2015-03-29

Post XXVI: FIBERGLASSSSSSSS! HOLY SHITBALLS!

Here begins the start of an EPIC day -- and I don't say that in the annoying "internet" meaning of epic where something is *woaaahhhh epic dude*. This was a long, arduous journey and I am really, really happy to have it done with. 

This job is best done with 2 people for a boat of this size. You might get away with 1 person on a dinghy, but a 17' boat requires at least 2 sets of hands.

There is debate on the best application method -- some say brush, some say roller, some say squeegee. I chose rollers because it's just easy and it gives the best chance of getting an even coat. Painting setup for this job:
  • slit-open garbage bag taped to the workbench for use as a mixing area. 
  • Tinfoil-lined 5" roller trays
  • plastic cups for mixing epoxy batches
  • cheap 5" foam rollers & handle
  •  bunch of stir sticks. 
  • A bunch of foam brushes
Step one is to apply a seal-coat to the cedar strips. Opinions vary on whether this is strictly necessary, but most people do it and I'm a majority-rules type of guy. Nothing too fancy here...just mix up small batches of epoxy and hardener (I used 5 pumps from each per batch), pour into the roller trays, and roll it onto the boat from one end to the other, taking care to smooth out drips and keep the coat even. Roller trays and rollers seem to last about 3-4 pots' worth of epoxy before it starts to gel and ruin the roller. Make sure to keep an eye on it and swap rollers & tray liners often.  


Figure 97: Start of seal coat


Figure 98: Another angle on that seal coat


Figure 99: Seal coat complete. Time for cheer. 


It's important to put the stem on before you start this process. The keel can go on after the glass is wetted out, but the stem definitely needs to be in place since it will eventually have its sides covered with fiberglass cloth

Figure 100: Stem in place



Figure 101: Applied a good coat of epoxy on all internal surfaces of the sternpost joint as well. 


Transom fiberglass is not strictly necessary and opinions vary on whether it's necessary. The name of the game from day-one for me has been durability so I decided I would do glass on the transom. I used 6oz instead of the 10oz used on the rest of the boat since it's made out of 1" thick ash instead of 1/4" cedar. This was a good practice piece also since my helper (father) and I had never done the fiberglass wet-out procedure before.

Figure 102: Practiced saturation techniques on the transom.



After the seal coat cured enough that it lost its aggressive tack, we rolled out the 10oz glass cloth on one side, taking care to seat it nicely in the keel/skeg trough. There was juuuuuuust enough tack left on the seal coat that the glass held in place on its own, and smoothing it out was very easy. Best way to smooth the wrinkles out is with a dry paintbrush. Just brush on diagonals away from spots where the wrinkles form. Fiberglass cloth is amazingly plastic stuff and will stretch/contract to fit the shape of the boat. Kind of amazing how it conforms to the shape so easily.

Figure 103: Cloth going on and being pushed into the slight tack on the seal coat to hold it in place


Figure 104: Fully covered, ready for glue.


A third helper (sister) showed up midday and suited up. At this point we were all-in on wetting the fiberglass cloth with epoxy. The procedure is to apply in 2-mold-wide sections (as denoted by staple lines) starting amidships and work toward one end of the other. With 3 people you can have 1 person mixing epoxy and drinking beer while the other two roll on the glue.

You need to use a bit of pressure with the roller to make sure the cloth is fully saturated and that the glue is pushed all the way through to the underside of the cloth. I was using as much pressure as I could while still having the roller turning (if you push too hard you drag it and deform the cloth). If the cloth looks opaque or semi-transparent after a wet-out pass, then you don't have enough epoxy in it...but keep in mind that saturation takes time. It's best to wet out an area with a preliminary pass, and work your section all the way from keel to gunwhale. By the time you reach the gunwhale, you'll see that parts near the keel are turning more and more transparent. Just keep working the section and evening out the coat until you get full transparency. Not too long though -- you need to keep advancing at a steady rate so the exoxy doesn't gel up on you.

Figure 105: Saturation coat starts: the moment of reckoning!!


About 20 minutes after completing each section, it's necessary to squeegee out the extra epoxy. Best tool for this are "bondo" scrapers available Canadian Tire or any other well-stocked hardware store. Hold the scraper at a low angle, apply light pressure and squeegee excess epoxy from keel to gunwhale. The idea is not to de-saturate the cloth, but to make sure the weave is in contact with the cedar everywhere. It's really easy to "float" the glass on an epoxy pocket (epoxets?) if you don't squeegee well enough. Epoxy pockets cure as a raised bump and look like shit. If you get one you'll have to sand it out and apply a patch (not a big deal in the grand scheme, but it's extra work you don't want to do at this point).

With the glass on both sides fully saturated, it was time to add the keel and squish down the overlap in the glass. Keel was all pre-drilled to make it quick and easy. I added epoxy and ahesive filler underneath to make sure the area was tight and well-filled. I took the opportunity to add a fillet before the epoxy fully cured. This is not the final fillet; it's mainly intended to fill the remaining gaps and poor craftsmanship around the keel & skeg.

Figure 106: Gap filler Fillets on the keel.


Figure 107: Gap filler Fillets on the skeg.


Figure 108: Saturation coat complete. This thing is looking pretty good actually. 


Figure 109: Another angle on the completed saturation coat with excess glass cut away. 


