The Everstart Maxx 29DC deep cycle battery is a good choice for use in boats. Available at Wal-Mart, Everstart Maxx brand batteries generally carry favorable reviews and are an economical choice. Using a deep cycle or marine battery for boat applications is the best way to ensure long battery life.
The manufacturer specifications for Group 29 batteries do not vary much between brands of batteries. Both Interstate and AC Delco group 29 batteries have essentially the same cold cranking amps and reserve capacity. Everstart Maxx compares favorably to both national battery brands in both cold cranking amps and reserve capacity and is generally priced lower.