Engine Set Back, Good or Bad?

[WillySteve]

If you have a bass boat, and the seats set rather forward, so the boat is fairly well nose heavy, is it not sometimes more efficient, (as far as getting more bow lift & top speed), to have the engine closer to the transom?
I understand the leverage effect with a jack plate, but I can also see it reversing the situation. At some point moving the engine back has to lose it's effect from the fact that the engine is having to lift more weight! In other words. try lifting a sack of potatoes hung on the end of a 1 foot bar, then try it again with a 2 foot bar!
Any thoughts on this welcome.

[rjdubiel]

but you have to think that more like a seesaw. you have a fat kid on one side and a skinny kid on the other. move the motor back(little kid) will help lift the fat kid (boat) with more leverage. also you can run the motor in better water that is farther away from the bottom of the boat and run it higher.

someone else will fill it in with more detail than i can.

[150aintenuff]

there is a point of optimum setback on all boats.... to much and itgets flighty because of to much lift..... to little it overtrims and slows down due to lack of lift boats ad motor setup are more like SEESAWS than a sack of potatoes...

[transomstand]

If you have a bass boat, and the seats set rather forward, so the boat is fairly well nose heavy, is it not sometimes more efficient, (as far as getting more bow lift & top speed), to have the engine closer to the transom?
I understand the leverage effect with a jack plate, but I can also see it reversing the situation. At some point moving the engine back has to lose it's effect from the fact that the engine is having to lift more weight! In other words. try lifting a sack of potatoes hung on the end of a 1 foot bar, then try it again with a 2 foot bar!
Any thoughts on this welcome.

Take your potatoes and bar, then rest it on a fulcrum(the rear edge of the pad). That's what your doing with set back. You move the engine back until the boat "balances" on the rear edge of the pad, so it requires little or no positive trim to fly the nose. The ideal setup has the propshaft nearly parallel to the surface of the water, applying maximum forward thrust. Too much set back, and you lose your fulcrum, you move the balance point behind the pad of the hull, then the engine only wants to drive the back of the hull down, you've lost your fulcrum, and can no longer appy leverage to lift the boat.

[WillySteve]

Thanks for the replies ya'll! I posted about this boat in the setup section last week. I've owned it since new, (it's a '99) and set it up where it did fair when I bought it.
(20' Charger; 260hp Merc.; 7" set back; 23" pitch (w/alot of rake) 4 blade Power Tech; 69.1mph @ 6500rpm)
Then got busy & no time, then divorce, then lost interest & now ready to do it right.
Here's where I'm at now:
I have to over trim to fly the bow. Raising the engine dosen't seem to help, more rpm, less speed. Lowering does raise the bow much better, but still have to over trim and still loses speed.
Also this engine is supposed to turn 7500 rpm, and I know it will turn better than 6500 with what I have if I can find the right spot on the boat for it.
Charger bass boats have always had slow hulls with their deep v in front of the pad but I'd like to fix that problem!

[spirit5.6]

Set back has a hell of a lot to do with the weight of the front of your hull too.. I have a built in set back on my hull of 6 inches, l ordered a 4 inch CMC jack plate off Fred at Trick Marine and never got it!!
I had to purchase a jack plate from down here and the only option l had was a 6inch Detwiler.. So l now have 12inches in total of set back. To tell the truth l did not notice a difference in trim heights nor speed or handling!!
I dont really beleive that set back has much of an impact, if any at all!!
On my boat anyway..
Cheers Dave G.

[HStream1]

Based on what your current set up is I'd say you need to go to 10" of set back but the motor needs to come up. I'll assume that you have a stock lower so raising the motor to much will cause loss of water and to much over the speed you're running right now increases the chance of BLOW OUT>. A bang for the buck would be a Bobs Nose Cone Kit. Then you can really raise that motor without the fear of water loss and Blow Out.

If you still need Bow lift after changes replace the power tec with a good chopper prop. They are great for Bow Lift.

