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post #1 of (permalink) Old 05-14-2001, 09:54 AM
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OT--boat and prop size?

I have a 20' deckboat with a 200hp mercury outboard. I run 47mph at 6000rpm. The bottom end torque is awesome. I'd like to go faster top end and lower my rpm some. I run a 17 pitch alum prop. What pitch would be best--I want to get over 50mph and I think 6000rpm is too much for that motor. ?? I still need to be able to pull a skier or two also.

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post #2 of (permalink) Old 05-14-2001, 11:35 AM
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Re: OT--boat and prop size?

Dont remember my prop/pitch lingo. Id say try a 19 pitch and see what you get with that. Youll lose some low end but your top end should pick-up. You could also try a 17 with a stainless prop (pricey). I suspect your local prop dealer would let you try them out to see what works best for you. I run the volvo duo prop. Great out of the hole torque but lose some top end. I have an inboard 185 hp and can do about 50 mph empty boat, otherwise about 45 with 5 or 6 adults.

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post #3 of (permalink) Old 05-14-2001, 11:48 AM
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Re: OT--boat and prop size?

If you ever pull skiers or anything else behind your boat then don't go any higher than a 19 pitch 4 blade. If you just run flat out all the time with no need for towing anything you can run a 21 pitch 3 blade stilleto but it takes a long time to plane out.

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post #4 of (permalink) Old 05-14-2001, 02:10 PM
 
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Re: OT--boat and prop size?

Maximium torque for pulling a skier 'out of the hole' and Maximium rpms for high speed are two seperate props. The pitch of the prop control s speed and torque, and they are in opposite directions. As one increases, the other decreases.

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post #5 of (permalink) Old 05-14-2001, 02:48 PM
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Re: OT--boat and prop size?

Man, stop it with all the boat talk [img]/wwwthreads_images/icons/smile.gif[/img], I sold my boat at the beginning of last summer (whih ended up working out well since the drought dried all the lakes up) and I really miss going out and cruising the lake.

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post #6 of (permalink) Old 05-20-2001, 10:37 AM
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Re: OT--boat and prop size?

What you want is two different things from the same prop top end speed and bottom end grunt the only prop i know of that gives both is the land and sea torque shifting prop starts out at a low pitch than weights shift the prop to a high pitch as rpms increase thay are adjustable to shift points but thay are real expensive around $700.00 and they can shift as much as 4" outher wise just get two props one for speed and one for towing as for ss it wont flex as much as an alum prop so the pitch stays closer the set they also have thinner blades so the cut thru the water easer you will see a slight rpm rise with a ss prop in the same pitch now what does this do for your jeep ?

post #7 of (permalink) Old 05-21-2001, 09:30 AM
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Re: OT--boat and prop size?

Okay, this is somethingt I know a little about. I have the same engine as you do in my boat. I went with a 19 pitch stainless steel high five prop. It's $$$$$$$$$$ but worth it. I get plenty of tork for pulling toys, with the five blades it will really bite!! On top end I pull around 57 empty and around 52 with six people on board. I'm running a 20' run about. With the stock prop I was running about 50 empty and 45 with six people. Use your old prop for a spare! Good luck.

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post #8 of (permalink) Old 05-21-2001, 09:49 AM
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Re: OT--boat and prop size?

4 blade 24 pitch stainless... x2
Cruising speed of 60mph

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