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Old 20 July 2010, 08:07   #1
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Country: UK - England
Town: Dartmouth
Boat name: Soggy Dollar
Make: Ribeye
Length: 6m +
Engine: Yamaha F100
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Posts: 3
Ribeye A600 Yamaha F100

Hi there, first post on this forum, but I've been watching it for a while. I've got a query about propellers, we currently have a Ribeye A 600, with a Yamaha F100. she's a lovely boat, and handles really well, but at the top end with three people and a bit of kit onboard 3/4 full tank of fuel, 25l extra onboard too, she'll achieve 35.6knts which is the maximum recorded by the Garmin 550s chartplotter. Now the current prop is standard, and we are looking to upgrade to a Stainless Steel jobby, ideally trying to get a bit more from the top end too. any suggestions on sizes or even how to work out what would be best would be greatly appreciated!

Thanks, Alex
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Old 20 July 2010, 08:52   #2
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Country: UK - Wales
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I don't expect you'll get a lot more top end than with your current prop.
What RPM are you hitting at 35.6kt, with this set-up?
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Old 20 July 2010, 10:02   #3
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Country: UK - England
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so would increasing the prop size have any effect on this? or a different pitch? that was at about 5500, it will rev to 6000 but we try to keep below that.

Thanks Alex
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Old 20 July 2010, 11:12   #4
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Originally Posted by ay4alex View Post
so would increasing the prop size have any effect on this? or a different pitch? that was at about 5500, it will rev to 6000 but we try to keep below that.

Thanks Alex
So how do you figure "max speed" if you are not going to firewall the throttle? It's either "max speed the boat/motor will do", or "max speed you're willing to take it to".

The latter makes it kind of hard to apply any kind of selection criteria for choosing a prop (not that it's a whole lot easier with the former, but still...)

Just wondering;

jky
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Old 20 July 2010, 11:14   #5
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Country: UK - England
Town: Dartmouth
Boat name: Soggy Dollar
Make: Ribeye
Length: 6m +
Engine: Yamaha F100
Join Date: Jul 2010
Posts: 3
35.6 is the max it can achieve at WOT, sorry I worded it incorrectly before!
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Old 20 July 2010, 16:00   #6
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The more important figure is the rpm it's turning at WOT, after trimming up to find the max before it starts ventilating. Flat water is best for this. Once you get the pitch close, then you can start testing props for max speed (which I personally find kind of irrelevant except as a bragging point, as any significant swell or chop usually has you off the firewall anyway.)

jky
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