From the ISAF OFFSHORE SPECIAL REGULATIONS Extract for Race Category 1 Monohulls
JANUARY 2010 – DECEMBER 2011
3.08.4 A companionway hatch shall:
a) be fitted with a strong securing arrangement which shall be
operable from the exterior and interior including when the yacht is
b) have any blocking devices:
i capable of being retained in position with the hatch open or shut
ii whether or not in position in the hatchway, secured to the yacht
(e.g. by lanyard) for the duration of the race, to prevent their
being lost overboard
iii permit exit in the event of inversion
3.08.5 If the companionway extends below the local sheerline and the boat
has a cockpit opening aft to the sea the boat shall comply with one of
a) the companionway sill shall not extend below the local sheerline. or
b) be in full compliance with all aspects of ISO 11812 to design
3.08.6 For boats with a cockpit closed aft to the sea where the companionway
hatch extends below the local sheerline, the companionway shall be
capable of being blocked off up to the level of the local sheerline,
provided that the companionway hatch shall continue to give access to
the interior with the blocking devices (e.g. washboards) in place
To comply with this, I designed and built last year a custom hatchboard, that can be latched in place with a deadbolt, is secured to the boat with a lanyard, and allows the sliding hatch (the top part) to be opened or closed and secured from both the inside and outside, such that one cannot be trapped either inside the cabin or outside on deck. The material had to be thin, which precluded embedding a doorknob type feature in the hatchboard itself.
Interior view of installed hatchboard.
Detail of spring-loaded latch of the hatchboard.
Exterior side of the hatch. The lanyard in the middle is pulled to allow the upper hatch to slide open.
The board is made from 3/8″ HDPE Starboard material from TAP Plastics. The latch is a transom latch modified so that the angle of the striker is reversed from the usual direction, so that when the board is in place the upper hatch can be slid shut and will latch without needing to pull the lanyard. I have since found that a gate latch is available with the right orientation from McMaster-Carr. Opening the hatch from the outside is a two-handed operation, you pull the lanyard and slide the upper hatch back.
It is possible to leave the board latched in place and enter the cabin from the open hatch, but it is a long drop from the cabin top to the first companionway step, and not a great idea unless you are pretty tall!