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Old 11 April 2012, 01:56   #1
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What propeller for a Yamaha F115 on Avon 620

as above, anyone now which stainless or alloy prop to put on a Yamaha F115 fitted to Avon 620? Any idea where from and price. Any help appreciated
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Old 11 April 2012, 09:49   #2
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Hi,

We use these on the Dry Stack for Avon 620 + Yamaha 115 4-stroke.

Propellers - Marine Tech

Hope that helps.
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Old 11 April 2012, 11:50   #3
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You really have to run the thing to know which prop to use.

Ideally, you'll rev to near the top of the suggested rpm range with a "normal" load (what you expect to run with usually) at WOT. You may need to balance the WOT rpm with hole shot depending on what you use the boat for.

I have an 18' aluminum hull RIB that's fairly beamy, and I'm running a Solas 4-blade SS prop spec'd at 13.75" (I think) x 15. I could probably stand to drop another inch in pitch, but that's not a standard size, and I haven't had the inclination to have the peop modified yet.

jky
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Old 11 April 2012, 12:34   #4
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On most of the other 20-ish foot RIBs listed listed in Yamaha's performance bulletins for the F115 they ran a 13x19 ali prop with a light load. Like this one:
http://www.yamahaoutboards.com/sites...an-f115txr.pdf

The avon is 330lbs lighter so I imagine would be a little faster. They used that prop on 18' Zodiacs with a max rpm of 6K too, so I don't think its will over-rev on your Avon. Based on these data I would start with a 13x19 ali 3 blade. The Yamaha props will have the same blade dimensions and area as those in the performance bulletin. Other brands 13x19 will vary in blade shape/area and you may overrev those. Since the Yam 13x19 operates at 6k on boats like yours I doubt using a different brand will result in under-reving.
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Old 11 April 2012, 14:05   #5
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Quote:
Originally Posted by Dry Run View Post
Hi,

We use these on the Dry Stack for Avon 620 + Yamaha 115 4-stroke.

Propellers - Marine Tech

Hope that helps.
what sort of top speed/fuel economy are you getting? thanks
speed with revs i.e 2000rpm = 3000rpm = 4000rpm = etc
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Old 11 April 2012, 14:12   #6
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Quote:
Originally Posted by captnjack View Post
On most of the other 20-ish foot RIBs listed listed in Yamaha's performance bulletins for the F115 they ran a 13x19 ali prop with a light load. Like this one:
http://www.yamahaoutboards.com/sites...an-f115txr.pdf

The avon is 330lbs lighter so I imagine would be a little faster. They used that prop on 18' Zodiacs with a max rpm of 6K too, so I don't think its will over-rev on your Avon. Based on these data I would start with a 13x19 ali 3 blade. The Yamaha props will have the same blade dimensions and area as those in the performance bulletin. Other brands 13x19 will vary in blade shape/area and you may overrev those. Since the Yam 13x19 operates at 6k on boats like yours I doubt using a different brand will result in under-reving.
i'm using a yamaha 13 x 19 ali prop and it goes straight to 6000rpm and i feel it is under propped. you don't get much extra speed between 5000-6000rpm?
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Old 11 April 2012, 16:59   #7
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i'm using a yamaha 13 x 19 ali prop and it goes straight to 6000rpm and i feel it is under propped. you don't get much extra speed between 5000-6000rpm?
Well you didn't say you had anything at all before...

Since you feel its underpropped why don't you try a 13x21"? Assuming the exact same load, that should drop you to 5600-5700rpm WOT. I would not expect much more speed with the 21", maybe 40kn. Once you have a starting point its all trial and error after that.
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Old 12 April 2012, 01:15   #8
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Originally Posted by captnjack View Post
Well you didn't say you had anything at all before...

Since you feel its underpropped why don't you try a 13x21"? Assuming the exact same load, that should drop you to 5600-5700rpm WOT. I would not expect much more speed with the 21", maybe 40kn. Once you have a starting point its all trial and error after that.
thanks, it could be the propellor has been re-profiled quite a few times since 2001 and just needs replacing like for like as maybe it's worn down? Getting about 41kn at the moment flat out, thanks for the suggestion and link.
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Old 12 April 2012, 17:08   #9
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I run a 21" on an F80 when cruising. Normally get 35kn at about 5,300 rpm one up.
Given the engine is 13yr old I would rather under rev it.
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Old 12 April 2012, 19:54   #10
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There are other F115s in Yamaha's performance bulletins but nothing matches quite as close as that Zodiac to your Avon.

At least over here people rarely fix ali props they just replace them. That said if the diameter is reduced via wear or repairs, that makes a huge difference on performance. As much as an inch+ of pitch IMHO.
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