SO……

[Destroyer]

Originally Posted by charlie_the_tuna

We’re turning 5,200@22mph. I think the prop is 14X17. Don’t quote me on that. I’ll take a look tomorrow.

Book says 4500-5500 rpm @wot. So if you're running a 17P prop you're on the high side of the range.
Given that I would think it would be safe to go up to a 19P prop for testing. That will give you less rpms, but maybe more speed. 18P for a SS prop.

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[spareparts]

that bottom paint is whats killing your speed

[charlie_the_tuna]

Yeah, the paint is a big part of it. The aluminum prop is an issue as is the size and pitch. I don’t know how to figure out the right numbers and if I did… I couldn’t afford it anyway. When I pull her out, I’m gonna hit the hull with a super stiff brush and take off as much paint as I can. Then I’ll figure out what my next move will be.

[spareparts]

at those speeds, stainless steel isn't any help, its really not until you get into the 50+ mph range that stainless helps, its more of an issue with prop design than material. If you luck up and find one of the old straight back blade, black painted factory Yamaha stainless steel props, they are great for lower powered boats. You can pick them up used pretty cheap because they aren't pretty like other stainless props, check with your local prop shop. To give you an idea, my 17 Sea Hunt has a 150 Johnson V6 on it, spinning a 19 pitch prop 5200 rpm, I'm only getting about 44 mph out of it. It should be a rocket ship, but its not. The previous owner was a diving company, and they left teh boat in a slip with ablative paint. Its had a bunch on it. I've hit it with 80 grit on a DA, paint remover, and a pressure washer. I've got about 50% of teh paint off, and it helped(wouldn't break 40 to begin with). Every time I haul it out, I hit the bottom with the pressure washer, between that and sand bars, I'm slowly removing the paint. i need to crawl under it with a scraper at this point.

[Destroyer]

Originally Posted by spareparts

at those speeds, stainless steel isn't any help, its really not until you get into the 50+ mph range that stainless helps, its more of an issue with prop design than material. If you luck up and find one of the old straight back blade, black painted factory Yamaha stainless steel props, they are great for lower powered boats. You can pick them up used pretty cheap because they aren't pretty like other stainless props, check with your local prop shop. To give you an idea, my 17 Sea Hunt has a 150 Johnson V6 on it, spinning a 19 pitch prop 5200 rpm, I'm only getting about 44 mph out of it. It should be a rocket ship, but its not. The previous owner was a diving company, and they left teh boat in a slip with ablative paint. Its had a bunch on it. I've hit it with 80 grit on a DA, paint remover, and a pressure washer. I've got about 50% of teh paint off, and it helped(wouldn't break 40 to begin with). Every time I haul it out, I hit the bottom with the pressure washer, between that and sand bars, I'm slowly removing the paint. i need to crawl under it with a scraper at this point.

Soda blasting. Messy and it costs a bit but it works wonders for paint removing without hurting the glass underneath.

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[charlie_the_tuna]

Ok, numbers on prop are (I believe) 13X19. After running it a few times, the paint wore off. Almost looks stainless underneath. Weird that the paint wore off just from running it. We sure didn’t hit anything. Dying to get out there. Wouldn’t dream of leaving the dock on a holiday weekend. I took a shift with Wednesday/Thursday off for the summer so we could enjoy the water without the entire Italian navy and the Israeli fleet. Of course they’re calling for rain on W and T this week. I don’t give a sh!t! I’m going fishing!

[Destroyer]

Originally Posted by charlie_the_tuna

Ok, numbers on prop are (I believe) 13X19. After running it a few times, the paint wore off. Almost looks stainless underneath. Weird that the paint wore off just from running it. We sure didn’t hit anything. Dying to get out there. Wouldn’t dream of leaving the dock on a holiday weekend. I took a shift with Wednesday/Thursday off for the summer so we could enjoy the water without the entire Italian navy and the Israeli fleet. Of course they’re calling for rain on W and T this week. I don’t give a sh!t! I’m going fishing!

Good luck on the fishing. If you have a 19P prop and are turning close to max WOT then I would say to try a 13.5 or a 14 inch prop at 19P.

Hint... Check Craigslist for your area (NYC) under boat parts. You'd be surprised at the deals you sometimes find for props. I got a 4 blade 21P alum prop last year for my Merc engine for $100. Brand new, never been used.

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