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Advice, Suggestions and General Help New Topic Printer Friendly Version

  wood gunwales pulling apart
  Posted by: nycmhandy on Oct-01-13 3:29 PM (EST)
   Category: Canoes 

During a recent rescue operation, I came down on the seat of my RapidFire much harder than normal, and I think I stripped out the horizontal screws that hold the inwale and the outwale together at the seat (the right side of the seat). The symptom is that, when I'm not sitting on the seat, there is a gap of a couple of millimeters between the two gunwales, only at the seat, only on the right side, that wasn't there before. When I do sit on the seat, the gap widens to maybe five millimeters.

There have long been dark circles around the two screw heads that hold the gunwales together, presumably water damage. Ideally, my fix would prevent further water damage. Most of the gunwale screws have this water damage; it's not specific to the screws where the gap has opened up.

To be clear, I am not talking about any of the screws that hold the seat together and in place. Those are solid. It just happens that the load on the gunwales was applied via the seat, so the damage occurred near the seat. Also to be clear: This is a RapidFire rigged for kneeling, with a cane seat hung from the rails.

And finally the question: My inclination is to abandon the two existing screws, drill two or three new holes, put some epoxy in the holes to seal against water damage, and put in new stainless screws. I am happy to hear about variations or alternatives, and especially about whether there is something special about the placement of the original screws.

Mark

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Messages in this Topic

 

  Why ask us?
  Posted by: kayamedic on Oct-01-13 3:39 PM (EST)
Joe Moore, the maker at PBW, would be the best to advise you.

 
 
  asking Joe
  Posted by: nycmhandy on Oct-01-13 4:09 PM (EST)
I am planning to ask Joe, but I wanted to get multiple opinions, for two reasons: First, I just like to have multiple opinions, for my own understanding and risk assessment. Second, since water damage started appearing around the screw holes and along the seam between the inwale and outwale within two weeks of my bringing the boat home from Lake Placid, I figure Joe might not be expert in sealing wood gunwales against water. Ever since, I have speculated that that is why they like those composite gunwales!

Mark
 
 
  Or something may have gone wrong
  Posted by: kayamedic on Oct-01-13 4:16 PM (EST)
with the process.No one is error free and I think you owe it to the builder to contact them first before you air the laundry.
 
 
  Your suggested fix may work, though
  Posted by: g2d on Oct-01-13 3:48 PM (EST)
I might be inclined to stuff wood dowel into the stripped holes, using quality epoxy like West. Then I would drill new holes right where the old ones were.

Not saying anything against Placid, but center thwart attachment to the inner gunwale on many canoes has always seemed vulnerable to me. I had a similar break when I ran a similar canoe, loaded with me and camping gear, down a 5' high sloping ledge. When the boat hit the bottom, it was caught between a rock and a hard place, and the center thwart broke the inner gunwales and broke loose. So I had split inner gunwales, and damaged screw holes.

I had to graft on a length of thin ash along the inner gunwales in order to restore enough strength to attach the thwart.

It might make sense to double thwart that zone in order to spread the load. But your fix sounds OK for the time being. Just watch those gunwales in case they start to break.
 
 
  Planning for future gunwale work
  Posted by: Guideboatguy on Oct-01-13 4:15 PM (EST)
-- Last Updated: Oct-01-13 4:17 PM EST --

To be frank, I don't know much about epoxy and wood-steel connections, but speaking from my level of ignorance, I'd be worried that screws "sealed" in place with epoxy might be impossible to remove at some later time, such as if something like this happens again. Being more optimistic, and assuming you'll never need to do a similar repair, you might get it in your head to disassemble the gunwales someday. Let's say you want to re-finish them, which to do "right" means treating not just the surfaces that show, but the mating surfaces as well. To do that, you'll need to be able to get those screws out again.

On that note, if these are oiled gunwales, you can do a really good job of sealing the screw holes if you occasionally loosen the screws and dribble the oil of your choice into the threads (tilt the boat so screw heads face up, so the oil runs in properly), then re-tighten (when I do that, I actually allow some "soak time" before re-tightening, but that may not make much difference).

 
 
  Removing epoxied screws
  Posted by: kelvin1 on Oct-02-13 3:00 AM (EST)
I haven't done it but I'm told the best way to remove screws that have been epoxied is to heat a screwdriver with a blow torch then hold the screwdriver on the screw before unscrewing. The heat should melt the epoxy and allow the screw to be removed.
 
 
  What I would do
  Posted by: pblanc on Oct-01-13 7:35 PM (EST)
If you are concerned about water damage of the gunwales at the holes in the inwales that secure the gunwales together (it may be more than you want to do).

