1970 60hp Evinrude Prop to big?

So i have been told that my current prop is to big (pics will follow) i do not know the current size of the prop as im not sure what to measure, i know the diameter is 14in and the height of the blade is about 6in? Im having the motor bog down at full throttle and thinking the prop is taking to large of a bite into the water. can anyone suggest a proper prop? (no pun intended)






Also have some sort of trim settings on the bottom of the lower unit? Not sure what it changes or what i should have it set at. Any ideas?

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

Re: 1970 60hp Evinrude Prop to big?

So I don't have a tach I know it revs good in neutral slow speeds good but as soon as I throttle up all the way it just seems slow and bogged down what's a good prop for pulling a tube and just general use

Re: 1970 60hp Evinrude Prop to big?

No! Get rid of it. You are telling me that you already have your engine overloaded with it and just the boat. Water toys and just driving around, half on/half off plane require a lot more hp out of the engine and lug it more than it's already getting. 2 stroked don't like to be lugged. I compare them to Mustangs......want to run free with the wind.

Get a tach so that you can get some numbers and then we'll go looking for a prop. Water toys can require 2" less pitch for a given diameter prop on that sized engine so that has to be taken into account anyway. At wot that engine ought to be singing to you at WOT, literally.

Mark