I had AT4 in Touche', 35-1, for a few years. Had Martec folding 14x5P prop. Fuel economy was about 1 gph for usual conditions.
If you were motoring into wind and waves, you were more than likely "making bubbles". That is, in order for you to get to the full horsepower of the AT4, you were near max rpm, 2500-2800. Your AT4 is probably a 1:1 transmission. Your boat speed was slower therefore your prop was probably cavitating quite a bit due to the high prop rpm. The resulting inefficiency drove your fuel usage up. Diesels are usually reduction drives, usually about 2:1. Therefore, a diesel running 2800 rpm has a prop speed of about 1400 rpm. Diesel drives are pitched at 12-16, give or take. That, and a flatter torque curve, is why diesels are better for punching into waves. Dennis C. Touche' 35-1 #83 Mandeville, LA On Sat, Jul 14, 2018 at 9:29 AM, jay hackney via CnC-List < cnc-list@cnc-list.com> wrote: > 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 > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > >
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