Life guarding

I am moving to St. Thomas on July 10th with the hopes of landing a teaching position. Through college I worked as a lifeguard and have been giving private swim lessons on the side to make extra money. I was wondering whether it is worth renewing my certification before moving. I am interested in working on boats and teaching lessons as side work, but I am unsure if the certification is necessary. Also, if it is necessary are there classes available anywhere on the island? There is only one class scheduled here before my departure and I would have to take off of work to attend. With it being my last two weeks teaching at my school, I would prefer not to, but will if necessary. Any advice would be appreciated! Thanks in advance.