Ventilation Problems

[swmohunter]

I would first like to say that I have recently joined this forum and have found it extremely helpful. I have done a search on ventilation and have not come across what I am looking for. Sorry in advance for any ignorant questions.

I am fairly new to boating and have recently rigged up my boat. I have a Lowe Roughneck 1655 and have got a short shaft 25hp 1971 Evenrude on it at the moment.

The cavitation plate sets about 2 maybe 3 inches above the bottom of the boat. I am having trouble getting the throttle past half way before it starts to ventilate. I think it is ventilating? When I get past half throttle or so the prop acts as if it is not catching enough water. The rpm's also go up.

I am wanting to get this motor through the rest of duck season so here are a few questions. I am guessing that I need to lower the motor. If I get a mini jack plate, will I be able to turn it upside down (lowering the mounting point) and be alright. If I am able to do so, will I lose my ability to turn the motor due to the arm hitting the transom (if that makes sense).

If there are any suggestions I am all ears. I am trying to get away as cheap as I can to get me through the next month or so.

Nathan

 

[Specknreds]

Welcome to Tinboats!!

A jackplate will allow you too run your motor higher than the bottom of your boat. I have found that for every inch of setback the plate has, you can raise the motor a 1/4" to maybe a 1/2". If the minijacker sets you back 3", you could possibly get away with 3/4" - 1 1/2" above the bottom. You may not need to flip the plate. The further back your motor is from the transom, the cleaner the water is making your motor more efficient.

 

[Rat]

Definitely sounds like it is ventilating. Speck may be on to something as well. If you buy a jackplate with enough setback you may not need to flip it over and try to lower it; it may be far enough back that 2" high will work. You can also try running a different prop, not sure what's available for a '71 tho, but there are props made for ventilating/surface piercing. Also, you could buy a longshaft lower unit for the motor, this is what I would do.