While some may say 10" is to much some boats just require it. Example: I have a 20' Hydrostream Vulture. I could never get it to fly properly with 6" of set back. Finally got some information that Ron Pipcorn (the boat builder) published and he recommended AT LEAST 10" for the Vulture. I set it up with a 12" and raised the motor 4" running a Sportmaster and a 14.5 X 26 Mazco OS Cleaver and WALA!! boat started flying.

Remember the closer the motor is to the transom the more vaccum is created preventing the stern from breaking loose. To go fast a boat needs both Bow lift and stern lift. With that comes a significant change in stability and you'll need to learn to drive the boat differently.

GOOD LUCK!!

[TEXAS20225]

A 260 on a charger with a stock lower unit hmm must be a something else deal:eek: 260's came with a cle or sporty most of the time also a 23 pitch sounds like your out of prop before 260 goes to work i had a guy come to me with a charger with a 150xr6 on it it ran 65mph i put a 200 on it and it ran 73 mph with a stock lower on it sounds like you just need to put a 25 tempest on it and roll:thumbsup:

[150aintenuff]

contrary to popular belief, you DO NOT need a cone you need more setback, less height and more leverage. your lower is good to 80MPHish without blow out...

[TEXAS20225]

said any thing about needing a cone i just said those kind of motors come with them on it my Bullet /Pmax i bought brand new came with a torqmaster it ran 82 mph right out of the box with a 91/2 jack plate on it .im aware of cone no cone prospects as i build custom lower units all the time (Welded Not Glued) I just find 69mph with a 260 alot of somthing not set up right It sounds like to me he needs to get the transom out of the water so it can run not the bow i personally ran a 23 tempest which was a 15" prop for a couple of years i twisted it to7000 regular and it ran 79-80 but it had a vicious hole shot and bad to the bone mid range just out of prop on the other end im running a 26 trophy now which puts me mid 80's all the hocus pocus ive been thru the last 12 years lower unit changes engine mods of every description ive only gained 3 mph over a out of the box set up

ps i dont make any 100mph claims either , most folks who run them numbers know when you full of hot air any way

[150aintenuff]

hstream 1 did

[HStream1]

I never said he needed a Cone I just said it was a bang for the buck. If he starts lifting the motor he will need low water pick up. And at 80MPH Luck was on your side by not having blow out. Face it If Frogs had Wings. Therefore no two boats and set up's provide the same results. Prop slippage, Blow Outs etc happen differently on different boats.

I've seen blow out in the low 70's, It's all about finding that sweet spot for each individual Boat.

[150aintenuff]

ive ran 86 with a stock case.... its all about setup, and the hull... 9 times out of 10 a cone will slow down a hull..... because most people dont run high enough to utilize it

[HStream1]

150:

I think we are saying the same thing just in a different way. Read both our reply's to this thread.

Maybe it's because you're from the left coast and I'm from the right coast.:cheers:

Have a great Forth and don't blow yourself up. http://s3.amazonaws.com/advrider/kboom.gif

[WillySteve]

OK guys, It's my mistake for not giving all the info.! The engine, of which I am the original owner is:
'95 Hi Perf. 2.5 EFI, with a 1.86 ratio CLE gearcase and approx. 40 total hours running time. (I had this engine on a 19' Contender, not made anymore Tunnel hull which would run an honest 112 with an old Merc. 26" chopper!)
Back around 2000 when I originaly bought this Charger, I tried around 15 different props with my current setup and settled on this PT prop for decient all around performance. With the current setup there was little difference between them.
I'll agree with Texas on that this boat needs stern lift, however if you've not seen a Charger hull it's hard to imagine just how deep the keel drops below the pad. I'm guessing it's about 10'' lower? To me this all adds up to having alot of bow lift in order to get the keel out of the water and on the pad where the stern will lift?
Also Charger claims to have a "built in" setback of 6" and I am running a 7" jackplate bolted between the eng. & transom. Again, when I lower the engine from my current setting I notice more bow lift but speed & rpms are down I presume from gearcase drag.
I also have an old Laser 21" which I use for pulling skiers. This prop is a total Bear out of the hole and midrange, but has very little lift and will only top end about 65 @ 6900rpm with current setback and height! At this point I'm thinking of removing my jackplate, and then trying a 12" plate to go from 1 extreme to the other looking for the answer. I also know there are probably better props, however that will be the icing on the cake whenever I find what this hull needs for setback.

