If the contract is "build to print" then the boat is not their design, and the finished item must be correct. If it is their design (or even build to print), a first piece example will be thoroughly, documented and tested by the government prior to approval of production. Either way, a government inspector will inspect all boats, will probably sea trial a couple before he signs off on each batch.
Several times throghout the life of the contract the government will perform audits on costs, material certifications, employee training, documentation and records keeping, as well as many other aspects of the build process.
If they build a product that doesn't measure up, performs poorly, falsification of documents, etc., the government will shut them down in a heart beat and pull the contract. I've seen it happen before.
I know how the system works. I'm employed by a defense contractor and deal with the government on a weekly basis. I also perform specialized testing and inspection on our product.