Newbie. Dumbest question yet??

[rebuilt]

Been wrenching for years. The whole boat thing is a new one to me. I finally got a decent little starter boat. 15' fiberglass tri-hull (Mongoose). 35 hp Johnson. The boat is under motored, but it's a start. I live on the East Coast, and am looking for a long legged approach. I'm going to fish the sounds and bays around Morehead NC. Out to the Cape and back. I've looked around, done some reading, and I believe I want the most pitch I can get for the motor I have. Hole shot means nothing to me, no skiers, no races to the favorite hole, no performance tricks. I just want the tallest ratio I can get so I can get the most top end out of my little 35. Distance is my enemy, long runs will be a norm. So I found me a pitch I think I can live with, and low and behold, it's only offered in a counter rotating prop. The tallest pitch I could find is 15" for an '83 35hp standard rotation. (I bought the boat used, the prop is bent and nicked, it shows to be a 10X13) OK.... the question is, why would a manufacterer offer a tall pitch only in a counter rotating aplication? There is a 19" and 23" available, but only in counter rotating, not standard. If I had two outboards on this little boat, and needed a standard rotating prop with a high pitch, where would I get one?? 'Preciate the feedback, Thanks, KR

 

[Bob_VT]

Re: Newbie. Dumbest question yet??

Starting your truck or car in 4th or 5th gear is too much strain..... it could be done but something is going to give out. You have an older heavy boat for a 35 hp.... get the suggested replacement prop and if you need to go further in the water........... leave the house earlier....... or save your prop money and look for a larger outboard.

 

[kenmyfam]

Re: Newbie. Dumbest question yet??

I'm with Bob on this one. You need to spin that motor in it's maximum RPM range at WOT. A bigger pitch does not necessarily mean that the speed will go up as the WOT RPM will go down as the motor does not have the power to turn the bigger pitch prop as fast.
You should post your WOT speed and RPM to get expert help on this. Also try it with different trim settings till you find the optimum, make certain that the motor is not sitting too low in the water causing increased drag. The anti cavitation plate should be even with the bottom of the hull (give or take an inch) but you must be far enough in to draw cooling water.

 

[rebuilt]

Re: Newbie. Dumbest question yet??

Thanks, makes sense to me. I drove 18 wheelers for 6 years and understand gearing. We'll just hang tight and re-motor later down the road. Maybe I can get away with a 10X14. Thanks for the reply. KR

 

[steelespike]

Re: Newbie. Dumbest question yet??

Get the 13 repaired and run it. Check the rpm you'll need to be about at your max rated rpm to try to use the 14 and going up in pitch could cost speed if
the rpm goes down too much.Also it can damage the motor if can't reach its reccomended rpm. Kind of like trying to get that 18 wheeler over a long hill in too high a gear.
Raising the motor vertically can give you a little more speed.Just be sure it
pumps water.

 

[Zeusdafreak1]

Re: Newbie. Dumbest question yet??

Heres how I got my max speed out of mine. I bought a tiny tach to read RPMs. I went out one day and spent a lot of time identifying which of the 3 props I had that performed at the top end of my RPM range. I then spent twice as much time with weight distribution in the boat itself. Changing tilt and weight distribution around and stopping to record readings. After all the testing I had gone from 4700RPMs to 5100RPMS and increased speed dramatically. Most of which came from the testing of the weight distribution and the tilt with each weight ditribution change(moving battery,etc. from rear to middle, to front). It made a huge difference but it took a lot of time a data collecting.

The boat goes ALOT faster now and I know I am getting all thats possible from my setup.