Tunnel extension / load carrying question

[Mr. Demeanor]

My boat has an engine that weighs about 100 pounds more than it was designed for. I have been looking at the tunnel at the transom and thinking I can easily extend the lifting area with two small square extensions, one on each side of the tunnel.
The boat has 4.5" of built in setback. Because I have to mount my engine very high, I have to run another 4" of setback for the manual jack plate.
If I add a filler piece, could be made of stainless or aluminum plate, on each side of the tunnel, I would effectively be adding 4.5" to the length of the tunnel.
This is the transom and you can see how the sponsons are set forward of the transom (4.5")
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0304.jpg

This pic show the area I am looking at nest to the trailer bunk.
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0409.jpg

Closer pic:
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0408.jpg

I mocked up a filler piece from cardboard just to give an example of what I would be doing. The real piece would need some tabs so it could be screwed to the transom.
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0410.jpg

It would be a fairly easy, inexpensive, and reversible modification. The boat is only 13' long so 4.5" of extra lift might be helpful. Let me know what you think.

The second option would be extend the entire tunnel.

[Miss Isle]

Have you tried a cleaver prop to give more stern lift, you might find out that's all you need. I think your problem is your trying to use a through hub prop for a surface drive application.

[Mr. Demeanor]

Thats an old pic. I am running a 24 Yamaha Drag prop now. The Trophy ran pretty good but steerig was horrible. If I ever come across a small cleaver I would like to try but they are rare. Regardless, I wondering if this modification is worth trying.

[Miss Isle]

I've been thinking about your question a little more. you have a pretty small boat and it appears that you have pretty substantial engine.

Prior to trying anything as drastic as you are proposing, have you tried shifting some ballast around to compensate for the change in angle of attack. Go to your local lumber yard and buy a couple of bags of "Tube Sand" and throw them in the bow, that may be all you need. I've seen drag racers do that to settle thier overpowered too light rig to settle down and ride right.

[Maple Leaf]

I doubt doing that will do any good.


Go with less setback, Bobs makes that convertible jack plate that goes to 2 inch setback or something like that. Or Go with a lighter engine.

[Brabender]

Talk to Wildman (Randy)

Maybe something like this

Obviously smaller, but you get the idea

<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/4ztbug.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Jason Johnson]

You can use a traditional plate (T&H) and flip the outside angles to the inside, this will yeild about a inch and a half set back. I have that on my Alli.

[OFFSHORE GINGER]

Talk to Wildman (Randy)

Maybe something like this

Obviously smaller, but you get the idea

http://i41.tinypic.com/4ztbug.jpg (http://tinypic.com)Chris what boat was that Tunnel Extension for .

[BUZZIN' DOZEN]

Chris what boat was that Tunnel Extension for .
http://forums.screamandfly.com/forums/showthread.php?t=198454&highlight=tunnel+extension+21

[Mr. Demeanor]

You can use a traditional plate (T&H) and flip the outside angles to the inside, this will yeild about a inch and a half set back. I have that on my Alli.

Got a pic? I looked ay TH Marines plates and cant figure out which one you talking about.
http://thmarine.com/category.cfm?CID=43&CHID=1

[Mr. Demeanor]

I've been thinking about your question a little more. you have a pretty small boat and it appears that you have pretty substantial engine.

Prior to trying anything as drastic as you are proposing, have you tried shifting some ballast around to compensate for the change in angle of attack. Go to your local lumber yard and buy a couple of bags of "Tube Sand" and throw them in the bow, that may be all you need. I've seen drag racers do that to settle thier overpowered too light rig to settle down and ride right.



I moved everything I could to the bow (battery, safety stuff, fenders, etc) and removed the oil injection and every nut and bolt not absolutely needed from the motor. Took 25 pounds off the engine including the big oil tank which was under the splashwell (and only had about 2 quarts of oil). I have moved everything I can forward and removed as much weight as possible. One problem with this little boat is that any weight forward significantly changes how high I can run the motor because I have to use a static plate (for weight). I can set her up to run great with just me or with three people (one in the back) but with just one passenger (up front) it raises the engien too high.
I found a 4 blade 26 cleaver I can try and I think it will be too big but that can be fixed. Thats as much stern lift as I can get and it should be interesting to see how it runs. It may have to much torque steer for thios little boat though. My Trophy tried to walk the stern sideways.

[Brabender]

Time to switch steering
to dual or hydraulic

Engine hts put a big strain on that single cable
if it snaps you will be on your head in a hurry.

