Extending the Engine Room Bulkhead to the Bilge

     On Saturday, November 23rd, I was finally able to get back onto the boat for a little bit of forward progress...to keep the forward 'momentum' going.  I started off by water washing the port main bulkhead tabbing.  The water washing removes the amine blush that forms on the surface of the epoxy as it cures.  Removing the amine blush is the first step in preparing the surface for additional epoxy work (if needed); it otherwise would prevent a good mechanical bond with any additional epoxy work.  Water washing it is as simple as using a spray bottle to mist the surface with water, a good scrub with a Scotchbrite pad, and then wipe off the surface with a rag.  Done.

While I was at the water washing task, I cleaned up the surfaces of the cabin sole supports too.

I then took a 40-grit psa disk and gave the port main a good scuffing.  Scuffing up the surface of cured epoxy, after it has been water washed, is the final preparation in getting it ready for additional epoxy applications.  The sanding creates microscopic 'nooks and crannys' that epoxy forms a mechanical bond with.

I also sanded the cabin sole supports in the same manner.  After I had completed the sanding of the port  main and cabin sole supports, I took the wet/dry vac to the surfaces to tidy up the space in preparation for another job - the engine room bilge damn.

During Tim Lackey's visit, we removed the engine room bulkhead and replaced it with fresh 18mm meranti.  Due to the companionway's max 41" clearance, we could not slide an entire 4'x8' sheet of meranti into this space.  The result of this constraint was to leave a gap of roughly 21" from the bottom of the bulkhead to the bilge floor.  After some back-and-forth in trying to decide whether or not to leave a gap, allowing water to pass underneath the bulkhead, I decided to partition the salon bilge from the engine room bilge.  This decision would also prevent engine room bilge water from flowing into the main salon bilge, where the water tanks would reside - a cleaner solution.  

I used a templating method that had proved successful on the cabin sole installation.  First, I extended the boat's center line on the engine room bulkhead down to the bilge floor.  I then clamped a scrap piece of lumber to the engine room bulkhead, on plane, resting on the bilge floor.  I then marked the boat's center line on the scrap piece of lumber.  My next task was to take small stir sticks and hit glue them to the scrap lumber, just touching the hull both on the port and starboard sides.  The hot glue gun (seen below) is a "sleeper tool" on a boat build.  These guns come in pretty handy while installing bulkheads, templating, among other tasks.  

My next order of business was to transfer the template to a scrap piece of 18mm meranti - that scrap piece in the photo is probably $45 worth of BS 1088 18mm meranti...scrap has a whole new meaning.

After transferring the measurements onto the surface of the meranti, I prepared to cut it out.

Using a jigsaw, and a well-worn blade, I removed the lower portion of the engine room bulkhead from the scrap piece of meranti.

With some final shaping and sanding while onboard, the piece fit nicely in its new home.  This lower portion of the engine room bulkhead would serve to isolate the main salon bilge (housing the water tanks) and the engine room bilge (fully planning to keep this space clean and tidy, but you never know). 

After I dry-fitting the piece in place, I removed it and prepared the surface for bonding.  Using my Porter Cable 7335 and 40-grit psa disks, I thoroughly sanded the surfaces around the installation area, including the bilge floor.  I then vacuumed the surfaces to remove any sawdust, fiberglass dust and wood shavings.

With the area prepped, I again inserted the lower portion and made scribe marks on the bilge floor and hull forward and aft of the bulkhead. The scribe marks would provide a good visual of where to apply the thickened epoxy for bonding.  I removed the piece after scribing reference marks, and gave all surfaces a good solvent wipe down.  Next, I painted straight epoxy on the edge surfaces of the lower portion of the engine room bulkhead to be installed and then set it aside.  I then made up another batch of epoxy, but this time I thickened it with cabosil (fumed silica).  I spread the cabosil mixture between the forward and aft reference marks, and then slid the piece to be bonded in place.  A scrap piece of wood was screwed to both pieces keeping everything plum and in line.

With a squeegee, I cleaned up the squeeze out and worked it into the very small voids around the circumference of the new installation.  The picture below is the forward side of the engine room bulkhead. 

The picture below is the aft side of the engine room bulkhead.  Fillets and tabbing will eventually be placed onto the bulkhead from bilge on up.

Total Time: 4.5 Hrs.