Holding Tanks
I don't know the exact answer, but I do have a 25 and have wondered about that for some time. Here are a couple of suggetions. Install a portapot with the fittings that allow you to pump out from the deck. However, they're still only about 5 gallons. There is a unit available from West Marine that is a 'regular' marine head sitting atop a ten gallon holding tank. It goes for about $400. Only problem is that I think it's about an inch or two to large (depth-wise) to fit. Although the potable water tank on an outboard O'Day 25 is located under the cockpit sole, it is located under the V-Berth on those eqipped with Inboard engines. You could perhaps place it there. Access was through the top of the V-Berth (under the mattress) through an access identical to those in your settees. If your potable tank is already there, I would try to move things around a bit to fit both. I once saw 'saddle tanks' that were shaped to be placed in the area under the settees. If you can get them in there, this would be good. I thought they were from JSI sailing. But I don't remember if they were potable or waste tanks. Practical Sailor did a test on holding tanks not to long ago. Basically, stay away from flexible tanks unless you MUST use them. For hard tanks, the trick is to get them as thick as possible. Most are only about 1/4" thick. The best tank appeared to be the Sealand, but it's $125 (20 gal) through Defender. The Kracor tanks were the worst, they leaked through the fittings rather quickly. The Todd tanks were not much better, although they didn't leak, they bulged quite a bit. The reason for the thickness is twofold. First, thicker tanks prevent odors from seeping through. Second, thin tanks bulge more. This can deform the threads for the fittings allowing odors at a minimum, possible some spillage (yeeech!). The aformentioned are plastic tanks. Don't use an aluminum tank, sewage will corrode aluminum rather quickly. Stainless is suppose to be OK, but obviously very expensive. You can read the review in PS Sep 2000. If you subscribe, go to http://www.practical-sailor.com Russ Marcks
