilling a few 4" holes inside of girders so that a hand pump can get access. But this may be a problem being that we closed in the top sides today.

Should we open it back up and cut a trench?
457625457626

Seanj85
01-31-2020, 06:55 PM
Start watching e-bay for props. You’ll want as much ouch as you can find.

Gary, I found a chopper prop that will fit that is 23 pitch, that is the biggest I can find, it seems like 13 spline props are a little hard to come by.

Do you think 23 is enough? I calculated gear ratio to be around 1.6:1

Dave S
02-01-2020, 03:35 AM
Merc HP props came in even#s... a 23??? chopper? not so quick to buy I hope...Show picks before ya buy.... That old merc has a small shaft....so most choppers will not fit....unless a merc 25 chopper... hard to find and wrong splines.......Pete Delacker had a prop that might work.....He is not with us... he has passed.....but his son might have said prop......

Instigator
02-01-2020, 08:45 AM
At least you figured out auto fill changed pitch to ouch??

Yes, the smaller the prop, the harder to find.

Spline count is the key.

A Chooper (be sure that’s really what you have as they’re miss listed all the time) has a lot of bow lift built into it which you don’t want/need. If it’s cheap, try it anyhow.

Most likely a cleaver will run better on your rig. Most have very little lift built into them.
Your hull has all its lift built into it.

I ran 23” pitch x 1.6 gears x 5000 RPM x 10% slip and got 60 MPH.
That may be close.

Depending on how everything works together and how healthy your motor is, you may see more.
5500 = 67 and 6000 = 74 ��

Depending on your plans for the rig, if it is to be more than a one time toy, you might want to start collecting props.
Way easier to try 3 or 4 props when you have them w/you.

Another tip is to build a test horse for the boat.
Basically a metal saw horse (iron plumbing pipe works well) so it doesn’t float away, w/carpet on top where boat will set.

Set it in water, just off the shoreline.
Deep enough water where prop is just out of water when back of boat is on the stand.
One guy on either side of motor will easily lift it onto stand.

There it will be easy to change props, set up, driver, add fuel etc.
Youre also not clogging the ramp.

Youll also likely spend time experimenting w/engine height and trim angle.

Have you engineered a fuel tank yet?


Gary, I found a chopper prop that will fit that is 23 pitch, that is the biggest I can find, it seems like 13 spline props are a little hard to come by.

Do you think 23 is enough? I calculated gear ratio to be around 1.6:1

Seanj85
02-01-2020, 12:56 PM
[QUOTE=Instigator;3186397]
A Chooper (be sure thatís really what you have as theyíre miss listed all the time) has a lot of bow lift built into it which you donít want/need. If itís cheap, try it anyhow.

Most likely a cleaver will run better on your rig. Most have very little lift built into them.
Your hull has all its lift built into it.
/QUOTE]

I'm sorry, I misread. It is a Ron hill 13 spline 12 1/2" x 23p cleaver not a chopper. Hopefully that is enough ouch 😜. He says he also has a 24 and will trade it as long as I pay shipping. I'm thinking about jumpin on it and seeing what it does. Attached are some pics of it.

As far as gas tank goes I was just planning on running a 6 gal portable strapped down.


457682457683457684

Instigator
02-01-2020, 01:53 PM
Looks good.

Ron is a good guy and used to race that style boat too.
He also used to be a school teacher and likely will want to help if he knows your story.

Problem w/the tank is where to put it and it’s weight.
They make some smaller, plastic tanks for against the inside of the transom on dinghies.
Location wise, that would be perfect.
I doubt they will fit your narrow cockpit though.
Probably around 16” ???

Anywhere forward is worse case scenario. It will hold the sponsons on the water, preventing their lifting, and will scrub speed.


[QUOTE=Instigator;3186397]
A Chooper (be sure that’s really what you have as they’re miss listed all the time) has a lot of bow lift built into it which you don’t want/need. If it’s cheap, try it anyhow.

