pontoon prop question

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ando

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I have a 24' Sweet water pontoon boat with2- 23" DIA pontoons ( dry weight 1920lbs) with a f70a yamaha 4 stroke ( wot range 5300 to 6300 rpm ). Test weight with motor , gas , gear and 2 people is apx 2750 lbs. Prop #1 is 13 5/8 x 13 . WOT is 5400 to5600 rpm speed 23mph gps . Will not reach 6300 rpm . Prop #2 14x11 . WOT exceeds 6300 rpm , speed at 6200 rpm 19 mph gps . The boat and motor are new , set up looks good . What prop to try next . I noticed on most of the yamaha performance pontoon boat test they used the 13 5/8x13 prop and only listed 5400 to 5700 rpm's . All the info I read says you need to reach close to max WOT rpm,s . Thanks for any suggestions .
 
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steelespike

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Re: pontoon prop question

I think there is a reason they use the 13.It works!If you often run with a bunch of people you may have to consider the 11 or perhaps a 12. The motor developes its hp at 5800 The operation range is 5300 to 6300.A 12" prop could put you at about 5800 with about 22 mph. The 12 might have better slip numbers due to the slightly higher rpm.could make a little more speed.
I like the 13 with its respectable 23 mph.
 
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ando

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Re: pontoon prop question

If I tried a 14x11 or 14x12 dual thrust prop would it improve slip and reduce rpm,s ? How about speed ?
 
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lakegeorge

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Re: pontoon prop question

We had a 60hp 4stroke Yammy on the boat that we just traded in. It had a 14x11 prop, I believe, and our WOT was 21 mph by gps.
I think 23mph is the best that you can expect.
 
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ando

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Re: pontoon prop question

Thanks for the help . The 23 mph is better than expected , however I am concerned that 5400 to 5600 rpm is to low for this motor .
 
lncoop

lncoop

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Re: pontoon prop question

Kudos to you for providing so much info. That's pretty rare. It does sound like you need to try a twelve pitch. Let's hope that's the ticket, because where else is there to go?:confused::eek: Welcome aboard.
 
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steelespike

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Re: pontoon prop question

ando said:
Thanks for the help . The 23 mph is better than expected , however I am concerned that 5400 to 5600 rpm is to low for this motor .
Click to expand...
The Yamaha specs say range is 5300- 6300.If you generally run with a load of people then perhaps a 12 would be in order.
Considering the test reports; I don't think either prop would be wrong.
 
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