Video: Epoxy Repair of Rotted, Cracked Gunwale

[Glenn MacGrady]

This is a detailed video of my three-day repair with G/flex epoxy of the rotted-out and cracked inwale on my Bell Wildfire, for which I got a lot of advice here in THIS THREAD. I'll post the video in that thread, too. If you don't want to read all the advice discussion, you can skip that earlier thread and just watch the video, which covers the repair steps in detail, as well as the West G/flex Aluminum Boat Repair Kit and the carving, sanding and cleaning-up of the epoxy.

Bottom line: The repair is structurally very sound, almost perfectly blended into the original gunwale shape, but the silica-thickened epoxy has left a light lemon yellow patch on the gunwale that is not particularly aesthetic. I've yet to varnish and will post some photos when I do.

 

[Alan Gage]

Nice work Glen, very thorough job and it looks like a great result. Perhaps you'll have to do some fine artistry now and do a faux wood grain finish on that epoxy so it blends in better.

Alan

 

[ppine]

Glen,
Thanks for the video. You could edit out some of it to make it easier to watch. I have made similar repairs in my old OT Guide gunwales only more extensive ones. I have never liked the look of the silica as it shows up yellow or white. The wood flour trick I learned from a Pygmy assembly manual and it works great. You can use the same species of wood that you are repairing. Then the repair is the same color as the gunwale, it just tends to be a little shinier. The flour controls the viscosity just as well as the silica or micro-balloons. It is another material you do not have to buy and it looks much better.

 

[Guest]

Enjoyed the video. The repair is remarkably well done given your self-professed lack of experience in such matters. The battle scar gives the Wildfire character, and I bet in a short time it will fade and blend in and you won't ever hardly notice it.

 

[Hanz]

Nice Job! I bet it's stronger that the rest of the wooden inwales and outwales.

 

[pblanc]

Glen,
Thanks for the video. You could edit out some of it to make it easier to watch. I have made similar repairs in my old OT Guide gunwales only more extensive ones. I have never liked the look of the silica as it shows up yellow or white. The wood flour trick I learned from a Pygmy assembly manual and it works great. You can use the same species of wood that you are repairing. Then the repair is the same color as the gunwale, it just tends to be a little shinier. The flour controls the viscosity just as well as the silica or micro-balloons. It is another material you do not have to buy and it looks much better.

I have used wood flour to give a better cosmetic appearance to externally visible fillets on Pygmy and Chesapeake Light Craft stitch and glue kayaks as well. I gather from perusing some of the wooden boat forums that there is some controversy regarding the strength of joints made using epoxy/wood flour mixes. It may well vary with the variety and consistency of the wood flour used, but some feel that the wood flour soaks up too much epoxy resulting in an epoxy starved joint (others do not).

I have found that the wood flour/epoxy mixture when cured, results in a considerably darker color than the surrounding wood, even when the same type of wood is used for the flour, but this could be a function of how much of the flour is mixed in. Microballoons can also be used as a thickening agent, and result in a reddish brown color when the epoxy cures, and the microballoons do not absorb epoxy the way wood flour might.

It would certainly be possible in this case to obtain some ash wood flour, sand down the light colored areas of the cured epoxy/silica powder mix, and cover these areas with epoxy/wood flour to darken the color without compromising the strength of the repair.

 

[Mihun09]

I have used wood flour to give a better cosmetic appearance to externally visible fillets on Pygmy and Chesapeake Light Craft stitch and glue kayaks as well. I gather from perusing some of the wooden boat forums that there is some controversy regarding the strength of joints made using epoxy/wood flour mixes. It may well vary with the variety and consistency of the wood flour used, but some feel that the wood flour soaks up too much epoxy resulting in an epoxy starved joint (others do not).

I have found that the wood flour/epoxy mixture when cured, results in a considerably darker color than the surrounding wood, even when the same type of wood is used for the flour, but this could be a function of how much of the flour is mixed in. Microballoons can also be used as a thickening agent, and result in a reddish brown color when the epoxy cures, and the microballoons do not absorb epoxy the way wood flour might.

It would certainly be possible in this case to obtain some ash wood flour, sand down the light colored areas of the cured epoxy/silica powder mix, and cover these areas with epoxy/wood flour to darken the color without compromising the strength of the repair.

I've never had epoxy/wood flour come out close to the actual flour colour, it is always darker, but when I need it to be as close as possible, I'll mix Microballoons and wood flour into the epoxy, the MB I have are white so they tend to lighten the overall mixture. As for starved joints, perhaps it isn't the thickened epoxy as the issue but the user did not pre-coat all the bare wood with unthickened epoxy to soak in before the filler mixture.

 

[pblanc]

Yes, I have not had any problem using wood flour for filleted joints either, but then the joints were 'glassed over so not subject to as much stress.

What I have taken away from these forum discussions of the pros and cons of wood flour is that as you suggest, the bare wood should first be coated with unthickened epoxy, and that those who have had problems may have been using sawdust as opposed to wood flour, which may have absorbed a lot more epoxy. Proper wood flour should be very fine, like the consistency of sifted baking flour.

West System sells a variety of wood flour, although they don't call it such, which is 405 filleting blend. Here is a guide to West Systems fillers which shows that for structural gap filling, 405 filleting blend is not as good as colloidal silica or microfibers but its not bad:

http://www.westsystem.com/ss/filler-selection-guide/

For fillet bonding colloidal silica is hard to beat.

 

[Glenn MacGrady]

Here are pictures of the repaired Wildfire.

I vigorously hand sanded the woodwork and used three coats of a wipe-on varnish, which should offer more UV protection to the G/flex epoxy than oil. I cleaned the interior and exterior with acetone and Penetrol. Penetrol masks gelcoat oxidation, until it wears off after a season or so, and it also causes water to bead on the interior instead of forming those notorious white blushes on the annoying Bell vinylester resin.

I like my boat a lot better now, and am looking forward to a month with it in Florida. Thanks to everyone here who offered advice and helpful information.

 

[Guest]

I saw the Wildfire gunwale repair firsthand yesterday (and this morning*) and Glenn made neat work of it. Impressive for a guy who didn’t even own a clamp prior to this job.

*I also saw the Magic Bus. And Glenn. The “Retired Paddler’s Network” has had its first hit as Glenn spent the night before continuing on his travels.

 

[Glenn MacGrady]

*I also saw the Magic Bus. And Glenn. The “Retired Paddler’s Network” has had its first hit as Glenn spent the night before continuing on his travels.

And I had barely finished saying hello to Mike before he was offering his shop services to repair the side mirror on the Magic Bus and a broken strut on my camera tripod, both of which have held up so far.

Thank you, Mr. Wizard.