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Old 24-01-2018, 15:56   #1
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Propeller advice

Hi, I have a 26 Folkboat with an 8hp yanmar and offset shaft.
It has a fixed 12 two bladed prop at the moment. I have just seen a Hydralign three bladed feathering prop for sale at a reasonable price.
My question is would this be a suitable change over ?
Cheers Tom
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Old 24-01-2018, 16:14   #2
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Re: Propeller advice

The Hydralign three bladed feathering prop will most likely give you better motoring and better sailing performance compared to your existing 2 blade fixed prop ASSUMING
1. The diameter of the Hydralign prop is suitable for your prop aperture (and engine).
2. The rotation is suitable. I guessing your existing Yanmar is either a Y or an S series engine and these require a LH prop while most later engines use a RH prop.

The two main advantages of the Hydralign will be better pitch control (i.e. adjustable pitch) and lower drag when sailing.
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Old 24-01-2018, 16:33   #3
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Re: Propeller advice

Quote:
Originally Posted by Windward mark View Post
Hi, I have a 26 Folkboat with an 8hp yanmar and offset shaft.
It has a fixed 12 two bladed prop at the moment. I have just seen a Hydralign three bladed feathering prop for sale at a reasonable price.
My question is would this be a suitable change over ?
Cheers Tom
First off I'm not a propellor expert but you need to find out a few things. Is the shaft size & taper the same? Also the the pitch & diameter if it's not an adjustable pitch. The pitch & diameter can be altered by a prop shop but you need to price it first. Small differences in diameter/pitch make a big difference to a Yanmar 8hp. I'm going thru the same process with our Yanmar YSM8. Have already changed props ( it was a gift) but we are over-propped.I am soon to try re-pitching it myself. You know yours is a left hand prop I assume? They are less common. Our replacement is a r/h prop but we are using reverse as fwd. Yanmar rep said that was ok. Our 26ft fin keeler calls for a 12" dia x 7" pitch L/H prop according to the free Vicprop online calculator ( Google it). We have a 1" prop shaft, dont know what the taper & keyway size is but you should measure yor shaft for a start. Hope that points you in the right direction anyway.
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Old 24-01-2018, 16:56   #4
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Re: Propeller advice

I should add that like Compass790, I also am not propeller expert and he made some good observations.

After looking at the Hydralign website, it seems their props might work as either LH or RH but it would be good to get confirmation on this aspect.
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Old 25-01-2018, 20:41   #5
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Re: Propeller advice

Thanks for the advice, interesting about running the engine in reverse for a right handed prop. Can this be done as a permanent solution with no repercussions?
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Old 25-01-2018, 20:50   #6
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Re: Propeller advice

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Thanks for the advice, interesting about running the engine in reverse for a right handed prop. Can this be done as a permanent solution with no repercussions?
Generally speaking - no, most gearboxes won't like it.

However occasionally it is possible, see this recent thread
Folding prop question
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Old 26-01-2018, 00:09   #7
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Re: Propeller advice

Well the Yanmar rep said I can run using reverse but I'm basing my use of it by examination of the gearbox & clutch drawings & my memory of it ( not to be relied on! ) when I had it apart. This only applies to the Kanzaki gearbox supplied with the YSM8. Re the prop u wanna buy as Wotname has said it's variable pitch so that can compensate for diameter somewhat.Also his suggestion to contact the manufacturer is good as some of the variable pitch props have inserts that can compensate for differing shaft sizes & tapers. Personally I'd love a variable pitch prop, best of all is one you can change whilst in motion. Dreams are free :-)
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