A collections management policy is a guidebook, bible, and operations manual all in one on how you accession, handle, dispose, loan (yes or no) artifacts, what you look for (why would a WWII sub museum look for Korean War-era Air Force uniforms?) and what you are trying to achieve with your collection. Remember, the boat is the main artifact, and all of the "treasures" you want to aquire on long-term loan from the USNHC to enhance that artifact is why you need a good collection management policy... Nobody wants artifacts to be lost due to poor handling... not pointing fingers, but there have been some mishaps in the past (not anyone I know these days...) -- a good place to look is any small, ACREDITED, museum. They should be willing to help.
Rather than copy an existing sub collection policy, it is vital that you look at each element of say a land-based museum CMP and translate it to your situation... by doing so, it will make you think and make specific decisions about how your particular group will operate.
Good luck and remember, it's not rocket science!