How to adjust low speed running

[blueboat1]

I have a 17' aluminum fishing boat with a 1974 70 hp looper. WOT the boat runs 32 mph, at idle it run 4-5. When I try to troll at 8mph it wont, either it will climb to 10mph or it will drop to 5 mph. I can’t get it to go 8mph. Would dropping from a 17 pitch to a 15 help this? I don’t mind losing some top end. Any tips on

 

[OBJ]

Re: How to adjust low speed running

Hi TinCan.....<br /><br />I would go up in pitch. Slow the rpm down. Best thing to do is look around for a prop to try. Know anybody with one that would let ya' use it for a test?

 

[oldboat1]

Re: How to adjust low speed running

believe if you increase the pitch, you will get lower rpms but increased speed (bigger "bite"). If your carbs are in need of cleaning or rebuilding, the need would show up at low speeds. You might pull them off and clean them thoroughly, with special attention to the low speed jets. With clean carbs, dial in the low speed setting for smooth running, then reset the idle speed adjustment if appropriate. In addition, I would recommend looking for a five to ten horsepower trolling motor that you can hook up as an auxiliary. Your 70hp just isn't going to be well-suited for prolonged trolling speeds.