Estimate of amount of epoxy

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hughhallhh56
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Estimate of amount of epoxy

Post by hughhallhh56 »

It was a good weekend. Made the trip to Vancouver to get some cedar. Yes I now live in the center of wrc territory bur couldn't find anywhere to buy it so I went to sunbury cedar. It is the candy store of cedar. I picked up 7 5/4 x 4 clear vertical grain boards. Beautiful stuff.

Anyway now I'll finally be ready to start in earnest. This then leads to fiberglassing so to get ahead of the curve I bought some west system 105 / 207 epoxy. I really am not sure how much I will need. I am building the rob roy and using 6 oz cloth. Would anyone have an idea of what I should expect?

Hugh
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Cruiser
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Re: Estimate of amount of epoxy

Post by Cruiser »

Hi Hugh,

Probably the easiest guide is to look at a store like Noah's Marine which offers "Canoe Kits" with the fiberglass/epoxy/rollers/dispensers etc., just look at the kit quantities for amounts and things you need. Although, in the end the kits are likely the most cost effective way to buy.

On another vein, I believe I saw a previous post that said you are building a pair of Rob Roys and that less weight was one of the goals. On a boat that small, you could likely be quite successful using 4 oz. cloth, instead of 6 oz., and that would save a lot of weight. Less cloth weight, less epoxy weight, just a thought.



Brian
Rick in Pender Harbour
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Re: Estimate of amount of epoxy

Post by Rick in Pender Harbour »

Absolutely go with the 4 Oz cloth if you can get it, it will use less epoxy and that means less weight, and is strong enough for this purpose. I'm just finishing a pair of wee lassie II's with 4 oz cloth; maple trim. Not really trying to be super light, but will certainly come in under 40 lbs, hope for 35. I will weight them and attach pictures in a few days.

Rgds

Rick

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Re: Estimate of amount of epoxy

Post by Cruiser »

Not to highjack this thread, but on the weight topic, you may want to consider Uni Wales, I did that on my Solo Freedom, plenty strong and saved a lot of weight.

I think I used 3/4" cherry and just built out a bit for attaching the thwarts and seats .... a lot easier to install if you think it through as well, a bit of extra planning, but I will use it it again, if I make a another solo boat.


Brian
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Jim Dodd
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Re: Estimate of amount of epoxy

Post by Jim Dodd »

Hi Hugh

I'm wondering about your choice of grain, in your lumber ?

If your planks, are 5/4 x 4", VERTICAL grain. When you cut your strips, they will end up HORIZONAL grain. They look neat, but they are weak, and prone to splitting. On top of that they sand uneven, and hard to bead and cove evenly.

I will try and post a pic tomorrow, that might help explain this. I have strips in my rafters cut like this, from years ago. that I never used.

When you look at the end of the plank laying flat, the grain should run left to right, or horizontal. That in my experience gives you the strongest and easiest to machine strips. If you plan to make it light by using 4oz cloth, you will need the strength in your strips.

Jim
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Jim Dodd
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Re: Estimate of amount of epoxy

Post by Jim Dodd »

Hugh

This is what I look for, as far as grain orientation in the planks I buy for strips. The magic marker is used just for illustration.
Hope this helps ! JimImage
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Re: Estimate of amount of epoxy

Post by Cruiser »

The grain orientation is important for all the reasons Jim has laid out, but since you have already made the trip and bought the wood, it is not the end of the world if any of the boards are not the correct orientation.

There are a few threads on here that give some details for how to get around the fairing and shaping issues, it is a bit more work ... but in the context of all the time you will invest, it is not major. If you do have some, make sure to work their patterns into your book matching scheme.

As far as the strength goes, my understanding is that the wood core is not a major source of hull strength and it is largely a space holder for the epoxy/fiberglass layers, which do provide the majority of the strength.


Brian
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Jim Dodd
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Re: Estimate of amount of epoxy

Post by Jim Dodd »

I have a Kevlar canoe, built without wood. It was terribly flimsy. I ended up laminating a 1/4" foam core. It helped big time, but still not as good as a 1/4" wood core.
Wood core IS a major source of strength in a cedar strip canoe! As well as durability !

