Hi all, first time poster here!

I've am a recreational sailor and boat builder with plans to sell everything and set off cruising in a few years, preferably on a boat that I have built.

I'm also quite ecologically minded and would prefer to avoid dependence on diesel. With that in mind the harryproa designs are quite attractive to me, particularly with the large unshaded area for adequate solar panels.

With an electric tender as prime mover on a C60 it would present some interesting design opportunities:

A generously sized outboard for the tender would be in the 40kw range, probably with a 40kwh bank of LiFePo4 batteries (e.g. the bmw i3 banks marinized and sold by torqueedo).

With 40kwh of capacity weighing ~280 kilos your dinghy would still be relatively light weight and have plenty of range.

With a bank this size on board you open up the possibility of running air conditioning overnight without running a generator, and fitting electric appliances in the galley. It would require some creativity but I could see the dinghy propulsion bank being plugged into the mothership to provide power to the main boat and be charged by the solar panels or a DC generator.

The main boat would still need a 12v or 24v bank to power lights, fans, radio, navigation electronics, etc... while the dinghy is away but this bank could be relatively small and charged off the solar or the dinghy bank.

With a high voltage lithium bank like the bmw i3 pack (360v) the amperages would be relatively low so cable runs from the dinghy to a 7kw inverter on the mothership would be not need to be oversized (less than 20 amps of current at peak load). It would be quite a unique setup and would have some strange limits like not being able to cook without the generator when the dinghy is away, and your dinghy would be heavier than if powered by petrol.

It would have some extra side benefits:

You could charge your dinghy from shore power with the main boat anchored out and then bring the power back to use on board - the cleanest fuel run I can imagine.

If you were to build the bank yourself (by purchasing cells and bms components through a vendor like electriccarpartscompany.com) it would save half the $$ and allow you to build it in sections, you could leave one pack on the mothership for short trips, saving weight in the dinghy and enabling more comfort for those onboard.

This would also enable you to move the batteries to optimize weight location and shorten cable runs, and though that wouldn't be a big deal with a high voltage pack, it would allow you to build a lower voltage pack with shorter wire runs at the sacrifice of the plug and play convenience of the  high voltage always-on-the-dinghy design.

Extra point for the high voltage pack: Inverters operate more efficiently when fed with higher DC voltages.

What are your thoughts on this concept or broader design of electric propulsion systems for harryproa