I understood continuous duty to mean not only an ability of the engine to
run reliably for extended periods at full load but also that all the
metalwork, fittings etc are of a superior standard. Hence the cost.

I may be wrong here but I seem to recall that running engines off load or on
reduced loads for extended periods is not good for them. Leads to glazed
barrels or something like that???.

Referring to air cooled, I rather like the smell of engine rooms but I can
see on a boat you would have to build in a heat exchanger to isolate the
cabin from the "raw" heated air, I just think that a heat exchanger for air
is easier to build that one for a sea/fresh water combination. Also no holes
in the hull. However on the down side, don't water cooled engines run
quieter than air cooled. So many points to consider!.

Having said all of the above however I believe that the engineering required
is beyond me and by the time I gather the experience and tools to do the
work too much time will have gone by!. I will just have to save a bit harder
and buy a marine engine.

Steve

I was going to suggest talk to Polar Engineering, but they have closed
and Bowman have taken on their product range.
http://www.ejbowman.co.uk/news/News_polar.htm

From my research when I was looking for a marine engine, the only
difference between continuous and intermittent rating is the power
allowed and duration. I bought a Daewoo L136 from Watermota UK - 160Hp
at 2200 rpm continuous rating. Excellent engine, very reliable, frugal
and well priced and this particular engine is used when re-engining
trawlers whose Gardners are beyond economic rebuild or repair. Daewoo
do a 70 Hp engine - http://www.watermota.co.uk/daewool034.html

Give Mike Beacham a call - you might be surprised!!

Colin Stone