quay sails in Poole may be able to help, we had a custom made cover made for a hobbie cat by them. superb job. My dad had a few bits made up by the sail maker at Mercurey yacht haven, the too were very good.
I am having one made for my zodiac 260 FS so that it protects the PVC at all times, and has a built in fender strip. The normal covers are only any good while the boat is on the davits, or out of commission.
We had one made in 2002 for an Avon 310 by Lymington sail and tent. £80 and was a very nice job. We just bought a cover supplied by Avon for the 320 jetrib, £110, also perfectly ok.
You need to get the right fastenings, eg if you want to put the cover on while boat is in water you might get a cover with hooks that attach to the fender strip. The fender strip on recent 310s is made in a section that allows hooks to attach
Oops Jim, sorry I made a mistake. I just checked the invoice, I have it here. The cover was in fact £190 for the 320jetrib. From Ron Hale Marine. Sorry for providing you bum info.
It seems the small firm bespoke cover makers can supply for less cost than Avon
The Avon official cover is perfectly ok. Fairly lightweight canvassy fabric, felt bit cheap at first, but actually this allows it to stow easily. Has very deep skirt so the sides of the cover go right over the rubber tubes to the joint with the GRP, and it fastens mainly with a big drawcord, pull tight and tie at the transom.
You need to do some diy mods to the drawcord, fit stopper knobs and make up a loop to tie and trim it all to size
So yes, perfectly ok imho, but a custom cover maker on the south coast UK can probly do as good a job for less money
Beware one thing. Check if the cover will clash with your dinghy tie downs. We are ok because our dinghy is on chocks and it has 2 short tie downs, one from the bow eye vertically down to the bathing platform, and another from the transom ski-tow eye vertically down to the bathing platform. This works fine but is the only arrangement that does. If for example you fasten the dinghy down with big straps that go right over it athwartships then the straps will prevent the draw cord drawing in the hem of the cover, and the cover will come off. You would in fact have to fit the tie down straps on top of the cover which is less convenient.