What's happening in your shop this winter?

[Peach Canoe]

Robin, nice work.

Alan, the CF hockey shafts I have are hollow. They're made by wrapping stacked layers of thin pre-preg carbon fibre material around a mould or mandrel, and then it's oven-cured. First the mould is wrapped with thin clear poly release film (this stays inside the shaft), and then the carbon fibre (could also be fibreglass, Kevlar, or some combination) is wrapped over that. Processes are proprietary of course. The orientation and concentration of fibres varies depending on the specific requirements for a particular stick-- it would include specs like stiffness, weight, and location of max flex on the shaft (the sweet spot).

I've taken some measurements of wall thickness, and it varies (I found some as thin as .054" and as thick as .075", with .063" as a nominal thickness); the range is probably greater, but this is taken from the armful of sticks I have in the shop. Apparently there are up to 15 layers of carbon fibre in the wrap. I don't know what thickness of cloth they use, but it must be very thin.

A typical sample of 3Kx3K 2x2 Twill @ 5.7 oz/sqyd bags out to .009". It would take just 7 layers of this basic CF cloth to bag out at .063". It would seem they are using material half that weight and thickness-- perhaps 3 oz that bags out at .0045". But I don't know.

 

[Alan Gage]

Robin, nice work.

Alan, the CF hockey shafts I have are hollow. They're made by wrapping stacked layers of thin pre-preg carbon fibre material around a mould or mandrel, and then it's oven-cured. First the mould is wrapped with thin clear poly release film (this stays inside the shaft), and then the carbon fibre (could also be fibreglass, Kevlar, or some combination) is wrapped over that. Processes are proprietary of course. The orientation and concentration of fibres varies depending on the specific requirements for a particular stick-- it would include specs like stiffness, weight, and location of max flex on the shaft (the sweet spot).

I've taken some measurements of wall thickness, and it varies (I found some as thin as .054" and as thick as .075", with .063" as a nominal thickness); the range is probably greater, but this is taken from the armful of sticks I have in the shop. Apparently there are up to 15 layers of carbon fibre in the wrap. I don't know what thickness of cloth they use, but it must be very thin.

A typical sample of 3Kx3K 2x2 Twill @ 5.7 oz/sqyd bags out to .009". It would take just 7 layers of this basic CF cloth to bag out at .063". It would seem they are using material half that weight and thickness-- perhaps 3 oz that bags out at .0045". But I don't know.

That's interesting, thanks for the info. I'm sure they have their reasons but you think it would be more expedient to use heavier cloth in fewer layers. Maybe the thinner layers let them more easily build bulk in one area and reduce it in another. Or maybe it's just simpler to carry one weight of cloth rather than multiples. Tough to make one shaft .062 and the next .066 when your cloth is .009

I'll be making some carbon tubes and supports for seats in the next couple weeks. Curious to find out how much thickness it takes, how strong they are, and how much weight savings there is compared to aluminum. I'm guessing not much. Carbon is so expensive that I hate to waste any by breaking it but I might have to to satisfy my curiosity.

Alan

 

[Robin]

You do work Robin, looks excellent. I have one in F/G as well and have regunwaled it twice now. What are going do for decks?

I'm just going to glue some 3/4 x 1/2 ash together and screw them on top of the inwales/gunnels. I'm not that good to inlay them between the inwales. This is for re-sale and it helps to keep the canoe affordable.
No point in trying to learn new tricks at this stage of the game, and this canoe will go quick come spring.

 

[Peach Canoe]

Alan, I think the use of very thin aerospace cloth enables gentle transitions between areas of varying stiffness-- to avoid mechanical steps, or stress risers.

How thick is thick enough? That's a good question, and I spent some time attempting to answer it. For a 3/4" X 26-inch thwart to feel as stiff as my bench-mark Honduras Mahogany thwart, I found I needed a wall about .050" thick in carbon fibre and about 20% more in Kevlar (maybe .065")-- say 6 layers of carbon and 8 layers of Kevlar, each @ 5.7 oz per yd, and vacuum bagged at 25"HG.

To simulate Western Red Cedar (which is 33% lighter than H Mahogany), 2 Soller 11.9 oz sleeves over balsa will do that nicely, but the saving is only half an ounce-- in this case I'd opt for the WRC with an epoxy-plus-filler hard point for the screw (a 1/2 inch hole through the thwart, then filled with epoxy and filler and drilled out for the thwart-to-gunwale bolt). 3 Soller 11.9 oz sleeves over balsa makes a good stiff thwart, however.

I used the heat-shrink sleeves and found them unsatisfactory; it's probably better to make a poly sleeve and vacuum bag the thwart-- though I never did this. Instead I made a mould (see the two thwarts in the photo).

Using the rectangular hockey shafts for the seat, the most challenging and time-consuming part was joining the cross-pieces. I used small mortise and tenon joints made of ash and inserted them from the ends of the shafts and epoxied them in. Alternatively, one could wrap the joint with CF 1" tape and epoxy, but that makes a lump. I drew up a mould for a CF seat, but I haven't made one and probably won't.

The weight saving between a carbon fibre seat and an ash one is only half a pound. I'm about 20 LBS overweight . . .

 

[Jim Dodd]

Great info Peach !

The CF sleeves are pretty spendy. Is it supposed to be that much stronger, or is it more of a cosmetic, ease of use thing ?

I'd like to lean more towards layering tape, over cedar that was epoxied to the hull, for the gunnels.

I need to do some tests !