Most likely a cleaver will run better on your rig. Most have very little lift built into them.
Your hull has all its lift built into it.
/QUOTE]

I'm sorry, I misread. It is a Ron hill 13 spline 12 1/2" x 23p cleaver not a chopper. Hopefully that is enough ouch . He says he also has a 24 and will trade it as long as I pay shipping. I'm thinking about jumpin on it and seeing what it does. Attached are some pics of it.

As far as gas tank goes I was just planning on running a 6 gal portable strapped down.


457682457683457684

Seanj85
02-28-2020, 03:48 PM
Well its been a few weeks since I posted. We have been getting into the finishing process with fairing, glassing, staining and varnishing. We closed up important seams w epoxy and some woven strips of glass. When necessary we made some fillets w cabosil and glassed them over. I tried to limit the amount of glass and epoxy as it weighs a ton and we are already overbuilt. Attached are some photos of our progress.
459574
459575
459576
459577
459578
459579
459580

Seanj85
02-28-2020, 03:51 PM
459581459582459583459584459585459587

Dave S
02-28-2020, 05:40 PM
You can not be over built...... only under powered.........

Seanj85
02-28-2020, 07:37 PM
Lower unit setup
459599459600

rock
02-28-2020, 07:40 PM
Congratulate those kids for me Sean. That's really impressive. You should be proud.

Rock

Seanj85
02-28-2020, 07:53 PM
Congratulate those kids for me Sean. That's really impressive. You should be proud.

Rock
I didnt thinking was going to turn out like this. My students wanted to paint it but my theory is you can always paint over stain. Once the varnish went on the top sides they all changed their tune. I have a special group this year, they have really bonded as group.

Instigator
02-29-2020, 07:23 AM
Killer!

Good call on the finish ��

RONNIE
03-02-2020, 07:14 PM
looking good!! Glad to see younger kids doing something other than playing on there phones

tux974
03-03-2020, 06:10 AM
Looks awesome, great job. Lifetime memories for most I'm sure.......:thumbsup:

bbezok
03-04-2020, 09:52 AM
Looks Beautiful......awesome to see a shop class take on something out of the ordinary. When i was in high school back in the 70's, my Dad and I built a Glen-L "T-N-T" as a winter project in our garage, was the best Father-Son project. That spring I did a class project on the entire build (wish we had the photo ability we have today back then). Teacher was so impressed he asked me to bring it to school and show it, had the entire class out in the parking lot.
Great job kids, keep up the awesome work, and can't wait to see some vids of her in action!

Dave S
03-04-2020, 05:15 PM
Back in school..... My shop teacher..... let me cast ......crankcase stuffers........

Seanj85
03-07-2020, 06:58 AM
Kids wanted to paint the middle white since it was kinda ugly. Applied a few more coats of varnish and installed mahogany rails on top of girders. Next week we are going to install a cedar floor, then flip her over and finish up the bottom sides. Then we will add the skeg and start rigging her up. We are going to fab up a steering bar out of some 6061 aluminum stock.

I put in for a HIN a few weeks back and havent heard anything back from New York yet. Anybody have any idea how long it takes to get a HIN in NY?

460088

Seanj85
03-07-2020, 07:03 AM
Back in school..... My shop teacher..... let me cast ......crankcase stuffers........

Not sure what that is, but I would love to have aluminum foundry back in school. We could 3d print parts and sand cast them for endless possibilities.

Seanj85
03-07-2020, 07:04 AM
looking good!! Glad to see younger kids doing something other than playing on there phones

Hey Ronnie, I heard you met the other tech teacher that I work with.

David - WI
03-07-2020, 07:58 AM
Old "Deadman" racing throttle: https://www.ebay.com/itm/QUINCY-VISU-MATIC-Boat-Racing-Throttle/124102987308 (https://www.ebay.com/itm/QUINCY-VISU-MATIC-Boat-Racing-Throttle/124102987308?_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=225086&meid=61934f149fe24efe96ee5507ab6aa0bb&pid=100290&rk=1&rkt=4&sd=124102987308&itm=124102987308&pmt=0&noa=1&pg=2060778&_trksid=p2060778.c100290.m3507&redirect=mobile)

tnelsmn
03-08-2020, 12:08 PM
The wood finish is a nice touch and the two tone color combo looks great!

