Thought I would Post this for what it is worth, really only means a lot to me, as we know each vessel has different circumstances. Earlier this year we did a 3 1/2 month round cruise from Sydney Australia ,down and around Tasmania and back. These are the stats we recorded.
We have twin 3406 Cats 540 hp each , we weigh 36 tonnes , carry 6,500 litres of fuel, 1,600 litres of fuel,Cruise at 9 knots at 1150 rpm with both engines running. Max rpm for the vessel is just on 2000 rpm.
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Below is an Email to a fellow friend who has a Marlow 57 on our dock.
Hi Bruce
You asked me on Sunday how much fuel I had used and I said just under 10,000 litres, this was not quite true, I was close but not correct.
Yesterday I sat down with the fairly comprehensive log for the trip and collated the important Stats for Liberty , and they are as follows
Total of Nautical miles covered. 2,469 Sydney to Sydney.
Total Fuel consumed 10,428 litres
Total Hours run. 273 hours
Average speed. 9.04 knots
Average litres per hour. 38.19 litres/ hr combined.
Mechanical issues
1 x port Starter motor
Leak in the port mechanical raw water pump which happened on the trip home --- resulted in damage to alternator, now not charging. The pump will come off next week for repairs.
Port drip less shaft seal was overheating near Eden on way home made phone call to mechanic, also reviewed the details of the seal on the web( handy whilst at sea) followed instructions from mechanic and then there was no issue , appeared to be an air lock /blockage in the coolant line to the seal.
Have got a couple of oil leaks , which we will attack whilst servicing the engines in the coming weeks, might need a new gasket here or there ?
Lazerette bilge pump failed ( old age caught up with it) on way to Hobart, replaced it before we started circumnavigation .
So all in all the prep we did for the trip paid off, and we got off lightly .
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Thought you Guy's might be interested in this information .
If I was to cruise at possible a knot faster at 10 knots my fuel consumption would be an extra 1,400 litres at 1.36 / litre = $1,904.00 Aus or US $ 2,475.20 so on a cruise like this it is important to to get the boats sweet spot where you want it.
Our fuel in Australia is expensive compared to the States, at 1.36 a litre that is 5.14 US /Gal. We feel this is quite reasonable at present, we have been paying up to 1.60/litre on the water or 6.04 us / gal. I have seen references to 3.00 us /gal this would be 79 cents a litres , this would be like going back to the early 90's in Australia !!!
Cheers Chris D Liberty Australia