In our last thrilling episode, we had finished up the basic bone structure, and now we are ready to tackle the unknown (at least to this newbie SOF builder); putting on the polyester skin.
Part One – Part Two – Part Three – Part Four
Part Three: Puttin’ Skin On Dem Bones
Dave advised contacting George Dyson (www.GDyson@gmail.com ) for the fabric. George promptly sent an email with a very comprehensive review of nylon and polyester fabrics, and of various coatings, with the pros & cons of each,. I decided on polyester, to take advantage of the greater heat-shrinking properties. My choices were between the 8 oz polyester (69″ width, $2.50/foot), which has been widely used on hundreds of boats, and a new tougher 10 oz fabric (64″ width, $3.00/foot), with little feedback on use so far. For the difference in price, I decided to go with the heavier fabric, and ordered four pieces, each 13′ long. As with many other materials, I ordered enough material for both boats I intend to build. This ran about $170 for both boats, including a standard $10 shipping charge from Bellingham WA. The fabric arrived in only a couple of days. I found Mr. Dyson’s service to be excellent.
One of the advantages of Dave Gentry’s designs in my mind, is that the fabric is applied in two parts; the hull bottom up to the gunwales, and the deck, overlapping at the gunwales. This means that the only hand sewing required is at the bow and stern openings, rather than the entire length of the deck, plus the ends. And that also gives the boat a neater look. The disadvantage is that it might require the purchase of more fabric than if you could find fabric wide enough to wrap around the entire boat. That’s why I had to get four pieces of fabric for the two boats.
I am much better with the wood than with the fabric, so it is fortunate that my wife Carole is around to help. She is an accomplished seamstress, and has been a real helpmate throughout the entire build! Here she is sewing up the bow.
The hull was inverted. One edge of the fabric was placed along a gunwale, the fabric smoothed out over the bottom, and push pins placed in a few places along the keel. The keel location was then marked in a few places with pencil on the fabric, and the push pins were removed. The idea is to keep the warp of the fabric aligned fore and aft along the keel.
The stainless steel 3/8″ long Arrow T-50 staples were started at the center for a foot or two, the fabric stretched and stapled on the other side and sides alternated until the bottom of the hull was completely covered. The fabric was then rough trimmed on both sides using a gun-type soldering iron, to keep the edges from developing a run in the fabric. The soldering iron did an adequate but not really neat job.
Our elder-hands don’t do well squeezing a mechanical stapler, so we used an Arrow model ETN-50 electric stapler we had bought for an upholstery job some years ago. This worked fairly well in places where there was structure behind the gunwale, but in between frames, the wood was too springy, and the staples required some hammer work to drive them home. Some bent staples had to be pulled and redone.
After this boat was completed, we found an Arrow pneumatic stapler for about $25 at Amazon, which can be used with the Bostich air compressor we already had for our nail guns, but the air pressure must be kept under 90 psi to protect the stapler. The stainless T-50 staples are easy to find locally at Lowes or Home Depot. Stainless narrow crown staples for some other inexpensive pneumatic staple guns are not easy to find. The pneumatic staple gun works like a charm on test pieces, even when not supported from behind.
Also, after this job was done I located an inexpensive hot knife (Chicago Electric model 60313, $19.98) at Harbor Freight, which seems to do a very neat job cutting test pieces of fabric.
At his point I made a decision I later regretted. The plans called for flotation foam to be installed in the small spaces between the bow and frame #1, and between frame #5 and the stern. I didn’t think that would provide much flotation, and since I had bought a 4’x8′ sheet of 1″ thick blue foam, I decided to use it all. Placed between frames #2 and #3 in the bow, and frames #4 and #5 in the stern. Both foam blocks were notched to clear the floorboards. The bow foam was glued as a block and painted black, and inserted through the framework. The stern foam had to be inserted through the framework in pieces, so couldn’t be painted easily.
There should be plenty of flotation, but the foam blocks added still more weight to the assembly. And the whole idea of building these boats was to save weight vs. our plastic kayaks!
The hull was turned right side up, and the covering process was repeated on the deck. In the cockpit area, the fabric was slit lengthwise, and sidewise cuts allowed the fabric to be pulled tight and stapled to the inside of the cockpit carlins. This was the most difficult stapling job because of the lack of support structure behind the carlins.
