help with prop

[kerryd15]

Hi I have a 97 merc ELPTO 50Hp, the prop is a 3 blad aluminum with # 48-73136-13 on it. The prop has some minor dings in it. maybe not minor some of the gouges are 1/8 to 1/4 in deep in the leading edge. Is this worth fixing? I am thinking of going to a 4 blade. i installed a tach on the boat which is a 89 bluefin with side consel livewell and 3 batteries. I can get 31 MPH GPS by myself at 5000RPM. In the book this engine can go to 5500. With a couple friends along I can get to 4900 to 4950RPM. If I change prop which should I try? I would like to keep the top speed if possible. A little hole shot would be nice. If this engine has been running these RPM since new is increasing the RPM going to be hard on it. I know lugging it is not good also.

[20lbSloughShark]

Our 25 hp has some dings in its prop. The notches dont do that much, its when the propeller gets bent that you loose performance. I have heard with a 4 blade, you should drop a pitch to get the same performance, 31 mph with a 50 hp seems pretty good, I get about 25 mph with my 40 hp.

[Moose-Hunter]

Hi I have a 97 merc ELPTO 50Hp, the prop is a 3 blad aluminum with # 48-73136-13 on it. The prop has some minor dings in it. maybe not minor some of the gouges are 1/8 to 1/4 in deep in the leading edge. Is this worth fixing? I am thinking of going to a 4 blade. i installed a tach on the boat which is a 89 bluefin with side consel livewell and 3 batteries. I can get 31 MPH GPS by myself at 5000RPM. In the book this engine can go to 5500. With a couple friends along I can get to 4900 to 4950RPM. If I change prop which should I try? I would like to keep the top speed if possible. A little hole shot would be nice. If this engine has been running these RPM since new is increasing the RPM going to be hard on it. I know lugging it is not good also.

Depending on how large these "dings" really are may or may not throw the prop out of balance. Which would NOT be a good thing for your lower unit. A pic of the prop would do wonders here.

Before doing any prop swaps... Check to see your engine is set at the proper height. If your cav plate is even with the bottom of the hull you should be there or very close. If it's low, it creates drag that sucks the performance out of any set up.

As far as a replacement... A four blade may not be such a good idea. I will give you a better hole shot BUT... It will slow you down on top end. Also, seeing that your already running 500 rpm below your WOT rpm... Adding another blade will further drop your revs. Possible too far.

I'd recommend you just replacing the prop with a new one identical to what you have. Your options being droppoing the pith to a 12 for more hole shot and raising your revs a bit. OR... If you want to drop the doe, going with a stainless prop in the same pitch. Which will probably keep your present performance and raise your revs a bit.

I'm no expert but I have proppped a boat or two in my day. As always... Your mileage may vary.

[Finns]

Might look in to getting your prop 'refurbished'. If nothing else you could have it as a spare.