I visited a French Konsort this summer and was intrigued to see a compan- ionway seat. I had long decided that such was a good idea when sailing or motoring to windward in rain or spray, when I hide behind the sprayhood and sit on the 1⁄4” edge at the base of the slot for the companionway boards, which is little bit hard on the bum. (I have tried sitting on the outer edge of the cockpit coaming behind the sprayhood, but its slope makes it very difficult.)
I had just purchased some thick boards and very substantial fittings for my approximate design, but this seat was light and easily stow-able. I copied the measurements and began to make my own, slightly modified seat. No doubt the idea would be appropriate to other Westerly yachts.
I thought it a good idea to have the seat the full width of the companionway in order to secure it better when heeled. However, half the width is sufficient and would allow easier access in and out of the companionway. I wanted to use a hard wood for the legs and front board, and stainless steel fittings. However, I was unable to purchase stainless steel hinges in a hurry in France. (I am sure that Google would assist you.)
The board for the seat was a shelf in a previous life, of pine and of thickness 18mm. It is 220mm wide, but 150mm might be fine (depending upon the size of your bum!).
The edging strip at the front is hard wood, 15mm x 45mm (the same as the legs). I cut it 10mm short of the full companionway width. It is also recessed 15mm from the edge of the seat board which is secured to the seat board using stainless steel screws. Note: I positioned the screws to enable a recess to be cut (using a multitool later) which will enable the folded legs to recess into the front edge for flat storage.
For the aft edging strip, I used pine softwood 13mm x 32mm cut 35mm short each side of the full width of the seat.
I decided to angle the seat so that the front edge was lower than the back edge because I thought that this would help when pounding into waves.
To prevent the seat collapsing when in use, the legs are at a slight angle, not vertical. Hence, precision is required when cutting both ends of the two legs, and when attaching to the two hinges. I also used a cross piece to make the legs more secure, this was not positioned at the bottom of the legs for two reasons as follows:
1) I wished to be able to fold and stow the legs as close to the seat board as possible.
2) Although putting the cross piece at the base of the legs would have given extra security it would also have entailed more work, because the cockpit seat where the legs rest is not flat but slightly curved. The bottom edge of the cross-piece would have needed to have been carefully beveled and at the ends, exactly the same level as the foot of the legs. However, the advantage would have been to spread the load and wear on the non-slip paint of the cockpit seat.
You will need an assortment of lengths of counter-sunk screws. By the way, I like to use a dab of Vaseline on each screw. It makes the screw a lot easier to screw in, and easier to remove at a later date if required.
It would also be possible to fit a piece of wood that flips down to secure the legs in position against the upright fibreglass in front of them and prevent them fold- ing accidentally, however I do not think that necessary. Otherwise, I hope that the seat is slightly over-engineered and long-lasting.
I have a plastic (closed-cell) foam garden kneeler on the boat. It would be possible to glue such to the seat for a more comfortable ride, but I have not found that necessary so far. Now where do I store the folded seat in an already cluttered boat? There might be room under the nav table, since I have not yet used that space for anything.