After some more poking and prodding here is my revised sketch of what I am
pretty sure I will find
This is offered with the caveat that I have not yet taken anything apart so I am not certain:
Note the change from the last drawing: that the void near the rail is created by a short piece of "ceiling backer" mounted vertically. It would appear that this part is tabbed to the hull all along its lower edge and probably screwed somehow to the overhead liner piece at the top. It is about 7 or 8 inches high aft and less forward. This not only looks like what I have, it also would be a fairly straight forward means of assembling these pieces which afforded some adjustment/flexibility to allow for manufacturing tolerences and so on.
This overall design would be in keeping with the Napier design of the entire boat. It was originally built in modules. The hull / the cockpit deck / the weather deck / the house / the fly bridge / the bulkead or canvas or half bulkhead at the back of the house / the galley module / and so on. You picked your desired configuration from a menu and they put it together for you using the appropriate parts.
My experience in working on this boat tells me that they left a great deal of room for manufacturing variations and tolerencing. So the overhead module; the weather deck module; and the hull module would not have been tight fits one to the other. Instead some allowance would have been made for adjustment and placement during assembly.
Note that additionally the continuous tabbing along the botom edge of the backer makes a water channel that would (does) re-direct any deck hardware/ hand rail/ rub rail leaks aft and away from the bunks and forepeak keeping the bunks cozy and dry and the forepeak less musty and moldy. Was this benefit their intention or just a happy accident? Probably an unexpected consequence because the backer ends at the chain locker bulkhead forward and the electrical locker bulkhead aft and there is no specific provision for any leaking water to go anywhere special at these points. My guess is Bertram intended to build these boats to not leak at all, period.
Now I'm guessing here: But I'd suppose during manufacture you first put in the bulkheads. Then put down the overhead piece and get it more or less where you wanted it. Then you put in the ceiling backer panels fitting them between the overhead module and the hull. Once placed you screw them in at the top to hold them where they need to be and then tab them into the hull at the bottom.
This is clever design. Recall that this pre-dates CAD and since it is a boat nothing is straight or square. Everything is curved and tapered and so forth. So designing this stuff so that it fits together properly would have been a pretty intense three dimensional excercise. Bertram Yachts, Napier, and his team must have spent a good deal of thinking figuring out how to create the design, produce the tooling, and develop assembly techniques for all these big molded parts so that they would fit together. And that would have included how to allow for the above mentioned tolerencing and manufacturing variations... but doing so in a way that was efficient to build and assemble. Not a lot of place-and-scribe; test fit and retry.
I do not know how many B26's Bertram built, but certainly there are more 25's around. I always assumed that the 26 was a "value engineered" 25. One where they took away the tumble home and curved transom and so on to avoid using a two piece mold. And at the same time fixed the head room problem by putting a curb in the weather deck and adding a longer, taller house. But all this was a trade off of a certain sort of classic beauty for a more slab-sided utilitarian look. Now I also see how much effort was put into the stuff we don't see from the outside: the modular production concept,tooling, and technique, and I have to offer my admiration for thier efforts.
I wonder if they ever recouped thier engineering and design costs?
Meantime I probably will not go after this project this spring.
I am thinking about tearing out the carpet in the fall. Then cutting long-ish slots into the backer to gain access to the back sides of the hardware. I would re-apply some sort of ceiling (I don't know what yet) leaving these holes open. Then I would then finish them by putting in some sort of little shelf pocket. It would have an inside liner so you don't look straight at the outer hull or hardware when you look in there and it would flange-mount around the edge of the access hole to finish the edges of the ceiling. The bottom of the shelf could extend (cantalever) into the interior space an inch or two without getting in the way of using the bunks. This would trim out the access hole and still leave me an easy way to get at the rail hardware in the future while preserving the original integrity of the design.
Those are my thoughts for now. If anyone beats me to the project on their boat, or has already been-there done-that, I'd like to hear fom them....
Peter
