I''m actually in the process of putting a new tank on my boat. There were bladder tanks on this boat and I would never recommend them except as a last resort when nothing else will fit. There was a review of several tanks in the Sept 2000 issue of Practical Sailor. SeaLand appears to have some good tanks and does make a large (52gal) bow tank but it is kind of pricey (www.sealand.com). There is a company called Ocean Link that makes all sorts of shapes and sizes (www.oceanlinkinc.com). I''m sure there are many more companies doing this as well. Just search the web for "Holding Tanks". Of the tanks reviewed in PS Sealand appears to be the thickest (3/8"), i.e, no smell and very little side flex. I am considering getting their entire system, with tank monitor, vent filter and discharge pump
, if I can figure out how to make it fit on my boat (only 2 sizes available 28, 40 gal rectangle)
As far as your rails, I don''t have an Ericson, but if you are refering to standard teak grab rails, West Marine carries several different sizes.
Good Luck- Steve