Do you have a water pressure guage?

[Mr. Demeanor]

Steering is definitely on the to-do list. Have a water pressure gauge and have good pressure with LWP.
Current prop is a yamaha drag.
The weather has been bad and I really need a good day to spend some time playing with the setup some more. Its a PITA with a manual jackplate that doesnt have adjusters. Boat has to go back on the trailer and then I use a jack to move the mototr up or down. I have been waiting for a good day when someone can help me so I can just leave the trailer on the ramp and make passes and changes. Otherwise, tying up the boat, getting the truck...would take all day. I think I can still go a little higher.

[Mr. Demeanor]

This is a pic of the boat running at a fast cruise and trimmed right about at the sweet spot. She runs best with just a little bit of positive trim. I think its because of the weight of the motor I need a little positive trim to get the lower unit to run straight through the water. At neutral trim when the bow starts to lift the L/U moves to position like it trimmed negative. This is with the drag prop.
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/CabbageKeyRun.jpg

[Miss Isle]

Definately get at least dual cable steering, but hydraulic would be better. With cable, you'll eventually get Popey forearms trying to drive it.

From the pic above, I think you're too high, Can you use a slip calculator and figure out where your at with that, also, are you on the rev limiter's with the engine that high.

How about a torque tab, maybe the gearcase is crabbing, scrubbing off speed.

In reviewing your above pic, Is that the tip of the nosecone sticking out of the water? If so, your motor is Waaay too high.

[Mr. Demeanor]

That is not the nosecone. That is water on he other side of the boat. When I first saw that pic I thought the same then went out and looked at my gearcase. Its an optical illusion. The engine is in a good spot right now. I have great watar pressure and the boat steers easily with one hand at wide open. Slip is at 5%. I dropped the engine a half inch and lost about 1.5mph. Now need to go up 1/2" and see what happens.
I am going with hydrualic mainly becasue I boat in salt and its just less to maintain. I have a pretty good torque tab molded in.
I am at 63-6400rpm which is the sweet spot for the motor. Rev limiter wire clipped. I am told that spinning it below 6000 is hard on the wrist pins with this motor. Acceleration in this thing is a blast.
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0262.jpg

[OFFSHORE GINGER]

http://forums.screamandfly.com/forums/showthread.php?t=198454&highlight=tunnel+extension+21Thanks buzzin .

[200valeroyt]

miss isle, no offense but you think every setup is too high? why? if a prop will still bite and not blow out and drop the nose, more speed is the result. he may need a different prop or hyd plate if his boat could stand it? but i dont believe he is too high with prop. i have been in this boat with prior owner.

[Miss Isle]

miss isle, no offense but you think every setup is too high? why? if a prop will still bite and not blow out and drop the nose, more speed is the result. he may need a different prop or hyd plate if his boat could stand it? but i dont believe he is too high with prop. i have been in this boat with prior owner.I appologize, the photo looked like the motor was Way too high. That was clarified in a later post.

Slip calculator is showing 5% that's great. I think your getting all you can get with those numbers. If you review post #11 he was complaining that when he shifts weight to the front or adds passengers, the added weight raises the engine too high. That's nothing more than having a boat not well balanced, and the engine is too high.

I normally don't feel that hydraulic jack plates are worth the money, more or less just "toys" for the operator to play with, but in this case, since the boat is soo small and weight sensitive, I agree vertical adjustability is probably the answer.

[Mr. Demeanor]

I think less setback will help with the prop lifting when I add a passenger. The boat has about 4.5" of built in setback and really doesnt need the jackplate except for the ability to raise the motor above the transom and have some easy adjustablity. I am hoping Jason can tell me what TH jackplate he was referring to as that would be perfect for what I am doing. I cannot swap my jackplate parts around to get less setback. Its either thr one Jason mentioned or the Bobs convertible with 2.5" setback. If I could get that 340 pound motor moved forward 2.5" I am sure the results would be good.

[Jason Johnson]

These are the only too pics I got. I actually had to change it around when the short housing broke, so that I could get the long motor to the hight I wanted. I am ready to go back to the short one real soon. When I do I'll get you some good pics.

