Re-engining my Kingfisher 30

[DaveS]

On the point about alternator load with smart regulator. A cheaper solution than a bigger engine is to fit a switch in the feed wire to the smart regulator. It can then be temporarily disabled if there is difficulty getting the engine to rev up.

 

[DGuthrie]

Hearty thanks to one and all. This from an experienced sailor friend of mine. He reckons that 16 - 20 hp should be adequate for my boat, reckoning that she's a 4-tonner (8624 lbs being 3.85 British tons @ 2240lbs per ton). Interesting that there's so much scope for argument, all rational. An article he sent me from a source (unknown) was to reckon on 3hp per ton. The article cited a 22-tonner running with an 18hp unit "to give her a speed of 5 1/2 knots in quiet weather". So go figure!
Responses on this thread havebeen nothing short of excellent and informative. I still don't know what I'll fit, but at least the discussion has left me feeling more confident if I end up at the bottom end of the hp range.
Again, many thanks one and all.

 

[SHIT]

Can I just say that you should go for the Beta BD722 20hp. I have a similar size and weight boat with a 13" folding prop and I dont have problems!. Can i suggest you talk to Beta and have you thought about a 3 bladed prop!

 

[DGuthrie]

Milmar ~ Thanks for the suggestion. The boat had, in fact, a 13" (or maybe it was 12.75") 3-blader, but left-handed. I'm in touch with Beta, actually, but they don't have a registered fitter in this area. Since my surveyor was quite clear that the boat needed "10hp plus a 25% margin" and he's on the RINA Small Craft Committee (I now know) I'm inclined to go with that. But you're right, 20's beginning to sound about right. What amazed me about this business was that there was such a range of sizes when it came down to what I needed! Much appreciated, though.

 

[sailorman]

my Co 32 had a yanmar yse 12.
this was not enough power in a seaway

min requirement you need is 18 > 20 hp imho