Need Help Choosing Prop Please

[Revtec]

I would appreciate input to help me choose a new prop for my 15' Sportscraft Bowrider boat. Motor is '81 Evinrude 70 HP

The current alum. prop needs repair and the local repair people say $60 to $70. So I am thinking about a 12 1/4" 15 pitch Solas Amita from iBoats for $74 instead.

My problem is that I do not know the specs on the current prop so I am sort of in the dark in choosing a new one.

I believe the damaged prop is rebuilt since it has some numbers x'd out. On the housing of the prop is see 657H. Near the nut as near as I can tell is 7608372v (it is not clear and the 7608 is x'd out). I don't have a clue on the pitch and the diameter seems to measure at 12 5/8.

On the boat I measure max speed at 30 mph @5100 rpm. (RPM range is 4500 - 5500). Seems a little slow out of the hole.

The OMC manual says the motor comes with 13 1/4 17 pitch and lists the following options.
14 x 9
14 x 11
14 x 13
13 3/4 x 15
13 x 19
12 3/4 x 21
12 3/4 x 23

What prop (mfg & size) would you recommend for pleasure & skiing?
Any guess from the numbers as to the current prop?
Any comments on the Solas Amita prop?

Thanks in advance for any input.

 

[vistacruiser]

Re: Need Help Choosing Prop Please

Revtec,
I agree you'd be better off replacing than repairing, since you don't really know what you've got to work with. That prop may be holding you back.
If you're boat and motor are in good shape, I would think a 15 pitch may give you too much RPM, and a 17 would be a better place to start.

My opinion is based on experience with 55 and 60 hp OMC 3cyl's. on a 15' 1963 Thompson runabout. Different boat granted, not fast but easy to plane with the hull almost flat at the stern. I scrounged 3 stainless props for this boat when the deals were good.

With a 1969 55hp, a 15p OMC SST was a good tubing prop and a 17p Michigan stainless was my cruising prop, ran about 31 mph at close to 5500 rpm with the Mich.
Later I put on a 1986 60hp with trim, (you're motor with smaller carbs) and the 17 became the new tube prop reving to around 6000. I could easily pull Two kids on tubes with Two adults in the boat. I got a chance to demo a new13.25x18 Raker at that time, meant for a V-4, and fell in love with it. It had the hole shot of the 17 and the top end of a 19 SST, which I also demoed, and was a dog out of the hole. The Raker gave me 36 mph at 5600 with Two in the boat, and was my cruising prop for 18 years.

This is not meant to steer you away from the Amita, I am also considering an Amita4 or a TurningPoint Legacy 4 for my current boat, as these props sound like a bargain. Just saying, in my opinion, a 15 may not be enough pitch.
Sorry for the book, hope it helps.

Brad