Fiberglass Hulls

For thousands of years, wood was the hull material of choice. This was the norm until fiberglass was introduced! Some will argue of the virtues of other hull materials but the truth is, all hull materials existed when fiberglass was introduced and fiberglass has dominated the market as the standard hull material for all personal boats being built.

The expert I interviewed was Matt from MJ Sailing as they have sailed extensively on a fiberglass sailboat, then an aluminum sailboat, and are now building a fiberglass catamaran to go on their next adventure!

Head Refit: Closing Holes

The shower sump used to discharge through a below the waterline seacock that also served as the intake to the old head. I had long since converted from the standard marine head to a Composting Toilet, which means I no longer required an underwater intake. This also means that I no longer required having this below the waterline through hull.  

It is time to seal it up! 

The seacock was always stuffed away inside this tine cabinet, which means that we couldn’t access it to seal it up. Now that the head is gutted, this is a wonderful opportunity to close up that through hull! 

The sea cock was removed and the hole sealed on the inside with roving and cloth, just to keep the dust out while I grind the outside of the hull to make a proper plug. 

Repairing Dry Core

Cored fiberglass is great when it works well because it makes the the structure significantly stronger without adding much weight. The only problem with cores is if there is going to be any problem with the structure, it will be in the core!

Cores are like a sponge, soaking in the resin that is covering them. If the core is over-saturated with resin, it will result in a brittle structure. If the core is under-saturated with resin, it will be dry and not as strong as expected.

This one piece of cored sole in our head during the head refit suffered from a dry core. It was just a little soft no matter how many layers of fiberglass I applied over it (I applied 9 layers of fiberglass!) so the decision was made to put more epoxy into the core.

I had two choices, I could either strip off the fiberglass and expose the dry core, or I could make my own access to it. I chose the easier way!

I drilled a pattern of holes in the top of the core, but not all the way through. This would allow resin to soak into the core and saturate it further. The holes were evenly spaced about 1/2 inch apart to allow the resin to soak through and through, saturating everything.

The wonderful part was after the resin had cured, I could test it by stepping on it and if the core was still soft, I could always simply pour more in through the holes. Luckily, this one attempt fixed the whole issue and it became stiff as a board!

Head Refit: Shower Sole Part 3

Epoxy is expensive and impractical to have been using for a project of this size! I switched to polyester resin.

One gallon of epoxy cost $112. One gallon of Polyester cost €18!

That is a major difference! I was using epoxy because it is what I have learned with and what I was comfortable with. I have always done relatively small projects so the plan was simply to scale the project up to this much larger size.

This polyester resin has fairing compound already mixed in with it, so all I need to do is mix in the catalyst and smear it on everything. It also sands more easily than the 407 thickener that I had been using in the past.

Everything got a layer of fairing putty so that the next time I sand, everything will simply sand down to a uniform surface. Oh, and the best part about this resin is the curing time. 20 minutes instead of 4 hours! This means that additional layers can occur in the same day!

Head Refit: Shower Sole Part 2

We have a shower floor! We can stand in here! Ouch, there are some prickly spots!

The fiberglass is mostly smooth, but there are some sharp spots, and some rough spots, and worst of all, some holes.

I thickened the epoxy with 407, as it gives good strength, somewhat ease of fairing, and most importantly, that lovely purple color! Once the surface was smoothed up, it was just a matter of sanding, then filling, then sanding, then filling, then sanding for days on end.

Fairing honestly felt like it was the longest part of the project. In the beginning, we had a giant hole. Once the foam went it, there was a drastic and rapid transformation. Progress! Fairing is just more of the same, with lots of work hours and little change. This can really dampen morale in the boat when days are spent working but it looks as if nothing is occurring.