I’m no former marine electrician, but it’s harder than you’d think. I asked a union friend and he sent me some links. The first one had a default of $9.99 a month and no way to change it. I’m guessing it’s a bit hard for them to update their website without electricity.
This one worked: https://www.fcpr.org/. In case your Spanish is as bad as mine, HAZ TU DONATIVO means exactly what you think it does. Paypal or credit card. If anyone has a better suggestion, please post it.