Batteries are a great topic of conversation around boat owners. Charging, mounting, type, longevity; all opinions are valid.
That said, here's my experience with Interstate. When we were cruising on Our Journey, a 36' sailboat, good lead acid batteries were beyond my ken, and they still are. I did buy an Interstate, 4D, deep cycle when we were cruising the East Coast. That meant the battery got cycled once per day and rarely had a full, 24 hr charge. I think I kept the battery in the "good" area of % discharge (>50%.) That said, the Interstate died in about a year. Discussing that fact with an Interstate dealer, he pointed out that a years use was 365 cycles, and that was about what the battery's rating. In other words, I got what I paid for, according to Interstate. I don't think that Interstates are better or worse that any other "good" battery, so I began to realize that normal lead acid "deep cycle" batteries didn't do my job.
That's when I went to golf cart batteries for the house bank. I've never worn out one of those. Three sets: first the boat was sold: second, in use on the trailer (6 years old): third in use in the boat (1 year old.)
The starting battery which the factory gave me was an Interstate, and since it was never discharged, lasted for about 5 years and then died. That was reasonable.
So my conclusion is that if you want a battery that will accept a large number of cycles. Interstate ain't it. You have to change battery types. I picked golf cart batteries (lead acid,) because they were the cheapest.
Boris