Hull Repairs (White Dhow)

April 7, 2018

I had planned to get to both Dhows today: removal of hardware and brightwork, hull washing, sanding to remove the old topcoat paint, and any fiberglass work and filling of surface voids.  Alas, the day started with a waffle and copious amounts of butter and maple syrup...enough said.  By mid-morning I was out on the boat, and decided to focus on the one Dhow for the day.  I have washed the hull the prior evening, and so was ready to begin sanding to remove the old flaking topcoat paint, traces of barnacles, and fairing filler used in previous repairs.  I set up the RO sander with 80-grit pads, connected it to the vacuum and got straight at it.  In the picture below, you can just make out the freshly sanded areas from the remaining old surfaces.

Once I had completed the sanding the hull, I outfitted the vacuum with the brush head and removed as much of the sanding debris as I could.  The next step was to evaluate the areas of damage to the hull for further repair.  In addition to the following three photos, I found numerous areas that required dishing-out the area with the angle grinder and 40-grit flap wheel; also, I went around the sheer line and ground a taper in the old fastener holes that secured the rails, oar locks, and seat braces.

Mid-ships to starboard at the transition from topsides to bottom:  chipped gelcoat and gouges.

Aft sheer to starboard: fiberglass topsides cracked through. 

Aft sheer to port: voids in fiberglass and chipped gelcoat.

Prior to getting started with grinding  and removing the damaged gelcoat and fiberglass, I "went below" and marked the locations of the seat braces and oar locks since these fastener holes would be filled with thickened epoxy.

With the seat braces and oar lock fastener locations marked for future reinstallation, I then began the grinding necessary to remove any loose gelcoat and voids in the laminate.  I started at the aft port quarter and took care of the largest of the areas requiring repair first.  With the angle grinder and flap wheel, I took removed material so as to leave me with solid laminate and gelcoat.

I moved forward on the starboard side of the hull, and as I went I ground out areas requiring it.

Moving over to the aft port quarter, I ground the surface area surrounding the crack at the sheer.

Again moving forward on the port side, I removed loose material that required removal.

Finishing at the bow, I dished out a few spots before moving on to the next phase of the hull repairs.

Because I would be filling the old fastener holes today, I need to apply a backing plate of sorts so that my efforts at pushing thickened epoxy into the openings did not result in goopy extrusions on the inboard side of the hull or droppings onto the concrete below.  I simply applied tape to the inboard surface to prevent aforementioned catastrophe.  

Since the Dyer Dhows are comprised of a fairly thin laminated fiberglass hull, offering plenty of flex as the Dhow enthusiasts climb in and out of her, I decided to further strengthen the repairs by laying a light ounce cloth in each of the larger areas requiring repair (filling and fairing).  To that end, I applied a sheet of plastic onto the location requiring new cloth, and then traced a pattern for the new fiberglass.  I labeled the patterns, and then also transferred that label to a piece of tape set next to each repair area on the hull.

I grabbed the 6oz cloth and transferred the patterns onto the cloth with a sharpie.  In doing so, I made sure to orient the direction of the fiberglass in order to ensure a good fit.

The process of wetting the repair areas out, laying glass, and filling the holes was fluid, and occurred over a 30 to 40-minute period.  The first step was to wet the areas out with 'neat epoxy' (epoxy not thickened with any filler agents); the epoxy used in these repairs is West System.  Application of the neat epoxy was to all of the areas requiring attention, whether filling old fastener holes, filling shallow gouges, or for more severely damaged areas requiring new fiberglass to be laminated.   

With all repair areas wet with neat epoxy, I moved on to mixing another batch of epoxy, and this time applying thickeners to fill voids.  The thickeners applied were 406 colloidal silica and 407 low-density fairing filler.  I thoroughly mixed a small batch of epoxy and then thickened it with a combination of 406 and 407.  I applied this thickened epoxy to all areas requiring fill work with the exception of the areas requiring additional fiberglass.

With the filler work complete, I turned my attention to cutting out the fiberglass cloth (per each numbered pattern) and then applying them.  With all of the fiberglass cloth set in place and wet out with epoxy, I then came back and filled the weave with another batch of thickened epoxy.  Next steps will be to sand the repairs areas to knock down the proud material, and then apply another skim coat of fairing filler.

Total Time Today: 4.75 hrs