Monday, September 25, 2023

Too Many Holes

I don't like boat holes, especially the ones below the waterline.  I'm not particularly good about servicing seacocks and as a result, I have had a number of them sieze up on me over the years.  The Marelon plastic seacocks are a bit better than bronze because they don't corrode and generally don't need much in the way of servicing so I appreciate that the new seacocks for the boat are Forespar Marelon, but I still don't like the idea of so many holes below the waterline.  

When I was looking at the boat before purchase I was struck by how many below the waterline openings there were.  My last 35' boat originally had 5 seacocks and I reduced that to 3 after the refit.  I was able to eliminate 2 because I switched to a composting head.  Velorum, on the other hand had 6 seacock openings (no seacocks are currently installed) and 2 instrument holes and it looked like swiss cheese.

After identifying what each hole was for, I determined that I didn't need one of the 1.5" seacocks up under the v-berth.  This particular hole was intended for a holding tank offshore discharge via a macerator pump and I just don't plan on dumping the tank offshore and will rely on either direct discharge if offshore or use a pumpout facility (boats and shoreside pumpouts are available in most harbors on the east coast these days).  I'll go into detail about the sanitation system later this year (I hope to get to it this year). 

Exposed balsa, not good
Another problem I found with this particular seacock was that it was the only through hull (above or below the waterline) that went through balsa core.  Hinterholler Yachts were pioneers in balsa cored hulls and they took great care with through hulls and made sure they went through solid glass. The one I'm eliminating was probably not a factory install because it goes right through balsa and it was not isolated with epoxy.  The only thing keeping the water out was a thin coating of sealant.  Fortunately, the core wasn't damaged, but that had to go.

Closing up a through hull is pretty straight forward when it's solid glass, but it gets a little more complicated with a balsa core.  The first thing that has to be done is to get rid of the core surrounding the opening.  I used a combination of an oscillating saw and a drill with a an allen key in the chuck to dig out the core between the outside and inside layers of glass.  Once that's complete the process follows what one does when closing up a through hull on a solid glass hull (12:1 bevel) except the bevel only goes as deep as the outer sking (in this case about 3/16") and the hollowed out core is filled with thickened epoxy before the outer skin is reapplied.

I cut out 4 layers of 1708 biaxial fiberglass and mixed up a small batch of laminating epoxy and layed them into the beveled recess where the hole once was and covered it with release plastic sheeting and painters tape to keep it in place until it cured.  Finally, I applied a thin layer of fairing compound to get a smooth surface after sanding.  Probably easier explained in photos below, but it's done now and time to move on to painting under the v-berth (where the through hull was located).

Core removed and bevel complete

Core filled with thickened epoxy

A layer of biaxial glass applied over the filled hole on the inside

4 layers of biaxial fabric
Fairing compound added

Faired and ready to go

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