Here's a rear-view of what on a scaled 16' watercraft will be ample accommodation of around 24" square. Big as an IKEA armchair it's likely a little too much, and if we reduce its proportions it allows decks and uprights to be a little longer as they are effectively cut from the same cloth.
Note at this stage that we do not insert the foam in the back-rest: step away from the vehicle if you could, Sir? That will allow us to drive a screw into each side-bar to fasten the seat-back to either boom to reduce flexure further.
You can see the advantage of foam sheets as thick as the timbers, because then we'd be able to double-skin each element of the seat. As it happens, in a process of continuous improvement we could eliminate separate skins altogether because the backer-board is already double-skinned.
Note how I've included just a soupçon of recline in the chair for your comfort, and a cushion will of course be provided. The recline is done when all is fixed together, by applying sufficient force to bend the fasteners and brackets... a process that takes years to perfect, and which is handed down from one generation to the next.
Ideally the seat-back would be perforated to some extent to allow the fullest draft to pass through to the air-screws, but that's a job for another day or even someone else, isn't it Gromit?
