The National Maritime Museum is looking for help with its Warship Histories Project.  They are looking to harness the knowledge their users have about their collections to enhance the existing information they have on over 20,000 British warships from about 1500 to 1950. This information includes:

The data includes the name, type and launch date of almost every British warship in the time period concerned. For many ships there is also data on the shipyard which built a vessel, and details of the service history and captains of the ship concerned. For some ships further technical details (for instance, construction materials or dimensions) are available.

However, it is not complete and they are going to work with wikipedia to capture knowledge from experts in the wider community.

You can read more about it on their blog.