Have you considered
electric drive(s)? Quieter, not smelly. No massive
fuel tanks with all the pumps, filtering etc. No
gearbox. No dangerous smelly,
exhaust gases ever entering your
boat. Probably no
salt water heat exchangers needed (minimising
hull fittings). No possibility of over
heating. The possibility of
power regeneration from the spinning prop. when under sail?
Now that
electric cars are all the rage, large
battery banks should be more readily available and the technology is now stable and reliable.
While at the construction stage the design
work could be aimed at maximising
solar panel
installation (collection area-wise, shade provision etc.).
Having lived in the tropics for most of my life, I can assure you that good shade is essential. PV
panels can do this for you.
I would expect an electric
installation may well be lighter as well, allowing possibly for a better ballast to displacement ratio.
My expectation is because of rising fossil
fuel costs and local legislation, that electrically propelled boats will soon start appearing from the production companies.
Considering that most boats spend most of their time in
marinas, then
purchasing electric power has got to be much cheaper than
buying diesel.
At this stage diesel
propulsion may seem initially to be preferable cost wise, but any one who tells you diesel engines are "install and forget" is telling very big fibs.
Having a large
battery bank also means you can run not just
refrigeration but also
cooking, winches and possibly A/C off them as well.
On a larger vessel such as yours, you may also consider an "off the shelf" dedicated gen set for emergencies.
I am sure you are aware of the special
electrical corrosion issues involved with aluminium hulls.
Being in
Europe, I am sure there are many progressive electric drive companies.
My final observation is that it is rare to see anyone building their own boats in todays market place. There are just so many excellent boats on the second hand market going for a song - and a few years
work.