[HStream1]

Thanks for "The Rest Of the Story". You definately need more set back. IN MY OPENION ONLY. And a different prop wouldn't hurt for stern lift.

[HStream1]

Oh you mentioned the other things that prevented you from working on the Boat. I.E. Divorce etc. Not knowing where or how the boat was stored. Check for water Log. Just another thought.

[150aintenuff]

setback setback setback....


heres the rule I have found to work well.....especially on heavier hulls

1" for EVERY foot of boat and engine length for setback total from front of gear case to back of pad.... +1" for every 100 lbs over 1500 lbs of bare hull weight..


so a 20' boat that weighs 1600 lbs would require 21" total setback.... so if you have 6 built in and 2" at the engine bracket you would need atleast 12" of jack plate length to get close... then the next rule i use that works prety good is 1" up for every 6" back and +1inch for every 10 mph over 50 MPH.... so say 75 mph speeds.... 21/6=3.5+2.5=6" (or 2" below propshaft centerline height)

[specboatops]

setback setback setback....


heres the rule I have found to work well.....especially on heavier hulls

1" for EVERY foot of boat and engine length for setback total from front of gear case to back of pad.... +1" for every 100 lbs over 1500 lbs of bare hull weight..


so a 20' boat that weighs 1600 lbs would require 21" total setback.... so if you have 6 built in and 2" at the engine bracket you would need atleast 12" of jack plate length to get close... then the next rule i use that works prety good is 1" up for every 6" back and +1inch for every 10 mph over 50 MPH.... so say 75 mph speeds.... 21/6=3.5+2.5=6" (or 2" below propshaft centerline height)


Not always true, I have a 20 Ft. Gambler SuperSport, running a steel sleeved 2.5 weighing a heavy 2200 lbs. I added set back and LOST performance ( went from 6 to 12 inches)
maybe just me????

[skydog]

Not always true, I have a 20 Ft. Gambler SuperSport, running a steel sleeved 2.5 weighing a heavy 2200 lbs. I added set back and LOST performance ( went from 6 to 12 inches)
maybe just me????

Yea that is nuts!! I would never think that, but you seen it for your self!

Skydog

[HStream1]

Skydog, how much set back, lift and prop are you running on your Vulture? I'd like to compare notes. My Vulture is what my Family Likes. God forbid I ever get them in the Liberator.

I'm at 12" set back with 4" Lift running a 14.5 X 26 Mazco Cleaver. I'm at 92 GPS by my self.

[skydog]

Boy i was right on with your numbers! 12" setback not sure on hight but your MPH is much better than mine was. But that was years and years ago! :) :) I sold her... The Vulture likes as much set back as the transom can handle!! :) :)

Skydog

[HStream1]

Skydog

I'm glad some of us are on the same page!!!!

[d311_5uxor]

setback setback setback....


heres the rule I have found to work well.....especially on heavier hulls

1" for EVERY foot of boat and engine length for setback total from front of gear case to back of pad.... +1" for every 100 lbs over 1500 lbs of bare hull weight..


so a 20' boat that weighs 1600 lbs would require 21" total setback.... so if you have 6 built in and 2" at the engine bracket you would need atleast 12" of jack plate length to get close... then the next rule i use that works prety good is 1" up for every 6" back and +1inch for every 10 mph over 50 MPH.... so say 75 mph speeds.... 21/6=3.5+2.5=6" (or 2" below propshaft centerline height)


i am not driving one of these super speed boats that you all have, however i was wondering if this calculation will work on my bass boat?
1985 Challenger 15.5' 70hp Johnson 13-1/4x17 3blade, unsure of total boat weight
i can attempt to dig up more specs and post pictures if it will help any?
thanks in advance :thumbsup:

