hole shot problem

[mtblackdog]

I am having a problem with my boat on take off. If I go to full throttle, the boat bogs down, throws the nose way in the air and then does what I call over revs or maybe cavitates. If I throttle up slow at first and then hammer it it pops out just fine. It is a 91,90horse Johnson on a 16 foot lund tyee II. 13 1/4 X17 prop, with a hydrofoil, with the motor mounted on the deepest setting. Any help would be great.<br />Jamie

 

[OBJ]

Re: hole shot problem

I ain't the resident guru on engine set up Jamie....Dehadly is...but just a question, you posted the engine is mounted on the deepest setting....does that mean it's as low as it can be mounted? Where is the anti-cavitation plate in respect to the keel of the boat?

 

[mtblackdog]

Re: hole shot problem

It is as deep as it will go. Walleyehead also recommended that I raise the engine at least one hole to optimize the WOT as well could this be my hole shot problem as well?

 

[OBJ]

Re: hole shot problem

Yep....got to much engine in the water. That's why your nose is going vertical until the revs pick up and you gain some forward momentum. Triming out as you come up will help also.<br /><br />You can even play with the engine height to see what is best. But do get it up at least a hole and go from there. I think you will be very surprised what one hole up will do.

 

[mtblackdog]

Re: hole shot problem

Thanks OBJ any good ideas on lifting that motor. maybe blocking under the motor and then jacking the trailer? Also do you think one hole is enough

 

[floatingwoody2006]

Re: hole shot problem

you should feel lucky.. Mine only has one hole...

 

[Dhadley]

Re: hole shot problem

A silly question so forgive me but when you go to take off is the motor trimmed all the way in? Is the thrust rod in the hole closest to the boat? If it's gone that's OK too.

 

[mtblackdog]

Re: hole shot problem

The trust rod is in the number one position or closest to the boat.

 

[mtblackdog]

Re: hole shot problem

ttt

 

[Dhadley]

Re: hole shot problem

OK the rod is where it should be. Do you start with the trim all the way in or partially out?

 

[mtblackdog]

Re: hole shot problem

I have tried both, she really is bogging when it is all the way in.

 

[Dhadley]

Re: hole shot problem

If it's trimmed all the way in, it bogs. If you start with it trimmed out, the nose comes way up and it blows out. Lets look at one issue at a time. <br /><br />We're going to end up right where Walleyehed had you going before. With the motor mounted all the way down the fin is probably working aginst you on acceleration. I'd also bet that Walleyehed was trying to get you to raise the motor to improve top rpm as well as holeshot.<br /><br />What's the top rpm and have you tried raising the motor?

 

[mtblackdog]

Re: hole shot problem

rpm are only 4800 so I do need to raise the motor, according to walleyehead they need to be at least 5300, do you think one hole is enough or should I go for it and take it up two.

 

[Dhadley]

Re: hole shot problem

Are you using an aluminum prop or stainless? What brand?

 

[mtblackdog]

Re: hole shot problem

Original stock Aluminum but planning on stainless. Bought this boat in the fall, it has less than 20 hours on it. Walleyehead suggested raising motor first, then possible a jet change and to me last resort would be to go to a 15 pitch prop.

 

[ob]

Re: hole shot problem

Where is the anti-ventilation plate in relation to the bottom of the transom when trimmed down?

 

[mtblackdog]

Re: hole shot problem

Even or slightly below.

 

[mtblackdog]

Re: hole shot problem

Alright I raised the motor up an inch and a half two holes (3/4" per hole). The AV plate is now 1 1/2" above the boat. Dang near killed myself doing it one of those 1/2 hour jobs that turned into two and half, but a little patience and persistance got er done. So I guess I will go test now and see what happens. Still looks like a lot of motor left in the water.

 

[ob]

Re: hole shot problem

Just be sure you have the engine trimmed in when coming up on plane and then trim out.This will keep the bow down and prop from ventilating.

 

[raybujt]

Re: hole shot problem

Have you checked the rubber coupling in the prop hub?