Yanmar1GM10

[JohnL]

Hello, I am considering buying a Centaur with a recently fitted Yanmar1GM10 with a 3.22:1 reduction. I have been told the boats speed under power is 4 knts. and the engine is not labouring,would a larger dia/pitch prop increase speed? or am I asking to much of the engine? Would a larger prop affect sailing performance? Thanks for any advice. John L

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[steve28]

I would have thought you should have got at least 5 knots, on my 1gm10 with the same ratio box and a 14 x 11 three bladed prop i got 5.8 knots this is on a 24 foot triple keel boat.
What size of prop do you have at the moment ?

steve

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[JohnL]

HI Steve Dont know present prop size but present owner thinks she is under proped

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[snowleopard]

don't change the prop until you have tried it out. if when you open the throttle fully it goes straight up to max revs you are under propped so can consider a larger or coarser prop. if however it takes some while to get up to max or struggles to reach it at all then you prop is big enough.

the 2 & 3GM engines are rated at max continuous revs 3,400, max intermittent 3,600 and are governed at 3,800. i don't know if the 1GM is the same but for this set of figures the prop size should be such that the engine will just make it to 3,600 at full throttle.

for best sailing performance you need a folding or feathering prop. they aren't cheap, 4-10 times the price of a 2-blade fixed so you've really got to want that extra 1/2 knot badly.

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[JohnL]

Hi, Snowleopard the boat is on the hard I believe,hopefully I will be able to get down to Essex on Monday to see it.The owner says the engine rev's up easy under load.In PBO.the expert says the max.continuous rating is 3400 but I think the gear ratio my be unusual

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[toad]

I would think a 1GM10 is a bit marginal on HP for a Centaur and 3:22.1 reduction not ideal for a sailing boat in this size range.

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