aluminum to stainless help

[92nitro]

Im running a 17'6" Nitro fish and ski with a 1992 115hp Evinrude 2 stroke. Currently I have a 13x19 3 blade prop and am considering moving to stainless. I can get up on plane just ok and my top speed is just under 40 mph. I'm running a touch above 5000 rpm according to my analog tachometer ( probably not the moat accurate) Operational range is 4500 to 5500
Ive been reading up and trying to collect as much information as I can but have been left a bit confused. First off. Is it even worth it to switch to stainless on a motor running under 150 hp? Seems to be varying opinions on this. Also Ive read that you should pitch down when going to stainless. would this be the case on a 115 hp motor? Apparently the lower hp motors like mine don't have enough torque to cause enough flex in an aluminum prop to necessitate the need to pitch down? Or If I pitch down to a 17 pitch and go up in circumference 7/8" how would this effect my performance? I ask as I am considering the viper tbx prop in a 13 7/8" x17. https://www.boatpropellerwarehouse.c...opeller-763930 Or would I be better off staying with the same pitch and going up in circumference as I can get the same prop in a 13 7/8" x19. But nothing smaller than that.
Any help with this would be greatly appreciated. Seems like the more I research this the more questions I have.

[21XDC]

I'd stick with aluminum, But I'd increase blade area and reduce pitch. More diameter, or extra blade and drop 2 pitchs. Based on the info you posted...

[92nitro]

Ok interesting. So basically instead of going stainless 13 7/8"x17 stainless i should go 13 7/8x 17 aluminium? Will this improve hole shot and crusing speed or will improve one or the other. Sorry for all the questions. Just trying to wrap my head around different changes in pitch and circumfernce in relation to the change in performance

[21XDC]

SS is not as beneficial in lower HP situations.... Other than more durable. I can't tell you for sure how your boat will react.

[92nitro]

I gotcha. Well on the bright side trying out different aluminium props will be a heck of a lot cheaper than trying out stainless steel. You may have just saved me a whole lot of money. For that sir I thank you. I greatly appreciate your help

[21XDC]

Please post your results.... The merc spitfire might be a good option.

[92nitro]

I definitely will. And ill look into the spitfire right now

[92nitro]

So after looking into all the different options I've decided to go with your recommendation and pick up a new spitfire 4 blade. I've also found that I was originally wrong about the current prop that is on the boat. Turns out its stainless steel just painted black. So I would be changing from a stainless steel 13x19 3 blade to a 12.5x19 4 blade aluminum. So here's my thought process on this...I'm thinking that keeping the same pitch in the 4 blade but going down in diameter to 12.5 might be the way to go. I was running just under 5000 rpm with the S.S So the motor is turning the blade ok. Just a sluggish hole shot. The aluminum prop should be lighter even with the extra blade i'd imagine? Plus Less diameter which means less drag so My rpms may rise a touch which wouldn't be a bad thing. Same pitch so I don't lose any high end. But the extra thrust of that extra blade should help with acceleration. Dos this thought process track correctly or am I way off?

[21XDC]

The weight of the prop wont change much. It's all about thrust diameter, grip and lift. You want to be near the upper rpm max for your motor when trimmed out.

I hope it does what you want. I think if you want to stay with SS, I'd consider a 17P Trophy plus.

[92nitro]

Well I definitely like the price of aluminum a whole lot better. So do you think then that the 12.5 diameter would be too small? Or is it just one of those deals where its hard to say for sure and I just need to try it out? I'm a bit torn between the 12 3/4 x 17 and the 12 1/2 x 19.

[21XDC]

I'm a fan of larger diameter props. PVS venting allows for a controlled slip on holeshot. I'd be guessing, So I can't offer much more. Sorry.

[92nitro]

Understood. Definitely appreciate all your feedback!

[Jordan3206]

Less diameter is going to give you more slip. This will let the boat rev faster but also reduce top end. This will be magnified in an aluminum prop because that prop will flex and flatten out under load.

For an underpowered boat a less pitched 4 blade will help the boat get out of hte water and carry the weight better. I would try a 13x17 4 blade and maybe even a 13x15. You really want to be pushing 5500 rpm. Check out the Turning Point Mach 4 stainless props.

[92nitro]

So I ended up ordering a 13x17 spitfire. Unfortunately it would not fit my motor. Turns out the gear case housing on my old Evinrude is too small. So I was never able to try that out. I did however order 13x15 4 blade turning point as well as a 13x17 4 blade turning point. Both aluminum. Surprisingly, the 13x17 made almost no difference. I was topped out at 5,000 rpms (same as the 13x19 3 blade Evinrude stainless) hole shot was maybe a tiny bit better and I lost about 1 or 2 mph on the top end. Then there's the 13x15. I hit the throttle and almost ended up in the back of the boat. Acceleration was fantastic and I jumped out of the hole immediately. The excitement didn't last for long however as I lost about 5 mph off my top speed and I'm pretty sure I hit my rev limiter with a little bit of throttle left. Trimmed down lower than I typically do and was running at 5800 rpms at wot. After running the 13x17 and not gaining any rpms at all I was definitely not expecting that. So Now I feel like with the 13x15 I'm underpropped and with the 13x17 I'm over propped. Now I don't know what the hell to do. The 13x17 does have vent holes. I've heard that drilling these out bigger can increase rpms and hole shot? Wondering if anybody can chime in that has tried that before or can offer any input and any more recommendations . I'm all ears

[bassfisher444]

Get a stainless prop, aluminum props don't belong on a bass boat that has more than 60HP.

[blkfalc4]

Raker V-4 maybe?

[Rangerdeepv]

Had a Lund Angler 1700SS for a few years before the first Ranger and went through more aluminum props and had a rotation of 3 which were either in the shop getting fixed, on the boat or the slightly dinged up spare. The motor was the unbreakable Merc 115 EFI from 2003. Post divorce and spending numerous hours fishing the propeller budget was becoming untenable. I stumbled on Piranha props and life was good until I bought the first Ranger with a 150 and SS prop on it. The composite prop was the ticker for that boat as I could change from blade size to a smaller or larger in a few minutes. Also when a blade became dinged up I always had a spare or two. May sound flaky but it worked for me on that boat for a few years.