new building Shipyard in claim
- can be built in your claim at water level
- give it levels as all other buildings (1-10 limiting what size of ships you can build there)
- you can build bigger ships there (introduce new ones)
- you could also make upgrades to your ships there (cargo/speed/sails/visuals/etc)
- you can put your ships for sale there (global market for ships at shipyards, especially those that cannot be put into vault)
- those bigger ships need a LOT (and i mean a lot - make it insanity project) of materials
- those bigger ships cannot be put into vault, which means, those bigger ships are tied to the "local" area body of water only / if there is some huge inland lake/river system and you want big ship there, there must be shipyard with big enough level (means also claim with same or higher level) somewhere there
- personally i would make it all ships need to be built in shipyards except the raft
- similar building "stables" could be also made for rideable mounts