Solar Power

Solar power is another option for improving the range of your boat. The challenge is in getting enough wattage deployed to make a difference. For example, a 200watt, 48V panel is almost 15 square feet (3x5). If you put a dedicated arch off the back of the boat, as many cruisers do, there should be room, but it would be difficult to find anyplace else on a small boat to deploy one. Some folks have crafted clever solar biminis as well.

And for sailboats in particular - you're adding significant windage and weight aloft.

Now...what would that get you? 200watts adds 5A back into a 48V bank. So if your draw was 40A it's now going to look more like 35A - slightly less than a 15% improvement. So if 10NM was your prior range, maybe now you get 12.

But consider a different scenario. Sailing in the British Virgin Isles, trips between anchorages are usually around 2 hours. Let's say you had to motor the whole way at 40amps. That's 80AH total used up. But now you've got the rest of the day to...well drink mostly, but try to get some snorkeling in. You arrived at 11am so you'd have a good shot at getting a mooring. It's winter, so it gets dark about 6pm. But your panel has been generating power all day - 12hours @5amps/hour = 60AH. Now you're only down 20AH.

On smaller boats, the improvement will be greater because the ratio of cruising amp-draw to the amps provided by the panel is lower, but on a smaller boat the challenge of mounting one becomes higher.

Another option is amorphous silicon flexible or thin panels that can be walked on - you could literally cover your deck in these. Overall efficiency would be low, but su\rface area would be high. But the phrase "streets paved in gold" comes to mind - this would be prohibitively expensive at today's prices.