I ended up buying one of those sub £100 covers on ebay, and thought I'd let everyone know about the sizing issues I experianced.
After talking to the company I was advised that because my Ocean is quite wide for a 6.5M and because of the large console, I'd need to go for the largest cover, so I went for the Size 7.
When it arrived I was impressed, its a good quality material with all the strap anchor points sewn on well etc and comes with a mesh bag to stow it in and plenty of straps.
When I tried to fit it, the stern section fitted like a glove around the A-Frame and over the Tube ends.
The Bow section was however Far too narrow to fit over the rubbing strake of the Ocean, and looked like it was meant for a more 'pointy' bow like a Scorpion etc.
And with both ends fitted it was obvious the cover was far too long as well, so I considered my options.
The next size down (6) would have been the right length, but still too narrow at the bow, and too narrow in the centre to cover the console and still go right over the tubes..
So what I did was quite simply slice the front 4 feet from the cover, tie off the elastic each side, and use Mrs Nashers sewing machine to turn a hem along the front edge. (Don't tell her, she was out
By doing this at one of the strap points on the cover I've actually created a better strap down method at the bow.
I'm very pleased with the result.
For the price, and the small amount of work, I could not have expected such a well fitting cover. I just need to see how well it stands up to the wind etc now.
I would recommend one of the covers to anyone that is willing to put a small amount of work in to make it fit, but not to anyone who expects a perfect fit straight out of the bag.
As a bonus I have enough material left over that is already shaped almost perfectly to make an engine cover, I just need to wait until the sewing machine monitor goes out again to make it up.
See piccies below.