My ticket for the return flight to Belgium is ready, the flight is leaving Kuala Lumpur on March 25th at 2000 local time! After a stop in Doha, I should reach Brussels the day after and land in Zaventem at 0630 local. The reason the word “should” is used here is not by coincidence, there is a major troublemaker on the scene for the moment: a certain corona virus! This virus is apparently putting the complete planet in an emergency mode, several countries have already closed their borders for any inbound voyagers, airports being the first target of this drastic measure. For the moment Belgium is not in a full quarantine but who knows how that can evolve in the days to come. This is one of these situations where there is nothing to do but wait and hope for the best!
All right, what’s new since the last report?
I’ve essentially worked on the starboard hull these last days. I was hoping to have it finished before heading back to Belgium but a major hick-up hit me, I’ll have to come back on that later.
In the last post, I showed an illustration with the principle for the deck-hull lamination in replacement of the former wooden rub-rail that had been mounted on that specific contour. Well, this is what I have started to work on, with mixed results till now! It all starts with the gluing of the mass foam layers on the original surface of the lower deck. The foam I have used is known as SEARFoam, a product from SEARTEX, it is basically a PUR/PIR closed cell foam reinforced with glass fibers in different axis. The little “white hairs” you see sticking out of the foam are actually these fibers, they are intended to bond with the fiberglass that is surface laminated on top, all resulting in theory in a super solid structure. At this stage, I don’t realize they will become my worst nightmare…
This thick layer of glue is essential for two reasons. It fills the small remaining surface gaps for one thing but it essentially helps the fibers of the foam to embed on the deck surface. It is important to exercise a minimum of pressure on the foam to ensure a good bond and have these fibers really blend in the glue.
It would have been good if this simple task was enough. But no, why is it supposed to be easy? The panels I used are 2 cm thick while some portions of the curved area on the deck surface reach almost 4 cm. For that reason a second layer has to be applied on some parts of the first foam layer. The only way to know where that foam needs to come is to start sanding the initial portions of the curve and see where some additional thickness will be required.
The readers who paid attention in the previous posts will remember there were some portlights on that part of the boat. Indeed there were! I’ve decided to close them and leave the option pending to add some future portlights a bit lower on the hull side like with a large majority of the modern boats. Lower portlights serve both an esthetic and practical function. You can look at the water surface from the inside of the boat, that seems to be a very well appreciated feature when cruising. For me it’s more about avoiding glassed surfaces that are exposed to the sun directly, therefore creating a lot of radiation heat inside the boat: the lower deck portlights were in an approximate 30° angle to the vertical while a hull portlight would even be 15° negative oriented! Essentially, I leave it as a future growth feature keeping in mind that any opening on a boat is a source of water intrusion, so let’s be careful here.
Ok, now it’s time to implement some of those nice curves! Everybody likes good looking curves, boating people make no exception to this universal rule! Again, the profile templates are used to perform this progressive sanding of the excess foam, layer by layer. The danger here is like when cutting hair: you can take material off but not put it back (though hair would grow back progressively :-)).
So, was it worth it? I would argue yes indeed. It is a structural requirement for the external junction of the deck and hull that used to be done by the use of bolts, and it is at the same time an esthetic improvement, at least in my eyes. A bit of a before – after comparison so everyone can make up her/his own mind.
But he, now there is another problem. What about the scoops, are they affected by this surface change? The answer is not simple, I could use the magic formula “it depends”… This is how the stern portion looks like after the addition of the foam.
Those readers who paid attention noticed some strange assembly installed on the stairs of the scoops… Yet another template maybe? Yes it is. Call me lunatic, OCD, whatever you want but I had the song of Prince in mind that day: let’s go cray, let’s get nuts! My intent is to totally blend the shape of the hull with the scoops, I never really liked the way that junction was made from the beginning. How can we do that? By adding more of that foam or course!
From here on the sanding portion will determine the final shape of the scoop extension.
OK so far, but there are lots of gaps that need to be filled. Not just the scoop top surface where the foam panels need to blend into one another but also the junction with the hull. The best way to do that is to create a custom made light way filler for bigger portions of volume. I elected to chop some foam rests in small entities and mix that with polyester resin added with colloidal silica. Purists between the readers will claim: that’s good as a filler but it is not water resistant as you are creating air compartments in your compound! They are right, this is where I compromise and leave the OCD thing aside a bit to keep things simple while affordable.
So, this is the stage where things started to go wrong… The obvious step after having prepared the inner surface is to start applying the fiberglass layers on the foam. I mentioned earlier about the fact this foam is reinforced with fiberglass hairs on the inside, a bit like chopped strand mat. I my head that simply meant these fibers would conform with the first layer of CSM applied after have seriously impregnated the foam with pure resin because it absorbs it a lot. Like hell they did…
Frustration, a lot of frustration as you can imagine. It’s hard to determine what caused this adverse effect, but the most logical (and to me the only) explanation is that all the fibers sticking out of the foam actually push the fiberglass off the surface, hence disrupting the bonding process between the two media. On portions where the foam was not sanded, i.e. with a lot of fibers the effect was even worse. I made some tests on rests of foam that same evening trying to reproduce the process in order to identify what could be the origin of this nasty phenomenon. All the samples I laminated turned out to generate the same effect, the fiberglass is each time is pushed off the surface of the foam and there are gigantic bubbles of air forming between the two elements. Delamination is something you can repair if it necessary, that does not mean you want to induce it already in your building process, no way Jose! Best thing to do in these circumstances: do nothing and take the time to think it over!
Having talked to a few people in the yard with knowledge about foam core laminates, the only logical conclusion was this kind of foam is actually meant to be used for vacuum bagged infusion! The pressure on the laminate and the infusion of the resin in the foam will in that case make everything very strong, that is where these internal fibers in the foam serve their purpose. I don’t see myself starting a vacuum bag infusion here…
All for nothing? Well no, what I need to find is some way to eliminate those little fiber hairs sticking out of the foam. I can not pull them out one by one, that would take at least a year of time and damage the foam as they are blended in. What I could do is to try to make them become hard and sand them off to the surface of the foam without actually sanding into the foam. So I came up with the following course of action with the help of a smart Dutch boatbuilder I met here recently:
- Create a series of new curved profiles in the foam using fairing compound every 40 to 60 cm. That means taking of 5 mm of the foam, fill it with compound and then sand it back to the initial curved shape. These profiles will serve as guides for the next steps;
- Impregnate the foam between these profiles with polyester resin where some micro balloons have been added for more surface resistance of the foam. This is the only way to harden the vertical fibers;
- Sand the foam in between the guide profiles until the little fibers sticking out are blended with the surface while trying not to damage the outer foam surface.
Last thing to mention is the chain plate. The added foam will come in conflict with the space needed for the connection buckles between the plate and the shroud. I will have to make an opening there before laminating the surface.
A good thing there are occasions where all cruisers get together for dinner and talk about… boat building 🙂