Hi, SLL, here's another thought. If they have a jerry jug aboard, then they could pump
out 20 l. into it. That's their emergency
reserve. They can use the engine oil removal pump
to suck it out.
If they do not know their normal usage of fuel per hour, it is going to have to be guess work
, and they will need some fuel at the time of landfall.
We used to never run the engine till the boat
speed got below about 2 knots. And there is a light air game
, which we have played at sea, which is to see if we can get her moving at all. Then steer at ~60 deg to the wind
, and she'll build up to whatever she can do, maybe as little as .3 knot
. Then keep her moving. The direction doesn't really matter because you're going so slowly anyway, and the wind
always comes back. In a day, or two, or three. Take down or furl the sails
to keep them from slatting. We've gone down to the 3rd reef, just for the roll damping effect, big long lazy swells do roll the boat. It is a time to chum, and see who comes. Remember the wind ALWAYS comes back, eventually.
What A64 wrote seems correct to me. Our engine uses less when just charging batteries
, and uses a great deal more at 2400 rpm than at 2000 rpm.
My advice to your friends is to not worry about going slowly. Run the engine in gear
at about 2/3 total revs, for the charging periods, if they want to change which spot of windless ocean they're in, and only use the fuel for charging, especially if they have no way to create the reserve.
It is kind of contrary to the ideals of modern life, but conserving the fuel is really the safest thing for them to do. Accept the no-wind situation. Play with it. They can stay frustrated with it if they want; but they can also change how they think about it. Read my signature line. Soon enough they will have plenty wind.