For my 305 I have an off the shelf cover from PM winter boat covers. The cover is made by carver. Its not a perfect fit but does the job. Its currently on the boat for its 9th New England winter. Its not a perfect fit as there are small exposed area above the gunnel on both sides about mid ship. This is d.t. the large hardtop with domes on top. It hasn't been an issue. Before this I had a similar carver on my 265 which went with the boat when i sold it after 9 seasons. the cover were considerably cheaper then the custom option and have paid for themselves and then some compared to shrink wrapping.