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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Rate of Fuel Consumption

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Jack8409
Deckhand

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USA
3 Posts

Initially Posted - 08/09/2013 : 09:59:28

I have a Honda 9.9 and expect to be motor sailing on the upper Chesapeake for 4+ hours this weekend (total 9 hours maybe) to and from the Chester River in calm weather.

What's the consensus experience on fuel usage per hour travelling at, say, 5 kt?

I'm trying to figure out how much extra gas I need to carry - I have 6 gallons on board normally.

Capt. Jack
"Baywynd"
'81-#2586-SK/TR

Edited by - on

Kennyge
1st Mate

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USA
76 Posts

Response Posted - 08/09/2013 : 11:43:04

I have a Honda 8HP 4 stroke on my C-25 and average 1/2 gallon per hour. From what I have read, this is pretty standard. 6 gallons of gas should give you 12 hr of motoring.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 08/09/2013 : 12:29:53

My Tohatsu 9.8 consumes roughly 1 quart/hour at 4.5 knots (1400-ish RPM), if I bump it up above that, consumption almost doubles (I don't actually have a good value on this because I haven't done enough runs at "high" speed to test it, I just know my tank empties faster that I expected).

If I'm going anywhere long distance, I fill my standard 6.5 gallon onboard tank, and bring the 3 gallon OEM tank that came with the outboard as well.

The USCG Auxiliary recommends you plan trips so you only use 1/3 of your total capacity to get there, 1/3 to get back, and 1/3 in reserve.

Edited by - on

frog0911
Master Marine Consultant

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USA
1349 Posts

Response Posted - 08/09/2013 : 13:13:58

Fuel usage seems to be much better when new vs my 9 year old Tohatsu. When new,I used a little over 1/2 gallon per hour at 3/4 throttle, now its a little over 3/4 gallon. I try and maintain 5 knots on all our trips when under power. So for safety sake I plan one gallon per hour when we go cruising. I have a 6 gallon tank in the fuel locker and a 12 gallon that sits in the cockpit up against the galley step.

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Steve Milby
Past Commodore

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USA
5895 Posts

Response Posted - 08/09/2013 : 13:46:46

The rate of fuel consumption depends on other factors than time and distance. When you motor against a current, your average speed is reduced, which means you will have to run the engine for more hours to reach the destination. If you can motor at 6 kts in calm waters, your speed might be reduced to about 3 1/2 or 4 kts if you have to motor to windward against 12-15 kt winds and a heavy chop. I think the USCG Auxiliary recommendation should be considered a bare minimum, and would personally recommend more. If you find yourself running low, you can't just pull into a nearby Wawa to fill up, as you can in your car.

I was on the Bay, taking a sailboat with an Atomic 4 gas engine from Annapolis to a point about 30+ miles south, with 12 gallons of gas, against a 15-18 kt wind and heavy chop, and our forward progress was so slow that we could see that we would run out of fuel before we arrived, so we had to turn around and go back. You probably won't encounter conditions like that, but you can't predict it with certainty.

If you plan to take longish cruises, I suggest you take a second 6 gal fuel tank, with quick disconnect fittings, so you can connect the hose to it without disconnecting hose clamps, and so you won't have to try to pour fuel from a jerry jug into the fuel tank. It's very difficult to fill a tank from a jerry jug on a wildly rolling sailboat. WM currently has a 6 gal tank for about $45. They also sell the quick disconnect fittings.

Edited by - Steve Milby on 08/09/2013 13:48:06

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 08/10/2013 : 21:54:31

I burn about 1 qt/hr at around 4.5 kts., going even to 5 increases consumption significantly. 5.5 - 6 doubles my consumption. As Steve brings up, there are other factors to consider. You are talking out and back and motor sailing, so even at 1/2 gal/hr you would still have some reserve in 6 gal. I expect to sail and carry 6 gal. when I'm heading for Canada. That said, a 3 gal reserve tank is cheap insurance.

Edited by - Dave5041 on 08/10/2013 22:01:27

Stinkpotter
Master Marine Consultant

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Djibouti
9076 Posts

Response Posted - 08/11/2013 : 07:52:07

My Honda 8 (same engine as the 9.9 after 2000) used something close to 2/3 gallon between 5 and 5.5. I didn't do much distance motoring at less than 5, so can't speak to that. But drag does increase exponentially with speed--you can tell when you quickly decelerate from 5.5 versus let's say 2 knots. From 2, the boat coasts... From 5.5, it slows quickly.

I always wanted a 50% cushion, for the reasons Steve says.

Edited by - on

Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 08/12/2013 : 14:16:49

I just completed a 98 mile - 17 hour voyage, completely under power, with my Tohatsu 9.8. The current and wind was against me for half the trip and with me for the other half. Maintained 5.76 KPH (avg). Used 10 gallons of fuel. I always carry at least 5 gallons more than I anticipate will be needed when doing any extensive mileage as conditons can change rapidly and so will your MPG.

Edited by - on

CarbonSink62
Navigator

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USA
208 Posts

Response Posted - 08/13/2013 : 14:06:33

I also just completed a long motor cruise and my '09 Honda 9.9 burned 5 gallons to go 50 miles.

Ken

Edited by - on

GaryB
Master Marine Consultant

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USA
4303 Posts

Response Posted - 08/13/2013 : 18:37:59

Roughly 10 MPG.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.