Pat, thanks for pointing out my error with the incorrect tag. Much appreciated. Steve, the canvas vendor is Lippincott Marine, 74 Norman Avenue, Riverside, NJ 08075 (856) 764-8282 The owner's son Matt Lippincott is the fellow who actually constructed the cover for us. We found both the boat dealer (Winter's Sailing Center) and the canvas vendor to be good people to work with. I must say that Matt's workmanship on the canvas is excellent. I'm sure he could easily accomodate the tower for a cover as he already has his patterns from the cover he made for our 21EC. And he also has the luxury of having numerous 21's sitting right there in the Ranger dealer's yard from which he can readily take any additional measurements he may need to accomodate a tower. His office is in the same building as the boat dealer. I did ask Matt if they ship UPS and he said yes, all the time. Based on the product and service we experienced from them, we'd very much recommend them as a source for covers. Oh, the ribs you see under the canvas above the cockpit is the tubing from the canopy frame which we always leave in place.
We also have the tower on our 21EC but have opted to always remove the tower prior to installing the canvas cover since it's already down as we trailer the boat home. You might want to inquire if it's practical for them to make the mast cover removable (w/zipper) so that it's a little easier to remove the rest of the cover off the boat AND an alternate "dummy" cover in the case where you might wish to cover the boat WITHOUT the tower erected.
Hope this info is helpful.
Ed