There was quite a bit of excess fabric, especially from the deck covering, as the 64″ fabric width was much wider than needed for this design. Even so, about $80 for each boat’s fabric seemed a reasonable price for specialty fabrics from a low-volume specialty supplier.
The heat shrinking went well as expected, using a $10 Walmart iron I keep in the shop for attaching pre-glued wood veneer edging to bookshelves. After a light ironing, the skin was tight as a drum all over.
Time to start coating the fabric. Dave Gentry recommends that the bottom fabric, up to the first stringers from the keel, be given a “scrim coat” of PL Premium construction adhesive, and he has an excellent video on his website demonstrating how this is done with a plastic Bondo spreader or an old credit card, so I thought I would give it a try.
Unfortunately, my attempts at a “scrim coat” did not look like Dave’s video. In an attempt to get it smooth, I applied too much PL Premium, and as it cured it bubbled up and hardened. The result looked like lumpy frozen snot, and I was afraid to try and sand it smooth because of the fabric, and I also noted some unexpected tiny rough pinnacles sticking up throughout the mess. I had planned to paint the bottom black up over the first stringer anyway, and it looked slightly less objectionable in semi-gloss black Rustoleum enamel. After the black paint dried, I told myself, “At least it’s going to be underwater.” But it won’t look good when the kayak is on the roof rack.
I had tried applying masking tape to the unpainted fabric topsides when painting the black bottom, but the tape wouldn’t stick to this fabric. Hmmm….what’s going on here? I tried several tapes I had on hand, and the only thing that would even try to adhere was some white sail tape I had left from a Dave Gray Polysail kit I used on my old PDRacer years ago.
Beside the black bottom, the topsides were to be Safety Yellow Rustoleum, and the deck Semi-Gloss White Rustoleum. That ought to provide good visibility to those 300 HP Bass Boats screaming around the lakes. So I flipped the boat over, masked for the yellow paint, and laid on a coat with a foam brush. It laid on well, but when it dried it had those same little spiky rough spots all over it. Even after three coats of paint, they were still there. Hmmm….
Thinking the foam brushes might be contributing to the roughness, I switched to a foam roller, tipping the paint with a dry foam brush as I did the white deck. The same spiky roughness appeared, so I concluded the problem must be related to the fabric. When the white deck was fully dried in a couple of days, I decided to very lightly hand sand the surface with some 220 grit paper which removed the roughness and produced a very nice surface. Of course I vacuumed off the dust and wiped down with a damp cloth afterward. I then did the same on the yellow topsides, with the same beneficial result. I reported this unusual phenomena to George Dyson (copy to Dave Gentry), not as a complaint, but just as feedback on what I had observed with this new 10 oz fabric. If I had it to do again, I would go with the proven 8 oz polyester fabric, but I had bought enough of the 10 oz fabric to cover the second kayak, so there you go!
Here again, I got in a bit of a hurry because one of our sons and his wife would be visiting over the Thanksgiving weekend, and I had wanted to splash this rig while they were here. But I was no where near ready for that. At least I wanted to be able to finish the wood trim during their brief visit. So I had only done one coat of black over the PL Premium bottom, three coats of yellow on the topsides instead of the five I had planned, and two coats of white on the deck instead of three. We’ll see what happens when we launch!
In my lumber pile, I had a nice 1×6 piece of white oak about 6-1/2′ long. It was an actual 1″ thick, so would make great rub rails when sliced off in 3/16″ slivers, scarphed to length, edges rounded with a 1/8″ roundover bit, stained and varnished. When son Tom arrived, we installed the cockpit coaming with stainless screws on 3″ centers, and the rub rails on 6″ centers.
I got sort of carried away with this lashing thing, so I lashed the forward end of the coamings and bow and stern of the rub rails!
At Thanksgiving the weather here in East TN turned cold, so for the final finishing work I’d need a little heat in the shop. Thankfully, I have both a propane heater and an electric heater, which can get the shop temp up in the 50’s or low 60’s when necessary.
