Grandsport hooked hard right slowing down with 3.0!!

[xb03fs]

I know what I had screwed onto the propshaft and I know what it did with the 2.5. I was at 9.5" with the 2.5, not alot of distance regarding setback. I also realize it's not a Viper or anything else. Just because 99% of people does basically the same thing, means little to me. Are Allison's quirkier than a lot of other boats because of the lip? I'd agree. I made a driver error not letting the speed come down slow enough, it wasn't because of the prop height. Would it have looped around with it a bit deeper under the same situation... Maybe, maybe not. We will agree to disagree

My two cents but from my experience, little changes can make a difference in Allisons..

For example on my xb2003. Going from 12.5" setback to 13.5" setback allowed me to run 3/8" higher propshaft height.

Moving about 35-40 lbs to the passenger side allows approx. 1/8" more motor height

More motor height generally lifts with less trim until you get near the max, then the boat doesn't want to lift till your moving pretty good

4 blade props are like adding 4WD to the setup, turn like a slot car as well

Personally I have better luck slowing down by just a couple small bumps down to settle the hull, then getting out of the throttle and then trimming down once I get below 60... The long keel needs to stay up outta the water to stay out of trouble. Ie too little trim in a corner is no bueno

To cross wakes slow down well in advance, accelerate over them, the lip keeps the nose planted. Letting off the gas as you cross and you will see blue sky


The lip lifts the ass of the boat, even on an Allison is equivaelent to a much higher propshaft height on other hulls.

[200valeroyt]

True. I haven't looked at the Allison transom angle, but 1" of setback is usually around 1/4" in prop height. One thing that i haven't even mentioned prior, is that i have run this prop 1" over the pad when i had the 2.5 on it. It felt loose in the asx and i obviously didn't keep it there. I didn't want to freak all the Allison gurus out. The point is, the prop holds and i knew that before i even owned an Allison.

[Brian Harden]

I'm not sure if you are looking for help or just want everyone to agree with you but here are a few facts :
1. The setup of a Checkmate compared to an Allison cannot be compared at all.
2. Just because a prop does not blow out on a Checkmate at 2" over the pad does not mean it will not blow out on an Allison at 1/4" over.
3. The setup of the same Allison with 2 different engines/ lower units but the same prop will not necessarily run at the same height.
4. If you were running the 2.5 Promax 1/2" or more above the pad on the GS the only reason it didn't pitch you out is you didn't give it enough time.

You can obviously do what you want with your boat but a 3.0L setup on a GS to run max speed is tricky and you might want to listen to the people here who have some experience on these boats.

Oh, and yes I have ran several Allison's with a non ratcheting case.

[200valeroyt]

I wasn't looking for help or to have anyone agree with me. I originally posted to let anyone know of the experience I had, so someone else may not potentially suffer the same ordeal. Yes, i agree the differences in two different boats, one setup doesn't mean the same for another. I should have known this would have turned into a "what you should not have done and what you should have done thread, because this is how everything is". I never said that I don't agree with a lot on the information provided and yes, i realize they're tricky boats. One thing that I do know, nothing is written in stone regarding any boat, many different factors involved.

[Mrzip]

the guy from Ashville that posted on this thread.. had good advice.. that's what i would do...

[Mr. Demeanor]

I say wrap yourself in bubble wrap and let her eat.....but thats just me.

[200valeroyt]

I say wrap yourself in bubble wrap and let her eat.....but thats just me.

Ha... Good one

[jasonpijanowski]

I say put the pro max back on and be safe and I would lower it also...

[Boomer 880]

I wanted to thank the OP for posting his experience on what happened. I plan to buy a GS in the next year, and have read all the good/bad associated with the boat and what works for different people. In the end, we can all learn from each other to make our experience not so 'exciting', when we do not want it. Going 100 MPH in a small boat has a lot of inherent risk, and one can always second-guess the outcome of a bad experience. Thankfully, no one was seriously injured and we have a great platform to learn and discuss. I have learned a lot from S&F and other sites, which gives me good hip-pocket information. However, in the end I will hope to take what I learned on-line and successfully move this into the seat of a GS. I have had several larger offshore boats and been boating all my life, but there is such a difference in a boat, based on set-up, running conditions and seat time. I for one, will take it easy and go with a conservative set-up until I have a lot of seat time.

[myron]

You say you ran that high with the 2.5, but with what case, also from my experience no 2 sportmasters are the same, and the sportmaster has a lot of stern lift built into it.

[whipper]

Glad you just hurt your shoulder as odd as that sounds but it always could have been worse. I think the best advice hear is just set it up to run even to 1/4 below. The fastest 3.0lt GS I know of never ran above even. 1/4 and 1/8 below he ran 110. Theres so much more torque created buy the 3lt motor over a 2.5 you shouldn't need it higher to make speed. The GS hull has tremendous lift more so than most any vee hull. Thats why even with a 225 2.5 they can do 100. I know on mine ive tryed many different prop shaft heights and props up to 1 1/4 above. Coming off the pad above the pad has never felt right even with a ratcheting gear set and a light motor. i always felt i needed that prop in the water for more control. Ive hooked mine many times experimenting with gearcase shapes, different props,lip vs no lip,weight distribution, even made mine a center steer several years ago for kicks and giggles. This was actually the best thing ever!! Bottom line is I will never set up to run above the pad again on my GS. It actually slows you down buy requiring the angle of trim to be to high. Then when ya come off the pad the motors trimmed higher to get thrust but the vee settles first before the bow. The spray from this deflects away from the prop and if your prop is no were to be seen because most of it is behind the transom when you settle enough for it to bite its bad.:] Thats what Ive found with mine. The higher I went the worse it was coming of speed. Felt good getting up to speed because the tips rotated easier out of the water. But mine needs to feel planted not just going one way. The ratcheting gear case only ratchets when your right off the gas also . Coming of of speed with a big wheel is the same as non ratcheting if you have your foot still down a little. i hope you never hook again and I hope I never hook again. its been years since i have knock on wood. A few times gaining speed over trimmed and more times coming off. So it doesnt matter what engine you have on it happens as you said and others. The main concern Darris has with 3.0lt motors is because they are heavier up top than a 2.5 your chances of barrel rolling not just hooking are greater. A hook leads to a roll. Ive almost barrel rolled mine with a 2.5!! Thought for sure it was going over!! i had my motor to high when I hooked and it grabbed and did an about face in the AIR sidways!! 30 pitch prop broke at 93mph!! Ive always felt the key to a 3.0lt is to match the center of gravity as the 2.5.A 15 inch mid and a ratcheting gear case would sure help!! Also battery in the front and weight down low under the floor.