[Miss Isle]

I think less setback will help with the prop lifting when I add a passenger. The boat has about 4.5" of built in setback and really doesnt need the jackplate except for the ability to raise the motor above the transom and have some easy adjustablity. I am hoping Jason can tell me what TH jackplate he was referring to as that would be perfect for what I am doing. I cannot swap my jackplate parts around to get less setback. Its either thr one Jason mentioned or the Bobs convertible with 2.5" setback. If I could get that 340 pound motor moved forward 2.5" I am sure the results would be good.
That's been my thought from the start. I used to use a 3.0 liter OMC with a 10" setback, not to mention a 11" notch transom (that translates to 21" total setback for those mathmatcly challenged) Worked pretty good.

I wish I could remember the name of the jack plate I used to use. It was cool. All you needed was a 1/2" ratched with a 3/4 socket as it had a large threaded screw to raise and lower the motor. All you had to do was loosen the four slide bolts on the sides. and crank on the screw to adjust the height, then tighten the clamp screws. That's how I figured out I needed an extra 2" of Jack, so I made new angle brackets that were two inchesl longer to give me more height.When I added the additional 100lbs to the transom with a V-8 (I decreased propshaft HP, but probably increased torque, so it's probably a wash) My angle of attack was all wrong.

I decided to manufacture a 1" thick aluminum plate Jack plate for my rig. Now remember I'm still 10" from what the water actually recognizes as the end of the boat.

I did this to compensate for the added weight of the engine and change the CG (center of gravity) and make the Angle of attack of the hull better. I've benched this project for several years, as I've decided to spend my play money on campaigning a Sportsman Dirt track car.

I have recently decided to spend a little capitol on the Voyager, as it appears to be a minimal output of capital to achieve favorable satisfaction (since fuel costs have settled in the $2.50/gal price). This seems to be a pretty good "bang for the buck" as the Missouri river is a few minutes away and the closest dirt track is over an hour away. Believe it or not, the most expensive part about campaigning a stock car is Logistics. Racing is relatively cheap.

[Mr. Demeanor]

I have considered making a static plate to raise the engine but I think in the end I will have two sweet spots. One for every day running around and carrying a passenger and one for top end runs by myself. I want to keep the adjustability as any changes I make to the boat, or if I get fat, would require an adjustmet :)

[Mr. Demeanor]

I bought a 1.5" setback jackplate and will post the results in a week or so. Still searching for a 3 blade cleaver.

[Miss Isle]

Happy boating!!!

[Mr. Demeanor]

Update:
Finally had some time to run the boat and play with engine height. I only had 5/8" left in the jackplate so I went all the way up and picked up another 1 mph. Last pass was 69.7mph...damn close to that 70mph goal I had. I tried everything but it just stuck at 69.7.
My 1.5" setback jackplate and 26 cleaver both shipped today. I will run the cleaver first and see if its faster than the drag prop then switch out the jackplates. I think there is a 72+mph pass in this thing if I throw everything out of the boat. Not bad for a stock 130.
The boat ran 66mph with a my 200 buddy in the passenger seat. Carried a load better than I thought it would.

Once I get the setup good, probably going to put some more compression in it. Running premuim isnt a big deal. I swear this thing burns no gas.

[Miss Isle]

Great results for a 130.

[Mr. Demeanor]

My stock 26 Merc cleaver showed up and I couldnt resist.
74.1mph at 6400 :thumbsup:
I have a 28 cleaver coming and the new jackplate will be here tomorrow. The cleavers will need some additional setup time.
It just keeps getting better. Kind of funny that yesterday I was thinking it MIGHT run 72. Now I am thinking upper 70's with prop and more setup / driving time.

[fastcat]

:cheers::cheers:

What dia. Is the 26 cleaver.

[OFFSHORE GINGER]

:cheers::cheers:

What dia. Is the 26 cleaver. Dawg , whats up and we really need to see some pics where you put the carbon fiber.:D

[Mr. Demeanor]

:cheers::cheers:

What dia. Is the 26 cleaver.

14.25" and she BARELY fits.

http://forums.screamandfly.com/forums/showthread.php?p=1939059#post1939059

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0472-1.jpg

After the run:
http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0473.jpg

[Mr. Demeanor]

I guess this will just be my progress thread :)
Mounted the new jackplate today. I reduced setback by 2-5/8".
Before I started, I put a scale under the tongue jack and got a weight of 85 pounds. After the change, I got a weight of 107 pounds. Pretty significant change. I set the motor 1/2" lower than where it was just guessing the stern will sit a little higher now.
Testing tomorrow along with a bigger prop to test but one change at a time :)

I said I would post the info on this jackplate when I got my hands on it. It has 1-3/8" setback. This was a jackplate built by T-H Marine about 20 years ago. They could not sell them and none have been built since. I got this one from a private party that had it in storage. It was brand new in the bow with original packaging when I got it. T-H Marine will not build you one and does not even have the plans for it. This was all before CAD. I have had a bunch of PM's form people wanting info on where to get one. I work with a local machine shop that is going to take a look and let me know what it would cost to duplicate.