All that remains to be done is to mount some bungee-cord on the decks, run some silicone sealer around the base of the coaming, and mount some sort of comfortable seats. Our elderly backs appreciate some support. I recently found some “SitBacker” stadium/canoe seats with steel frames and decent padding for $25 each at Amazon, so ordered two for both boats. They will require some minor mods to the rear of the coamings, but no major surgery. However, they will again add some weight, about 3 lbs. But they seem to be comfortable.
Also at this time of year, the TVA lakes and rivers are drawn down to accomodate spring rains and snow melts from the nearby Smoky Mountains. We hadn’t had any rain to speak of in over 3 months, and no rain over 1 inch in a day in over 5 months. At some favorite launch points, the low water exposed mud and rocks for quite a way out. At our 80-ish ages, the splash may have to wait for some warmer days and higher water. Bummer! The proof of the pudding……..
Time to take stock of what has been accomplished short of actual launching:
1. Construction has been completed over a period of about 3 months. This is not bad, considering that while I no longer have to go to work full time, we travel to Knoxville anywhere from 1 to 4 days a week to various doc visits, which consumes most of a day including some shopping, lunch, etc. Plus a little time for some consulting work, plus the Thanksgiving and Christmas holidays, plus at 83 my max good working time is about 6 hours/day, on those days I had available. I didn’t keep a record of actual hours spent at the task.
2. I have kept a detailed record of costs, and have bought a lot of stuff for two boats. Dissecting the records, my best estimate of costs for just one boat is:
- Plans: $55.
- Marine Plywood $81.
- Pine $80.
- Polyester Fabric $86.
- Paint, Brushes $75.
- Misc. Materials $75.
- SitBacker Seat $27.
- Total $479.
Considering that I used a lot of stuff I had on-hand, this total is a lot more than I expected. But also, I had a lot of stuff left over, such as half-cans of paint, stainless staples, glue, epoxy, stainless screws, artificial sinew, etc. However, if you were only going to build one boat, you would spend close to this amount.
Since I had sold our plastic fantastic kayaks for $400 each to finance this job, the total is doubly disconcerting.
3. So how did we do on weight. I began to get concerned when I weighed the bare frame before the floorboards were in, and it weighed the full 26# that the finished boat was supposed to weigh. Today, I weighed the “completed” boat, including the SitBacker seat, and it came in at 39#! My wife’s 12 ft Wilderness Systems Pungo weighed a claimed 43#, so all I have saved is about 5#, which is far less than the 15# weight saving I had hoped for. I recognize that I used heavier wood than specified; meranti vs okoume plywood for the frames, and pine vs western red cedar for the keel and stringers, plus extra foam flotation, plus heavier fabric, plus a 3# seat. Just like cost, little things add up!
So, am I disappointed in the outcome? A little perhaps. Maybe a little more than a little. But I thoroughly enjoyed this build, which reminded me of the many flying model airplanes I built as a boy, lo those many (70+) years ago. These planes had balsa wood frames, balsa stringers, and tissue or “silkspan” covering, which was shrunk with a little water sprinkling and coated with cellulose dope. Very much like this SOF build. And the ultimate result is a nice little kayak to play with.
My intention at this point is to continue on with the build of the second Chuckanut 12 over the winter, although I have not yet experienced this first boat actually on the water. I can see where ingress and egress may be a little more difficult than with our previous plastic fantastics, and may require some modification to the rather high coamings for us elder folk.
And I may, just out of curiosity, build a foam kayak to see how they compare. After all, the winter is a long time, even down south here in TN. Dave Lucas has a version that uses cheap white foam, but is covered in expensive fiberglass and epoxy; plans $25 at Duckworks. And there are other versions, such as the Sawfish, that use more expensive blue foam, but are covered with cheaper cotton fabric stuck on with cheaper TiteBond III wood glue.
And then there is the Chautauqua Sailing Canoe that just appeared on Dave Gentry’s website. I have been coveting one of those ever since before I bought Todd Bradshaw’s book, “Canoe Rigs, The Essence and the Art”. Hmmmm…. more decisions. Such is life!
I know you faithful readers are disappointed, as I am, not to conclude this series with an actual on-the-water paddling report, but that will have to wait for a while.
I’ll keep you posted on when I learn more.