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Guide boat construction techniques

Discussion in 'Adirondack Guideboats' started by Lazy Jack, May 20, 2012.

  1. Lazy Jack

    Lazy Jack LOVES Wooden Canoes

    This is a cut-and-paste of a PM sent to John Michne which he answered with the suggestion that I post it here to generate more discussion. I also received input from Charger who I PM'd as well...he sounds very satisfied with his results.

    I designed and built a 14 foot guide boat stripped with white cedar screwed to ribs on 6 inch centers. The outside was sheathed in 4 oz glass and epoxy. Painted black and living on the roof of a car over several seasons the epoxy has continued to post cure and the glass has printed through - I was striving for lightness so I added only enough epoxy to fill the weave plus a little for sanding before painting. Not only is the glass printing through but the texture of each of the underlying planks as well as the fasteners are visible through the paint. I'm not allowed to strip the paint and add more epoxy because the owner values the light weight and her ability to car-top and carry the boat independently. The slight texture on the outside does not bother her at all.

    As much as I would like to plank a boat traditionally, I know it wouldn't withstand extended unprotected storage on a vehicle without checking/splitting etc. However, I would love to avoid the use of glass/epoxy. I know another Forum member (Charger) strip built his guideboat in pine with titebond III and no sheathing. Structurally, the glass isn't essential as it is in a pure wood strip boat.

    In your collective opinion, would a lay up of bead and cove strips with resourcinol on six inch rib spacing be stable enough to live on the truck rack through the season without cracking or splitting? I would probably roller on a sealer coat of epoxy prior to paint both as a primer and to provide a base over which to add glass/epoxy should that become necessary later on it it's life.

    I totally get the dark paint sun thing so I'd have to swallow hard and paint it a light color...maybe white with black rails and pink interior?
  2. Dan Miller

    Dan Miller cranky canoeist Staff Member

    Gee, that sounds Ghostly... ;)

    The thing about resorcinal is that it wants an extremely closely fitting joint and good clamping pressure. That might be hard to achieve over the full length on a strip-built guideboat.

    Historically, there were a number of builders that built strip-built boats. Thompson, for example, used edge-nailed bead and cove for rowing boats, duck boats, etc. The scantlings were a bit heavier though, 1/2" and 3/4" are specified, depending on the model. One thing they did that was called "Compressed Seam," where a roller compresses the center of the strip, the edges are planed away flush, and when the center swells on getting moist, seals up the joint.

    Another approach was used by Bowdish on various boats, including canoes. Here a groove is plowed the length of the strip and a spline inserted to span the joint. An end view of this is attached. I've always thought this would be an interesting, if challenging way to build a canoe...

    Then there is of course the Peterborough tradition, with ship-lapped strips. Note that the rib spacing on these is a whole lot closer than that typical of guideboats...

    Attached Files:

  3. Charger

    Charger Woodworker

    Bill, If I may add to this, My boat was finished with a very good Marine Varnish that is made in France. The first coat is Le Tonkinois Bio Flat Linseed Oil Primer. This product in the can is as thin as water. The salesman told me that it would bleed through the wood thickness of my hull (3/16" ) and I told him " Get out of here." He was right. Not only did it bleed through the wood it did it in both directions. I applied it on the inside and outside before applying the other varnish for the finish. Now the final varnish was Le Tonkinois Classic. This is a High build Varnish that requires no sanding in between coats and has a very good UV protection. It does and didn't crack, peel, fade,yellow,or cellophane. It does not require yearly re-coating and what I like the best is it's longevity. They say 4 - 5 years before any re-coating and it only require a light sanding with 220 grit. Living in upstate NY the temps and humidity varies greatly. I store my boat in an unheated old weather tite green house and it has survived in Great condition. Today it will see water for the first time this season. I'll let you all know how it faired. I transport it on the roof of our Grand Cherokee and it has seen many hundreds of miles up there. My next long trip will be to Saranac Lake on June 30th for the Gathering of Guideboats. I hope that this helps anyone deciding to build a stripper in not using Glass in the hull.
  4. OP
    Lazy Jack

    Lazy Jack LOVES Wooden Canoes

    Dan, I had thought Aerodux 185 Resorcinol from CP Adhesives which is described as a water proof gap filling, heat resistant, high-hazard structural adhesive. According to the TD sheet, the clamping pressure for laminated structural timbers should be between 0.6 and 1 N/mm^2. No idea how this translates to a bead and cove joint - set a dowel in the cove and stretch rubber bands? Is Titebond III any less pressure? They offer several hardeners on their website to change the viscosity of the mixture to prevent run out of " thick glue lines" on uneven surfaces...

