Actually when we were kids in the sixties our Dad would throw a tarp in the back of his 53 pickup when it was about to rain hard for a couple days, and we'd have a blast splashing in it after it filled up and the sun was back out.
Usually we'd have to add with the garden hose to get it deep enough tho.
Terrence I used 3 2X4X10 wit metal plates holding them together and saw horse brackets that you add 2x4 as legs. Tie stern back to cleats wrapping ratchet strap around backbone and same forward to bow cleats 1 on deck 1 on cabin top and 1 in stern of cockpit. I made mine for snow and worked well.
Over the winter I used 1/2" PVC to form a conestoga type cover for the boat. I just drilled and zip-tied the ends to the toe rail. Then I drilled the center (peak) and tied some cord to them to keep them equally spaced, tieing the ends to the pulpit and pushpit to keep the whole thing upright.
It probably sounds more complex than it really is. It gave me room to get in and out and even crawl along the side decks.
I stripped down the mast and used it for a ridge pole. One 1x4 cross buck at each end lashed to the pull pit and stern rail and a lenth of PVC over the mast step. I used a T shaped piece of aluminum in the end of the pipe to help give me some thing to lash the mast to. I put a few lenghts of left over 1/2 and 3/4 inch PVC pipe over the ridge and tied the ends to the life line just enough to hold the pipe in place. Some lines and bungie cords from the toe rail to the mast and a big tarp overall. It gives me standing room on the deck and enough room to run an old window AC in the front hatch.
Unless you really plan to work fast buy the expensive tarp. I got less than 4 months out of my 1st really cheap one and it leaked. The PVC coated tarp cost $200 but does not leak and is holding up real well. It should last for years as a cover.
The mast would seem to be the simplest way to go, but note its condition in this early photo. It needs an overhaul as much as the Chrysler. A complete new paint job, perhaps all new standing rigging and replacing the spreaders are all still in question. Ah yes... new mast lighting and wiring, too much work to leave it on the boat.
Terrence
Wilmington N.C.
Chrysler 26 1980
Pandora (for now)