[QUOTE=ranchero76;2215530] I'm not building boat yet, it's all at research stage right now. [QUOTE]
I think what you need to do is step back and define what you are trying to accomplish first.
As I see it, if your goal is maximizing efficient propulsion
and are willing to sacrifice performance. More importantly, you are trying to minimize generator
, there are options. It still won't make financial sense but at least it will make functional sense. (assuming your 50-55' cat)
- If you accept 6kts cruise
and flat out 7kts, you could drop the typical 75hp conventional diesels back to 30-40hp each. This reduces up front costs a bit and maximizes efficiency (though not by much). Downside, you give up capability to fight your way into harsh conditions and it will hurt the resale value but if you don't care about resale...
- 10-15kw of solar is just silly. Even if you cram the panels on, you will be lucky to get more than 60% of the rated output due to shading much of the day. Drop back to 3kw and you can actually fit it on the boat reasonably.
- Manage your power consumption
. 3kw of solar with a proper inverter
covering startup loads should be able to run a couple of 16k btu air/con units routed to the main salon
- Spend some money
insulating the main salon
to keep the air/con cycling down.
- At night have a vent system to route
those air/con units to the staterooms.
- You still need probably 5-10kwh of battery
- Assuming you leave the boat for 3-4hrs per day, that solar production can be used to top of the battery
banks and provide for overnight air/con
- Add a 200amp alternator to each motor with a clutch
as a backup if you run into a situation where the solar can't keep up. Negligible power loss when not engaged but together should be able to keep up with the house loads.
It's still going to be much more expensive than just running a moderate size generator
with the standard propulsion
engines but at least it will have some value.
PS: I didn't run detailed calculations so some of the numbers may need some tweaks but they should be correct at least in order of magnitude and you should be able to make them work.