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PostPosted: July 20th, 2012, 8:27 pm 
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So I have this lovely laminated cedar beavertail paddle that I am repairing. I've filled in the dings (not my doing - honest) with epoxy and sanded everything down. However, before putting the finish on, I'd like to reinforce the whole thing with fiberglass and epoxy. I was thinking one layer of glass over the whole thing, and another on the blade/throat.

Does anyone have any tips for using fiberglass on paddles? Should I get cloth and taylor it to fit the best I can, or can I use overlapping strips of fiberglass tape? How many layers do people usually use?

Also, would West Systems epoxy be flexible enough for the cedar? I have the #205 fast hardener, but I can get other hardeners, if that makes any difference. I assume the reinforcing layer will stiffen the paddle, but I'm a bit worried about the glass/epoxy shell cracking if the paddle flexes too much. I might be overly paranoid, though - I've never worked with glass/epoxy before, other than installing bow/stern Kevlar felt skid plates once upon a time.


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PostPosted: July 21st, 2012, 12:13 am 
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I wouldn't glass the shaft. If the shaft hasn't broken by now, it doesn't need reinforcing.

And I would only partially reinforce the blade. Glassing adds weight. Glass is the heaviest cloth used in boat building and paddle building. It wets out nice and clear, but carbon cloth is FAR lighter.

What I've done in a similar situation is to glass one side up maybe three inches, and glass the other side up maybe five inches. AND I cut the top end of each piece of glass into a convex or concave shape. The reason for these measures is to prevent a straight-across stress riser that could cause the paddle to split across the blade. That happened to me one time when I had glassed halfway up the blade on both sides. I caught the bottom of the river, and the blade (laminated yellow spruce) snapped straight across, clean as could be!

Four ounce flat weave may be enough, and six ounce won't weigh much more. You might want to get 206 hardener to give yourself more time to work.

Many more details, but I gotta go now.


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PostPosted: July 21st, 2012, 8:01 am 
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Quote:
So I have this lovely laminated cedar beavertail paddle that I am repairing.


Cedar isn't known for strength or durability... I carved a paddle from western red cedar and after the final sanding, it was so light and flexible I doubt it would have taken a single good stroke without snapping. So the entire thing was glassed with 6 oz and now it's OK, for a lighter paddle. Good looks, too.

Your cedar paddle might be different and durable enough already... if not, adding glass sure will make it stronger. Maybe overkill if too much... I've glassed axe and maul handles to prevent splitting away and the improvement in durability afterwards is really something. Way too much for a canoe paddle, though, so use your judgement.

If you're going to glass a thin blade, I'd suggest glassing both sides at once, since epoxy curing on one side only might warp the blade. I know EZ will disagree with this, but the effect was pretty dramatic with all the warping on one side and getting the warp out afterwards took some work. I used East epoxy which might be different from West.

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Last edited by frozentripper on July 21st, 2012, 8:17 am, edited 2 times in total.

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PostPosted: July 21st, 2012, 8:12 am 
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Definitely don’t glass the shaft. If you are happy with the weight and balance of the paddle as it is I wouldn’t fully glass the blades. I’ve done so on some loaner paddles and even with lightweight cloth and good epoxy technique the weight and change is balance is striking. Every added ounce makes a difference.

Even the additional weight of partials added to the end of the blace will be noticeable and may affect the balance.

If you want to add some reinforcement to the edges of the blade once the paddle has been sanded (before varnishing or sealing the wood) I’d simply add a bead of Gflex (or Gflex with some thickener) all the way around the edges of the blade.

I have used carbon fiber tow between coats of Gflex on the edges of a bunch of paddles, including some beater sticks and they have held up well for several years even under incautious loaner use.

I just clamp the paddle with the blade positioned vertically, paint a thin bead of Gflex along the top edge of the blade, lay a length of carbon fiber tow atop the wet resin and smooth it out with gloved fingers. Once that has begun to set up I add another bead of Gflex on top of the carbon fiber.

