I wouldn't worry about the container too much. If you want to ship the mast in one piece, it's going to require a full container. If you break the mast in two, as Matt suggests, you're good to go in either a half or a full container. But you're not really talking a lot of weight here. Matt's saying 400 pounds total and that isn't much in a container.
Instead, I'd focus on seeing whether I could get the boxes from my local Hobie dealer. If I couldn't, I'd make two containers from plywood and 2 X 2 supports. One hull in one container, the other hull in the other. The balance of the boat (sails, mast, trampoline, rigging, and frame would be divided between each crate. You should be at about 250 - 300 pounds per container.
Realize that the hulls force special handling. You've got a lot of length to weight. Shipping charges will be expensive as a result.
Contact an international shipper who will then load your boat into a container with other small individual shipments,. For a good breakdown of shippers, take a look at
https://www.easyship.com/blog/most-popu ... g-servicesAn international shipper will also be able to help you with customs, something that will create headaches you can't even imagine.. Anticipate a shipping time of at least three months. Further anticipate a major hit to the wallet. You're not going to get any discount for volume. However, US to China tends to be cheaper than China to US.
Jim Clark-Dawe