I used to use Interstate for years on my boat. I have a 2 battery setup with a Perko selector switch. It's only a 19' boat with a 150HP outboard, but having battery issues on a boat is not something I want to chance.
My Interstate dealer closed his shop - retired. So now I'm going with another brand from my FLAPS. A
Super Start Marine battery - conventional. About $100 each, so not too bad. Some of those fancy batteries can really cost some big bucks!