Of course you need all the best safety equipment both on ship and personal EDK , you never know when you will be knocked into the water or capsized. A (fictional) year at sea and you will probably see some weather!

With a crew of four you want this craft to be sailed singlehandedly if needed. People sleep and you can't always just drop anchor.

Here is a link you may find interesting BoatDesignNet
they have detailed discussions(read as "out of my league") on hull design , fuel consumption for various designs, etc.

A year without contact, means either a sailboat, nuclear power, or a pre-positioned fuel&supply Island.

In addition to the solar panels that Chris mentioned, I would add solar thermal panels for hot water. And if you do a search on Air-X wind generators , those are also being used on boats to generate electricity.

I assume you've packed some nice dehydrated foods, besides the mainstay bars. You will probably want to fish , will it be hook and line or a net/trap of some sort?

You might want to consider a composting head, as I recall the chemical ones needed pumping more frequently than yearly.
CompostingToiletWorld

The gardener in me says you need a mini-greenhouse just for the cherry tomatoes and chives! 8^)

For just "coolness factor" here you go..(from the boatdesign.net gallery)


Sorry for rambling
Lee