I have always stored my pontoon boat indoors, either deflated and broken down, or inflated and ready to go in a garage. My problem is that I do not have a garage at my new place, so I have been thinking about storing my pontoon boat inflated and assembled outdoors under a tarp. Has anyone else done this and do I have to worry about rodents/critters chewing on my pontoon boat?
Aside from rust issues, you should also be mindful of seam rot issues if your boat has any sewn seams. If it does, providing ventilation as Ed suggested is a good idea. You might also treat the seams with a waterproofing agent. Several come to mind, a DWR like Nikwax or a true seam sealer like SeamGrip, but I'd contact your manufacturer for their recommendation.
Space for circulation during wet months can prevent rot. During warm months cooling. The cover right on the tubes in wet time holds water in contact, and in summer the hot sun may heat the cover. Pressed on the tubes the heat is transferred, the space reduces the transfer of heat.
I've stored my Skookum pontoons outdoors for several years with no ill effects. Recently moved them indoors because what I thought was a never visited, secure spot was not, and someone "borrowed" my downriggers. Covered but ventilated as Ed and others mentioned is a good idea and other than throwing a chain and lock around them that's about all you'll need.
