Prop Advice - Aluminum/Stainless Princecraft 166, 90 Merc 4

[howie]

Looking for some advice for a replacement prop...
I bought a 2003 Princecraft 166 with a Merc four stroke. The existing prop has some dings. I don't notice any vibration but want a clean prop just the same.

I read I'd not realize the advantages of a stainless prop for this style of boat and motor size. More a factor on bigger motors on performance boats.

Appreciate any thoughts and advice out there.

[NMG]

What prop do you have on there right now and what are your maximum RPM's?

[howie]

Thanks for your response. I copied the number off the prop but only thing that I can extract from that is that it is a 17 pitch.
Far as max RPM goes, embarrassed to say I'll have to track on that next time I'm aboard. Speed tops out at 43mph.

[howie]

Just to add to my decision making paralysis...anyone have any experience with Piranha (Composite) props?
Many thanks.

[bostonwhaler]

From what I have heard, Stainless steel props can be dangerous. It sounds like you have tacked a few rocks or loggs with your comp/aluminum prop. If you were to have done that with a stainless it would have not have flexed and broke off a piece, but the impact would have went straight threw to your shaft and lower end. If you do go stainless I think you go down 1-2 pitch and stay with the same overall diameter. You will notice more snap on the the take off and a slight increase in speed.
thats my nickel. good luck, I cant help you with the RPM's for a 4 stroke, Im sure they are allot lower than that of a 2

[moonshine]

max rpm is probably around 6000 and I agree, you should probably stay with aluminum

[bostonwhaler]

Wow. I didnt think the rpms of a 4 stroke would be the same as a 2 stroke

[moonshine]

mine was, it should state max rpm on the shaft where the model and serial number are

[lape0019]

The max rpm is 5500-6000 rpm as per the manual for a 2006 merc 4 stroke 75hp (essentially the same motor provided the year is close).As for a stainless prop, my mechanic said to stay away as well. How I fish will result in me hitting a rock and if done with a stainless prop, it will cost you more than just a new prop. Plus for a 75 or 90hp motor, it will not really give you that much more top end.

The piranha props are a great concept that allows you to pick different pitches for not too much money but the few people I know who have had them and no one seems to like them too much. I like the idea that of you hit a rock and shred a blade (because instead of dinging a blade, it will shatter) it costs you next to nothing to replace compared to getting and aluminum one fixed.

Adam

[howie]

Thanks for the input folks. Thinking an aluminum makes most sense for my purposes. From my web serching, the composite, while not without it's fans, doesn't get rave reviews.

[NMG]

The only thing I'll add is to double check your RPM's next time you are out. You want to be able to hit the upper RPM limit for your engine with your normal load. If it's 6,000 RPM, then you should be running 5,800 to 6,000 or thereabouts. This may not give you the most speed (you may need a lower pitch prop to get there), but you'll typically get the best hole shot, cruising performance, mid range acceleration, etc.

[howie]

Thanks for that. Will check that next time out.
Much appreciated.