Need new prop... recomendations?

[Doc]

Just bought a 24 privateer, "shallow" (11 degree?) deadrise, with a yamaha four stroke 225 on a 30" bracket, I weighed the boat and it comes in at about 5500#'s dry; the best I can figure.

Boat is currently running a three blade 15 1/4 by 17, cruising 28MPH at 4500 , WOT is 38 MPH at 6200. Im happy with theese numbers, but boat is slow to plane when under load, and falls off plane at 18 MPH .

Im looking to move to a four blade to increase my load carrying capacity and low speed plane ability and maybe help cuise a bit, and help with stern lift. WOT speed means nothing to me and I dont care if I lose a few MPH.

I think the ideal prop would be a four blade 15 x 16, but having problems finding one at a decent price. I have found some very good deals on the "apollo" 14 3/8 x 18. by michigan propellers... anybody know how this will work for me? Too much pitch? any other reccomendations on specific props?

[joel mcqueen]

do you have trim tabs

[stevemc1]

You never want to go down in diameter. You will lose efficiency. Try to find the largest diameter, in your case I would assume it is 15 1/4" , stay there. Yes a 4 bladed may be better. Do you have a stainless cupped prop now? If not going to a stainless cupped prop, may be the ticket, but going down an inch or 2 in pitch. Some prop shops will lend you a prop or figure out what prop you need. I am down in Sarasota, and General propellor is a good one down in Sarasota.

[Doc]

Yes to the tabs, they help, the boat runs very good, but I know I can get it running better with a different prop...

Yes to the stainless; lightly cupped. No reason to drop pitch if a three blade, as the WOT RPM's are at max specs of 6200...

On a four of the same diameter yes I should drop pitch... but what is the trade off if I went with more pitch and less diameter on a (higher surface area) four blade? Would that get me where I need to be?

I think the 4x15x16 will be the best setup for my rig, im just looking at different options before I make the decision through.

[stevemc1]

I know if you went with less pitch, your wot rpm would be higher, you said you werent worried about wot. 4x15x16 might be good. If your plan of getting the boat up on plane quicker and hauling a load, you must use as big a diameter prop that you can. And yes a 4 bladed prop can help this too. 6200 seems like a lot for a 4 stroke, but I dont work or play around them much. We have twin 4 stroke 200 Mercury Verados on our boat at work, but it doesnt get that high of an rpm. I am not familiar with your motor. I would go to a prop shop. You never want to over rev your motor, especially when it is already overloaded.

[stevemc1]

I quess what I am getting at, is you dont want to go smaller on the diameter of your prop to lower your torque peak, you would lose effeciancy and waste power to achieve that, but that is not the way to do it.. You would probably want to get the most effeciant prop type, possibly a 4 blade, and maybe lower the pitch, but still try to eliminate slippage by having a good cup. 15 x 16 4 blade seems like it may work for you. You want all the push you can get. Your rpm and speeds are in the ball park at least for a 2 stroke, as thats what my 2 stroke does. Our work boat is overpitched but well powered 4 strokes, and it is way lower in the rpm range. You may need to weight to the front more, I dont know if you have tried all the moving around etc.

[Mobile Diver]

I found these guys in Sarasota surfing around. They will meet you & let you try out different props. Might be worth a try. www.propgods.com

[Gamble]

Call power tech props. they can run the numbers on your prop and get you the exact four blade you need. I have used there four blades on 3 different boats now and personally think you can't go wrong with there four blades.

[CWitch]

Doc, I know a guy that has one, brand new, he is trying to sell. Call me.

[JimW]

For what it's worth, I have the same motor as you and the prop on mine says "17 M" on it. Max rpms are at 5,800, maybe 5,900 at wot. Perfectly proped IMO. My ride dry is a lot lighter than yours though.... Mine's like 4,600 dry, 5,800 max'd out.

[Doc]

Jim thats the exact prop I have on mine, standard yam issue I think. Everyone Ive spoken to with a heavier boat says they get better load carrying ability and better mid range cruise with the four blade, sound like your lighter boat is dialed in.