For blankets drawing the same number of watts, the inverter approach is
probably less efficient. Depends in part on whether there are
significant losses in the cables from the battery to the blanket. But
the good news is that all of the losses will probably wind up as an
additional heat contribution to the boat's interior!

Chuck


Keith wrote:
So what's more efficient... using a straight 12V blanket or using a
110V one through an inverter? Seems the former would be more efficient
overall, although I don't know if the difference is enough to worry
about.