At 4 - 5 knots into wind and waves a consumption of 1.8 CND gallons per hour is possible. Very roughly a 4 stroke gas engine running efficiently will yield about 15 HP at 1 gallon CND per hour. Subtract losses for the alternator and water pumps and 1.8 might give you 20 - 24 HP at the prop.
One thing to check is the timing which seems to have an effect on the A4 under load. Pick a flat windless day, come up to a reasonable speed and measure it by GPS. The best is to adjust the distributor while running for highest speed, may not be possible or safe. A guess is that some of the distributors may not be advancing well. There are some weights and springs inside that should be advancing the timing as the engine revs up but the few that I have looked at for people either didn't move at all or had a significantly reduced range. Michael Brown Windburn C&C 30-1 From: jay hackney <jayw.hack...@gmail.com> Hello colleagues Filled with gas for the Atomic 4 in Port Whitby Canada Day and sailed back to Toronto. Wind out of the West and tight timeline meant we had to motor against the wind and waves for 2.5 hr. That would be relatively ?hard? motoring at 4-5 knots. Since then I?ve motored about another 3/4hr for a total of 3.25 hours, again at about 4.5 knots. Filled with gas again the other day to measure gas consumption and got 7.9 litres per hour, or 1.8 gal per hour. I?ve got a 2-blade folding prop (which, by the way, make reversing difficult - in the sense that there is no quick stopping). Does that seem normal? Online research seems to go from 0.5 to 2-3 gal per hour. Anyone with an A4 on a C&C34 with a gas consumption comparison out there? thanks Jay Hackney Windblown Toronto
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