The tow will wrap around even the thinnest blade edge, something that is almost impossible with cloth, and the end result is looks decent.

http://entertainment.webshots.com/slide ... 1176iFFBNl


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PostPosted: July 21st, 2012, 10:18 am 
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The paddle in question is a Whiskeyjack Good Sky (discontinued). My canoeing partner accidentally dumped some firewood on it, which promptly crushed the grain on the shaft and gouged a sizable hole. Now, this definitely constitutes paddle abuse, but a maple or a cherry paddle wouldn't have sustained nearly as much damage. This was an eye-opened - cedar really is soft (duh...).

I'm a bit worried about using this paddle for tripping. I usually take good care of my tools, but when you're out on the trail, things happen. I'm trying to decide if I should relegate this paddle to pleasure-paddling only duties, or reinforce it so I can trip with it and still have some peace of mind.

If it becomes a dedicated day tripper, I won't glass it and will just refinish it, though I'll probably add two thin coats of epoxy to the whole before varnishing, to prevent the surface from denting so easily and to really seal the grain. I also really like the graphite tow idea - I like that look on paddles and hadn't realized until now how it's done. I'd just have to find a place that sells small spools.

If I decide to use the paddle for tripping, though, I will happily trade light weight and change in feel/balance for added durability. Would one layer of glass over the whole thing be enough, or would I need more?


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PostPosted: July 21st, 2012, 12:07 pm 
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kolgrimr wrote:
The paddle in question is a Whiskeyjack Good Sky (discontinued)

I'm a bit worried about using this paddle for tripping. I usually take good care of my tools, but when you're out on the trail, things happen. I'm trying to decide if I should relegate this paddle to pleasure-paddling only duties, or reinforce it so I can trip with it and still have some peace of mind.

I also really like the graphite tow idea - I like that look on paddles and hadn't realized until now how it's done. I'd just have to find a place that sells small spools.


I don’t actually know if that is how it’s done, and I’m not sure if I’ve seen other paddles with carbon fiber tow edging. It’s just how I’ve done it. I was told by folks with materials experience that carbon fiber tow was less than ideal, but I haven't found anything that will wrap the edges of a paddle blade as cleanly.

Or as easily. I’m lazy and semi-skilled at best, and the tow is simple to apply. Having two layers of Gflex sandwiching the tow probably provides most of the durability.

That Whiskeyjack is a nice paddle, and whatever you do it’s worth doing well. If you opt for the carbon fiber tow route I’ll offer a couple of hints.

Gflex is easier to work with for that application than regular epoxy resin (unless thickened). A bead of Gflex on the edge of the blade is less drip prone (although I’d have a rag or two and some acetone to catch any drips that do begin to run down the vertical blade surface).

I’ve been applying the tow by doing one side of the blade at a time, and overlapping the tow on the bottom of the blade end, so when I do the other side I end up with a double layer of carbon fiber tow at the bottom of the blade.

The carbon tow I am using is ¼” wide, and since it is composed of linear strands with no weave it will lay down along a U curve with no puckering. I just lay the bead of G/flex along the blade edge, lay the pre-cut length of tow atop that and smooth it into a U with my gloved fingers. It helps to wet my fingertips with a little epoxy when doing so.

Once the tow is in place I paint another bead of Gflex on top of the tow and repeat the next day on the other edge of the paddle. Lightly sand the edges when the Gflex has cured, epoxy the full blade, wait a week or more, lightly sand the epoxy (unless your epoxy technique is much smoother than mine) and varnish the whole thing.

kolgrimr wrote:
If I decide to use the paddle for tripping, though, I will happily trade light weight and change in feel/balance for added durability. Would one layer of glass over the whole thing be enough, or would I need more?


One layer of 4oz or 6oz glass on each side of the blade would be plenty. The epoxy coat will add more weight than the glass, so good technique there will help keep the weight down. The lightest epoxy resin technique would be to squeegee off any excess, and maybe lay a piece of peel ply over the cloth to help fill the weave with a single resin coat. The peel ply would eliminate a lot of sanding and help avoid accidentally sanding through the lightweight glass when smoothing out the resin coat.

If you cut and lay the glass on the bias it’ll be easier to get it to droop over the edges of the blade. Do one side at a time with the blade held horizontal. When the glass has set along that side you’ll need to trim and sand any loose glass that extends past the blade edge before doing the same to the other side.