...
ok i found dry weights on NADA.com unloaded boat is about 800lbs motor is about 248lbs + gasoline which weighs ~6.15 pounds per gallon (18 gallon tank) ~110.7, myself with gear ~170
so boat =~1328.7

[stiletto200]

with the above equation this is what i come up with
16 ft boat
2000 lbss
65 mph
15 " setback
3" lift
does this seem right???

[gmjim]

Wow, is that what your stiletto weighs? Fully rigged i guess!!
I'm not sure that your transom will withstand 15 inches of setback!!!
Does the stiletto have a pad or just a vee??

[stiletto200]

i'm thinkin pretty close to that,
yeh fully rigged.
i dont think the lil' transom would take all that stress
with 15" of set back
how the hell am i gonna strengthen it enuff?
unfortunately no pad just vee shoulda put 1 in when i re-did
the floor i guess

[skydog]

Wow your boat has to be wet!

Skydog

[stiletto200]

thoughts appreciated,but im pretty sure its not.mo0re likely im wrong on the weight as i have never weighed it.
saying that tho i have a 94 2.5 200 on it and havent hit 70mph in it yet am thinkin theres alot of set up issues with it....?

[d311_5uxor]

is this considered a built in setback?

[gmjim]

That is what i have always thought was built in set back!!

Stiletto200, i reckon your a bit out with your guess on weight is all, fully rigged on the water with fuel @ me in it my dancraft weighs around 1250 to 1300 lbs. I did the weighbridge thing to find it out. Your rig is gunna fly when you get it sorted.

[stiletto200]

i'll find a weigh bridge round here somewhere one day then i'll be more acurate
i've been tinkering and tweaking all sorts of things in my stiletto thought it wouldve flown by now im starting to think its just one of those hulls that only go so fast.
whats the best set up performance mod you would suggest?
what you rekn bout the whole set back thing?? ive heard and read so many different things..

[150aintenuff]

i'm thinkin pretty close to that,
yeh fully rigged.
i dont think the lil' transom would take all that stress
with 15" of set back
how the hell am i gonna strengthen it enuff?
unfortunately no pad just vee shoulda put 1 in when i re-did
the floor i guess

the 15" is TOTAL setback, not the ammount of jack plate, measure at your normal ruinning angle and trim. on the transom that yeilds about 5" from gearcase to hull, the equasion I wrote works well IF you measure the distance from the hull to the front edge of the gearcase... it may only take 6" of jack plate to get you to 15" total setback.... also this is just a general equasion that works well for me, not all hulls will work but most do most of the time... also its only a baseline..

[150aintenuff]

i am not driving one of these super speed boats that you all have, however i was wondering if this calculation will work on my bass boat?
1985 Challenger 15.5' 70hp Johnson 13-1/4x17 3blade, unsure of total boat weight
i can attempt to dig up more specs and post pictures if it will help any?
thanks in advance :thumbsup:

...
ok i found dry weights on NADA.com unloaded boat is about 800lbs motor is about 248lbs + gasoline which weighs ~6.15 pounds per gallon (18 gallon tank) ~110.7, myself with gear ~170
so boat =~1328.7


the setback changes as does the height on hulls that run under 50 MPH due to water compression and rise rates..

but I would apply this general rule of thumb on a smaller hull..

basically cut the ##'s in half... 1" for every 2' of hull, up 1/2" for every 6" of total setback... a slower hull doesnt utilize the lifting pressures of water as well and needs prop leverage.. you will probably end up with a 6" plate and up about 1"

[150aintenuff]

is this considered a built in setback?

yes it is.... you would begin your measurements from the bottom of ypour pad near the drain plug...

[Pro300x24LD]

hmmmm 24' boat, just a hair over 2,000 pounds, running just a click over 80, looks like i need another 10" of setback according to that equation.

