Deciphering prop numbers

[NWhippie]

I think my boat may be underpropped. The previous owner did a lot of Columbia River bar fishing and I'm wondering if maybe he put a non standard prop on so he could slow troll. The numbers I get off the current prop are: 25041 and 19324.

I'm not entirely sure of the 4 in the first set of numbers as there's a little scuff right there. When I'm at WOT, it's turning around 5500 and I'm only going between 23 to 26 mph. This boat should go close to 40 if what I've read is correct. Cruising at around 3300 or so, I'm only going around 12 to 15 mph and pushing water like a tug. My mechanic told me not to cruise above 2500 RPM and at that rate, I'm only going about 7 - 10 mph. I've tried positioning the tabs in various configurations with no appreciable difference. Also trimming out the drive does help a little but pushes my bow too high. I do fish but getting from point A to point B quick is my first priority. According to the Sea Ray site's prop chart, I should be only at 4600 at WOT and a prop size of 17.5 x 23. Any suggestions for a higher top end speed?

Thanks,
Ed

 

[Nehalennia]

Call John at The Prop Shop
He'll set you straight. Yes it sounds like you are way overpropped allowing your engine to run too high.

 

[Sundancer]

Is there any hint of burning rubber when revving her up? I'd try what Todd suggested and then see if you can borrow a prop from a local prop shop. That will give you a benchmark to determine if you need to go up or down a notch.

 

[NWhippie]

Heck yeah there's a burning rubber smell! But only when we're goin' (for my boat) fast. I've been complaining about it since I've had the boat. I thought coupler, prop pack, belts or hoses. Mechanic checked all and found nothing irregular. Ya think I'm spinning the prop? Would I smell that even though it's underwater and going away from me when I'm planing?

Ed

 

[Sundancer]

NWH, I'd definitely start with the prop first. I'd go with the Sea Ray recommendation for now. You can take your current prop in and have them check the hub, but you should get a spare prop anyway. They should be able to tell you what the diameter and pitch are. After that is done, you can report back with the results to see if that cured the problem or made any difference at all.

Good luck!!