I would take the gunwales off and sand the outer surface of the inwales and inner surface of the outwales. Drill the inwale holes slightly oversized then coat the hidden areas of the guwales and the inwale holes with either epoxy, linear polyurethane, or varnish which will have more staying power than penetrating oil.

Fill any stripped holes in the outwales with epoxy (I would use West G Flex) and let it cure. When remounting the gunwales, drill pilot holes for any screw holes you have filled with epoxy.
 
 
  Some Data for Consideration
  Posted by: CEWilson on Oct-01-13 7:39 PM (EST)
-- Last Updated: Oct-02-13 11:27 AM EST --

Mike McCrea has done an excellent and exhaustive study of weathering characteristics of the wood finished available to boat builders. To my surprise, MinWax Spar came out as the longest lived protectant. That is the product Placid boatworks has used on it's cherry trim since 2004. We selected it because it was easily available in almost every hardware store in the continent, so customers could easily maintain their watercraft. I remember writing something about customer maintenance, it's probably still on the Pb website? Of note, from the beginning, Joe insisted on coating the inside of the rails too. I wonder how many wooden rail using builders do that? Rail screw and hanger drop screws have always been separated by a linear inch of wood to minimize weakening.

I'd be interested in the OP's maintenance schedule. He's a friend, has a high powered job, stores his boat at a remote, club, site, etc, what's the chance he buys a can of MinWax and a foam brush once a year....?

A second issue is that the OP's boat has a custom, seat hung from the rails. The rails were, of course, deigned for pack canoe use with a bottom mounted seat.

So we have a good sized guy, skimpy rails with perpetually postponed maintenance and we have an inwale failure, or a start thereof.

Simple solution would be to add another rail screw 1" aft of the machine screws mounting the seat's front bar. Get a pilot bit, drill the holes[s], let's do both sides, and clamp the rail together before hand tightening both new screws home. Then, if glue and wooden matchstick need be applied to the existing screw, so be it.

Oh yeah, while buying the pilot and SS screws, pick up a foam brush, a pint of MinWax Spar and some 150 grit sandpaper and get to work on those rails. Joe will probably mail Robertson head screws NC, but buy the varnish and use it

The many reasons for the Pb movement towards integral synthetic rails was not to address Joe's workmanship, which has always been outstanding, but to save four to five pounds a boat and to eliminate customer maintenance, which builders know can be a sketchy thing at best. Worst possible case, the boat can be rerailed at the factory in the off season.

bon chance, Charlie

 
 
  replies
  Posted by: nycmhandy on Oct-02-13 10:25 AM (EST)
Thank you all for the very helpful replies.

Two clarifications: First, there is no visible break, crack, or tear in the inwale. The inwale has just pulled away from the outwale. I suspect the wood stretched when I loaded the seat (is it possible for wood to stretch?). Second, I am not saying that the screws failed because of water damage. For all I know, they would have pulled out even if the wood had been perfect. Or they might have held, and the damage would have occurred at the next weakest point, somewhere else. My reason for bringing up the water damage is that, if I am going to add new screws, I want to do it in such a way that they resist water better than the current screws do.

GuideboatGuy, thanks for the warning about the permanence of epoxy and screws. Kelvin1, I hope to avoid the blowtorch solution! Pblanc, do you know how to tell if polyurethane is "linear"? I have Minwax Helmsman spar polyurethane on hand, and I am inclined to use that for the screw holes.

Thank you all for the idea of filling the existing screw holes with wood/epoxy, then drilling new screw holes in the same place. I hadn't thought of that possibility.

G2D, can you explain how you "grafted" a thin strip of wood onto the inwale? With glue or screws? I thought of doing something similar, but with fiberglass around the gunwale (the inwale only, or both the inwale and the outwale).

And finally, the rest of this post is in response to Charlie:

As I said above, I am not convinced that the water damage made the inwale problem possible. I suspect that, given the excess beef in the paddler and the minimal beef in the rails, something, somewhere, would have broken when I came down hard on the seat.

As for your contention that I am not maintaining the rails enough, or not at all: I admit to not enough, but I have maintained them at least three times since getting the boat in 2006. The water damage started occurring within two weeks of my picking up the boat from Placid, at many of the screws and long sections of the inwale-outwale seam. That initial damage you cannot attribute to lack of maintenance; it was a problem with the original sealing of the wood. I have surely made the damage worse by not resealing enough, and I guess I missed my chance at taking the rails off, sanding and finishing them, right after I bought the boat. New rails will be necessary at some point, but I'm not nearly there yet (unless the recent strain on the inwale has weakened it and I have more problems coming).