Instigator
03-21-2020, 04:57 PM
Here’s the the gas tank for the back of your steering bar.

Put the weight where it should be.

https://www.ebay.com/itm/Racing-outboard-fuel-tank-steering-bar-mount/372994417845

Seanj85
03-27-2020, 07:44 AM
Well school has been closed for a few weeks now and it doesnt look like it will be opening up any time soon. Teaching remotely from home sucks big time. Last week on friday they opened up the school for a few hours to let teachers get supplies since we closed so abruptly without warning. I grabbed the boat and all the parts associated with it, in case we dont go back (which is likely). This is a bad situation, I was really hoping to get this finished with the students. All that is left is rigging really which I can tackle once I get my own boat ready and splashed for the season.

I have a student who works at a body shop. He resprayed the cowl and sent me a few pics. Check it out.

461498461499461500

Seanj85
04-01-2020, 08:17 PM
Started finishing her up in my backyard. Cut some inspection holes in the sponsons, sanded and added a final layer of varnish. Then finally assembled the motor for the final time and rigged up throttle. Next is wiring up key switch, battery and kill switch followed finally by steering.
461931461933461935461936461937

home made tunnel
04-01-2020, 10:30 PM
Does she float yet??

LakeFever
04-02-2020, 05:26 AM
Looks great congrats! Wish I had this shop class when I was in school :smiletest:

Would be cool to see some vids when you get in in the drink

Instigator
04-02-2020, 06:31 AM
Gorgeous Sean!

You should be proud.

Sucks you have to deal w/the school shut down.

BTW, I think you’ll find you’ll be able to raise your motor another 2 or 3”.

Also, that fuel tank is still in e-bay.
Perfect for that boat.

Seanj85
04-02-2020, 07:54 AM
Gorgeous Sean!

You should be proud.

Sucks you have to deal w/the school shut down.

BTW, I think you’ll find you’ll be able to raise your motor another 2 or 3”.

Also, that fuel tank is still in e-bay.
Perfect for that boat.

Gary, I've been watching it on ebay, but I want to see how low she sits before hanging more weight off the back.

How should I go about raising the motor? Can I add a few shims?

Seanj85
04-02-2020, 07:56 AM
Looks great congrats! Wish I had this shop class when I was in school :smiletest:

Would be cool to see some vids when you get in in the drink

I will definitely take some documentation. Still waiting on the state for my hull Id number. Then I can register her w motor vehicles

rock
04-02-2020, 09:00 AM
Looking good Sean. Kinda sucks the kids did not get to finish but they did do most of the build. Very nice.

Rock

Seanj85
04-02-2020, 09:28 AM
Looking good Sean. Kinda sucks the kids did not get to finish but they did do most of the build. Very nice.

Rock

Rock,

We would probably have been done by now if the school hadn't closed. I am going stir carzy in this quarantine. Cant help myself.

rock
04-02-2020, 09:40 AM
I understand completely. I have moved back into my barn/shop just in time. We converted my old billiards room into our bedroom as before the 1 bedroom was a loft and I am soon going to fear stairs. That means I can justify building me a new billiards room which has given me plenty to do. Hope you are doing well.

Rock

Seanj85
04-02-2020, 12:49 PM
Does anybody know what this mercury switch is? Do I need it? 462015

rock
04-03-2020, 07:28 AM
A mercury switch kills motor if over trimmed. It takes ignition to ground. Motor will run fine without it.

Rock

Instigator
04-03-2020, 09:33 AM
You’re probably right on weight distribution.

Your motor is 30 - 50 lbs heavier (do we know height?) than what it was designed for.

If even w/the intended power on it, it would float low enough at rest, w/you in the back cranking on motor, to easily take water over transom/combings and sink the boat if not careful.
Add the weight of your motor to that equation...

