PlagueisMD

No tourist visa is needed. The D visa allows you to seek entry to the US while your cruise ship is in a US port.

1st time u are doing a contract , so u will be flown in a few days ahead of departure to go over the contract and cruise ship rules
after this initial 1st time,  if  u sign for contract with same line,  they will fly u in closer to date of departure
 
if going with another ship,  the process will be repeated 
Contracts usually are for 7 or 8 months  and u may be able to sign for another months long contract when this one is over 
but usually the ships give u a few months off and fly u home  as u work 7 days a week on board 
trust me u will need this break between contracts
 
 

Cruise ships fly the worker into the US just a few days (or even the day of ) departing 
you will have time off the ship in the different ports for a little shopping (not all cruise ship members are allowed off at the same time)
you have time to do a little shopping and wash clothes as ship crews hate to wash on the ships
 
ships are only in home ports a few days before it sails out again 
 
when your contract is over   the cruise ship flys u back to your home country
 
u will never be in the US for 29 days
and no ,  u do not need tourist visa the C/1D acts as the transit visa for the length of your contract
make sure u keep your passport and another form of photo ID with u when u are off ship
 

You will need a tourist visa. 

Yes, with the understanding that entry into the US depends on approval of the US immigration officer, as always.

The C1 (transit) part of the visa gets you into the US to join the cruise ship.  You are admitted into the US at a Port of Entry for the sole purpose of onward travel to the ship within 29 days (or the departure date of the ship if it's less than 29 days from date of your entry).  Once you've joined the ship, the C1 serves no purpose until you are no longer working on that ship -- then you can use the C1 to transit the US to go home or to travel to join a different ship.
 
The D (crewnember) part of the visa is used once you are working on the ship.  It will allow you (with immigration officer approval, of course) to enter the US when your ship is in a US port, with the requirement that you will depart with the ship or on any other vessel within no more than 29 days.