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gunnel repair

Posted by rhbridgeman 
gunnel repair
January 24, 2017 09:46PM
I need some advice on how best to restore the gunnels on my skiff, the old Montana Boat Builders' kits. I followed Jason Cajun's kit directions, but chose not to epoxy my gunnels, but rather, to oil them, instead. I'm not sure if the oil was detrimental to the bond of the epoxy to the wood, but my gunnels have begun to separate badly enough after 7 years that water and debris are getting inbetween the ash gunnels and the top edge of the plywood, which is sandwiched inbetween them. I'm sure rotting will eventually occur if I don't repair the defects, which might as well be the entire gunnal, 360 degrees around.

My plan, is to sand the top edge of the gunnel down beyond the defects (hopefully not more than 1/16-1/8"), fill any deeper defects with peanut butter (epoxy/microballons), then epoxy and glass them over. Any better ideas built on real experience would greatly be appreciated!
Re: gunnel repair
January 24, 2017 11:51PM
A photo might help. Oiling gunwales is a good way to go I think, but only if you bolt them on rather than glue them on. If you use glue then you need resin on top too. I like resin and glass. I'm one of the few builders who does that but I do.

Glue the gunwales on solid with no spaces. Coat with wet resin. Add fiberglass tape. That gunwale is strong and it will last more or less forever.

If you use oil only I think you have to use bolts so you can take it all off every few years, clean it up and re-oil it. Bolt it back on. Gluing and oiling is a mixed meta-oar



Re: gunnel repair
January 25, 2017 05:26PM
Hope the picture uploaded alright.

You can see the inside gunnel (ash) is the one separating from the ply. Per the instructions, I glued it and screwed it, so removing it is probably not an easy option.

It's interesting that the outside gunnel isn't separating as badly, I suppose it's because it can move with temperature and moisture changes, whereas, the inner gunnel is blocked by the fore and aft transoms.

I'm also planning to re-build the oar-lock blocks. What wood should I use for those blocks? White oak, ash, or something else???


Re: gunnel repair
January 25, 2017 07:55PM
Yes I think you want to leave those in place now. Wash them with acetone. Sand them as best you can. Dribble some hot epoxy down into those cracks and then clamp it tight.

Then sand lightly again and coat with resin, cover with an end to end strip of 6" fiberglass tape. That's what I would do.



Re: gunnel repair
January 26, 2017 02:19AM
Would you use this opportunity to replace oarlock blocks since they're oiled, as well? What kind of wood is ideal? Should it be a solid block, or could I join some peices to make them stronger?
Re: gunnel repair
January 26, 2017 03:09AM
Perhaps I'm missing something. I don't see the oarlock blocks in the photo so it's hard to say.

I like oarlock blocks NOT to be glued in a fixed place. I've made them many different ways but always so they can be unbolted and moved further forward or back. I've been trying for 30 years to invent a quick change way to move oarlock blocks but still haven't managed it. So I bolt them in place. You can mail order brass or monel hardware from expensive marine hardware dealers, so those bolts don't corrode and eventually rust.

I used monel once or twice and then gave up on it because it's way too expensive.
Re: gunnel repair
January 28, 2017 06:23PM
Here are the pictures of the gunnel seam failure in the area of the oarlock block. It is beginning to show some separation within the block, which occurred on the port side and led to catastrophic failure of that block. I figured I might be better off to go ahead and replace it while I'm at it. I figured I'd make it a little bigger for strength.

Is white oak suitable? I will have to glue it, as I don't have a piece thick enough to equal the original block.


Re: gunnel repair
January 29, 2017 01:54PM
Here are the pictures of the gunnel seam failure in the area of the oarlock block. It is beginning to show some separation within the block, which occurred on the other side and eventully it led to catastrophic failure of that block-- it split in two. With this one showing the signs, I figured I might be better off to go ahead and replace it while I'm at it. I figured I'd make it a little bigger for strength.

Is white oak suitable? I will have to glue it, as I haven't located a piece thick enough to equal the original block.


Re: gunnel repair
February 12, 2017 03:14PM
I am having some of the same issues. My boat is outside all season long. No way around it, moisture and ultraviolet light have a strong effect on wood fiber. The stuff is not stable. Wood is constantly moving due heat causing moisture to move in and out of the material. Epoxy the gunwales and it just won’t last. Oil is a constant headache. I am ready to remove my gunwale epoxy them with light glass, then apply a the best UV resistant paint I can find.

Next there is the sandwich issue of the plywood, in my case plascore between the gunwales. I have a 1/2 inch space between. I still have not found a good solution for this. But, I will through out my latest thought. My gunwales are mounted about 1/4 inch higher then the sides. So I have a space to fill. Anything used to fill that void must move along with the wood. If it can’t move, it will crack. Water will get in and the process will accelerate. So I had a though (which in my case is often dangerous). Log homes have the same issue. Some old ones which were chinked with mortar, have cracks all over the place. Now there are modern flexible materials which are used. I wonder if it could be used to fill this type of gap. 3M 5200 would do it but at 20 bucks a tube, it’s not a practical material, it’s a pain to work with and takes 5 days to cure but the stuff will bond to anything and stay flexible. I wonder if 5200 could be mixed with some of the fillers we use with epoxy?

The materials are out there. 3M makes double sided tape which is used to hold glass panels to skyscrapers. Yes, the glass is held on the buildings with a flexible tape. Dow makes high tech adhesives which are used to bond components of the new F150 truck frames replacing welds. A problem we have is the time it takes to search through thousands of compounds looking for the right ones.

As for clear finishes, varnish, Brystol. The flat out don’t cut it for the long term. Use varnish and it will need to be reapplied constantly if a boat is out in the weather and what good is a boat which is in a garage? So far a good polyurethane paint is the best solution I have found and that still leaves us with the issue of bonding joints with something which won’t crack.

Our friend Pearl is on the right track even though it’s tough admitting that Pearl is right. He is using aluminum stock for his gunwales and I have to say he is on the right track. Aluminum is a magic material which paints it’s self. Sand off aluminum oxide formation and it will reform and seal up again all by it’s self, how can we beat that, no paint needed.
Re: gunnel repair
February 12, 2017 03:23PM
Pearl's got a lot of energy and good ideas. If he didn't make such a long skinny boat he'd really be doing good work.

;=))



Re: gunnel repair
February 12, 2017 03:23PM
You asked about your oarlock blocks. For very light rowing they might be okay but on bigger water I would suggest blocks which are wider and bolted through on each side.
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