So we have a race boat design being converted for recreational use so what concessions must be made?

Your hull is a 3 point hydro. By design, the nose catches, traps and compresses air which causes lift.
As speed increases so does lift.
You control the amount of lift by crawling fore and aft on floorboard.
When sufficient lift is created, it will lift and carry the sponsons off the water thereby eliminating the drag of the sponsons and the boat only riding on 3 or 4” of the main bottom.

This is what makes the 3 point, the fastest hull design in the world.

Where you carry your gas will have a huge effect on this.
If you put it forward of dash as I have done before, it will ruin how the boat runs.

If you put the gas tank in the cockpit, it will limit your movement and ability to “trim/control angle of attack”.
Fuel placement will likely determine if you end up w/a way cool, 55 mph toy or a 70 mph rocket.

Clear as mud?

Assuming you’ve never driven one before......, you’re not ready for 70 anyhow ��

Is the motor going to be electric or pull start?
Electric requiring more weight and it’s placement.

Way cool project either way.

Seanj85
04-03-2020, 01:44 PM
I've driven hydrostreams with padded bottoms but no, I have never driven a hydroplane before. I'm sure it will be a learning experience.

Motor weight is about 150 all said and done. I think the boat was originally designed to run the mark 55h which is about 100 lbs.

Clarkcraft plans call for up to 60hp so im guessing heavier then 100lbs is okay; however I dont know what 60hp weighed way back when these plans were drawn. We beefed up transom and supports in that area regardless. Clarkcraft also advertised the boat as being able to run 2 people, so I am hoping that we could offset that 2nd person with a heavier motor? I dont know.

Gas tank: I have a 3 gallon portable and a 6 gallon portable both will fit inside cockpit.

Motor will be electric start. I have a small marine battery i used on a yamaha 25 I acquired, and it cranks the 70. I dont know what it is called but it's about half the size of a 24 series battery. I was planning on mounting it right in front of the transom. If weight winds up being a big issue I can delete it and run a rope. If it is still too heavy, I will try and keep an eye out for a lighter motor. I would after all like to get the kids out on the water when this quarantine is all said and done. That is what it's all about.

Instigator
04-03-2020, 08:42 PM
If that motor is 150 lbs that is not good.
Plus battery....

Two people........, ugh, no.

JPEROG
04-03-2020, 09:18 PM
I had a class D hydro that I mounted the battery up front (just under the steering) and it really helped with weight offset when the boat was at rest. If I was to do it again, I would have it on an alum. slide rail so that I could move it back when I moved back.

Joe

Instigator
04-04-2020, 06:20 AM
Take it to the ramp for a test float and move weight around and see where it ends up.

That hull may be big enough to absorb more weight than I think.

See if you can get in the back of the boat, to the motor, w/o taking in water.
Electric start will negate some of that need but if you have motor issues, while out, it would suck not being able to get to motor.

Seanj85
04-24-2020, 07:06 PM
Just about ready for sea trial. I put my big boat in this week and literally lbew up one of the motors on my way to the dock slip. So I have been dealing with that (1996 merc 225 efis).

New York State is shut down, so no hull ID # which means no registration, which means no insurance and no driving... however I found a way to sea trial, not going to get into it.

Took a little time to figure out steering, I had it looped all weird and the steering bar was also a little long. Rigged the steering cable 3 times and finally got it right.

Got the old motor rigged up and running like a sewing machine. The lower carb seemed to like 2 turns out and the upper liked 1 1/2. Hope everyone is well.

Motor running:
https://youtu.be/zRif9I29MD8

Pics:
464053464059464060464061464063

rock
04-24-2020, 09:12 PM
Sounds good Sean.

Rock

Seanj85
05-13-2020, 02:37 PM
It floats!

Alright, so since I last posted I managed to find a jet ski trailer and modify it with bunks that will support the boat properly. I am still jammed up with a registration for the boat but I am hoping I will have that all sorted out by the weekend.

