I have been using the Optima Blue top in many boats for years. Best batteries ever. You can search the internet and find them at greatly reduced prices with free shipping.
Not to long ago I was playing an outside Music Gig, took the Optima out of my boat, hooked an inverter to it, and it powered my Amps, PA System, my Guitars, Pedal Board, and 2 Keyboards for hours. Much easier than hauling a big noisy Generator.