I have always felt this is one huge advantage for well powered catamarans and other twin engined boats. Designers of single
engine boats have a tough compromise. Use a smaller engine to keep it loaded (a true "auxiliary") and you may not get to hull speed
, especially when punching into the wind
and waves. Use an engine that can do that, which is what most customers will ask for, and you are seriously overpowered the rest of the time which means your engine is not sufficiently loaded ( I am talking about pleasure boats here, and sailboats, mostly).
On a cat with good sized engines, on the other hand, you can run on just one engine most of the time, and run both on those situations where you need more power. In either configuration, the engine(s) are loaded up. On my cat, I can cruise
all day at 7 knots at 2850 rpm
. With two engines, same RPM, I get maybe 8.5, and after that, I just push more water
. I can get 8 knots with both engines at about 2650-2700 rpm. Guess what is my favorite mode, most economical, least wear and maintenance
(one engine) and well loaded up.
It frustrates me to see cats with smaller engines, because they are back in the same soup as the single
engined boats, except with twice the maintenance
. The bigger engines help maneuvering in wind
, too. I can come off a mooring
in 20 - 25 knots of wind with mainsail
up, and do a 360, almost in place.