need knowledge

[biggernbetter]

I have a 1999 tohatsu 30 on a j16 carolina skiff. At top speed the rpms jump up like its out of the water or out of gear. If I take it out of gear and start again it's fine until I'm at high rpms. I already had a new liner pressed in the prop. What's next?

 

[Bozo]

Re: need knowledge

Sounds as if it could be a cavatation issue to me. Are you sure that you are getting proper water height on your lower unit during high speed operation?

 

[Hooty]

Re: need knowledge

I think Bozo's right, the prop is ventilating. Where's the cavitation plate in regard to the bottom (keel) of the boat?<br /><br />c/6<br /><br />Hooty

 

[biggernbetter]

Re: need knowledge

center of prop is 6 inches beneath the bottom of the hull. small prop.

 

[biggernbetter]

Re: need knowledge

there's a set of dolphins on it and they're even with the bottom of the hull. Engine can't be lowered. clamp on. maybe trimmed down with manual locking pin???

 

[Bozo]

Re: need knowledge

Unless it is a tunnel hull, then the cavatation plate should be level with the bottom of the hull.<br /><br />The cavatation plate is what you have your dolphin attached to.

 

[rickdb1boat]

Re: need knowledge

Might try triming the motor IN one hole and see if that helps, if you have not already done so. Maybe you could have someone drive the boat while you take a look at it over the stern and see what's going on.