I have a Sea Ray 240 BR with a polished aluminum 17p prop. It has plenty of torque down low for pulling skiers and tubes, but I'm running ~46mph at 4900-5000 rpms. I know thats a little high on rpms for a 5.7, so my question is what would be my best choice for a prop to bring the WOT rpms down a tad and gain some top end speed? I was looking at a 23p stainless prop, but worried it may be a little too much. Thoughts?

23" is way too big.

How many blades on your 17" ??? If you keep the same number of blades and style of prop, then go with a 19" aluminum or 18" SS. Both of these should reduce the rpms by about 400.

mine is a 3 blade

magnum 350 , i have a 24 cuddycabin also with a 350 mag,running a 23p quicksilver 3 blade @5200rpm@52 mph.i am looking at going with a revolution 4 blade 23p to bring rpm down .you should have no problem turning a 23p 3 blade.mirage plus would be my bet for top end gain

OK, somebody's got to ask. What's a "polished aluminum" prop? Aluminum props are rarely polished and usually just painted. Stainless steel props on the other hand are quite frequently polished.

The reason I ask is that Aluminum and SS props of the same design and pitch behave quite differently.

Too little info here.
Which 350 do you have?
Year of motor?
Dia. of the alu prop?

It's really hard to say anything exact based on your current info.

Doubtful... Not trying to get into a pissing match, but unless you have a bunch of motor work done or your RPM gauge is way off I highly doubt it. Friend of mine has the same boat as me, 23' Mach 1, his has a 350 mag and runs a 19p Laser at 4900 at 52mph, I have a 454/330hp and can run either a 22p Bravo 1 4-blade at 4700 or a 23p Mirage (not plus) 3 blade at 4800 both at 58-60mph. Sorry, but I'm having a hard time believing you run a 23p 5200 at 52mph. I could very well be wrong, but...

Magnum- if I was you I'd try both a 19p and 21p 3 blade, although I would think the 19p would work best for you all around. I would think it would give you decent lower end for pulling people and get your rpm's down 2-300. I think the 21p would work also, but pulling people would lag and top end would get you a little low in your rpm range. If you're interested in a 21p Stiletto (stainless) I'd be willing to sell it. But like I said, and I'm sure others will chime in also, I think the 21p will be too much for your motor. Just my $.02...

I was mistaken. It is a quicksilver stainless prop that is polished to a dull finish.

1994 model....
350 mag w/4barrel carb. I think its rated at 270hp?
not sure of the dia. as I havent had a chance to measure it yet.

4900-5000 is not running really high r.p.m.s. I twisted the 350s in my Chris Craft Stinger to 5200 - 5300 (I did have Crane Cams and a few other mods). My thinking is just switching to a stainless prop will probably lower your wide-open r.p.m.s as they flex less. Going up two inches in prop pitch would drop you back at least 400 r.p.m.s. or more. I'd be tempted to talk to one of the prop shops that support this forum. They have a loaner program. Paying for a little freight is a lot less than buying the wrong prop!