aluminum vs. SS

[Cruzomatic]

I own an '05 Caravelle 207 w/ volvo 220hp I/O my WOT is about 4700rpm running 50mph with GPS. I currently have a 14.3 X 21 aluminum prop on there. The stock prop is a 14 1/4 x 21 and the 14.3 found its way on there when my dealer bent it during my test drive. My question is would changing to a 14 1/4 x 21 SS increase performance, overall, speed and holshot? We mainly use the boat for "cruzing" and water skiing/towables. <br /><br />Thanks,,,,

 

[Silvertip]

Re: aluminum vs. SS

The slight change in diameter will not provide any significant change either way. When you switch prop material (aluminum vs stainless) you very likely change prop design as well so there are two factors that come into play. Two props can have the same diameter and pitch but have different blade designs (rake for example) so one may perform much better than the other even though they are both aluminimum, both stainless, or one stainless and one aluminum. Generally, changing prop pitch provides the most significant change. More pitch might provide better top end but you sacrifice hole shot. Less pitch generally provides better hole shot but you risk over reving on wide open throttle. Happiness is when the engine runs at the upper end of the manufacturers recommended wide open throttle RPM range. You are close to optimum and in fact might be just a tick on the high side for WOT RPM so you might look for a SS 22" pitch prop. Should bring the revs down a tad and it may not affect hole shot. Check with your dealer -- sometimes they will provide some props for you to try (with a deposit of course to ensure you bring them back).

 

[Cruzomatic]

Re: aluminum vs. SS

Thanks for the response.

 

[walleyehed]

Re: aluminum vs. SS

If it's a tad high with aluminum, a good quality SS will drop it some in the same pitch..may only be 100RPM but a 22 in SS may be like running a 23 in aluminum.

 

[Texasmark]

Re: aluminum vs. SS

Hey Cruz,<br /><br />Back in '72 I bought an 18' Caravelle open bow trihull with a 125 Johnny, turquoise in color. The family and I had some really sweet times in that very pretty boat. Named it Squirrel for obvious reasons, but that was before the days of the monster engines we have today. As I recall, with a ski prop on it we did 39 tops. I may have seen 41 once or twice in the winter with a tail wind. Grin.<br /><br />Mark<br /><br />Mark

 

[Texasmark]

Re: aluminum vs. SS

Back to your topic. The prop was one of the new then OMC SS. I had several aluminums on it and seems we couldn't go out one time without dinging a blade on a tree stump or something. After buying the SS never had the prop off again.<br /><br />Mark

 

[Cruzomatic]

Re: aluminum vs. SS

But will the SS help my performance with the 14 1/4 x 21?

 

[Cruzomatic]

Re: aluminum vs. SS

I guess what I'm asking is,,,,if I put a SS on there will it help with overall top end speed and holeshot? I'm not really interested in going fast, just don't want to 'hold' back the performance of my boat staying with the stock aluminum prop.

 

[walleyehed]

Re: aluminum vs. SS

The best answer to your question is Yes, the SS prop will be more efficient than an aluminum prop. Picking the correct one is the tough part.

 

[Texasmark]

Re: aluminum vs. SS

I agree on both points. I vaguely remember getting improved performance with the ss. Certainly longevity of the blade integrity improved.....didn't ding it up every time.<br /><br />And since you are changing technology (going to ss), picking the right prop is the bummer. Best if you could talk a dealer into loaning you a prop (or 2 or 3 just for the test...promise to not ding them) just for a quick run on the lake to see if it is right for you. That's the only way you will really know and you may have to compromise at that. Like I did when we used to ski all the time. I propped for the skiing and it cost me top end. That really wasn't ok cause I liked to run flat out when I was playing, but I didn't like to be swapping props all the time and stayed with the single pitch....besides we were raising 4 kiddo's at the time and I was lucky to have a boat and one ss prop. Grin.<br /><br />HTH<br /><br />Mark