Caveat – I have never been able to get the glass to lie fully over every bit of the blade edge, and usually end up sanding through to the wood in a few places when removing the excess cloth droop and trying to get the blade edge back in proper shape.

G2d’s suggestion of altering the shape and position of the glass is a good idea, whether you use just partials at the end of the blade or fully glass the blades. A distinct and even transition between glassed rigid and unreinforced wood would be the most likely point of failure, whether that is up at the throat with full glass or down at the bottom with partials.


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PostPosted: July 24th, 2012, 1:22 pm 
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Thank you for all the details, Mike. I'll skip glassing and stick with tow and epoxy. I just did one edge and everything seems pretty straightforward. Now I just have to find a decent roller (brush?) for epoxying the blade.


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PostPosted: July 24th, 2012, 2:43 pm 
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ezwater wrote:
...Glass is the heaviest cloth used in boat building and paddle building. It wets out nice and clear, but carbon cloth is FAR lighter.

4 ounce cloth is 4 ounce cloth. Period. Unless I'm way off in my understanding of composites, 4 ounce glass cloth should weigh pretty much the same as 4 ounce carbon fiber cloth.

I agree with most of the other points though. I would use 4 ounce glass cloth, but if you want to use carbon cloth instead, I'm sure that's good too. 6 ounce cloth would be OK, but you are going to get enough strength with 4 and I'd use the lightest cloth I could. The thicker cloth adds weight not only in terms of the cloth weight, but also the extra epoxy it takes to wet out the thicker material. Fairly small amounts, but it can add up. Having said that, if I had 6 ounce cloth on hand or if was easier to get, I'd just use that.

Interesting points about making the glass curved and higher one side to avoid stress points. I haven't bothered with that before, but it's been on bent shaft paddles that were already asymmetrical.

Also, the point about epoxy adding more weight than the glass so that careful epoxy work being important is spot on.

A thin layer of epoxy is plenty flexible on your cedar paddle.

I just brush on my epoxy, usually. Do it warm so that the epoxy is thinner.

Cheers,
Bryan

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PostPosted: July 24th, 2012, 7:16 pm 
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I just clamp the paddle with the blade positioned vertically, paint a thin bead of Gflex along the top edge of the blade, lay a length of carbon fiber tow atop the wet resin and smooth it out with gloved fingers. Once that has begun to set up I add another bead of Gflex on top of the carbon fiber.


I like this concept!

Mike can you confirm the number of strands in the tow you use? I'm guessing it's 12k?

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PostPosted: July 25th, 2012, 2:08 pm 
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kolgrimr wrote:
Thank you for all the details, Mike. I'll skip glassing and stick with tow and epoxy. I just did one edge and everything seems pretty straightforward. Now I just have to find a decent roller (brush?) for epoxying the blade.


I’ve used (foam) rollers when doing an entire hull, but have always used brushes on smaller jobs like paddle blades. Actually I’ve used foam rollers on hulls and then a brush to tip out the rolled epoxy – two guys working their way up the hull, roller man first immediately followed by tip out man.

I epoxied one full hull by myself, and by the time I got around to trying to tip it out it was too late. The epoxy coat had a slight “orange peel” dimpled finish to it. The hull got wet sanded and varnished afterwards, so the end finish was smooth.

About brushes for epoxy. I don’t have many good quality brushes, just a couple for varnish work that I take care of, but for epoxy I use inexpensive chip brushes and toss them afterwards. Cleaning epoxy from a good quality brush seems futile.

I’ve tried disposable foam brushes as well, but I have better control over loading a brush to put down an even epoxy coat.

I’ll be interested in what you think once the paddle is done, and in how it feels weight and balance wise and how it holds up.

recped wrote:
Mike can you confirm the number of strands in the tow you use? I'm guessing it's 12k?


I’ll start counting the strands.

Seriously I have no idea. I don’t even remember where I got the tow I’ve been using. Gift from a friend I think. From the info I’ve found on carbon fiber tow 12K looks about right

http://www.fibraplex.com/tow.asp

Confused? Try this link instead – less technical info, and available in 25’ lengths.

http://www.cstsales.com/carbon_tow.html

I have enough left to do another dozen blades, and I’m working on two paddles now, so I probably should probably order more. At $6 for 25 feet I might get some 50K as well, just see what it’s like.