In the meantime I pulled the hydro down to the ramp to test the waterline. Without a driver, and with the battery and gas tank moved forward about 18inches I have about an inch of waterline left before water submerging aft end of boat. With battery and gas tank (6gal) all the way aft the waterline is pretty much level with the top of the transom. When I hopped in the level did sort of see-saw back. If I slide the gas tank forward, I am able to get to the transom in case of an emergency. All in all I am pretty happy with how it sits. I would like to replace the 24 series battery w something a little smaller, it is just overkill for this application.

So even though I am unregistered and uninsured I couldnt help myself from taking it for a little spin right in front of the ramp. I believe the technical term for how it runs is: ****-your-pants fast... it is scary how fast this little thing is. I only had about 300 ft of space in the canal to test and registered a speed of 44mph on my phone gps with A LOT of throttle left, leaving ample room to turn around and decelerate. It really accelerates like a bat out of hell. I want to take it out to the flats once this registration comes in for some final tuning.

Next I need to look into seeing what we can do for all the students that worked on this project. Long Island, NY is being hit pretty hard with this virus and I doubt that schools will reopen anytime soon, but something needs to be done.

465533465534465534465536465535

bbezok
05-13-2020, 02:41 PM
awesome job!........she looks great! congrats on a job well done.

Instigator
05-13-2020, 03:11 PM
Wow!

I am astounded at how well it floats w/that tank and battery in it!
Awesome stuff dude.
And that you got enough of a ride to see what you just built.
Pretty sure I warned you ��

Find a 3 gal tank and a motorcycle or lawn mower battery.
Youll shed 50 lbs.
2 gals is good, 3 is too.

Sucks about the kids.
Maybe once it’s registered, have them meet you at the ramp some Saturday.

On registration, the one I built a couple yrs ago, I took it to them for inspection, showed them my plans and rect’s for materials and was done on the spot.

Love the name too Sean.
Good look to everything you are dealing w/brother.

And CONGRATS!

PS, bring it here and I’ll help you set it up, and teach you how to fly it, ifffff you let me drive ��

Seanj85
05-13-2020, 03:27 PM
Gary, thank you for all your help also thank you for the steering drum. I too was surprised with how well it floats, we did add about an inch and a quarter to the height of the transom. We figured we could use a little extra flotation to counteract the heavier motor. But yes you were right, I dont think I am ready for 70hp yet.

On that note, Rock: a big thanks for donating the motor. This thing is an absolute diamond, and it runs like a sewing machine. The key switch harness you provided also came in handy. We would have been stuck without this. I know I promised you a video of students getting off the boat w a tremendous smile on their face, and I know we will get that one day.

When it happens I'll be sure to post. Thanks S&F

mrichartz
05-13-2020, 03:34 PM
Cant wait to see a video of it running!

Seanj85
05-13-2020, 04:45 PM
Cant wait to see a video of it running!

I will try and get one this weekend.

89LASER
05-15-2020, 06:45 AM
That boat came out great. You and your shop class should be very proud.

tnelsmn
05-20-2020, 12:40 PM
Looks good! Makes me want to build one when I finish the current project. Can't wait to see it setting the water on fire!

Dave S
05-20-2020, 09:59 PM
A side note.... the steering arm ends MUST intersect with the C/L of the swivel point...… If not loose or tight steering cables.....when turning the wheel.

Seanj85
05-21-2020, 04:09 PM
A side note.... the steering arm ends MUST intersect with the C/L of the swivel point...… If not loose or tight steering cables.....when turning the wheel.

Ahh I didnt know this. Thank you for the info, just went and checked. I am not perfectly on the centerline but probably within an inch or so. Still learning.

Seanj85
05-21-2020, 04:17 PM
I tried to steal a go pro from work but they wouldnt let me in.

Took er out for a cruise monday, hit 55 on the first run. Sponsons were still in the water. Went back to the ramp and pulled the motor up another half inch and added a little trim. Hit 63 on second run, but I was too scared to look over at the sponsons while laying down. I am pretty sure they were out of the water. I could feel the lift and it was riding more... quietly...