Hooking isnt the problem with a GS. They hook from driver error or mechanical as we know they will with any motor. Its the center of gravity shift while hooking being top heavy thats the problem. If you plan on running the XB i would be looking at ways to off set the weight difference up top buy compensating down low. See most people aren't into doing this sort of thing they just want to hop in and go boat. Darris realizes this hence the warning. If you drive near the edge the greater the risk on and off the throttle. All 20ft Allisons are designed around the 2.5 for peek efficiency and performance. Going outside these design parameters requires you to do what you can to make it work as best you can. No different than stuffing a 454 in a Camaro that had a 350 in it. Your going to have to do some mods in the body and suspension to make it handle as good or as close to good as you can.

[200valeroyt]

You say you ran that high with the 2.5, but with what case, also from my experience no 2 sportmasters are the same, and the sportmaster has a lot of stern lift built into it.

Stock SportMaster, full skeg on both.

[myron]

I could be wrong but I believe the 2.5 case and the 3.0 case have a different profile

[Hot Shot Merc]

Ok Im officialy done reading this thread and its same thing over and over and over and over and over and over and over again.......................... You should just sell the damn thing sinse you cant seem to accept what people who have run this same boat for years are saying. I understand your frustration but god dang dude stop arguing with people who know what they are talking about already!!!!!!!!!!!!!

[200valeroyt]

Glad you just hurt your shoulder as odd as that sounds but it always could have been worse. I think the best advice hear is just set it up to run even to 1/4 below. The fastest 3.0lt GS I know of never ran above even. 1/4 and 1/8 below he ran 110. Theres so much more torque created buy the 3lt motor over a 2.5 you shouldn't need to to make speed. The GS hull has tremendous lift more so than most any vee hull. Thats why even with a 225 2.5 they can do 100. I know on mine ive tryed many different prop shaft heights and props up to 1 1/4 above. Coming off the pad above the pad has never felt right even with a ratcheting gear set and a light motor. i always felt i needed that prop in the water for more control. Ive hooked mine many times experimenting with gearcase shapes, different props,lip vs no lip,weight distribution, even made mine a center steer several years ago for kicks and giggles. This was actually the best thing ever!! Bottom line is I will never set up to run above the pad again on my GS. It actually slows you down buy requiring the angle of trim to be to high. Then when ya come off the pad the motors trimmed higher to get thrust but the vee settles first before the bow. The spray from this deflects away from the prop and if your prop is no were to be seen because most of it is behind the transom when you settle enough for it to bite its bad.:] Thats what Ive found with mine. The higher I went the worse it was coming of speed. Felt good getting up to speed because the tips rotated easier out of the water. But mine needs to feel planted not just going one way. The ratcheting gear case only ratchets when your right off the gas also . Coming of of speed with a big wheel is the same as non ratcheting if you have your foot still down a little. i hope you never hook again and I hope I never hook again. its been years since i have knock on wood. A few times gaining speed over trimmed and more times coming off. So it doesnt matter what engine you have on it happens as you said and others. The main concern Darris has with 3.0lt motors is because they are heavier up top than a 2.5 your chances of barrel rolling not just hooking are greater. A hook leads to a roll. Ive almost barrel rolled mine with a 2.5!! Thought for sure it was going over!! i had my motor to high when I hooked and it grabbed and did an about face in the AIR sidways!! 30 pitch prop broke at 93mph!! Ive always felt the key to a 3.0lt is to match the center of gravity as the 2.5.A 15 inch mid and a ratcheting gear case would sure help!! Also battery in the front and weight down low under the floor.

Hooking isnt the problem with a GS. They hook from driver error or mechanical as we know they will with any motor. Its the center of gravity shift while hooking being top heavy thats the problem. If you plan on running the XB i would be looking at ways to off set the weight difference up top buy compensating down low. See most people aren't into doing this sort of thing they just want to hop in and go boat. Darris realizes this hence the warning. If you drive near the edge the greater the risk on and off the throttle. All 20ft Allisons are designed around the 2.5 for peek efficiency and performance. Going outside these design parameters requires you to do what you can to make it work as best you can. No different than stuffing a 454 in a Camaro that had a 350 in it. Your going to have to do some mods in the body and suspension to make it handle as good or as close to good as you can.

To sum it up in my end, I agree with most everything you've said regarding height, coming off plane, etc..This particular prop isn't the only one I've run on the GS, the other 2 I've run would fall into everything you've stated very accurately. What I do know about this one, from, yes, a different boat, is that it stays hooked up. Just as it did with the 2.5 with more height and trim. Anyway, I'm pretty much done with this thread, I have nothing to prove and I don't expect others to follow, agree, or what have ya. But thanks, alot of good info in your reply. Sean