Prop selection help

[Raider33]

Hi guys this is my first post so if I leave any needed info out let me know. I have a 1996 sprint fish and ski fiberglass 17 1/2 ft. My outboard is a 1996 90hp Johnson. I'm looking to upgrade to a stainless prop my current prop is a aluminum 14x17. My dealer recommended rpm range is 4500-5500. My current WOT rpm is right at 5100rpm assuming my gauge is accurate, that is at 37 mph (gps) with the trim in the sweet spot. I'm looking for fastest top end speed. I use my boat strictly for fishing and my normal load is two people and light gear (that's what I tested WOT rpm at). My problem is finding a high performance prop in that dimension and pitch I'm finding a lot of 13 1/2 d. I was hoping somebody here could help me select a propeller (brand and dXp) to achieve maximum performance out of my outboard. Thanks for the help.

 

[Sea Rider]

Welcome to Iboats,

Why is it that every new boater wants SS, 4-5 blade pops when a prop maximization from current alum prop is all you need. If wanting to get the max out of that 90, re pitch that 14 x 17 to 14 x 16 assuming that per rule of thumb will theoretically achieve + 200 wot revs with 1 less pitch. That isn't known till a water test is done, but it's a excellent starting point.

As currently loaded while deck is well balanced, trim OB for comb and anticav plate to ride parallel to water level once on plane. If having back water splashes at back or over transom that's other story which needs to be corrected before playing with props.

Happy Boating

 

[Starcraft5834]

because SS props look cool? and most think it will make you go faster... Raider.... assuming your tac is right, you are running in the recommended range now with your 17 p prop... if you go up to a 19p, your WOT rpm will go down and your hole shot will suffer... by dropping down to say a 16, your WOT rpm will go up and you may not end up going any faster... with that said.... be happy with what you have, or get a larger engine, or a lighter boat :drum: not trying to be a smart ass... just that engines and boats and prop choices have all been hashed out before, you can go just so fast given your particular set up, tinkering with it can be fun, just dont blow up your engine doing it

 

[Sea Rider]

What will achieve while maintaining same diam going from a 17 to a 16 pitch is higher revs, how much isn't known. Could be 200-400 + revs. If 5100 wot rpm achieves 37 MPH, 5500 rpm should achieve slight more, not that wow increment. OTOH will have better hole shot than with a 17 as usually loaded. Repitching alum is cheap, much better than buying other costly prop to find out that didn't make the trick.

Happy Boating

 

[Raider33]

Yeah I agree with you guys the last thing I want to do is put stress on my OB and I'm completely happy with my three blade prop. I was curious about brands that you guys would recommend. Another question I had is if it would be ok to switch to a 13 1/2 X 17 I seem to be finding a lot more props with that dimension than I do 14x17. Thanks again for the help.

 

[Sea Rider]

As currently loaded, you're at the middle wot rpm range for that engine, if hole shot is not that fast a 16 repitch will make the trick, will help too if in a future will be adding more load. Playing with props is while running at full hammer down, once at full 5500 wot revs as currently loaded you can throttle at the speed you like most. Engine will work much better throughtout the whole throttle range while stress free..

Happy Boating