Also I thought the lower was at a 1.6:1 ratio however i messed up. It is more like 2:1.
That means 63mph is about 6500 on a 23pitch prop going thru a 2:1 reducer w 10 percent slip.

Spoke to the guys at ron hill, I have a feeling I am over-reving the engine, they are sending out a 26pitch. Going to give it a shot just have to pay shipping for the swap.

Also let a student take it out, I made sure the trim was back to original setting. His father docks his boat 2 slips down from me so we made a socially distant morning out of it. He had a blast.

I never thought 63 would feel so fast. It feels like you're going 100 mph. Gary I see what you mean about controlling lift w your body location. I am not sure how much faster I want to run. This thing rips.

Seanj85
05-21-2020, 04:19 PM
Looks good! Makes me want to build one when I finish the current project. Can't wait to see it setting the water on fire!

I would recommend it. The build is a lot of fun but actually running it is even better.

Instigator
05-22-2020, 08:29 AM
Love it!

I think somewhere in this thread I guessed you’d see 70 and based on results I’d say w/the proper wheel, you’re there.

Excellent of Ron Hill to help you like that.

Dont be afraid of the hull lifting.
Youll feel it when it starts.

On your next outing:

Make sure there's no wind, and water is calm.

That should probably start carrying the sponsons at around 55 if weight balance is close.
W/you up by the wheel, get it to a steady 50/55.
Then start walking yourself aft, one step at a time.
Pay attention to feel. You’ll also see the bow raise and your angle of attack change.
Once you get it to lift, still keeping speed steady, move fore and aft small amounts and watch for changes in attitude.
You will start to feel it and sense it.
And you’ll like it ��

It will transition from being/running like a boat to, a low flying plane.

Once you’re comfortable w/this sensation, at that speed, feed it some more throttle.
Your goal will be to keep angle of attack stable as speed and aerodynamic lift increases.
Youll do this by walking back towards the wheel.
In an oval course race, drivers jump as far back in the boat as they can when exiting the turns ( I used to have bruises on my ass from the motor clamp handles!) to get the bow up and packing air as early as possible.
As that’s happening they’re also walking up the floor board to keep the bow where they want it.

In theory, your having the hull carry its weight and your weight on a cushion of air.
Only the last 2” of the main bottom is in the water.
Near zero hydrodynamic drag.

Ive been waiting to see if you’d make it to this step or stop when you get to 55 like most do.
Well done grass hopper.

Here is a shot w/me in the close boat.
Notice sponsons of both boats.
Now, also notice driver position, both boats.
You can tell far driver is farther forward than me.
Either, he was lighter or his hull had more lift causing him to walk closer to wheel.
This is at wide open throttle, end of straightaway, at top speed.
We were both flying our boats where we thought they were fastest/most efficient.

Didnt matter, i was passing him and beat him anyhow.



I am not sure how much faster I want to run. This thing rips.

Seanj85
05-22-2020, 11:08 AM
Great info thank you Gary. Once this prop arrives I will take that information into consideration for next time. I am noticing that little changes in trim make a big difference. Did you run with any trim? Or tuck? Trying to find my sweet spot.

Hopefully i have a gopro by then. Driving this thing is so much fun, I also noticed it gets a lot of attention.

What year was the picture from? Are you running a yamato? How fast are you going in that pic?

rock
05-22-2020, 03:53 PM
I think Sean's been bitten.

Rock

Instigator
05-22-2020, 05:57 PM
The lift in the hull, weight, power, prop, conditions determine set up.

That hull liked neutral or a bit of down trim.

About ‘1980 in Laredo Texas.
Yes, Yamato 80 just after they came to the states.

High 60’s.

Was a fun race.