Another example, as to the importance of a good wood core. One of my best friends who built the MCA's Osprey, a tandem. Sanded the wood hull too thin. It cracked down the middle while we were in the BWCA. It ruined his trip, but taught him a valuable lesson !

Jim
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Patricks Dad
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Re: Estimate of amount of epoxy

Post by Patricks Dad »

If you have vertical grain planks, you can still cut vertical grain strips. It's a bit harder than simply slicing 1/4" strips off a flat grain plank. Just cut pieces off the planks the width of the desired strip width (note: this can be any or varying width). Then rip those pieces to 1/4" thick (or a bit proud of that and plane to thickness). Depending on your plank thickness this may or may not be an optimal use of material...

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hughhallhh56
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Re: Estimate of amount of epoxy

Post by hughhallhh56 »

Cruiser,

Thanks for the idea of looking at Noah's.

Hugh
hughhallhh56
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Re: Estimate of amount of epoxy

Post by hughhallhh56 »

On grain direction.

I went with the VG for two reasons.

1. Thirty years ago when building my first, I built it with VG planks. Lack of knowledge for sure - it was about getting it built. I had 3 months to build it and only a set of diagrams to work from. Canoe is banged up, but still solid.

2. Wood was cheap, straight, clear.

So, I will experiment. That is my style. I got lots of boards so I'll likely rip some to make face grain, and the other edge grain. Build one canoe with each. I'll use a hardwood sanding plank for the face grain to see if I can get the fair curves. This time it is not about getting it built, but rather building it.

thanks for the input.
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Re: Estimate of amount of epoxy

Post by Cruiser »

I was very careful on the wording of the strength paragraph, I didn't say wood wasn't important or that it did not contribute significantly. I will stand by the statement that the wood form does not contribute the majority of the strength to the finished canoe hull ... that honour goes to the composite formed by both the wood and glass panels melded together as a composite structure.

If you don't have the thickness (i.e. sanding too thin) you are already compromising the whole composite and for discussion purposes, that takes us into the weeds. As far whether the strips are quarter or flat sawn, I doubt there would be any significant difference in strength, for the final composite product.

Having said that, i do select to stay away from flat sawn strips, I have enough issues just getting stuff faired nicely and I don't need to complicate my task. My friend just completed a boat with about half the strips being flat sawn, looks pretty cool as an accent, but I find it gets a bit busy when a whole boat is that way ... I guess it comes down to beauty being a very individual thing.


Brian
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Jim Dodd
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Re: Estimate of amount of epoxy

Post by Jim Dodd »

I apologize if I'm sounding, like a Know it all. I realize every builder has his set of goals when building a craft. Beauty is certainly one of them. I have viewed some knock out canoes and kayaks here. ! Having said that, I think I'll go back to Hugh's original question.

The hull on the Rob Roy should be able to be done with 1 1/2gal or less of resin. If a large deck is in the works, another 1/2 gallon, give or take.
Personally I like to have plenty of epoxy left over, for those just in case things. And since mix ratios are generally 2-1, resin - hardener. I end up buying a 3 gallon kit.
Stored properly, the left overs are good for several years. It's also an incentive to build again !

Good Luck ! And Keep us up to date on your build ! :tu

Jim
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Re: Estimate of amount of epoxy

Post by Cruiser »

Hi Hugh,

Not sure where you hail from, but if you talk with Noah's, you will find they will likely recommend East epoxy. It's what I started with and I really like it, and it is quite a bit cheaper here in Canada ... not so sure what happens when it crosses the border though.

Not a plug for East, just letting you know that it's a good product as well a lot of others mentioned on the forums.

And I think Jim's numbers are pretty much spot on, the canoe kit is 2 gallons ... and that should leave you with leftovers for other stuff. I can't believe I never used epoxy before my first canoe and now it is usually my go to adhesive for anything critical.

Brian
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