Electric propulsion has many benefits but may not suit all situations or be for all types of boating. You might check out the yahoo group 'electricboats' which has over 6000 posts going back several years. This group covers just about all of the ins and outs of electric boating.
There are many ways to convert a larger vessel and for a 41' I suspect that a hybrid would be in order unless you are just day sailing and need power to get to and from sailing waters. Without an on board generator you are looking at about 8-10 hours at 2-3 knots or maybe 2 hours at 5-6 knots. The limiting factor is the Amp hour capacity of the battery system used and not the Hp that can be generated. Amps go quickly when you want to get to hull speed!! If you are thinking that with a solar panel or two or a small Honda generator you will be able to sail the world then you should stay with a standard IC diesel system.
There are several companies out there that sell electric systems that are reliable and work well. The cost will be anywhere from $1500 to $15,000 depending on what you deem necessary.
I have converted a Ranger 29 and a HA-18 catboat to electric and have had no regrets. I use both boats for day sailing or short cruises. I wouldn't have
them any other way. Do your research and you will probably end up with a super electric system that will suit your needs very well.
Good Luck, KF