Local news had a helicopter there filming my race.
When I got out front they were filming me from just ahead, just above.
I remember I had these cool white leather driving gloves and was showing off for them.
Was working and racing for the builder of that boat.
That boat was very fast and very stable but I was hot dogging for the news chopper.
I made it look out of control for the camera.
Should have been killer footage but I never saw it.
After the race my boss asked me what was wrong w/the boat ��

The next day, while leading my heat, at the end of the race, I hit something in the water and blew a hole in the bottom of the boat.
It was bad and I was filling w/water fast.
Rules say you cant pit until last boat finishes.
I was 1/2 a lap ahead of second place boat and almost a full lap ahead of last place. So I had a while to wait.
The boat had so much water/weight in it, even w/the motor still wide open, it came off plane.
I did circles in front of my pits throwing water in the air so my boss would know what was going on.
He kept waving me off knowing I’d get DQd if I came in.
They had turn judges on a pontoon in middle of the course and I did laps around them doing same thing and they also motioned for me to stay out.

Last boat finally finished and I let off the throttle and the boat sank right in front of our pits!!

Funniest part was being that Laredo is right on the Texas border with Mexico there were a lot of Mexican spectators at the race. There was a group of four or five of them in lawn chairs Right by our pits and watching my race.
When they saw me win the race and then the boat sank in front of them they went freaking berserk!
It was hilarious. Couldn’t speak a lick of English but you could tell they were having a blast.

Was a fun race.


Great info thank you Gary. Once this prop arrives I will take that information into consideration for next time. I am noticing that little changes in trim make a big difference. Did you run with any trim? Or tuck? Trying to find my sweet spot.

Hopefully i have a gopro by then. Driving this thing is so much fun, I also noticed it gets a lot of attention.

What year was the picture from? Are you running a yamato? How fast are you going in that pic?

Seanj85
05-23-2020, 07:39 PM
Awesome stuff

RONNIE
05-28-2020, 05:32 PM
yeah lives around the corner from me

Seanj85
06-10-2020, 06:33 AM
Here is a link of her running. Still working on setup, I need to get rid of this battery and even though the plans dont call for it, Ron Hill suggested adding air traps. Also going to try another prop, just waiting on them to finish building it.

https://youtu.be/C3a5m93Jqn4

rock
06-10-2020, 06:43 AM
Looks to be pretty stable. Very cool.

Rock

bbezok
06-10-2020, 07:21 AM
Looks very stable.....great job!

Instigator
06-10-2020, 07:41 AM
Great video.

Am shocked at how well it handled that chop.
At the 4 min mark you had a great pass on decent water.

Once on plane and the
prop hooks, that thing pulls hard!

Sean, I have to tell you, this is the best executed, first time attempt at a home built 3 point hydro actually get it to run.
As I’ve stated before, most get to 45 mph and stop.

CONGRATS!

As to air traps, absolutely.
I didn’t catch that you didn’t have them.
Every one of my hydros had them and was one of my favorite things to play.
The plans probably said no to protect against liability from novices.
Thats why the bows not lifting at the speeds you’re running.

Think of them as a pop off valve for the pressure built under the bottom.

I always ran mine full depth, full length.
As in, w/the hull upside down, put a straight edge from the back of the sponson bottom (inside edge) to the edge of the main bottom at transom.
That builds full lift.

Once bow pops, it will then start dumping air so you will then be controlling it by walking fore/aft on the floor board.
As a positive side effect, they will cut down some of the sliding in turns but you will have to lean your body in to turns to keep the outside air trap from catching and tripping the boat.

My boats ran 1/2 the power you have (but way less weight) so you probably won’t need traps.
Id try full depth but stop them a foot from the transom.

Id also suggest that you mount them temporary in prep for alterations.

Again, congrats!

I would add, we can tell from the video that you have the thing smoking!
Be very careful at those speeds, and especially those conditions.
It can and will bight you.
I would STRONGLY recommend a race vest and helmet.
A ski vest won’t stay on if you go for a swim at those speeds.

In case I haven’t offered before, I’m happy to pm you my # and walk you through what to expect.

If you were excited w/where you were at, wait till you add air traps.
The sensation of flying the boat, and the changes in it that you control by body position will likely change your world.
Maybe we chat while your testing next time??

