Electrical thoughts.....
My first answer will probably provoke a lively discussion; although the West Marine's of the world will trumpet the advantages of gel cells (and, to be sure, there are some), they are not ideal for hot conditions, which include the engine box on the H33. If you REALLY press the technical support people of the companies who make them, they will admit that the gell cells are extremely heat sensitive (think of all those cruisers setting out for the tropics) since water cannot be added to the electrolyte, and that they really don't charge at a much different rate from the floodeds. I have had no experience with AGM's, but they sound interesting. Before I bought them, however, I would satisfy myself that they are truly a hot weather battery. And a salesperson is NOT whom I would ask! The Hunter 33 came with group 24 batteries, or at least my 1980 did. Group 27's will also fit in the battery area over the shower sump. I also use the area under the galley counter and sink for two batteries, one right inside the little door on the left side, up against the bulkhead that bounds the ice box, and another almost amidships, as far to the right as possible. For what it is worth, I started with two group 24's, then changed to two six volt golf car batteries as a house bank, with a single group 27 starting battery under the galley. Then I ditched the starting battery, and put two golf car batteries under the galley and sink, for a total of 4. I then succumbed to the lure of gel cells, and paralleled 4 group 27's as a house bank. Two were over the sump, and two were under the counter and sink. I had a fifth battery for starting. It was a group 24, mounted above the two that are above the sump. I learned my lessons regarding the gel cells the hard, expensive, way, and eventually retreated to the four golf car batteries, with which I have had great results, and much happiness. I toy with the idea of adding a fifth battery for starting, again above the two in the sump, but the system I have seems to work really well. Obviously, I use a smart regulator and an oversized alternator, and, depending on the situation, I either run the banks separately or parallel. I do have a large solar array, and I prefer to charge batteries that way. My final thoughts regarding batteries are that the biggest industry to use heavy duty batteries in a deep cycle mode for transportation is the golf car industry. They are in the business of efficiency and longevity, and you will see them use either six or eight volt batteries, ALWAYS. You will never see them use a gel cell, and I have never heard of them using an AGM, but I can't corroborate that. Trojan is one of the leading golf car battery manufacturers, and maybe it is a good idea to pay attention to the people who use these batteries because their incomes depend on them. Good luck.
