BobTidy

Ok thats intresting, the current set up could get an alternator to 4200 revs with the motor at 1500 which it might have just managed 50 years ago but would probably self distruct just after everything in the rest of the boat jumped out of the cupboards! Its a wonder I get any charge at all the curent alternator probably never betters 2000 revs and spends most of its time about 1400!!! Ok time to own up I know a woodrough key when I see one (even if I cant spell it) but whats a Dutch key please? It looks like the flywheel with or without a additional pully is required.

I think more output for not to much money I have 1 start and 2 leisure totalling 330 amp if my memory serves. New mountings is not a problem the old ones are bolted to the oak engine bearers and look like they came out of a scrap box. The existing pully is 7inch and behind the flywheel and not practical to change (and takes a 5/8 belt with a bit of oil compliments of the crankshaft oil seal! Would a flat belt run on the flywheel? its 20i x4 inches and unlikly to ever exeed 1000rpm.

Thank you all, for all the information, I now have to admit to owning a Lucas alternator that when last attended to (about 10 years ago) the auto electrician said was built about 1970 and once he cleaned the oil out, it worked ok, until I bought a new fridge! I think an alternator controller may not get blood out of a stone, so I now know, I need a replacement making over 14 volts and nice new, and fat wires. Two questions if I may, 1/ any recommendations for a vehicle sourced replacement alternator please? 2/ as my motor is a 1051 Bolinder just how fast should an alternator spin? I’m beginning to think a belt of the flywheel might not be too far out. Bob Tidy