I just went through this process for my Seafarer. After much research, I bought and installed a dual-bank (10 amps/bank) NOCO Genius charger. Several years ago, I put a Dual Pro charger in an earlier boat and also liked it very much. I don't think you could go wrong with either brand. Both are made in the U.S. (except for Dual Pro's lowest cost models), have excellent customer reviews, good factory support and the right features. Both are waterproof and have independently operating banks, temperature compensation, microprocessor control with staged charging and a maintenance mode that turns the charger on and off periodically to keep the battery at full charge (rather than a constant trickle charge which can shorten battery life). A three-bank charger for your sailfish in these brands will run about $240-$260 online.
Before you order a charger, be sure to check the available space in your boat against the charger dimensions. If you're using gel batteries, you need to specify that when ordering a Dual Pro. Good luck with your installation, whichever way you go.