Incidentally, did you know that Minwax Helmsman is now available in a spray can? That was fun for a while, but it turns out that it's hard to hit the underside of an inwale with a spray can.

I don't fully understand your proposed solution. Two gunwale screws have failed, one aft of the forward mount point of the seat, the other forward of the aft mount point of the seat. I hear you saying I should add one new screw and, only if necessary, fill-glue-redrill the failed screw. I could do that with both failed screws, potentially ending up with four newly installed screws, but that seems like overkill.

What do you suggest for sealing new screw holes?

What do you think of some kind of strengthening of the gunwales from the thwart right behind the seat to a few inches in front of the seat? I mean either G2D's idea of a wood splint or my idea of reinforcing with fiberglass. I am wary of stiffening one section of gunwale so much that any future stress is localized right at the end of the reinforced section.

Mark
 
 
  OK, take Two
  Posted by: CEWilson on Oct-02-13 11:22 AM (EST)
-- Last Updated: Oct-02-13 11:28 AM EST --

Wood rails are like mates. They can be beautiful, they can be functional, but they also require inordinate maintenance. The case of weakened inwales pulled in and down by weighted seats is pretty common. Bell/Placid placed the rabbet on the inwale to eliminate the down.

I have a paddler's diet which eliminates the in over time.

My memory of your boat has become sketchy over these seven years and its records likely didn't survive the fire, so...

You need four not two Robertson head rail screws to bracket the seat bolts placements, 1" away from the drop screw hole please, and two more to close the gap between the Machine screws on each side. Six in all. Clamp the rails tightly together when countersinking new holes and tightening the screws. Drip, but drip a little MinWax into the countersinks before setting the screws.

Spray MinWax? Horrers, and indicative of the moral abyss our species has fallen into. Of course it's easy to spray the underside; turn the boat over! What seems difficult is to not spray the hull, mask off with newspaper I suppose, or ones trousers, etc. A brush and liquid gets into more crannies and leaves a thicker surface. Three coats every other second ot third year might suffice.

Then again, the insouciance to noxious liquids that blithely allowed NYC's oyster beds to disappear probably compromises wooden rails too.

 
 
  some answers
  Posted by: pblanc on Oct-02-13 12:23 PM (EST)
-- Last Updated: Oct-02-13 1:26 PM EST --

Miniwax Helmsan is a urethane rather than a traditional varnish. It looks pretty good, although in my opinion, not quite as good as a high quality varnish painstakingly applied. It will protect your gunwales and screw holes fine. I have found Helmsman Spar urethane to be rather prone to runs and sags (a bit more so than varnish) and the spray is worse than the brush-on, in my hands at least.

If you are going to take the gunwales off to fix stripped screw holes, you will find it a lot easier to sand and coat them off the boat. Just be careful not to accidentally break them. I would just fill with epoxy any stripped screw holes. The unstripped ones should be fine for remounting the gunwales.

I have not had any problem rethreading screws through stripped rails after filling the holes with epoxy, letting it cure and drilling a pilot hole through the cured epoxy, just as you would do if you were mounting virgin gunwales. As long as the epoxy is fully cured it will not bind the screws any more than the wood would do. If you find tight gunwale screws, heating the screw head as suggested can help. It is a lot more convenient to do so with the tip of a soldering gun if you have one. You may need to heat the screw head repeatedly to free it.

I have repaired broken gunwales and thwarts using G Flex epoxy and light weight fiberglass cloth (4 oz/yd). When fully wet out the cloth weave will be virtually invisible, however, the fiberglass-covered wood will not take up urethane, varnish, or penetrating oil as the uncovered wood will so it will be a slightly different color after finishing. The right sided inwale on this canoe just aft of the bow thwart was repaired in that manner: http://www.flickr.com/photos/42020723@N02/8597715638/in/photostream/

The photo (IMG 1977) doesn't show it too well, but if you look closely you might see that the fiberglass-covered area is a little darker.

Earlier this year I finished repairing and rerailing an old, Bell Black Gold Wildfire (with help from Charlie Wilson who provided technical info and from Marc Ornstein who provided the wood). I decided I didn't want to mess around with reoiling the gunwales and wanted maximum, long term protection. I coated the wood on all surfaces with several applications of a penetrating clear epoxy (System 3 Clear Coat) then applied several coats of a good marine varnish made by Petit (Z Spar Schooner). These photos might give some idea of the results: http://www.flickr.com/photos/42020723@N02/sets/72157636122331674/

 
 
  gunwale damage
  Posted by: ppine on Oct-03-13 12:27 PM (EST)
Try injecting epoxy in a syringe in the voids. You can add some wood dust for color.
 

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