set up question

[x120leecraft]

Have a prather 32" racing tunnel witha modified rossi 7.5. Started off with 225 prather prop but when pipe kicked in took off like a airplane. Motor is 1/4" below sponson. Put a 220 prather on and it went better but when it really kicked in went airborne. Is the motor to big for the boat or does anybody have any ideas. Different prop or prop height etc. Thanks Dave in CT.

 

[Jerry Dunlap]

32" seems a bit small for mod 7.5. You might try tucking the prop thrust under the boat a tad to see if that helps.

JD

 

[socco72]

I had one of these boats remember jerry and it had a 7.5 pro on it try adding weight to the nose i had 4 oz on each front sponson and it was fast but if there is any wind or chop this boat took off like a plane.goodluck.DW

 

[topfuel443]

Dave, the Prathers are just known for blowing off with any power on the back... Just the way it is, not much you can do to fix it.

~James

 

[dizzy dean]

if i can keep a lapcat 1 with mac/lawless on the water, then you can to. it took a lot of trial and error. like jerry said tilt motor down. my frustration level was high but when you hit the sweet spot it's all worth it. bad thing is i have to do the same with my 32 racing tunnel. just dont give up!

tim

 

[mikeferretti]

if i can keep a lapcat 1 with mac/lawless on the water, then you can to. it took a lot of trial and error. like jerry said tilt motor down. my frustration level was high but when you hit the sweet spot it's all worth it. bad thing is i have to do the same with my 32 racing tunnel. just dont give up!

tim

Mr X. In My humble opinion you may end up with a set up like this: Very little if any "tuck under" angle on the motor. several ounces of lead the nose. Possibly adding main weight at the Center of Gravity. In General your motor is pushing the boat to speeds it was never deigned to run at................... Best of luck getting around this fact. How ever if Dizzy can do it, I do agree that it might be possble. If you are running very much "Tuck" you may also be seeing a Very Ugly "Hop" as it goes down the straights.......... If so, I recommend slowy removing the tuck angle, a little bit at a time, and replacing it with lead on the tips of the sponsons. I've been running outboard tunnels for 20 years, and am just now starting figure these things out........... I agree that this will take a LOT of trial and error.......... Best of luck.

M.F.

 

[john v]

this was my first boat, a 32"lap cat with a 7.5 k&b semi pro. tried everything and nothing really ever worked , as soon as it started to get close to 50mph something wild happened, all kinds of different props, extra wide cavitation plates, lead up front, different turn fins. what i came up with as a problem was the boat had too much motor, removed the pro motor and put it on my leecraft and put a vintage amps outboard on that lap cat and it runs great at approx 35mph

 

[SayMikey]

if i can keep a lapcat 1 with mac/lawless on the water, then you can to. it took a lot of trial and error. like jerry said tilt motor down. my frustration level was high but when you hit the sweet spot it's all worth it. bad thing is i have to do the same with my 32 racing tunnel. just dont give up!

tim

Mr X. In My humble opinion you may end up with a set up like this: Very little if any "tuck under" angle on the motor. several ounces of lead the nose. Possibly adding main weight at the Center of Gravity. In General your motor is pushing the boat to speeds it was never deigned to run at................... Best of luck getting around this fact. How ever if Dizzy can do it, I do agree that it might be possble. If you are running very much "Tuck" you may also be seeing a Very Ugly "Hop" as it goes down the straights.......... If so, I recommend slowy removing the tuck angle, a little bit at a time, and replacing it with lead on the tips of the sponsons. I've been running outboard tunnels for 20 years, and am just now starting figure these things out........... I agree that this will take a LOT of trial and error.......... Best of luck.

M.F.

BINGO More weight spread out farther from the sponson tip should help. Too much on the tips and it goes from level to Sub Surface. ID try nearly level trim and WEIGHT. By doing this you help those unwanted antics in corners and slowing down