REPORT #10: Installing the "quarter berth" bulkhead -- MOA

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Date Posted: - Monday - 03/31/08 - 2:10am
Author: Randall ()
Author Host/IP: c-69-181-42-112.hsd1.ca.comcast.net / 69.181.42.112
Subject: REPORT #10: Installing the "quarter berth" bulkhead
In reply to: Randall, M31, Murre 's message, "Aft Cabin Bulkhead Replacement" on - Monday - 01/21/08 - 9:56pm

Rule 27: once started, any job will take much more time to complete than was originally planned, even if this rule is taken into account during the planning stage.

I don’t know why, but I just can’t correctly judge how long a particular stage will take to complete. For example, this weekend I planned to install the new “quarter berth” bulkhead, cut and fit the interior pieces above the ice box, and have time left over. As it turned out the bulkhead dominated the weekend. The jobs attacked and completed were more or less what I’d envisioned the previous week; there weren’t any major hitches or do-overs; it’s just that each element of this weekend’s work took much longer than planned.

Maybe this is a coping mechanism. If I knew how much time the entire project would consume, how many weekends in this cave of a covered berth (when it’s storming, this berth is heaven; when sunny, it’s hell), I may never have started.

The old divider of ˝” ply was plenty beat up, but it had come out easily and so was in good enough shape to use as a pattern. The new wood was the same I’d used on the aft cabin bulkhead, 5/8” Okume.

It was good as a pattern of shape, but not good as a guide for width. I’d cut the divider out of its inboard frame (and then circled back later to clean the frame groove—by now a familiar process).

So, instead I used the tiny top frame (pictured on top of the old divider) that had held the original in place. It too was rotten and chewed by disassembly something fierce, but it had held its original length exactly.

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Rewards too come calling on occasion. The new bulkhead fit the first time.

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The new top frame was cut from the same Santa Maria we’ve been using for framing on all projects since 2003. It’s heavy and dense and reassuring. This one matched the deck beam for width and was about 1 ľ” deep. Fasteners were stainless woodscrews, #12 x 2 ˝”.

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And more glass. On the aft side, a layer of 18 oz roving and 1.5 oz mat on top of that; on the forward side, the same regime but with the addition of 1 oz roving as the final layer to help smooth things out. Note the black felt pen line in the first photo across the top of the bulkhead. This is the aft side and I’m only applying the 18 oz to the area under the frame so that the jointing parts of the bulkhead still fit.

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Trimmed, lightly sanded, washed with fiberglass solvent, and ready for installation.

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And the hull has been ground clean and washed as well.

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A note on voids. If you pull up the insulation on your Mariner, you may find “bubbles” in the resin. Back in 2006 when I was installing a bulkhead at the aft of Murre’s cockpit, I noticed voids under the insulation I had removed for the bulkhead’s foot. After finding the same during this project and being worried again, I contacted a builder I know who has taken his fiberglass boat down to the bare hull (inside and out). His response: voids in glass, big problem; voids in resin (as here), no big deal. Very likely the resin was laid on extra thick in the final stages so as to act as adhesive for the insulation. As the insulation was applied, the resin “drew up” just as it does when one applies wax paper as a smoothing agent on smaller jobs. One can see the “bubbles” under the paper, but one cannot see through insulation.

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The bulkhead fastened and glued in place. I used #10 x 1 1/2" wood screws along the top, just glue along the inboard side, and...

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I secured the hull end of the bulkhead with two layers of biaxial tape fore and aft. It took a tremendous amount of massaging, mostly by hand, to get the tape to "wet-up" the resin. Not pictured is a small bead of 5200 in the gap (intentional) between the bulkhead and the hull. The gap was left to avoid the development of a hard spot. So, all the strength of the joint is carried in the biaxial tape.

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And that’s the weekend.

Well, not quite.

As a PS, I was inordinately pleased with this solution to a problem. The mahogany spacer that surrounds the inside of the aft cabin portlight like a washer had broken during the disassembly process, and then it broke again during the sand-the-old-varnish-off process, such that I was left with three pieces of a circle and no idea what to do with them.

So, in a fit of (unusual) brilliance, I glued each piece to a resined circle of mat, thus:

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Last edited by author: Mon March 31, 2008 21:50:15 Edited 6 times.

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[> [> Thanks Randall -- Steve Burge, - Thursday - 04/ 3/08 - 10:30am (tlw155.tillamooklightwave.net/69.1.115.155)

I just wanted to say thanks for the posts of your projects. I appreciate the experience and have printed all of the pictures and comments so I can have a better understanding of the process when I get to the cockpit rebuild. Keep em coming!

Steve

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[> [> More than welcome! -- Randall (), - Sunday - 04/ 6/08 - 11:17pm (c-69-181-42-112.hsd1.ca.comcast.net/69.181.42.112)

Glad you find the articles useful, Steve.

It is unlikely anyone on this board will learn much from my approaches to carpentry, but watching me go through the process may give others a sense of what's under a Mariner's hood and in that way may save time and heartache.

Good luck with your project. And don't make me the only one to post progress pictures!!! :)

RR

Last edited by author: Sun April 06, 2008 23:18:12 Edited 1 time.

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