might not be the right place to ask this, but feel a bit more at home in here!
Help! can't work this one out at all at all
43 foot 6 boat. think I'm wrongly propped. 120hp ford lehmann, 1.5:1 box, max revs we can get is 1600, engine is rated max revs 2750 (cruising 1800)
at max revs we can get, slack water, no tide/current to push, we get about 6knots
previously she had a Kelvin k3 66hp at 300revs, dunno about box though, think the kelvin boxes were 1:1??
I have a suspicion that when she was re-engined they retained the old shaft and prop, been trying to do the sums to see if it is a logical conclusion that the big old kelvin prop for those revs would hold her back that much?? does that sound logical?
other alternative is I suppose there's a governor on the engine (how do they work then and where are they and how do you remove them!)
hull speed should be 9-10knots or so (I think!)
any ideas?? what should she be swinging with the ford at 2750 revs
she's coming out the water shortly so I'll be able to see what she currently swinging
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Converting a Converted MFV Fifie.
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any prop calc boffins out there??
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