Stainless vs Aluminum

[starcrafter]

I know there are probably countless discussions about this but I am wondering if a Stainless prop of the same diameter and pitch as an aluminum will have more top end speed and if so, approximately how much more speed? My boat came with a 14.25?x 21 alum. prop. I can hit my limiter at 5400rpms and do approximately 54mph with 1 person and 1\4 tank at wot. I have tried a 14x23 alum and had about the same top speed and could only get about 5200rpm and the engine just didn't sound right with the 23. I want more top speed for everyday boating. I don't pull tubes or skiers alot so I could just put on the 21 alum for this. Would a stainless 21 give me 5400rpms but more top speed?

 

[Spidybot]

Re: Stainless vs Aluminum

If you could get a prop that had less slip and thinner blades to allow easier pass through water it would PROBABLY give another mile on the top.<br /><br />You are at the edge of theories so testing is the only way. Trimming, load redistribution, hull polishing etc. - and testing props! <br /><br />If you like here's all you wan't to know: Downloadable free book

 

[starcrafter]

Re: Stainless vs Aluminum

Thanks for the reply. I would like to find out as much as possible before potentionally laying out the big bucks for a stainless. There is a prop shop I have dealt with before that will let you try out props but I would like to narrow it down as much as possible before I demo.

 

[Doug Durako]

Re: Stainless vs Aluminum

Starcrafter----In my experience of running both stainless and aluminum on two different rigs, stainless will add 3 or 4 mph on the top end, but you'll still have the problem of over-revving with the same pitch steel prop. Also, if you are trimming out too far, you will lose speed and over-rev.<br /><br />Isn't the max rpm on your motor supposed to be about 4800? A 23 pitch should drop you about 400 rpm (200 drop for every inch of pitch increase).<br /><br />Stainless is expensive at first (don't get the cheap ones), but I run the rivers and I was spending $75 or more every year to rebuild at least one aluminum prop. I've never had to rebuild a steel prop, but the downside is, if you hit rock or metal, you will do serious damage to your lower drive.<br /><br />Hull design also has a lot to do with speed. <br /><br />If you can borrow some stainless props from a prop shop or a buddy boater, testing is the only way to know.

 

[Bondo]

Re: Stainless vs Aluminum

I'm with ddboater, You're Way Over WOT.... <br />If you don't get that motor down below 5000rpms, You won't Need a Prop.... You'll need a Motor....

 

[chads15]

Re: Stainless vs Aluminum

I think your tach may be giving you a false reading. or maybe a miss typed key. But, If it is a true reading your RPM's are way too high. Full Throttle RPM Range: 4400-4800. A A SS prop will give you a fiew more MPH. But less Insurance if you hit something..

 

[starcrafter]

Re: Stainless vs Aluminum

Sorry about the delay, thanks for the replies. My email is not alerting me to new replies so I may have asked similar questions in another post.<br />I will have to double check my tach as it seems i am getting a false reading. My engine does have a rev limiter so I don't think I will harm my engine by over reving because I back it down or trim down if I do hit it. It doesn't happen very often. This boat usually comes with a 4.3 and I am wondering if the sending unit or tach is for a six and not an eight. Just a thought. I'll see if the dealership can confirm