    I was thinking of gluing up individual planks in groups of four strips, removing them, fairing the insides then final screwing to the ribs.

    Interesting strategies by Thomson and Bowdish - I would consider a spline between adjacent "planks" to allow for collective movement between groups of 4 strips but pretty difficult to cut crisply and precisely in 1/4 inch strips - 5/64ths spline - would probably rather split than slide within a tight kerf - Another approach might be to roller a groove in the bottom of the cove between adjacent groups of glued strips and lay in some hard cotton string to create a seal. I believe this was a caulking strategy used in tight seam boat construction.

    Of course, all of this may be vastly over-engineered given Chargers results simply using Titebond III in a continuous lay-up - I'll be interested to hear about his seasonal launch today

    I've recently discovered Le Tonkinois while restoring my OT canoe - I'm impressed with the stuff so far. I just re-varnished my double planked Grant GB with it. It is nice to use and very forgiving. I'll read up on the Bio-Flat Linseed Primer to see what solvent they use to carry it through the wood like that. I would have said "get outta here" as well as I firmly believe that the penetration of oils into the face grain of wood is minimal at best despite advertising propaganda and hype.
  5. Charger

    Charger Woodworker

    Hey Guys, Well the trip today was great. The boat did just wonderful. No leaks or any imperfections to speak of. It rowed great and I paddled some too. Here are a few shots from my trip. The Lake is Lake Algonquin in Wells, New York. I took the boat from the boat launch to the bridge about 3/4s of a mile away and back. Plus did some exploring up a small side creeks.

    Hope that you enjoy them as much as I did taking them and being out on the water.
  6. Hi LJ,
    As you are well aware I am sure, the roof of a vehicle is about the harshest environment to which one can subject a boat. I am not sure that any construction method will survive long there day in and day out. Even an all composite boat will degrade quickly up there. The biggest problems will be the UV degradation of course, coupled with the fact that every thing will be moving at different rates. ie: The wood will move (shrink and swell) more than the glues. Transporting the boat is not a problem but it really should be stored out of the sun when not in use. I tell customers all the time that the most expensive thing about their boat will be the boat house!
  7. OP
    Lazy Jack

    Lazy Jack LOVES Wooden Canoes

    Inarguable truth there Chris.

    My user boat, a black and green ribless cedar strip epoxy GB is starting its 11th season of such unspeakable treatment on the roof of my truck. I dropped it in the river on my way home from work because it was already up there. That boat has seen a lot of miles, adventures and sleep-unders because it is the easiest, most care-free boat to use and is always on the truck. It has seen some re-paints and most recently, the glass (4 oz) has started to split along the turn of the bilge where the epoxy got rubbed thin from interval sanding/painting. It has served me so well, it deserves to be stripped, re-glassed and treated with a little respect but I'd rather put my energy into a new ribbed guide-boat that I could be as casual with.

    The shrinking and swelling relative to glue etc had me thinking for awhile about planking with strips of Torrified poplar - a heating process which oxidizes the hydroxyl (OH) groups in the cellulose structure rendering the wood non-food for microbes and markedly reducing moisture flux and movement. It does weaken the wood somewhat and makes it slightly more brittle. It is quite light compared to regular poplar probably due to the extremely low moisture content.

    But I worry about becoming known as a guy who built a boat out of charcoal
  8. Dave Wermuth

    Dave Wermuth Who hid my paddle?

    Charcoal? isn't charcoal carbon? And isn't carbon fiber......well.
  9. Yeah, it sure is nice to have the boat handy when passing by a possible looking pond. Spontinaity is the key to life ( along with bending your knees; more on that another time:p)
    Have you ever seen any of Robb White's work? Unfortunately he has passed on, but he had some interesting techniques and insights.
    Primary among them is his advocating for the use of local woods, which in his case would be Tulip Poplar (Liriodendron tulipfera) which he infused with epoxy using a technique that he created.
    Last edited: May 24, 2012
  10. OP
    Lazy Jack

    Lazy Jack LOVES Wooden Canoes

    I've read about his work in the past, possibly in Wooden Boat - the process, IIRC involved heating the shop up, applying epoxy then rapidly cooling the shop down so the contracting air within the wood would suck the epoxy in deeper.

    Don't know if he ever did direct comparisons of longevity against poplar simply coated with epoxy. Sounds high-tech and fancy though...

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