We have become firm converts to the new generation of lithium battery powered electric outboards. The battery technology gives them plenty of endurance and enough power for most displacement tenders. We have an inverter on board so re-charging is quick and easy but I understand you can use bespoke solar chargers though these aren 't cheap. The great advantages are that they are silent, very light weight and there is no longer a need to keep petrol on board.

Our Torqeedo 1003 has, on the whole, been very reliable but, during the second season an integrated circuit board in the battery blew. The dealer arranged repair under warranty without fuss but the UK service agency proved to be slow, unhelpful and arrogant. I hope that they get this glitch sorted as it 's a great outboard.
http://www.torqeedo.com/index.php

Thanks for the info. We shall see what spares we accumulate over time. When in the Bahamas, Carib. and Central America, we carried 2 outboards, a 15 and a 3.5 and a RIB. We used them all the time and they worked well generally. Since leaving those areas, having an "SUV" became far less important and we used the outboards far less. As a consequence, they became far less reliable. I am not sure what I would do if I returned to those waters, but I am pleased with the distances achieved with the Torqeedo so far. Dick