While as a general rule I think you are "kinda" on the right track, there are many many more variables that come into play.

As to the original poster, I think you do need some more setback and to play with some different props.

[150aintenuff]

whats your gearcase to hull measurement at full speed trimmed... i bet its close to that... because dont you have a 12-18" setback bracketry on your hull....

27" gearcase to hull measurement, give me your measurement and i bet its close...

[Pro300x24LD]

Looking at it that way you may have a point. I always think of it as to where the motor is bolted to the boat.

16.5" set back from transom to motor for me. Propshaft even with the pad, minimum trim, but could easily add 6-8" of difference down at the gear case.

[150aintenuff]

I measure setback differently then :) its the total distance from case to hull, thats how that equasion works... neutral trim with a stock profile case (tqmaster or std) is about 4-6" depending on what mounting bracket you have.. trim that distance goes up fast...

[d311_5uxor]

ok measuring from the built in setback to the leading edge of the gearbox = 10 1/2" does this mean i should have only 5 more inches? or do i use your rule for slower boats and divide the numbers in half, resulting in -2.75 from the factory location?

[150aintenuff]

you can go back either one... but I feel a bobs 2 7/8" jack will be about right versus a 5" but either will work if you have a lot of nose weight the 5 will do better I have a 5.5" CMC manual on special right now, something to think about

[WillySteve]

OK guys, It's my mistake for not giving all the info.! The engine, of which I am the original owner is:
'95 Hi Perf. 2.5 EFI, with a 1.86 ratio CLE gearcase and approx. 40 total hours running time. (I had this engine on a 19' Contender, not made anymore Tunnel hull which would run an honest 112 with an old Merc. 26" chopper!)
Back around 2000 when I originaly bought this Charger, I tried around 15 different props with my current setup and settled on this PT prop for decient all around performance. With the current setup there was little difference between them.
I'll agree with Texas on that this boat needs stern lift, however if you've not seen a Charger hull it's hard to imagine just how deep the keel drops below the pad area. I'm guessing it's about 10'' lower, with alot of deadrise? To me this all adds up to having alot of bow lift in order to get the keel out of the water and on the pad where the stern will lift?
Also Charger claims to have a "built in" setback of 6" and I am running a 7" jackplate bolted between the eng. & transom. Again, when I lower the engine from my current setting I notice more bow lift but speed & rpms are down I presume from gearcase drag.
I also have an old Laser 21" which I use for pulling skiers. This prop is a total Bear out of the hole and midrange, but has very little lift and will only top end about 65 @ 6900rpm with current setback and height! At this point I'm thinking of removing my jackplate, and then trying a 12" plate to go from 1 extreme to the other looking for the answer. I also know there are probably better props, however that will be the icing on the cake whenever I find what this hull needs for setback.

:rolleyes:Since my 1st email I have purchased & tried 2 props.
At a prop shaft height of 1" below the bottom of boat, & 18" setback on my heavy 20' Charger Bass Boat:

*The 1st one a Temp + in 21", PVS plugs removed.
At a prop shaft height of 1" below the bottom of boat, it seems to be close to being what this boat needs. This prop has GREAT lift, (much, much better than the PT), Top speed is down a little from PT, hole shot is great, rpm has improved, (7000), and trim angle is great.

*2nd one is a 21" Rev-4, PVS plugs removed.
At same prop shaft height, it has similar characteristics on lift to Temp+;), Top speed similar to Temp+, Hole shot is miserable:(, rpm is approx 6600, and have to use too much trim angle to get the rpm's up. I haven't tried this prop at a higher engine height, and maybe this would overcome the bad holeshot and over trim? Actualy, the hole shot is only bad until the boat breaks over. Then it's a rocket. This just may be the prop for this boat if you could get the same holeshot as the Temp+.
Being this engine is rated for 7500 rpm, I'm wondering what to do from here? I know that in general, a larger pitch means a lower rpm. However, getting the boat on top, means less friction, more speed and more rpm. I was seeing a little more speed, even though the boat was deeper in the water, with the 23" PT. I was turning it 6500 which makes me think that's where the best engine power & torque is, reguardless of the mfg. suggested redline.
Gut Feelings at this point:
Play with engine height on Rev4.
Try a Temp+ in 23":thumbsup:

[kris_tx]

I think the boat would run better with non nosecone gearcase.

