Saugeye,
Any local canvas shop that does marine canvas should easily be able to make one up for you.
Also there are many online sources that can make one up from your measurements and they also make a fit all that can cover many sizes.
Check out Craigslist, I've seen several on there as well. and are usually reasonably priced.
I bought one off craigslist that was close to the size I needed for my aluminum boat, had to do a little adaption but it it does the job keeping the sun out, and offers some protection in a light shower.
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All this,just for a boat ride
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