LakeFever
06-10-2020, 11:11 AM
Yeeee hawww that looks like fun, congrats! Thanks for the vid

Seanj85
06-11-2020, 07:58 AM
Gary, thank you. You are an invaluable source of information on this subject.

I am very happy with how she is running, it really is a rush to drive. Plus it burns such little fuel. As fun as it is, I k ow there is more speed in the tank.

What material did you use for air traps? I am thinking about buying some 1/8" aluminum stock and bending it up at work. I have a full sheet metal shop.

Would 1/8" be strong enough? How would you fasten it?
The sponson sides are 3/4 mahogany but the bottom is only 1/4 meranti.

Instigator
06-11-2020, 06:35 PM
For what you’re doing, I like the alum idea and 1/8” would be perfect.
Start w/them full size, then cut them down as you learn.

You could mount them w/stainless, pan head sheet metal screws.
You could cut them down and reuse the same mount holes.

Id break them so you had mounting flanges located over 3/4” wood, under the skin.

Drill and mount it first First time then pull all the screws, then thin down some resin 10% with acetone, and use a Q-tip to put it into the screw holes.
That will allow you to remove, and reinstall the air traps three or four times without stripping the screw threads.

Once you get the traps where you want them then use sealer on the screws the last time you install them and your done.


Gary, thank you. You are an invaluable source of information on this subject.

I am very happy with how she is running, it really is a rush to drive. Plus it burns such little fuel. As fun as it is, I k ow there is more speed in the tank.

What material did you use for air traps? I am thinking about buying some 1/8" aluminum stock and bending it up at work. I have a full sheet metal shop.

Would 1/8" be strong enough? How would you fasten it?
The sponson sides are 3/4 mahogany but the bottom is only 1/4 meranti.

Seanj85
06-11-2020, 06:46 PM
Ahhhh very nice! I like the way you think!

Dave S
06-12-2020, 01:05 AM
A guy I knew...… I built the 44 merc for him.... had a Hydro..... kinda big....had been used with the MK 75 H … I had bought.... in 1971....That boat had 2 inch deep lifting traps...….I tried it out and it lifted up 2 inches..... at 30 mph..... scarry for me being a flat bottom boat guy.....He ran even with my B boat with a 44......The old Dazzys…….Will try to post Pixs…..

Lake X Kid
10-25-2020, 01:53 PM
Here is a link of her running. Still working on setup, I need to get rid of this battery and even though the plans dont call for it, Ron Hill suggested adding air traps. Also going to try another prop, just waiting on them to finish building it.

https://youtu.be/C3a5m93Jqn4


https://youtu.be/C3a5m93Jqn4

Lake X Kid
10-25-2020, 01:54 PM
https://youtu.be/zRif9I29MD8

XstreamVking
10-26-2020, 10:50 AM
For an 11 foot boat she seems to handle the water very well. Motor sounds good too.

Dave S
10-28-2020, 04:01 AM
WOW having fun with out a 300 R...........Rope that motor down.....

Instigator
10-28-2020, 07:28 AM
Yep.
Missed that.

Keeps the motor from kicking up when you let off the gas, and losing control.

When I was 19 and (full of piss and vinegar) working for my new boss building hydroplanes, and at our first race, and running a Yamato 80 (his) OB on my Butts Hydro, while testing, I decided to show them who I was.

In a hurry to get in the water (full of.......) I forgot to tie down the motor.
Straight off the beach, flying the boat towards the first pin of the first turn and back off the gas to set the boat for the turn and....., the motor kicked up and I barrel rolled the boat in front of everybody!
A 100 yds from where I started!

They towed the upside down boat, me sitting on top of it..., back to the pits and once my new boss saw I was OK, he shook his head and walked away����

I did make up for it by winning the race the next day.


WOW having fun with out a 300 R...........Rope that motor down.....

Dave S
10-28-2020, 08:13 AM
HeeHee......Ya showed them who ya was.......The wet guy.