This is a "rim lock" deadbolt I installed on Scamper's companionway hatch. It required the drop-boad to be built-up almost 1/2 inch to add enough room for the key mechanism. I really like it - there's no need to fool with padlocks and it's easy to lock from the inside.

ORC requirements specify a mechanism to lock the companionway from both the inside and outside. In really heavy weather it would be a good thing to keep the companionway locked closed so I fastened a lanyard to a spare key and will leave the key in the outside lock and clip the lanyard to the eye to the right of the lock.

ORC also specifies the ability to fasten the companionway to the boat so that it cannot be carried away as it is being removed. I made up a lanyard to clip between the the eye next to the lock and another eye just inside the companionway.