Going to go from aluminum to stainless prop. Suggestions please

[aramnrtar]

I have a 1991 Sea Ray Bowrider that I have brought back to life and she runs great. It has the Mercruiser 4.3 205 LX and Alpha 1 Gen II out drive. It has a three blade 14.25" x 21" aluminum prop on it now that (trimmed out) gives me 44 mph (gps) at 4600 rpm with 25 gallons of gas (2) peaple and gear/coolers and such. I know that is pretty good as it has a desent hole shot also. I want to go to stainless to see if I can improve on efficiency/speed slightly and then I will have a spare prop with the aluminum. I see a variety of brands, types, and diameters on iboats and was wondering if I could get some suggestions. I know this is going to be a try and see thing but who makes a good one for my situation and does the diameter make some difference if it is a little more or less than 14.25?

Which prop/brand would you go with?

I am running in the rivers and sounds of NC.

BTW this forum has helped me greatly in getting this boat back in shape. Thanks!!

 

[aramnrtar]

Re: Going to go from aluminum to stainless prop. Suggestions please

Quicksilver? Solas?

 

[steelespike]

Re: Going to go from aluminum to stainless prop. Suggestions please

I don't have any hands on experience with this setup but the Solas props seem to be predictable.
Don't worry about the diameter. If the prop is intended for your motor/outdrive it will be right.
What size is the boat?Your present slip is pretty high 20%. Is the prop tired?

 

[Texasmark]

Re: Going to go from aluminum to stainless prop. Suggestions please

Quicksilver? Solas?

At the top of the forum are pictures of a SS and an alum. prop. Notice the shape of the two. I don't know which brand is which, but the one on the left, the SS one has laid back blades and that's called RAKE. Rake is used in props for bass boats to get the hull out of the water....it's called bow lift. The one on the right is more conventional which I think is more appropriate for inboard/I/O's as they don't run in the water like bass boats.

Other thing is BB's usually have a lot of weight in the rear and get bogged down on hole shot. Ports are deliberately put in the front part of these props, just under the leading edge of the blades to allow the prop to ventilate on hole shot which allows the rpms to develop very rapidly which develops the HP very rapidly and improve the hole shot......they may not work on your inboard/I/O.

Merc/Quicksilver Laser II is just such a prop; really intended for a BB. Not sure about the rest.

When you go to the prop site for a particular brand, pay attention to the side notes as some will tell you what kind of use the prop is intended.

SS props, besides some having the BB enhancements , have thinner blades which are more efficient (more mph for a given power/load) and usually are cupped which can add an effective 2" of pitch at higher rpm's, besides improving the ability of the prop to hang tight in turns and choppy water. So, with that said and if you want a SWAG, the same pitch should give you a couple more mph at top end and as good or slightly better hole shot.

HTH, but I'm not the xpert.

Mark

 

[aramnrtar]

Re: Going to go from aluminum to stainless prop. Suggestions please

Thanks for the help guys I guess I left off the boat size its a 185 sea ray. I have not thought about slippage I need to learn how to calculate that. Now I'm wonderin.g what is normal for that boat. I'm thinking about the tempest plus and if that would be a good fit for my boat.

 

[bnicov]

Re: Going to go from aluminum to stainless prop. Suggestions please

Do you boat in waters that have lots of sunken timber, rocks and shoals?? If so, I'd stick with Aluminum for the sake of the lower unit. If it's nice consistent deep water, go for the stainless steel prop.

 

[Scott Danforth]

Re: Going to go from aluminum to stainless prop. Suggestions please

I would check with your local marina. many have sea trial props for dialing in your setup. I had a Solas prop on my SeaRay 190 and loved it.

 

[Texasmark]

Re: Going to go from aluminum to stainless prop. Suggestions please

Thanks for the help guys I guess I left off the boat size its a 185 sea ray. I have not thought about slippage I need to learn how to calculate that. Now I'm wonderin.g what is normal for that boat. I'm thinking about the tempest plus and if that would be a good fit for my boat.

Go to www.gofast.com and use their prop slip calculator. Put in all the data except the answer you want and punch the button.

 

[aramnrtar]

Re: Going to go from aluminum to stainless prop. Suggestions please

Thanks Mark it helps to see the calculations. If we could all go theoretical speed I wonder if we would be happy? Ha!
Looks like I have some slipage. I think its worth a try to put a stainless on and see how she feels. To answer the other questions above, the existing al prop is in excellent shape for an aluminum prop, (no paint loss yet!) and I do run in good water here in NC. Not to say there aren't stumps. But mostly sand/mud bottoms here. Im generally very carefull but I do like to think im running as efficiently as possible.
Thanks again guys!

 

[Bob_VT]

Re: Going to go from aluminum to stainless prop. Suggestions please

Just for FYI http://boatpropellers.iboats.com/ Look at that page and scroll down. The tabs have some good info in there.

 

[jimmbo]

Re: Going to go from aluminum to stainless prop. Suggestions please

My boat was also equiped with 21 alum prop when I switched to SS I found a 20 Raker a good choice. Improved Holeshot and better top end, boat road higher out of the water, not just the bow. Five or Six year ago I tried a 20inch Enertia. It holds the water well and is very difficult to get it to break loose.