Ill Handeling 40" outboard Deep Vee

[Foolwitools]

Hi Guys,

Prather 40" outboard Vee with a K&B 7.5 Pro...........

Never had an outboard Vee before. got no idea how to trim it out

assembled as per prather instructions with Prather's outboard hardware...... CG where it should be............

will not turn above 1/2 throttle. doesn't hook or spin, just rolls onto it's side.

also rolls over easily at full power in a straight.

prop depth is just below keel as per instructions. got a little up angle in the motor.

The only thing I did outside the instructions was to put in a larger turn fin. the one supplied in the kit was soo small, it didn't seem that it would do anything.

Could the larger fin be the whole problem??

Thanks for your help and ideas,

Bob the Fool :blink:

 

[Jack Garcia]

Hi Guys,

Prather 40" outboard Vee with a K&B 7.5 Pro...........

Never had an outboard Vee before. got no idea how to trim it out

assembled as per prather instructions with Prather's outboard hardware...... CG where it should be............

will not turn above 1/2 throttle. doesn't hook or spin, just rolls onto it's side.

also rolls over easily at full power in a straight.

prop depth is just below keel as per instructions. got a little up angle in the motor.

The only thing I did outside the instructions was to put in a larger turn fin. the one supplied in the kit was soo small, it didn't seem that it would do anything.

Could the larger fin be the whole problem??

Thanks for your help and ideas,

Bob the Fool :blink:

[

Bob,

Never used the Prather Vee w/an OB ( I used the Pinckert Chapparel ) but maybe I can help a little. You are right, the Vee OBs like the turn fin to be long. We made them long enough to be even with the keel or slightly longer. This is where you'll get stability in the turns. Radius the bottom from front to back. If the engine is not already set there, position the top of the propshaft bullet on the lower unit even with the bottom of the boat keel.

Good luck

 

[P THOMAS]

:lol: Im not going to be much help Bob. I thought thats the way they are supose to run. :lol:

I had a small vee with a 20 OB It was a fun boat but a bit unstable, It liked to do barrel rolls as it went don the straight too..

 

[Mark Poole ModVP]

One thing that you can do to improve the handling of an OB vee is to lock the engine straight and install a seperate rudder. Swinging the prop back and forth way behind the transom makes a vee do funny things. Also, keep everything as low as you can get it in the hull including the main fuel tank, this will help with roll stability.

 

[chunk t]

Bob,

Guess this is an other reason for us to get together sometime.

The prather is a rellatively narrow mono to it's length, compared to a Wild Thing or Seaducer. That's going to reduce the stability in the turn. #1 thing to do - relative to the keel set the engine thrust angle to zero (0) changing the thrust angle will make the hull roll in the turn (a little goes a long way here). Turn fins should be at least equal to the length of the skeg, correctly aligned. If you don't have trim plates off the transome, I'd recommend them; they will help with high-speed handling.

Still got my number? call me or PM me.

chunk t

 

[NAMBA860]

EVERY DEEPVEE OUTBOARD I HAVE EVER RUN NEEDS TO BE SLOWED DOWN IN THE TURN LET IT TAKE A SET AND THEN POWER OUT OF THE TURN ALSO THE PROPSHAFT CENTERLINE SHOULD BE BELOW THE KEEL JUST A TAD.