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PostPosted: September 10th, 2012, 11:17 pm 
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2 oz. glass is plenty strong enough for the task and the weave is very fine so the texture is smooth. Glass both sides of the blade fully. I usually go up the shaft, too. Not because the cedar can't be strong enough, its just that it takes such a beating that the bit of 2 oz. glass helps the poor old soft cedar. The added weight with 2 oz. glass is negligible.


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PostPosted: September 11th, 2012, 12:04 am 
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I have been making cedar paddles since the 70s when Mike Galt published his bentshaft article. I normally use 4 ounce. I apply it to both sides, and trim it back rough, the perimeter of the paddle then has a gutter around it because the glass wets out beyond the edge, and so one can add glass tow for tip strength as desired.

I try to avoid glass lighter than 4 ounce due to print through, though if that was not a concern, it is sure nice to work with.

Be careful doing this kind of project that you do not wait too long to do the second side if you are doing them separately, as humidity changes can cup the wood a lot and they will not always drop back to zero when the humidity change back.

Since bents have a power face, it is easy to tune them for stiffness. Even thought the 4 oz is not more effective at adding stiffness than an equal volume of wood, roughly speaking, it still ads quite a bit of thickness, which to the third power means the blade gets a lot stiffer.

My approach is to glass the power face, then further thin the paddle to the point at which is starts to feel flimsy, then glass the back of the paddle. If one doesn't do something like that, the paddle ends up feeling like a club, even if it is a light weight club.

When working with glass or even moreso carbon, use the highest quality hardest epoxy you can get, for best results. I use WEST, but there are other brands that are also fairly tough.


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PostPosted: October 5th, 2012, 5:03 pm 
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Mike McCrea wrote:
[
recped wrote:
Mike can you confirm the number of strands in the tow you use? I'm guessing it's 12k?


I’ll start counting the strands. Seriously I have no idea. I don’t even remember where I got the tow I’ve been using. Gift from a friend I think. From the info I’ve found on carbon fiber tow 12K looks about right. Try this link – available in 25’ lengths.

http://www.cstsales.com/carbon_tow.html

I have enough left to do another dozen blades, and I’m working on two paddles now, so I probably should probably order more. At $6 for 25 feet I might get some 50K as well, just see what it’s like.


I’ll be able to answer the CF tow thread count question with more certainty soon. I just ordered 25’ of 12K and 25’ of 50K (and some peel ply and, well, dang there is a lot of unusual shop-and handy material on the Composite Store site).

I have four old, high sentimental value Sawyer blades in the shop that I’m working on for a friend; originally rentals from his outfitter business, then left as loaner sticks at his family’s camp up north, recently retrieved and in need of much salvation.

Despite the fact that the time, effort and materials will far exceed any real-world value they’ll get a full refurb. And be good for another 30 years.

(I also have a full carbon Werner Camano double on which the female ferrule failed the truck test, as in driving over it with a Ford Ranger. I think it may be salvageable as a take-apart with some repair cunning, and almost certainly as a one piece double. I’ll know in a few days)

Time to go wipe the G/flex drips off the edges of those Sawyer blades with an acetone cloth.


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 Post subject: Post paddle repair?
PostPosted: October 5th, 2012, 5:10 pm 
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kolgrimr wrote:
I'll skip glassing and stick with tow and epoxy. I just did one edge and everything seems pretty straightforward.


Kolgrimr, If you have finished the paddle and had it out a few times I’d be interested to hear what you think after the repairs.

Or even an “It’s still sitting in my shop as a work in progress” report.


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 Post subject: Re: Post paddle repair?
PostPosted: March 25th, 2013, 10:47 pm 
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Mike McCrea wrote:

Kolgrimr, If you have finished the paddle and had it out a few times I’d be interested to hear what you think after the repairs.

Or even an “It’s still sitting in my shop as a work in progress” report.


Sorry, Mike, I've been away from MyCCR for a while. It's still in the shop, waiting to be sanded and epoxied. I'm stuck at home for the next couple of days, so I think I'll work on it a bit - just need a new brush for the epoxy. I'll try to remember to snap some "work in progress" pictures after I put the first coat on.


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