Bring Captain's credentials or not.

[Captain Mike C]

Starting with the question: "Should I bring my Merchant Mariner Credentials and TWIC card if I am not acting as a paid crew member ".
I am traveling to St.Thomas USVI from the US, to be an unpaid crew on a sailboat traveling to the Bahamas. In the past I flew into the Bahamas simply to give an estimate for a job. When the customs agent saw my tape measure, I was taken to a holding room and questioned about my travel purposes. I explained my trip was to give an estimate for work. This apparently was a problem. I was held until my contact there was able to get me released. (He was on the immigration board). I don't wish to cause these same problems for myself or the boat. On the other hand I feel it's beneficial to have them with me.