Lake St. Clair Fishing Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
268 Posts
Discussion Starter · #1 ·
I have a 25' sundancer with the Bravo 2 oudrive and 350. The boat came with a 23p X 17.5 Alum prop from the factory. The boat gets on plane relatively easy but I would like to go a bit faster at cruising RPM (about 3100-3300). I am considering a SS prop or maybe a 4 blade. Any recommendations would be appreciated.
 

·
Registered
Joined
·
15,073 Posts
Generally the factory props are the best ones for the boat. There are issues going from aluminum to stainless. The blades behave differently etc.

I'm sure someone can produce a formula or something to show pitch and material changes. I would imagine you would need to know the horsepower of the engine and maybe the ratio of the drive.
 

·
Registered
Joined
·
9,917 Posts
QUOTE(Stodge @ Jun 10 2009, 06:59 AM) <{POST_SNAPBACK}>Generally the factory props are the best ones for the boat. There are issues going from aluminum to stainless. The blades behave differently etc.

Not always the case. Usually when a boat is propped its propped with the idea of balance in mind - a balance of speed and planing times and is decided by what the manufacturer thinks you need. However, you can definately change the prop pitch a little to get the results.

Trust me, I had 3 or 4 different props for my first boat and each one produced a different result. One would get on plane very quickly but I'd lose top end mph (was nice if I had more than 3 or 4 people on board - would plane quick). The other one would take longer to get on plane but I could go 40mph+ (was nice if it was just me and Brian).
 

·
Premium Member
Joined
·
18,804 Posts
Aluminum flexes and is alot less efficient than Stainless. Stainless is stronger (hence less flex) has thinner blades and is more efficient cutting through the water. It is also harder on your lower unit if you hit something. If you hit something with aluminum, the prop will absorb most of the impact, opposite happens with stainless.

Being that we have MOSTLY sand in this lake, go with a stainless. You may want to get a higher pitch prop to increase your speed at cruise. But you willsacrifice holeshot.

There are aftermarket props that "shift" pitch based on your RPM's. Not very reliable though.

Best thing to do is contact the boat manufacturer as I am certain tests have been conducted with different props. Also a good dealer will have some test props that you can "borrow" before you purchase.

Good luck.
 

·
Registered
Joined
·
65 Posts
QUOTE(Sloppy Saturday @ Jun 9 2009, 09:00 PM) <{POST_SNAPBACK}>I have a 25' sundancer with the Bravo 2 oudrive and 350. The boat came with a 23p X 17.5 Alum prop from the factory. The boat gets on plane relatively easy but I would like to go a bit faster at cruising RPM (about 3100-3300). I am considering a SS prop or maybe a 4 blade. Any recommendations would be appreciated.

Stainless is better than Al in all cases. The 4 blade vs 3 blade will give u more acceleration and transom lift. At those RPM a stainless Bravo 1 four blade shouldbe an improvement.

Use this calculator to figure your slip so you can see how poor your current prop performs.
http://www.go-fast.com/Prop_Slip_Calculator.htm

On our race boat, which we spend ungodly $$ on props, are at 6% slip.
 
1 - 6 of 6 Posts
Top