Both these sets of figures agree, basically, with what I've observed
Originally Posted by Zanshin
4JH3-TE should run continuously at no more than 3100 RPM
(this is 85% of maximum continuous rated RPM
(3700)) and uses 10l per hour at that speed. thus I'd need 740l of fuel
for a full-RPM 3 day run. ... At 2200RPM using my 'overdrive' mode in calmer waters or if motorsailing the engine
only drinks 4l/hour so a 740l tank would give me 185 hours or 7.5 days of engine
My cruising speed is 8 knots .
Originally Posted by Eleebana
75 brochure says I'll use 6 litres per hour at 2400 RPM and cover 6 miles. If I drop to 1200 RPM the brochure says it only uses 1 litre per hour and maybe it will still cover 3 miles.
Ours is a Yanmar 4JT3E 56 HP and our RPM range seems about 1,200 is just in gear
and moving (Yanmar guys said OK and wont polist the cylinders) and 3,300+ is maximum revs and 3,100 is about as much as the engine will do comfortably.
The only time we have done over 3,000rpm we were escaping pirates.
Normall max cruise
is 2,400 to 2,500 we never use that unless forced.
Our normal cruise
is 1,500 to 1,800 RPM and I feel we use 2 L per hour at about 4.5 to 5.5 knots.
1,200 rpm is go slow at 3 knots and just used for anchoring
etc (and charging)
We do the slow and economical way
Sailing we really only do that if very low revs can give us an appreciable benifit. For example if we have 5 knots wind
on the quater the engine at 1,200rpm may give us 8 knots wind
at 60 degrees which would be 5knts boat speed, say.
Lots of boats motor
past us but at $2 per liter (US$7 per US gallon
) I don't give a rats bum, they can have all the space they need at the fuel