Replace Yanmar YSE12 with YSE12G?

[Orcades]

I'm looking to replace my Yanmar YSE12 (which was stolen) with a suitable replacement engine. Would the YSE12G be a good replacement?

It's for a 30ft narrow fibreglass cruiser which is used as a live aboard

Here's the tech sheet with info on both: http://www.powerequipment.com.au/wp-content/uploads/2014/05/YSE-BROCHURE.pdf

they're identical apart from YSE12g has a 3:1 reduction ratio (980 propeller shaft rpm) vs 2:1 (1518 rpm). Wondering how much slower this would be and if the current prop set up would be suitable for it?

If not I'm wondering if anyone has any suitable suggestions

Thanks

 

[neil_s]

I think you would be disappointed if you kept the original prop. Maybe half speed? The new engine wouldn't be very happy, either, since it would never get to do some proper work and you would have to listen to it racing away while you don't get very far. You need to check that there is enough space in the propellor aperture for a bigger prop before going ahead with this. I did a quick check on my own boat and found that I would need to swap a 16 inch diameter prop for a 21 inch to match the new gearbox ratio. A plus point is the new engine and prop would be more efficient.