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Old 16 March 2013, 14:54   #1
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Country: USA
Town: Miami Beach
Boat name: T/T Premium
Make: Yamaha YAM480R
Length: 4m +
Engine: 50hp Yamaha Outboard
Join Date: Dec 2012
Posts: 11
Prop for YAM480R with Y 50G

Hi;

I was hoping any of the guys... or girls... on here, with a YAM480R with the 2-stroke 50hp Yamaha could give me some prop advice. I dented my original 11 1/8 x 13 prop and need to replace her and was wondering if anybody for one reason or another had tried another prop or a brand they'd recommend? iboats only has the Vortex and the Match in exactly the same diameter and pitch, the others are slightly different (ranging from 10 3/8 to 11 3/5)... no idea whether that would make any difference. These are aluminum I'm looking at because I am running under the assumption that 50hp doesn't really exert enough torque to change the pitch significantly, no? I do still want a good prop... ie not one that reads "ideal as a spare prop" as their prime marketing... anyhow; any advice before I order would be much appreciated...

Thanks! Peter
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Old 16 March 2013, 18:30   #2
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Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
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Do you have a tacho on the boat? Before changing the prop, you need to know what it's running at at WOT, based on normal load, and within the maximum operating rpm of your engine (great engine by the way). As a general rule of thumb an increase in 1" pitch will lower the rpm by 200-250.

Avoid the Yammie stainless steel props and stick to aluminium.

I'd also send your existing prop off to be refurbished.
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Old 16 March 2013, 19:07   #3
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Country: USA
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Make: Yamaha YAM480R
Length: 4m +
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Thanks for your reply. Unfortunately the LCD is half dead/ bleeding LC... and I'd rather have a new prop than dropping a couple of hundred on a new tach... wish I could do both... unfortunately most people around me have 4-strokes so couldn't borrow one... I can sort of make out 5|... I'm pretty sure it is 51 or 53... although hardly conclusive, would you then suggest dropping an inch in pitch...? speed range is 4500-5500 @WOT... also I loose 5.5 knots@WOT with 3 people vs only myself... not sure that's expected... didn't think to check rpms with 3...
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Old 16 March 2013, 19:51   #4
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Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
If you tend to head out fully loaded it might be worth changing it. Changing the prop may give you improved hole shot, but another prop may give you overall increased top speed, but its always a compromise depending on weight and intended use. Sure you couldn't change your digital Yammie tachometer for a cheaper analogue one? No point guessing, as you don't want over-rev the engine because you couldn't read the display!

Seems your engine can take quite a varied range of props (typical Yammie choice!)
10 5/8" x 12 pitch
12.25" x 9 pitch
11.75" x 10 pitch
11.38" x 12 pitch
11.00" x 15 pitch
11.25" x 14 pitch
11 5/8" x 11 pitch
11 1/8" x 13 pitch
11 3/8" x 12 pitch
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Old 16 March 2013, 20:03   #5
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Country: USA
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Make: Yamaha YAM480R
Length: 4m +
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I do know the right answer to that... guess I'll just bite the bullet... thanks so much for making me do the right thing... lol... with my luck I'd very soon regret not getting that tach...
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Old 20 March 2013, 19:44   #6
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Country: USA
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Make: Yamaha YAM480R
Length: 4m +
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Join Date: Dec 2012
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Well; I got the tach in today... pulled off of eBay for $51... an old but seemingly unused analog Yamaha tach; no oil level, trim or anything... makes my Rib look like it was made in the 80s imho, but it does the trick... WOT does not go beyond 5100 here either so I was thinking dropping the pitch by 2" but also increasing the prop size to 12"... from 11 1/8"... now I'm not sure whether prop size is determined by something other than the physical space limitation but I'd have room for it... I'm thinking dropping 2" in pitch would bring her up by about 400rpm though the larger/heavier prop would slightly limit the increase as well; hopefully preventing her from spinning beyond 5500... or am I pushing the limits here too much?... my current thoughts go out to a Michigan Match 12 x 11.

Thanks in advance

Peter
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