You posted a message earlier today asking about the QRP. If you plan on working, that is not the program you should be looking at. You'll need a work permit and if you are going to stay you should apply for Permanent Residence after you have been here a year. I'm not sure you could get a work permit for a mechanic's job. You would have to own the shop and employ Belizeans. After you have permanent resident status you'll be OK I believe.
Your question about a trade. Well there are marine mechanics here. Most boats have outboard motors. There are dealers and mechanics who work for them. Of course a good mechanic is employable I suppose but it is competitive. Have you ever been here? You really need to come down and stay for a few months to get a feel for what is going on here. Good luck.