This is one of my dream possessions, a yacht that is. If I get one I probably will install a yacht wind generator to charge my onboard batteries. You know the modern yachts now carry a lot of electronic equipment on board things like gps, radar and if you have autopilot that also needs power to run. If you are out on the sea you definitely can not stop and recharge your batteries. You could have solar panels installed but what if there's no sun. What do you do then? It makes sense then to have a marine wind generator installed on your yacht, so you can enjoy your ride to the fullest. Nowadays they now even have yacht wind generators that also double up as water generator which generates power by using the water to turn a propeller a the yacht moves. This is kind of like the old hydro electric plant design just on a smaller scale.
One of the most popular such generator is the Duo Gen. They recently released the newer model Duo Gen 2 which has some improvements on the older version, mostly just stronger fixtures and installations to make it more durable and therefore last you many yours to come.
Another type you could consider is the Air-X-Marine. This is a more intelligent generator that has an onboard micro processor to improve all the functions including overall performance, battery charging and the reduction of the annoying flatter noise that is common on most other brands. It also has a built in high wind safe mode that automatically slows down the generator down in high winds as well as the auto brake system that stops the wind generator when the batteries become fully charged. It comes with a full marine tower kit for easy mounting on any sailboat.
There's also the Ampair brand. They produce more heavy duty type marine wind generators. Their generators tend to be all weather proof make up which includes a sealed design which does not allow you any access into the units sensitive areas. You can get them in 3 different power outputs that is the Ampair 600, Ampair 300, and Ampair 100 micro wind turbine. There are other brands of yacht wind generators available on the market, but I thought I would just mention a few here to let you know that you do have a few choices to choose from. I guess your decision will be based on where you are going to be doing most of your sailing.