Re: 1970 60hp Evinrude Prop to big?
Need more info on your boat, how you use it and prop. Need numbers like rpm and top speed with what you have after you supply the dia and pitch. On the front or rear of the prop hub should be some numbers. 13 1/4 x 15 for an example which is a good number to start with on that engine on a 15' semi-V boat with a couple passengers, gas and gear The 60 to 70 hp OMC triple loopers were very popular back in the era when my family and friends did a lot of boating together and they ran them.
The large diameter and shallow pitch seems to be for a heavy boat with that engine. I guess the prop fits your engine. I think the small gearcase can take up to 14 1/4. However a 14" dia prop is too large in my opinion on that boat for general purpose boating.
The first number is overall prop diameter and doesn't affect performance a lot as it changes in fractions of an inch and pitch changes in inches. Hence, with all else equal I don't pay that much attention to whether it's 13 1/4 or 13 1/2. A lot of time it is a result of the prop design in getting other things worked out in the calculation.
The tab sticking down it called a trim tab and it's purpose is to offset prop torque so that steering is straight and true. If you turn loose of your steering wheel and the boat veers off to one side, turn the tab a little at a time in that direction until it quits. If you have power trim and tilt, the trim position will affect the answer so you set the tab to where you want it when trimmed to the position you normally run and just live with the rest of it.
Mark
