Structural question....A-145.

[Remsbecher]

My question pertains to the aft bulkhead at the rear of the cabin. I have cut it out on both sides to make more room for the side berths. To what degree do I need worry about the boat structure, (having cut away the base of the bulkhead)? The ends, port and starboard, are left attached to the hull. I saw this layout on an Alberg 35 and I liked it. Or is the hull so beefy that there is no problem or at least not major?
Thanks. Arthur.

[Bill]

Review Ebb's Photo Gallery thread. He pretty much tore out everything.

http://www.pearsonariel.org/discussion/showthread.php?t=249

[ebb]

My opinion:
From the old tabbing evident there you ARE cutting into an important original bulkhead.:eek:
I'd say, while not seeing the whole picture, that you will be making the footwell as small as possible! However, as Bill points out by referencing 338, I think you have to make up for your sins in other ways.....

(Little Gull 338 has one whole side of that very bulkhead removed. Great lengths have been taken attempting to restore integrity. Least I think so. From port to starboard a laminated cross beam was put in along the top of the bulkhead under the bridgedeck against the cockpit well. I feel that it provides rigid support for the cockpit well and bridgedeck. Such radical support was necessary because of bodys jumping and banging around in the pit. Four celebrants weigh how much?

Vertical struts were put in at about cockpit well width under the beam. A substantial rib was laminated in along the hull on the newly open side where the bulkhead was removed that is incorporated into the new quarter berth and its bulkhead and what will be the seat for the dinette/nav table.)

All furniture will be installed permanently with tabbing. Looks like you are doing the same!

I feel that if you can box an adjoining area in with plywood: partial bulkheads, seat tops and front, ie a bunk or settee, even if they have large access plates/lids in them... you strengthen the hull immensely - you are tieing the structures together and structurally tabbing them to the hull.

Imco you have to support the cockpit AND the cabin with something that resembles the original bulkhead... BECAUSE THAT'S WHAT IT IS THERE FOR.
Furniture here can be thought of and maybe designed in as substantial support: the galley, settee, whatever has to do its share to help replace what you've taken away from the original diaphram.

(The pegboard in Little Gull was removed and supporting longitudinal bulkheads put under the length of the cockpit. Immobilizing the cockpit - which is for all intents and purposes in most Ariels merely hanging from the coamings - could be seen as major help in stabilizing this important and active area of the boat. The blkhds transfer the load of the cockpit to the hull. The new l. blkhds meet with the vertical struts mentioned above. This is also where the large rib terminates.)

So to say that in Little Gull we've gone to some extent to support that end of the cabin. AND the bridge of the cabin/companionway. The laminated monocoque mold forms of the big open companion way and the big open bridge-deck access under it need help keeping these buzy structures from sagging down and inward.
I do believe that.

Another suggestion is that Alberg's design has a longitudinal symetry, let's call it, that we should honor: in his spacing of the four bulkheads that comprise the interior. I feel that the INTEGRITY of the hull depends on the stiffness provided by those two main thwartship bulkheads. I believe they keep the vessel from twisting.
See the cabin with its two main bulkheads as a BOX. Imagine cutting out the ends of a sealed cardboard box and how easy it would be to flatten it. Cut out a major portion of both ends but leave a border of the ends all round. The box will be much stiffer, even with most of the ends gone. Removing parts of the diaphram-nature of the bulkhead requires replacement with something just as immovable. Hopefully we will rebox the Ariel-cabin with frame-like substitutions and offset structures.
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In short form, imco
you should think about tieing the remaining bulkhead into the settee/bunk fronts on the inside. Tab the remaining top of the bulkhead to the settee fronts and the hull on both sides. Depending on what you are using the opening under the bridgedeck for you could curve the top over the opening to get more material on the "legs" of the bulkhead you are thinking about putting back. An easy way might be to double up the bulkhead by glueing and screwing on another layer of 3/4" plywood with the shapes you want to add. The added weight would be insignificant - and there isn't much bulkhead remaining anyway.
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It's good you bring it up.
Many boats get destroyed when impulsively gutted.
However, inspired eggcrating and web-framing
will get the intrepid refurbisher out of trouble every time! :p

[Remsbecher]

Thank you, Ebb, for your insights and solutions with this remodel. I've taken on more than I bargained for with my project, and am hoping at this time to find my way out of the problems I created. My plan is to run vertical panels, fore and aft, under the full length of the cockpit supporting the base of the cockpit to the hull, just as you described.
This seems like it would compensate for a number of sins. At least I am hoping so....
I thought, too, I would laminate a piece of 3/4" plywood to what I have left of the existing bulkhead and glass it heavily at port and starboard.
My plan is to make a comfortable liveaboard and sail away somewhere. Attached is my galley stove. It's kerosene.
Am I looking for trouble? Arthur.

[ebb]

Arthur, Everything will be just fine!
A drawing or two would have cancelled all the windbaggery above.

I'm going with Kerocene also, but will try James Baldwin's single stove first. I've found one that supposedly will pressurize the kero for preheat. Have to make gimbals for it. We'll see. I'm not a chef, so a single burner, fry pan, pressure cooker and water boiler is all I need.....yeah, right.:o