Heavy-duty deck hatches, including custom designs. Also full-height doors. Freeman products are used by rescue craft, workboats, and other commercial boats.
One C&C owner's method of installing fan ventilation in his companionway washboards.
White laminated plastic hatch boards that are convertible from tinted transparent panels, to insect screens, to translucent panels for privacy. Lock and canvas storage bag available.
A versatile rain and spray door that can hold a chart protected from the weather. It's easier to get below or on deck than with normal companionway drop boards.
Heavy spray can squirt under the leading edge of many sliding companionway hatches. Here's a DYI method of building a hatch garage to keep water out, a transparent slider to keep your interior bright, and plastic gliders to keep hatch movements silent.