[astro@ptd.net]

Great thread guys. This is a question that plagues all of us. Sounds to me that 150aintenough is going about it logically and backed by experience and experimentation. May I ask for a bit of help with my bass rig without stepping on anyone else's requests?

[R.I.P.]

What is the weight of your boat? How is the pad set to your lower unit. Is their a step in your hull? How long is your pad Low water pick up is a must get if you are going to go over 80 . Money well spent..all above is true and you need to read up in the articals of tunnel boat tuneing and figure out the correct set back for your boat . Its hard and takes a long day for weeks to get that sweet spot. stay with one prop and play with hight and set back till you optimise the prop performance. read articals on home page HULL TECH>

[astro@ptd.net]

Thanks....'91 Astro 18FDX 18'8"...Merc 200 EFI, 1.87 gearcase (just plugged the top 4 holes on each side and have not tried it yet), Tempest Plus 25P, 5.5" CMC hydraulic plus 2.2 spacers for a total of 8" setback. Boat weighs in at 1640 plus my gear (a dozen rods or so, 6 plano boxes, spare prop, small tool box, 3 batteries and a few other incidentals) The measurement from the pad (where drain plug is) to transom is 12". Numbers by myself : air temp mid 80's, water high 70's, hole shot about 5-6 seconds, top speed 69.7 GPS at 5800-5900 RPM's. Trim is about half way. PSI at this point is around 15-18. If I were to trim up more the bow really starts to climb but the PSI drops so that is why I plugged the top holes in the lower. Astro's are not your typical hi-perf hi-speed hulls but I figure with this power I should get more. I have been told to get a bobs nosecone but i agree with others saying that it would slow me down since I am not in the 80's. Is the setback right for this setup? Thanks for listening.

[astro@ptd.net]

The spacers are 2.5 inches not 2.2...sorry, duh. typo

[astro@ptd.net]

150aintenuff....What do you think about these numbers? I mean with setback and all. Any advice for improvement?

[astro@ptd.net]

Hey R.I.P. Are you still there? I responded with my data but no feedback. I understand if you are busy, though. Thanks.
150aintenuff.....any input? I like your formula for setback. Am I in the ballpark....or should I do something different?
Thanks

[R.I.P.]

First get rid of all the bs three batteries . use 1 .tool box ? use a plastic bag with plug wrench and extra wires two plugs electric tap bring only the min. have an ore. I believe you have to much setback take out the 2.5 spacer and go with a cleaver 26p you'll get more possitive trim and less bow lift giving you more rpm and with a larger pitch =more speed. lower bow = better ride a cleaver will give you more stern lift ,also lowering the bow and giving more balance. If you have too much stern lift then add the 2.5 but, I think you should be fine + go for the low water pick up . I work shift dude sorry.

[astro@ptd.net]

Thanks for the info. I'll look into taking off the spacers. BUT, my fishing buddy is gonna think I lost it when I show up with an oar in his seat and tell him that I removed the 2 trolling motor batteries.

[R.I.P.]

Didnt say you had troll motor .this is a speedboat web , fishing is down the block.
maybe you need two batteries then.

[astro@ptd.net]

OK...sorry, didn't know this was only speed boats. The original poster was asking about his bass boat setup so I thought it was all right. I have seen other discussions here on bass boats. Where then do you suggest I seek help on these issues.

[shawnjetton]

this site has bass boats and all kind of boats. u dont have to go down the block.

