4-blade aluminum vs. stainless

[superbenk]

Had to buy a new prop last week in vacation then managed to bugger it up pulling the boat at the end of the week. First time I chewed up a prop in all my years of boating & I did it twice in one week! Both times were small rocks (2-3" in diameter probably) kicked up by the prop. The lake was lower than usual which is probably why I had the problem.


Anyhow, original prop was a 14.25x21" 3-blade aluminum Black Max (factory prop). The one I bough to replace it was a 14x19" 4-blade aluminum Alpha4. Really liked the change in hole-shot with the 4-blade vs. 3-blade though I lost 3-5 MPH on the top end.


So now I'm going to repair one or both the aluminum props as spares but need to get back on the water for the remaining weeks of the season quick. I'm considering a stainless prop now. Everything I read leads me to think stainless is the way to go. My main question is whether is should get a 4-blade or if a 3-blade is just as good as the Alpha4 because stainless is stiffer & cupped?


I think I've decided the striking things with stainless isn't a problem because of the plastic hubs & the fact I really never hit anything hard (I'm generally extremely careful about where I boat). But I'm open to thoughts on that as well.


Also, should I match pitch to the original 3-blade prop (21") or drop to a 19-20" with stainless? What about pitch in the 3-blade vs. 4-blade stainless? I get proper RPMs at WOT right now with the 21" 3-blade or 19" 4-blade.

Boat is a 2008 Four Winns H200 with Merc 5.0L Alpha One Gen 2 drive (carb not MPI).

 

[Scott06]

Answer depends on how you use your boat if you ski and tube where the 4 blade performs best stay with that. I wouldn't expect the 3 blades stainless the act like a 4 blade aluminum.

 

[alldodge]

As you have found out, hitting an aluminum prop will in most cases damage the prop but not the drive. Hitting with a stainless prop can damage the drive. The inner hub of the stainless prop will give but not like the aluminum blade will.

As you noted, 4 blade is giving you less top end, due to increase drag (more blades). One prop can be great for one person, another person may be not agree. This is all about what you want/like.

Yes, match pitch no matter which way you go. Not always, but in most cases the stainless prop will give better performance over the aluminum because the blades are thinner.

 

[superbenk]

Everything I've read (including on actual prop manufacturer's sites) seems to say that the aluminum being safer with hitting something than stainless is a bit of a myth or at least overly exaggerated. They all seem to say that the hub slip is what's really protecting the drive & the only time it really makes a difference is on really severe impacts on which case lower unit damage is likely with either. Hard to know what to believe. I don't really boat where that's likely to happen, but you never know when accidents will happen...

 

[superbenk]

I spoke with PropMD & decided to go with a Michigan Wheel Apollo 4 (14 3/8 x 18). I like that they have a pitch-exchange program & if I'm really unhappy I can switch to a different brand paying the difference. The alternatives were either the PowerTech ELE4 or probably a Quicksilver Q4 from somewhere else.

Choosing a prop is a nerve-wracking & frustrating process if you're not right next door to a shop!

 

[blamtro]

Were barking up similar trees: http://forums.iboats.com/forum/gene.../10239928-3-to-4-blade-prop-81-searay-srv-207

 

[superbenk]

Been sorta following your thread too. I really liked having the 4 blades over vacation because I tended to always have more than a couple people in the boat. The extra blade kept me on plane at lower speed & helped with handling significantly. Really curious how going to stainless will be. Should find out sometime next week!

 

[harleyman1975]

Watch your tachometer and don't over rev your engine.