(Hope this isn't a duplicate reply.) My 3200 was one of the last of it's breed. It was followed by the 34 that also had an
outboard. Then along came the
diesel version with the drive leg. All the 105's - which you are inquiring about - have the
diesel. If you were to buy an older, used
Gemini, it may have the
outboard. I prefer the outboard - easy to
work on, easy to replace, no diesel
fuel odor. But, you're right, the OBs have a magneto that puts out
charging current, around 6 amps max, that varies with
engine rpm. So, you really can't count on using the OB to charge the
batteries. As it comes stock, the
boat has 2 house
batteries and an
engine battery. Two house batteries don't have a great deal of house
power, but there are lockers - not collocated with the existing batteries - to put 2 more. (We haven't because of the extra weight it adds.) On our
boat we have a
Honda 2000
generator to help solve the electricity problem. I run it a couple hours per day - just like a boat with an inboard engine may run the same to charge her batteries. This short period is NOT enough to get to full charge, but I just want to get up to 85-90% of full charge. All I want is a computer, lights and
appliances until tomorrow... and tomorrow I just want enough charge to get to the next day... etc. (To fully charge the
battery takes around 10 - 12 hrs with the
generator.) This kind of regime is easy to deal with, and it seems to
work for my cruises. If you're going to be away from the
dock for a long time or don't have faith in a
single generator as the solution, by all means consider a
wind generator and/or
solar cells. This is the $$$ solution to the problem. MANY
Gemini owners have put one or both these chargers on their boat. I prefer to keep it simple, and I feel like I can because I'm pretty honest about the type cruising I do. I have no dream of going world cruising in a coastal boat. I'm going to the Abacos and Exhumas. My cruises are pretty short - a few weeks +/-. As to the
electronics, I have a
radar which I mostly use in "guard zone" mode - turning itself on briefly every 5 min to look for traffic. I use a notebook computer for checking
weather, watching movies, and for navigating. Then I only use it at the start & end of the day and on difficult legs. The rest of the time I use a
Garmin hand-held
GPS which is powered by AA batteries. (In other words, when I'm close to shore dangers I may use the notebook (power hog) and when I'm not so close I use the other.) I've already changed all lights on the boat to LEDs - this was a generational improvement in technology that helps with
power. I have a 7" LCD TV that I use with a coat hanger
antenna (works great) to look at local news &
weather while traveling. I run a ham
radio but don't talk much, and the receive power is low. All these things work for me using the generator regime I've described. I preserve the engine battery for starts. I don't combine with the other two because my engine battery is a different type from the house batteries. In short, if you identify honestly what type cruising you're going to do (not what type you dream-about doing), you can sneak up on the power problems over time. It will always be possible in the future to add systems (& complications) then, when you have experience that says you need them. Hope this helps.