Mark wrote:
Sea Jay wrote:
Better to use a step up DC transformer - much more efficient and
compact!!

Hmm. The DC-DC converter b393capt mentioned above is rated 88%
efficient; a typical boat inverter is nearer 95% efficient when
running a smallish load like a laptop. When the wall wart
inefficiency is included, they are comparable, the DC-DC converter
is not "much more efficient."

Nor are they very good at absorbing voltage spikes.