Prop size

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Chet Garling

Chet Garling

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I recently upgraded to a 26' tritoon with a 220 hp volvo penta, my boat will only do 26 mph at 4100 rpm and it will only rev up to 4500 rpm, do I need to go up or down in pitch, on my old 19' I remember I got better top speed with a 19 vs the 17 I used to pull up skiers. Also anyone with a similar tritoon that can give me an idea of how many gallons per hour I can expect, unless we had our tank siphoned we used 40 gallons in 4 hours doesnt seem right. Will a prop that I had on my old mercruiser A1 outdrive fit a volvo? Thanks for any help, can't wait for impending retirement to get here so I can spend more time on the new boat.
 
When submitting your question, be sure to state the make/model/year of the boat. The exact engine and which outdrive you have. If you don't list those, I guarantee that will be your first response.
 
40 gallons in four hours turning 4100 is about right. You got 2.6 miles to the gallon. Is it a stainless prop or aluminum and what manufacture. 220 hp for a 26' footer is a little low especially trying to get any speed out of it. Is 26 by the speedo or gps? Chet call me with more info. Peter
 
A typical v8 will burn between 18-22 gals an hour at wide open throttle. Turning 4100 and only burning ten gals an hour is not bad. Most boats get 3 to 4 mpg at cruise which is typically 3,000 to 3600 rpm.
 
I agree that you need to know what WOT RPM is on that motor. Is that the 4.3 EFI motor, or the 5.0 carbed?

You need to be at the right RPM, or going up in pitch (what you would normally do to get more speed) won't help because you can't reach the right RPM.

Volvo and Merc usually require different hubs for the prop. You might be able to change the hub out to use your old prop on your new boat.
 
It is the 5.0 carb and should be around 45-4600. So prop looks right I should be able to go down the weekend after next and will get a more accurate reading on the fuel usage, since I will start from full. Thanks for all the help, now on to the electric motor and Ipilot.
 
Do you know what leg is on your boat? Sounds like a single prop setup. I've heard on the Volvo forums of some folks being able to switch out the lower half of the leg for a Duo-Prop setup. Just depends on what you have to start with.
 
Chet, if your a single prop you may want to go to a 4 blade, a 5 blade will help with the hole shot but you burn more GPH cruising, also loose top end. depending what your pitch is, going up will lower your RPM, about 450 per 2" of pitch, or raise the opposite way. going to a four blade of the same pitch will lower your RPM by about 100-150, so if you have a 14.5x19 pitch, and are getting the 4500 RPM I would suggest a 14 x 18 4 blade and you should see 4700RPM wide open. its all a trial and error guessing game for someone like me. its a fun science, the guys at Hill Marine out of California are probably the best in the business and can suggest some great props and custom machine anything.
 
Surprisingly, props are huge in performance/gph and a fairly expensive trial and error process but a big difference.
 
I just put a new 4 blade, 17 pitch on my Glastron for use at CO altitudes... My boat has the VP/SX Combo, although rated at 305HP.... it's made all the difference trying to move around the tubes, and pull a champion HWT wrestler up on a wakeboard... when we get to high speed and fishing, I've lost some top end speed, but fuel burn is EXCELLENT.

Be careful however as others have mentioned. Regardless of the prop, if you exceed MAX WOT RPM, really bad things can happen! - In my case, if I am just cruising across Crawford reservoir, I can hit almost 400RPM over max WOT.... so you have to watch for sure.... I could never run this prop at LP, but will be buying a 4-Blade 19 Pitch for sure...
 
broski said:
I just put a new 4 blade, 17 pitch on my Glastron for use at CO altitudes... My boat has the VP/SX Combo, although rated at 305HP.... it's made all the difference trying to move around the tubes, and pull a champion HWT wrestler up on a wakeboard... when we get to high speed and fishing, I've lost some top end speed, but fuel burn is EXCELLENT.

Be careful however as others have mentioned. Regardless of the prop, if you exceed MAX WOT RPM, really bad things can happen! - In my case, if I am just cruising across Crawford reservoir, I can hit almost 400RPM over max WOT.... so you have to watch for sure.... I could never run this prop at LP, but will be buying a 4-Blade 19 Pitch for sure...
Click to expand...
Good thing about Crawford is, you can't stay at wot very long
 
Chet, you can't mix and match mercruiser props, with Volvo Penta props, the splines will never match up. And the advice of converting your outdrive to a dual prop, you cannot push a dual prop with the 5.0, it just won't have the power to push duals, and you'll roast the engine.

I recently sold a boat, that had a similar engine to you, except mine was fuel injected. I ran a 19 pitch for fishing/cruising, but would switch to a 17 pitch for watersports. I was within specs of peak rpm's with the 19, but it just didn't have the torque to yank a skier out.....so the 17 was a great option. It sounds like just dropping 1 pitch in prop will have you in a good range, especially if you get a 4 blade!

@broski what motor are you running on that Glastron that is rated at 305 hp? Are you sure it's not 205 ? A 17 pitch seems extremely low for a motor pushing over 300 ponies! I have a 350MAG on my Rinker, and that motor is 300 hp, and I'm running dual 24's on the Bravo 3 drive. That setup will also pull a skier at Flagstaff elevation (7000 ft)
 
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