I have a 15 foot Klamath aluminum boat with a 1991 Evinrude 30hp outboard on it. Currently I am running a 15 pitch aluminum prop and sometimes the boat has some difficulty getting on plane (depending on the load).
While I realize that this is understandable considering the relatively low horsepower I have available, I am considering going to a 13 pitch Solas New Saturn stainless. Iboats has them for a fairly reasonable price.
I think the reduction of 2" in pitch would give me better performance on the low end. I guess my question is - would the moderate cupping of the stainless help offset the difference at the top end?
I know, I know - the only way to really determine this is with a tach and testing each prop. The problem is - I don't have a tach, and even if I did, I live in the middle of nowhere and getting several props to test (without buying them) might prove impossible.
So --- I'm asking those of you with experience in these matters for your best guess. Your help will be appreciated.
I'm not sure spending the extra money for a stainless prop is worth it in your case as cupped aluminum are also available. Generally though, if a boat has a problem getting on plane its a sign that a drop in prop pitch will help. But -- before doing that, check engine height. The AV plate should be flush or slightly above the bottom of the boat. I assume you do not have power trim so you should also try moving the tilt pin and try different trim settings. Redistributing some weight in the boat also can help. When you have those things optimized, then a prop change can be considered. My previous boat was a 16 foot aluminum with a 40 HP Evinrude. That boat was happiest with a 15P. In your case, I think changing to a 13 would be beneficial.
The AV plate is almost exactly flush with the bottom of the transom. I've also experimented with the trim pin and leave it in the position where I get the best ride while at cruising speed.
From experience in a boat that had power trim, I know that the best cruising trim position is usually not the best hole shot position. My boat has a very sharp keel and tends to bow steer if I leave it in the optimum take off position though.
The thought behind the stainless vs. aluminum is simply a matter of durability, given my penchant for chasing redfish in shallow water.
I think you'd be fine going to SS..
The advantages out-weigh the dis-advantages, and most of the current aluminum props are cupped anyway, just depends how much and where. The Solas will be a good over-all lifter, and being SS, it should be much more efficient.
I think the thickness of the blade has a lot to do with performance and alum blades are thick by necessity. Unless I boat on the rocks, I doubt that I'll ever run alum again.....course if I'm putting along at 25-30 mph (WOT) then all bets are off, but for some serious performance running forget alum.
Cupped stainless vs. standard aluminum prop
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