That's it!! Saturation and seal coats done. The rest of the work consisted of adding filler coats to completely bury the cloth in epoxy and achieve a completely smooth surface. I added 2 more coats and could not stay up any later (this is 3AM by the way), but in the morning I was unhappy with the results because the cloth texture was still very visible. Not a big deal, but I could have avoided more work by knowing 1 thing:

***    IMPORTANT    ***

I missed the step of "tipping off". This is where you take a foam brush and wipe it across your entire fill coat. The foam brush wipes epoxy off the high points in the weave and transfers it to the low points. Had I done this I probably would have been done after 2x fill coats.

***       *********      ***

Armed with new knowledge, I waited 4 days for full-cure and did an 80-grit scuff sand of the entire cured surface before wiping it down with alcohol. This surface prep is recommended on the WEST system website for applying new coats over fully-cured epoxy .  I added 2 more fill-coats. This time I tipped-off both coats immediately after they were applied. The results were perfect and the outside of the hull is now smooth and ready for its final sanding before paint & varnish!

2015-03-11

Post XXV: Shaping the outer stem and making the outer keel.

This post spans two sessions (most span only one) but I put them together because it's all on a single topic.

A really useful piece of advice I picked up from my boatbuilding courses and from the various books I have on the subject is that you can mark a lot of parts in-place on the hull. For the stem, I knew I wanted 1/2" width along the outer edge, but the inside face varies a lot depending on the thickness of the inner keel and the angle at which the planking meets it. I took the rough stock for the outer stem and mounted it in place with a couple of screws and a clamp. Using a pencil, I transferred the width of the inner stem + planking over to the inner face of the outer stem. 

Figure 88: Outer stem temporarily clamped in place and ready for marking


Next thing was to establish a centreline on the outside face of the outer stem and 2 lines each 1/4" to either side of centre. After that, it's the old 3-step rolling bevel technique I discussed way back in Post XIV. Plane to the line on the inside face at a steep angle, leaving lots of material on the outside face, then plane to the line on the outside face at a steep angle, leaving a ridge in the middle, then plane away the ridge. At all points it helps to stop and slash the face with pencil marks so you know where you are removing material and where you aren't. 

I generally find work like this is best done by roughing things out with a drawknife, then moving from larger planes to smaller planes. You can use a spokeshave too, which many people prefer, but I fucked the irons on my spokeshaves on staple legs whilst fairing the outside of the hull. For this work the planes did a great job anyway. 

Figure 88: Outer stem temporarily clamped in place and ready for marking


Figure 89: My go-to shaping tool for finish work. Stanley bevel-up block plane. No idea of the vintage but it works wonderfully (even though the blade is almost sharpened away to nothing)


Figure 90: My go-to for hacking away bigger chips. Stanley No. 3. Same length and general shape as the classic Stanley No. 4 but the blade is narrower. 


For the outer keel, I purchased some ash from the local specialty hardwood store (Eaglewood in Fredericton) and scarphed it to make a piece long enough. Nothing fancy here, really. For cutting accurate scarphs, again use the 3-step method. Plane to the line on one side at a steep angle leaving the opposite side, plane to the opposite line at a steep angle leaving the ridge in the middle, then plane away the ridge. Use pencil slashes as a guide as you approach the final bevel. Drawknife and 2 planes got this scarph to within 1/16". I'm in about 20 minutes. Starting to get good at this!

You can see in Figure 91 that the grain dives quite aggressively into the scarph. Normally you would not want this -- in fact the opposite is much more desirable. When I originally picked the orientation of the pieces I was using the grain on the side opposite the one pictured. A nasty grain spiral near the end of the board made the near side (shown) look incorrect, but there was no way around it.

Figure 91: Glued 12:1 scarph joint in the middle of the outer keel.


This is the part where things started to get a little weird. I had to cut a bevel onto the underside of the keel all the way along its length so that it would fit inside the trough I cut earlier. Easy enough if the bevel is the same all the way along, but I realized I have quite a taper in both the trough and the outer keel itself leading toward the join with the outer stem.

It was a bit difficult to get it all looking and fitting right and involved a lot more trial and error than I would prefer, but in the end I got it all fitting together and seated nicely in the trough from stem to stern.

Figure 92: The underside of stem-end of the outer keel showing bevel and taper


Figure 93: Mating surfaces of the outer stem and the outer keel. A pretty good fit again. Definitely getting better at this now!



Last task of the session was to cut the end off the outer keel, put the correct rake on the aft end of the skeg and carve the ash piece that would protect the aft end of the skeg. It's a bit of a complicated piece and I wish I had more detail of it in pictures. The protector piece slots into the transom, ties (eventually) into the transom knee, screws to the skeg and fits into the outer keel with an open-ended mortise and tenon joint. 

It's a bit ugly to do it this way, but I felt like I wanted the skeg tied directly into the structure of the boat rather than just have it as a glued-on piece. The effect is similar to the sternpost you might find in a classic wooden boat. The reason for the added strength is twofold: a) the stern will one day sport a small rudder, and b) the skeg is made of cedar, which is not very good at surviving impacts!

Figure 94: View of the roughed-in keel from the stern.


Figure 95: Finished outer stem in place and temporarily screwed in place. Nasty wonk in the middle that will need to be fixed prior to fiberglassing.


Oh, and my epoxy arrived today! 2 gallons of resin and matching cans of hardener, plus graphite powder that will be mixed with the finish coat below the waterline to produce a surface that's better at deflecting impacts.

Figure 96: The goo arrives.