To be honest you don't need to take that much money. The big key is to have a credit card and to inform the company that your mid will be going to some strange lands.
If they need cash on the ship they can take an advance on their paycheck from the Captain. The officer's on the ship will usually slip the midshipmen a little extra money here and there if they work hard. The only real cash type money I would take is enough to get you to the ship and a few extra days worth for incidentals.
The two things they need for money are: 1)working credit card with billing address the parent's house (and possibly paying the bill too? no? maybe?
) and 2) an ATM card to their bank account.
The reason for billing address being the home is so the bills don't sit there and stack up at school accruing interest while your mid doesn't have access to them. My credit card was plainly told to me to be for "Emergency Use" only.