Last season the forward deck hatch was broken when a Genoa sheet got caught under the open hatch lid when trying to reef the Genoa in a sudden blow. They are also prone to break if you stand on a corner. A replacement lid cost £470. The new lid has been modified by by adding a circular rubber pad on each corner.
My B36(2002) is an ex charter boat, and each of the deck hatches was modified by the then charter vessel owner with a notice that reads "Keep Shut While at Sea." As a modification it works remarkably well at protecting the hatches from damage, but admittedly does nothing at all to permit ventilation of the cabin spaces when in hot weather. It does however help to reduce the risk of trips and falls while on deck, and prevents sheets from snagging as I found once when I'd left the hatch over the forward heads slightly open.