Installation of Primary Bulkheads

(For a great explanation of the day's work, see Tim Lackey Sailing, LLC)

     For Tuesday, November 12th, the day's goal was for installation of the starboard and port primary bulkheads - those bulkheads that would define the forward portion of the main salon, and provide structural support for the mast and rigging.  The previous day, prior to pulling out the factory installed bulkheads, Tim and I patterned the bulkheads with rosin paper.  Now, with a full day to devote to these monster-sized bulkheads, we applied the patterns to new 3/4" meranti marine-grade plywood.   As can be seen in the following two photos, the port primary bulkhead was laid out onto two 4x8' sheets.  Very large bulkheads indeed, for this sailboat with an 11' beam.  

     The photo above shows the pattern laid out onto two sheets of meranti; the photo below is after the pattern was transferred to the meranti sheets.  The process for applying the pattern was relatively straight forward:  the lines applied to the circumference of the pattern, known widths taken from the hull to a point on the pattern, were then recreated onto the meranti sheets, using those known widths.  For example, the compass was set at 1.5" in width and run across the hull, scribing the line onto the paper pattern taped to the original bulkhead.  Now with the paper pattern laid out onto the new meranti material, that 1.5" compass width was recreated, and following the earlier line scribed onto the pattern, this line was then transferred to the new material.  The process requires a slow and steady approach, but is fairly easy.

The difficult part of the installation of these new bulkheads was their weight and massive size.  So large, in fact, that we could not fit the two-part port bulkhead through the companionway; nor could we "ease" the bulkheads through the cockpit sole.  So, back on the ground, we re-cut the two-part port bulkhead to produce two widths that could fit through the companionway.  With that problem solved, a new one popped up.  Originally, the plan was to glue and screw a "scab" section of meranti onto the two portions of the port bulkhead.  This "scab" section would be hidden within cabinetry inside the head, creating a nice finished look.  So, with the new location of the joint (closer to the center line of the boat), the "scab" board would now be too far inboard to be hidden within cabinetry.  I settled on the suggestion to join the two with biaxial cloth and epoxy resin.  In order to avoid having a length of 1708 biaxial cloth cure "proud" of the adjoining surfaces, I routed out a 1/8" section, roughly 3" wide, on both portions of the two-part port bulkhead, front and back.  The 1/8" deep channel will be wet-out with epoxy, and the biaxial cloth laid in to bond the two portions of the bulkhead together.  Tabbing around the circumference of the entire bulkhead will further strengthen and tie in the two-parts.  The 1/8" step down can be seen in the right side of the photo below.

Here is the outboard portion of the two-part port primary bulkhead.  The 1/8" deep channel can be seen as the darker, vertical section of the inboard portion of the panel.  Positioning of this bulkhead proved to be a slow, deliberate and thoughtful process.  With no good reference point within the hull - a very large void with sweeping curvy lines - it was important to get this first portion of the port bulkhead in the correction position, plum, and perpendicular within the boat.  All other installations will eventually draw off this panel, so its position became nearly overwhelmingly important :)  Hats off to Tim Lackey for being the "One Man...One Boat at a Time."  How he manages to place these large, heavy panels in boats with no horizontal surfaces, ALONE!, is quite impressive.  The two of us struggled through finding just the right orientation for these bulkheads, using hot glue and scrap blocks to assist with alignment.  In the end, we got what we were going for:  correct position, plum, and perpendicular!

Below, Tim holds the inboard section of the two-part port bulkhead.  The 1/8" deep channels can be seen aligned, and nearly ready to accept the biaxial cloth.

The photo below show the two-part port bulkhead tacked into place.  The process for tacking in the bulkheads includes wetting out the edges of the meranti plywood with "neat" epoxy (no thickening agents), and then applying a 3/4" thick bead of epoxy thickened with cabosil (fumed Silica).  Towards the end of the day, the epoxy had kicked (hardened).  Regardless, the tabbing would wait until the following day.

The starboard primary bulkhead gave Tim and I the same issues - to wide to pass through the companionway.  So, the altered the joint location, but this time opted for a "scab" piece.  The scab board would ultimately be hidden within cabinetry, so aesthetics would not be harmed.  The photo shows the starboard bulkhead tacked in and awaiting tabbing.

The following photo shows the scab piece on the forward face of the starboard two-part primary bulkhead.  Again, this scab piece will be hidden within cabinetry.

Finally, the forward face of the port two-part primary bulkhead.  The horizontal boards are temporary alignment braces.  These boards will be removed prior to tabbing and joining the two panels with a vertically aligned section of  1708 biaxial cloth.  

Total Time: 8 Hrs.