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Repair to Wood Gunnel (Dagger legend 15)

Repair to Wood Gunnel (Dagger legend 15)

11329
Member
11329

    Dec 02, 2017#1

    I'm after some advice for how to proceed with repair or replacement of the gunnel(s) on a Dagger Legend 15. While poling a few weeks ago the kneeling thwart ripped out a section of gunnel:




    I'm trying to decide if I can get away with patching in a replacement section (I was thinking about a 1 metre length) even if just for the winter or I should just bite the bullet and replace both gunnels. I'm only so-so with this kind of project so expect it will be rather lengthy and fumbling - also its cold outside and the days are short and there is nowhere to work on the boat under cover - so wondering if a patch might keep it going until the days warm up. Winter isn't a downtime for me so need the boat going again.

    Looking at the point of break - the wood looks rather grey and I wonder if this part or even the whole gunnel has rotted. Despite the fact that the boat is used on white water a lot I don't have the heart to put on vinyl gunnels - but I have noticed that Endless river do a 1 metre section of vinyl which might work as a patch until the summer.

    What are people's thoughts - how long a task is it to do both sides? I've found the Fyne boat site who seem to do ash gunnels and an article from Instructables on how to replace.

    Any thoughts appreciated.

    Thanks

    2,1571,506
    Contributing Member
    2,1571,506

      Dec 02, 2017#2

      To get you going, just cut out a 2ft section. Find a bit of reasonably straight-grained timber, plane it to match the profile and glue and screw it in place. A nice long scarf joint would be nice but 45° would be enough. That's an hour or so's work for someone who can work a plane and a saw.

      I suppose it would take you a day or more to refit the whole lot but I'd want to dry fit everything, remove it and get a good couple of coats of oil on.

      2,94047
      Member
      2,94047

        Dec 02, 2017#3

        I'd agree with BYtractor's method. Its will do perfectly fine until you decide to replace the whole gunnel - if at all!.

        As an alternative to a scarf joint, a 'half lap' joint will probably be easier to do and won't leave you with a sharp edge at the end of the joint on the inside which may cut or cause a splinter in your hand. - the half lap can also be as long as you wish so you get enough contact between the old and new.

        Any inaccuracies in either can be filled or sanded down as necessary.

        The black looks like staining from the screw hole, but you've got a weakness in the gunnel there as you've three holes in the wood which weaken the gunnel in that area.

        11329
        Member
        11329

          Dec 02, 2017#4

          Thanks both. Should I screw through the lap joint (presumably not as it will weaken it). If not then is it worth trying a flexible glue at the joint?


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          967501
          Member
          967501

            Dec 02, 2017#5

            Thickened epoxy resin would be the best adhesive, and will be more than strong enough without screws, assuming you can clamp it in place while the resin sets. Low temperatures might be a problem for you though, as you ideally want 15 degrees plus. Warming wood and resin before you start would help ensure good penetration of the resin into the fibres, but the cure time will still be very slow if the temperature subsequently drops.

            11329
            Member
            11329

              Dec 02, 2017#6

              Maybe will have to evict the kayaks from the garage for the gluing job I guess.


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              1,6838
              Member
              1,6838

                Dec 04, 2017#7

                Another option is polyurethane adhesive, I'm a big fan of this stuff for woodwork and I find it more forgiving (of both conditions and user input) than epoxy. First make sure the joint is a good fit, put a piece of plastic between the gunwale and the side of the boat (so you don't glue the gunwale to the hull), apply the adhesive to one side of each joint then clamp the joint together tight as you like until set.

                Polyurethane will set in pretty cold conditions and if clamped, sets very solidly. It also sets well in damp conditions. I've made wood laminates for boat parts with it before and I've seen people make paddles with it. The wood will break before the glue does.

                I've been using 5-minute polyurethane recently which you can get from most builders merchants (and screwfix) in a mastic gun tube. I've just used it to make a plywood rabbit hutch for the wife using rabbet joints, took 10 minutes to set properly in my unheated garage yesterday. Those are only overlapping by 6mm and the ply would snap before the joints will let go.

                A more readily available version is gorilla glue. This takes longer to set, maybe 2 hours.

                Both foam slightly when they set so you do need the joint clamped down (or it'll push apart slightly). As such, it'll expand a little to fill any inconsitancies in your joint. The excess that foams out of the edges can be easily scraped off with a paint scraper or putty knife once it's dry.
                "I'm not getting in a boat which is DESIGNED to go upside down."

                2,3991,089
                Member
                2,3991,089

                  Dec 04, 2017#8

                  plywood rabbit hutch for the wife
                  Aren't you going to let her in the house for the winter?
                  using rabbet joints
                  Very good.

                  But, seriously, thanks for the info re polyurethane glue - I'll try that.

                  2,8046
                  Member
                  2,8046

                    Dec 04, 2017#9

                    My gunnels took a beating this year...


                    As a temporary repair we used Gorilla glue: which to be fair held. But I am going the whole hog and replacing the lot.

                    Your break is in an area where it will be submitted to a fair amount of stress, something to keep in mind..
                    Cheers
                    Tim
                    :canoe:

                    SMpiratePaddles a Prospector

                    11329
                    Member
                    11329

                      Dec 04, 2017#10

                      Thanks for the advice re polyurethane glue - will give it a go,

                      Rather harsh keeping the wife outside in a rabbit hutch in this weather - but each to their own.


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                        Jan 01, 2018#11

                        Many thanks for all the advice. Have managed to replace the broken section and have the kneeling thwart back on again. Went with the PVC glue and it seems to have set well at 8-9C,


                        2,94047
                        Member
                        2,94047

                          Jan 02, 2018#12

                          That looks good to me - and it appears you've spread two screws further along the gunnel. Nice work, and be careful next time you flop down on the thwart...;-)

                          136
                          Member
                          136

                            Jan 02, 2018#13

                            Given the probability of the kneeling thwart taking some shock load you could also consider reinforcing the gunwhale at that point (on both sides.) Glueing a piece 30cm (or more) long underneath the gunwhale to double its thickness would go a long way to mitigating the weaknesses introduced by the screw holes and spread the load of the kneeling thwart. The lines of the hull are pretty straight at that point so I doubt the extra wood would alter them noticeably. Shaped and tapered at the ends it shouldn't affect the aesthetics either. Would mean modifying the thwart hangers a little.

                            11329
                            Member
                            11329

                              Jan 03, 2018#14

                              Hi David, I put in a 3 foot section so the whole is held by 6 screws as per design and subsequent to photo I added a couple more filing down and matching profile. Will mull over strengthening options thanks Timon - think I’m inclined for now to see if it stands up to usage as is at the moment. The old section was a bit like a Swiss cheese with various plugged holes am hoping the new will be stronger. Don’t really know how I wolloped it actually as I executed an excellent back flip out of the boat in preference to capsizing it :)


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