Aluminum to Stainless Steel prop
8/30/15 @ 5:46 PM
I want to upgrade from my standard, came with the boat, aluminum prop to a stainless steel prop. The Merc 75 opti came with a 17p aluminum prop. With my standard load I'm running 5600 to 5700 rpm WOT. If I go to a stainless prop, what pitch should I be looking for? I was thinking I would stick with the 17p. I also want to stick to a 3-blade. Thanks. 4Lakes
9/7/15 @ 5:19 AM
4lakes. Call Mercury and ask to talk to a prop rep. Tell him/her what you are looking for. They know their products. I went from an aluminum three blade to a stainless four blade for my 115 Merc with the same pitch and the boat came to life!! I ended up buying a Trophy Plus model that can be tuned for different needs. There is a two piece plastic clutch that does cushion some of a hard hit. No matter what prop you have, hitting something can make bad things happen. They will also set you up with the right clutch. The old style will rattle at an idle. I does not hurt anything, but it sounds like a couple of rods want to leave the confines of the crank case. I keep the aluminum prop for a backup and can change it out if I might be rock knockin.
9/6/15 @ 8:00 PM
I have rigged boats for yrs I do know these two things for fact. you drop pitch going to stainless cuz they don't flex and who ever said stainless is easier on a lower unit needs to have a drug test!! They don't tend to break when they hit stuff but what they do is transfer all that shock into the lower unit cuz they front break.they don't just bounce off and go on their marry way.?As far as switching to a stainless on your set up spend that money on a couple good rods or a good locator. You mite and I mean mite gain 3 to 4 mph. buy a new aluminum prop if you feel like u need a prop. Save yourself 400 bucks
9/6/15 @ 9:38 AM
9/6/15 @ 8:32 AM
I always thought it was the other way around if you had a 17 pitch aluminum you would go to a 19 pitch stainless because it doesn't flex also was watching a fishing show with a mercury rep and he said stainless is easier on lower unit because it will bounce off were aluminum won't! aluminum is just cheaper to start with.
9/5/15 @ 11:45 AM
I have run stainless props for a long time now. However along time ago I put a stainless on a 50 hp merc and dropped a pitch and it was all the difference in the world. the big plus is a stainless will take a little abuse here a aluminum won't. However a stainless prop hits something it wont give as easy.
8/31/15 @ 1:30 PM
with only a 75hp motor, I don't think you are going to see any drastic differences between aluminum and stainless. you might be able to squeeze another 1 mph of top speed. The "flex" of aluminum really only comes into play with higher horsepower motors trying to turn higher pitch props on heavier boats. I personally would look at saving the $500+ for a different upgrade.
Edited on 8/31/15 1:35 PM
8/31/15 @ 11:42 AM
Major is correct. When switching from Aluminum to Stainless you can drop a pitch. However, every boat and motor combo is different. Go to your dealer. Most dealers have stainless props that are painted blue that they will let you check out for the day, perhaps they will let you check out two of them. Rather than saying well I know what my boat does under certain conditions, I would fill the boat with gas and what ever and run your prop, do a holeshot test, top speed, backtrolling what ever you are looking for. Then switch props and do the same tests on the same day. That way you can determine which prop is best for what you want to do.
8/31/15 @ 11:34 AM
Pitch is not the only thing that you have to think about when making this change. Diameter, cupping, amount of blade surface, plus rake all come to play when trying to prop a boat correctly. If I was going to make this change, I would deal with a good prop shop, or dealer in testing different props until I had the right one.