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0482.jpg

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0483.jpg

[sleekcrafter]

It's the shape of the sponson at the transom thats killing top end performance. It's flat and not allowing the hull to break free, to lessen drag.

[fastcat]

I guess this will just be my progress thread :)
Mounted the new jackplate today. I reduced setback by 2-5/8".
Before I started, I put a scale under the tongue jack and got a weight of 85 pounds. After the change, I got a weight of 107 pounds. Pretty significant change. I set the motor 1/2" lower than where it was just guessing the stern will sit a little higher now.
Testing tomorrow along with a bigger prop to test but one change at a time :)

I said I would post the info on this jackplate when I got my hands on it. It has 1-3/8" setback. This was a jackplate built by T-H Marine about 20 years ago. They could not sell them and none have been built since. I got this one from a private party that had it in storage. It was brand new in the bow with original packaging when I got it. T-H Marine will not build you one and does not even have the plans for it. This was all before CAD. I have had a bunch of PM's form people wanting info on where to get one. I work with a local machine shop that is going to take a look and let me know what it would cost to duplicate.

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0482.jpg

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0483.jpg

Hey Chris,

Nice jack plate. :cheers: Good luck testing. Cant wait to see the results.:thumbsup:

[Mr. Demeanor]

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0486.jpg

http://img.photobucket.com/albums/v399/MrDemeanor/Biel/IMG_0485.jpg

[Mr. Demeanor]

Ran the boat with the 26 cleaver and new jackplate. Took a little while to find the sweet spot and there still might be something left.
76.2mph at 6600rpm :)
Mounted the 28 cleaver for tomorrow. 80 is coming.

[fastcat]

Ran the boat with the 26 cleaver and new jackplate. Took a little while to find the sweet spot and there still might be something left.
76.2mph at 6600rpm :)
Mounted the 28 cleaver for tomorrow. 80 is coming.


Nice work :cheers:

[Mr. Demeanor]

Way to rough today to go fast. No new speed. I did run the 28 cleaver and was barley able to get on plane. Needs some work.

[Mr. Demeanor]

Finally ran the 28x14 cleaver today. I had replaced the battery with the Odyessee PC680 and moved it to a neutral weight location and relocated some other item from the bow. Lightened the bow by about 40 pounds.
It was a little windy and the boat is acting completel different so I need to put in some more time but I hit 79mph without too much effort. I am sure it would have run over 80 but the wind was not cooperating and I think I used better judgment to not push my luck. I have to keep telling myself it is a 13' boat.
I need to find a 14.5 x 28 cleaver. The boat is much easier to drive with the 14.5" prop through the transition zone at 50-60mph with the larger diameter. I have to trim it way up to get the "hop" out of it until about 60mph then can start trimmig back down. The good news is I gained at least 3mph and did it at neutral trim instead of trimming it to the moon. I think there is evenatualy an 82mph pass in her when I get it settled down and have a little more seat time.
This has got to be one of the fastest stock 130hp powered non-race boats around.

[Greg G]

To the top.............

[Mr. Demeanor]

Nothing new. I was laid up for 3 months and have just started running the boat again. Installed hydraulic steering and made some cosmetic changes while I was recovering from surgery. I have beem working a load carrying/cruising setup and have not even had the cleaver back on her. I doubt it will go faster until the weather cools off a bit but I still thinks thers an 85mph pass in her if the stars align :)

82.6mph was the best before I put her away.
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[Jason Johnson]

That was what I ment about the jack plate, somtimes you got to think outside the box, good job

[Mr. Demeanor]

Jason, good talking to you the other day.
Do you know anyone who makes intake stuffers fo rmy motor? I am thinking that might help out my midrange. I tried to make a set out of king starboard but couldnt get them to sit in there tight.

[Jason Johnson]

Got me a new machine today to do flywheels, remove the front half and have it milled, no then you will no longer be stock LOL Oh, sorry I had to cut you short on the phone call again, 4 - 7 am is real good time for me.

[Mr. Demeanor]

I am probably going to try for 85mph stock first but will give you a call.