I am the sole owner on our documentation. My husband will be taking our boat around Central America (Belize, Panama, possibly Mexico) and I read in a guidebook that we need a captain's letter in Spanish, notarized? Has anyone else done this? Is it needed when he's my husband?
I way I read the rule, I would say Yes he would need a letter from you. It certainly wouldn't hurt. ( a few copies) IF you are listed as the sole owner of the vessel in the documentation, the mexican government would have no other way of knowing that he has your permission to be in sole possession of the vessel if you are not onboard.
On deliveries, I always get a notarized letter from the owner, stating that I will be the captain for such and such a voyage of such and such duration. Letterhead and more official looking stamps is better.
I've never had to use the letter, but maybe that's because I don't wear a t-shirt to check in and I don't look French or Australian.
Our catamaran is documented in the Cayman Islands with British registry. A Cayman corporation own the yacht, and we have a note from the corporation that designates me as master of the yacht.
During our entire circumnavigation, I have never shown the paper that designates me as captain/master. They look at our documentation, and at the name of the corporation that owns the yacht, and they never ask any questions about who is master or captain. Port authorities only seem to care that the boat papers are in order.