What is the Range of Your Boat Under Power?

[Double-Wide]

Our 38' cat motored from Key West to Galveston without refueling. About 1150 nm. We wanted to sail but that week in June had NOOOOO wind.

[mbianka]

Originally Posted by Teeto

We can get about 750 to 800 miles with motors alone on our 44 foot sailing cat, but why would you choose to do it with all that noise, smell, expense and poor motion?

Indeed! I can understand using the motor when there's no wind but, more and more I see this:
DOESN'T ANYBODY SAIL ANYMORE? - YouTube

[Tony B]

Originally Posted by mbianka

Indeed! I can understand using the motor when there's no wind but, more and more I see this:
DOESN'T ANYBODY SAIL ANYMORE? - YouTube

I see it all of the time. It's not only a more comfortable ride to sail but I sail faster than I motor.
I just don't understand it either.

[Burls]

Here's the figures for our Lagoon 380:


Fuel capacity: 2 x 110 Liter tanks (Diesel)


For trip planning purposes (Conservative), each engine burns approx 2.1 Liters of diesel per hour @ 2100 RPM, which gives up to approx 52 Engine hours per engine per tank.


One engine @ 2100 RPM gives approx 4.3 kts of speed in calm water, which gives approx 234 nautical miles per tank using one engine.


2 engines at 2100 RPM gives approx 5.5 knots



Burls

[simonmd]

With both engines going, based on my last couple of trips to and from Gibraltar, I've worked out that with a 22 gallon fuel capacity, mine will do 308 miles. However, with one engine at a reduced speed I dare say 500+ is possible.

[Strygaldwir]

Aprx 500 miles.

Yes, you can take off the mast and boom. I have seen folks doing this when sailing the circle.

[seandepagnier]

My propulsion by sculling oar is optimized to 2 knots with up to a 3 hour range (then I need a rest heh) The overall range is limited by food for energy.

The other form of propulsion is also basically unlimited as it relies entirely on solar power. involves a near-silent dc electric motor consuming 250 watts and pushing the boat also at 2 knots (great to take turns with when sculling) There are enough solar panels to power the motor without battery drain in direct sunlight, however the battery bank limits to only 20 hours of runtime without sun.

Both of these are only used when there is either less than 3 knots of wind, or in relatively protected waters. There are cases when the true wind is on the beam, but only 3 knots, and it is possible to sail close hauled with the motor running at move 4 knots, and my boat is not a racer. Without the motor I would drop to 2.5 knots. I have done this while capturing enough solar power at the same time while sailing.

[DavefromNZ]

About 1600nm by running single engines at 6.5kts at 3ltrs per hour. It's a Lagoon 450 with 1000ltrs fuel

[dirkdig]

Thats good going Dave.
The 450 is a fair bit heavier and uses a lot less fuel,goes faster at the rate of 3 litres an hour too.

[Mr B]

At 7 knots, I burn .75 gallons an hour, I have 60 gallons on board in tanks,
I also carried 7 x 5 gallon containers, Total fuel on board, 95 gallons.

So I estimated a range of approx 500 Nautical miles, At 7 knots on one motor,

The large amount of fuel carried was just a safety factor for me,

[Sailmonkey]

We carry +60 hours of fuel in the tank and +22 hours of fuel on deck. In ideal conditions 82 hours of motoring will yield 426 miles. We only plan on being able to cover 350 under power, but have done 500 burning what I consider the in tank reserve (and having an extra 5 gallons unused on deck).

[TeddyDiver]

Just estimated so far becouse the build is still going on but shoud do 2200 nm at 6kn or 1100 Nm at 8kn with fuel tanks of 1.5tons.

[Siskiyous]

I am finishing a 31 foot Searunner with a Saab 18 hp diesel and since I am a power boat person I plan to use it as a power cruiser.

To really learn this subject you should read "Voyaging Under Power" by Robert Beebe. It has a detailed technical section on fuel usage and the math of Range under power. Buellers "the Troller Yacht" covers this ground too, but Beebe's work is really the bible of this subject for small boat voyaging.

The case for power is pretty good comparing mono hull sail vessels against mono hull power vessels. Researching multi hull power vessel performance is a little more difficult.

I don't intend to make the case here for power in a multi hull, and my reasons for going the power route are mine alone, but the one thing to keep in mind is that the weight of the vessel is the number one factor that will alter the range under power.

The conversion of a sailing mono hull to power cruising is handicapped by the ballast a mono hull is burdened with, a multi hull conversion does not suffer this burden.

A steadying sail is a good device on power mono hulls and should be considered on a power multi hull too. For obvious reasons flopper stoppers and other stabilizing gadgets found in mono hulls would not be part of a cruising multi hulls kit.

My goal is to burn .6 gallons per hour at 6 knots or 10 nmpg so 100 gallons would give me a 1000 mile range. There is room in my hull for over 250 gallons, and slowing down even to 5.5 Knts would boost my range - but I do not intend to pack around that much fuel on coastal cruises. For long hops additional 55 gallon drums would obviously add over 500 miles of range each. There is space inside for half a dozen of them, but it would be an ugly situation.

Six knots gives a consistent 1000 miles a week, which most mono hull sailors would kill for. I really can't picture anything short of a CAT 5 Hurricane capsizing a power multi hull boat. Even then it wouldn't be a capsize so much as the wind flinging the poor little boat through the air.

I would give you more accurate figures, but at the lower end of the scale fuel burn is more difficult to approximate than it is with heavier vessels, and because I am unsure what my actual water line length will be when the boat is floating.

Most multi hulls strive to keep weight to a minimum and so fuel capacity is much less for even a large multi hull than it is for a power vessel. Yet when you look at those people who responded to your question as asked, you see that fuel economy is very good at displacement speeds, and modest amounts of fuel can give you a substantial range.

[Barra]

On my 42 foot cat with 2 x 30hp yanmars and 330 litres fuel i get between 500 and 800 miles range so far but alot depends on sea state and how fast i want to go. most economical is single engine in calm seas and 4.5 knots for tad over 800 miles.

[ShaunJ]

I burn .68 GPH going 6 knots and hold 60 gal. I figure my range with a third in reserve to be about 350 miles. I am sure I can push it a bit more than that.