going from AL to SS prop

[flashback]

I want to go to a SS prop on my 210 scorpion (merc pre alpha 350 V8). I currently have a mich wheel prop, model 031052, which is 15 1/2" by 18" and has a quite aggressive cup to the blades. the boat runs about 46 mph at 4300 rpm, which seems pretty good. here's the question. it seems all the SS props I have seen are smaller in diameter. 14 1/4". If I go with the smaller diameter then i would most likley need more pitch. how much is the question..

 

[rickdb1boat]

Re: going from AL to SS prop

Flashback,<br />I would go with a 14 1/4" X 19" prop with the same cup. That should put you in the same ballpark as before, as long as you are running at or near recommended WOT Rpm's.

 

[sloopy]

Re: going from AL to SS prop

4300 sounds a little low to me.... whats the engines recomended rpms?

 

[Bondo]

Re: going from AL to SS prop

First Off, Don't Worry About the Diameter..!!!! You have NO control over it, the prop engineers have it All Figured out for you...... dia. is determined by many factors... pitch(more pitch= less dia.), blade style(larger area vs. smaller), base metals(alu. flexes vs. SS doesn't) etc. etc. etc. <br />That said,<br />Stainless props Don't Flex anywhere Near as Much as an aluminum... so you Don't want Any More Pitch.... you're already loading the motor down to 4300rpm... that's at the bottom of the "ideal" range(4200rpm/4800rpm) of your power package....I'd think you should be starting at about 17" on a round-eared, 3 blade prop.... you May want to try a 4 or 5 blade... depends on what you need it to do...try to find a dockmate that has a prop in this range, maybe you could run seatrials with a borrowed prop... Then go buy the one that works the best on your boat...<br />Try to find a Good prop shop... they can explain this better than i can type.....<br /><br />Good Luck.....

 

[Jack Shellac]

Re: going from AL to SS prop

The conventional wisdom is that you drop an inch in pitch when you go from Al to SS. That's assuming you were at the correct upper end of the RPM range to start with. As evryone will tell you, propellor selection is a tricky business with no set formulas that will work out right every time. A good propellor shop is your best starting point, in case you need to to return your trial prop.

 

[flashback]

Re: going from AL to SS prop

thanks for the info folks, guess Ill do a little more research and see what happens......actually I'm satisfied with the current performance of the boat, just heard so much hype over the years about how much better a SS prop is.. this boat has a terrific hole shot now, almost too much..it practically jumps out of the water. so I don.t think I want to go down in pitch but I guess what I need to do is find a shop that will let me try several different combos...... anyway thanks again...................