And I only use the one battery and keep the weight out of the boat for skiing. I bought the boat in 2002 and I time the stereo usage. I now carry jumper cables as I did replace a 500 watt subwoofer amp with a 1000 watt amp. The cables are used for the varibles like the stereo left on too long or the battery deteriorating. I go two hours and then I am forced to go run the boat or turn the stereo off. I have yet to use the cables.

It appears weight is no factor with the bigger boats so having the isolation is a real plus. For a system of 3+ batteries, I have been sold for many years with the golf cart batteries in my motorhome where I run without AC power for eight days at a time. I went through deep cycle batteries much faster and that may be the way I ran those batteries down. I now find the Trojan batteries jumped in price a few years back where the Costco GC batteries made by Johnson Controls works as well for the price. To each is their own style and assurances. I live on the fringe and I hate replacing batteries and tires that die from age rather than from useage.