[Pro300x24LD]

OK...sorry, didn't know this was only speed boats. The original poster was asking about his bass boat setup so I thought it was all right. I have seen other discussions here on bass boats. Where then do you suggest I seek help on these issues.
Stay right here, you have added weight in your boat, just means you won't realize the true potential gains that a lighter boat would. As long as you realize that you will be fine.

Have you played with moving the weight into different places in the boat to see how it reacts?

[astro@ptd.net]

Thanks...appreciate it guys. I know that my Astro is not a performance lightweight hull. I will take a serious look at the inventory in my boat and get rid of dead weight. I will be ultimately happy with my setup once I have eliminated any doubts in setup and dialed in as best as possible with what I've got. Initially, my first question which brought me to this post was the setback question. And that is the equation that 150ainenuff stated as a good starting point for knowing how much set back to use. Looking back up at my post with my numbers that I indicated, am I at the correct setback with the jackplate and 2.5 inches of spacers or go by what R.I.P. suggested (which I am not doubting)? Thanks for all your help!!

[astro@ptd.net]

Oh, I should probably mention that before I blocked off the top 4 holes on my lower I was at 3" propshaft below the pad. I am waiting for a new propshaft before I test again cuz mine was slightly bent when I bought this 1.87 lower. My mechanic just discovered it.

[wrechin2]

Hell, Don't guess some people has heard of Bullets or Gamblers. You know those SLOW NON PERFORMANCE fishing boats......or that alot of people here have alot of experience with fishing boats.
I had a 6" Jackplate (5" built in)on a 17' Glasstream Fish and ski. 150 2.0L 26 chopper. Could not lift the bow GPS at a whopping 55mph, I went to 8" then went to 61 gps, then 10" and went to 68 mph gps. Was so smoth my 12 year old could drive it on the pad. I went to 12" and could not drive it, would never settle down. No it wasn't fast but for a ski boat with a 150 68mph was pretty impressive to me. Point is... I gained 13 mph by adding 4" of set back and boat drove like a dream.
Just my 2 cents worth.

[astro@ptd.net]

Now that's awesome. I went to the lake tonight after work and with an extra 1 1/2" of height as a result of blocking off the top 4 holes on each side of the lower gave me 200 more RPM's and from 69.7 to 71.2 GPS. The hull lifted more with more positive trim and the PSI didn't seem to change much. Stayed around 15PSI.

[astro@ptd.net]

Glasstreams are very light fast boats if I remember correctly. Years ago one of the guys in the club I belonged to had a 17ft with a 115 Merc and he could blow away some of the guys with large HP motors running Rangers. It all boils down to experimenting with different setups and having to shell out the bucks to buy the mods to get there. That's what is so good about this site is everyone willing to fess up with what works and don't work.

[wrechin2]

This was the ski boat version. You set very far up front and it has to lift me and the boat. Same engine/ set up on a straight bass boat would have probably pick up a couple more on top end. Have one (17' bass only) now I am having to put back together. Guy stripped it to paint it then sold it to another guy who has no clue how it goes together. I'm making all new wiring harness, and putting all new gauges switches ect. If my engine wasn't in pieces I would try it!!! Got too much other stuff to do though. Hope you find the right combo!!! Good luck!

[astro@ptd.net]

No doubt about it!! That can be a fun project when ya have the knowledge, materials and time to do it. Good luck with it and can't wait to see it posted here. I think my rig is finally where it needs to be. Thanks for the input!

[Pro300x24LD]

Now that's awesome. I went to the lake tonight after work and with an extra 1 1/2" of height as a result of blocking off the top 4 holes on each side of the lower gave me 200 more RPM's and from 69.7 to 71.2 GPS. The hull lifted more with more positive trim and the PSI didn't seem to change much. Stayed around 15PSI.Now your making some progress :thumbsup:

[astro@ptd.net]

thanks up roktoy! Appreciate your help and input. It's like learning to drive this boat all over again. I'm sure I'll get a bit more when I am more comfortable with the different handling characteristis form what I had been used to.