Jim

 

[Peach Canoe]

Jim, the CF sleeves are perfect for composite gunwales, but they need to be bagged (preferably resin-infused) to achieve good structural numbers and nice aesthetics. Sleeves may be used for grab-handles and thwarts too, but they too should be vacuum bagged.

Charlie Wilson is the man on lightweight, beautiful composite gunwales!

I've not had much success with the heat-shrink sleeves, though it's probably my own finger trouble. One problem is this: when you use the heat gun to shrink the rubber sleeve, hot epoxy runs out the ends-- caution! This can happen too: some parts of the project may start to 'kick' due to the heat, and you'll end up with an uneven surface; if one part kicks too soon, it acts like a dam, and that's that. But with some practice and patience, results improve; I wouldn't write off the technology.

The sleeves aren't any stronger than flat cloth that's appropriately positioned (carbon fibre hockey stick shafts are made from stacked flat cloth wrapped around a mould). Sleeves are convenient for shaft-shaped projects: you can pull the sleeve tight and it snugs down into the contours as you wet it out. Tie or clamp off the ends and it will hold its position.

 

[Alan Gage]

Great stuff, Peach. Much appreciated.

I was surprised the carbon thwarts didn't fare better in the strength department, especially with the balsa core. I did a couple carbon over foam thwarts and thought they compared pretty well to a similar thwart of cherry. It did have a little more flex but I was impressed for what it was. One layer of Soller's 19oz. sleeve and regular 2lb builder's foam (XPS). I've got an extra carbon thwart and a grab handle I don't like the dimensions of. Maybe I'll break them and see how tough they really are compared to some hardwoods.

I've had good luck with the Soller shrink tube on carbon tubes. It left a nice even surface that didn't need any touching up. I've been leery of trying it on thwarts with curves and bulges thinking it might not shrink evenly. My initial attempts at vacuum bagging carbon over foam thwarts were hit and miss. I had a hard time keeping the release film from wrinkling as the bag was sucked down. More practice needed for sure. A few days ago I got some supplies so I can try my hand at infusion. I'm looking forward to placing dry cloth and having more time to fiddle without worrying about the resin going off.

Alan

 

[Steve in Idaho]

Peach - that's some interesting stuff. Thanks for posting it.

My canoe related shop work is delayed. I need to get that seat finished for the Sojourn and to finish repairing a broken paddle. Also intend to get bag cages installed on the Prospector before spring.

But I've run into a sort of snag.......

Beehives. Like I needed another hobby - this one has taken me. It was supposed to be my wife's gig, but I got sucked in. And I am enjoying it. We had only one hive last year, and now we're expanding a little. Currently finishing up on two more hive sets. That means five finger-jointed boxes plus bottoms and covers, and all the comb frames to fill - per hive. Ten frames per box. Al total - ten boxes...100 frames...two bases...two inner and outer covers. This all has to be done before new colonies are delivered this spring. I know it's early yet, but....priorities.....

 

[Robin]

I moved that Old Town factory fiberglassed 15' Trapper into the basement shop and removed the inwales. Tomorrow or Saturday going to rip some more ash and splice it to long lengths.
Got the second coat on the MR Malicite rails and the old seats sanded, varnished, webbed and installed. need to make the decks and waiting for a thwart from Ed's.
Nice working next to that wood stove at 60 plus F

 

[Steve in Idaho]

That Malecite should be an easy sell, Robin. Looking nice!

 

[Robin]

That Malecite should be an easy sell, Robin. Looking nice!

Thanks, I'm hoping to rub the hull down today, thinking I'll start with polishing compound and add a coat of wax, then add a few coats of varnish to the underside of the gunnels/inwales while the canoe is flipped.
I choose varnish over Watco oil for no special reason, but I have found alot of folks who look at my canoes and are not familiar with Watco oil think maintenance is bothersome. (which is incorrect imo, oil is really easy to maintain)

 

[Bob B.]

I agree Robin, I have always preferred oil finish, especially if I get a rub mark from my paddle on the gunnel after a long trip. A little sanding and oil, good to go. Have you ever used Boiled Linseed oil on the gunnels - or just Watco? Varnish looks nice too, but I like oil the best.

Bob.

 

[Robin]

Never tried boiled linseed oil on gunnels, I think I used some on paddle shafts and handles, I used the rest to soak an ax head/handle and have run out of it, so I use the Watco now.
I asked Schuyler Thomson if he ever saw a wood canvas canoe oiled rather than varnished. He has seen a few, and he says they retain alot of dirt and grim but otherwise hold up well with regular applications.

 

[Robin]

Finished cleaning up the hull and varnishing under the gunnels. The hull is in great shape for a 1990, very little wear.

 

[Mihun09]

Sure must be nice to have 2 shops available Robin, I suppose it is a tad chilly for the barn shop or is it just you have more space in the basement?
What's with the full peg board panel on the wall?

 

[Robin]

Ha, Yea I have the wood stove going in the basement for 27 Rhode Island Reds chicks, 3 weeks old, so I moved down there for the rest of the month. It was 3 below this am so it it helps to have 2 wood stoves going in the house. The peg board is a left over when I worked down there before the barn shop.
Very cozy!

 

[Robin]

I finished the Mad River fiberglass Malicite today, another good project to pass the winter away.

A little more sanding around the ends, and some varnish there too, but the big stuff is done.

 

[Canotrouge]

Good work on the boat Robin!! I'm sure it will go fast when spring is here!!

 

[sweeper]

Ya but not 'Red Fast'.

 

[Alan Gage]

Man, you're not wasting any time Robin. Good looking stuff.

Alan