How light could it be?

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Canoe_builder
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How light could it be?

Post by Canoe_builder » Wed May 29, 2013 11:08 am

I'd like to build the 16' 6" redbird, with emphasis on saving weight during the build.

What range could I reasonably expect the finished weight to be? And what would be the best techniques to do it??

Thanks!

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Patricks Dad
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Re: How light could it be?

Post by Patricks Dad » Wed May 29, 2013 1:27 pm

I won't predict your final weight but here are a few things you can do to reduce weight.

Your note references building the Redbird 16' 6". Did you mean 16' or 17' (the design is for 17' 6")?
You could shrink the design a bit but a whole foot is quite a bit. Shortening it by 6" will save some weight.
Use thinner strips (3/16") and find the lightest weight planks you can to cut your strips.
Use cedar for inner stems (if you aren't planning that already
Use lighter weight glass (4 oz instead of 6 oz)
Use a single piece of wood for the gunwales (or use much thinner inwale and outwales). Or build your gunwales out of carbon fiber.
Use tiny decks.
Don't add brass stem bands, just add 2 extra layers of glass over the outer stems.
Build your seat frames thinner and out of laminations with a layer of glass on the underside (and perhaps between the lowest 2 laminations).
Scrimp on the varnish (1 less coat).

All of the above will help reduce weight but at a cost. Some of them will cause you to worry if you built it strong enough for it's intended purpose or you will find yourself NOT taking it to places you otherwise might take it because you are worried about it. In particular, I would caution against using 4 oz glass unless you truly only plan to use it on relatively calm waters and don't foresee hitting rocks. Scrimping on varnish will only cause you to refinish more frequently (eventually adding the weight anyway). Depending on how much you weight (or any paddling partners you intend to have along), the thinner seats may or may not be a good idea (although the lamination approach can make a very strong structure).

All that said, the Redbird is one of the most beautiful crafts on the water. My advice is build it "right" so you and your descendants are proud of it. The first canoe my son and I built was the Redbird. It weighed in at 57 pounds (and with the exception of not adding brass stem bands an building it 6" shorter, we used NONE of the above ideas). It's gorgeous.

Below is a table showing the weight of the various elements of our Redbird. From this, you can make some good guesses as to how much weight you could save (but certainly less than 50 pounds)

Image
Randy Pfeifer
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HuffDaddy
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Re: How light could it be?

Post by HuffDaddy » Wed May 29, 2013 1:56 pm

I am building a solo 17 and trying to go as light as possible and have done some research on this. You can go thinner on your cedar strips. I've read of going as thin as 1/8 inch. You could use balsa wood which is 1/2 the density of cedar. The wood you use for all your trim can be lighter species than Ash or Oak. You can go lighter weight fiberglass cloth - 4 oz in and out and/or use S-glass for more strength. I've read of people using 2.5 oz glass. Vacuum bagging is supposed to save weight on the epoxy by minimizing the amount of epoxy used. You can cut weight on the gunnels and use only an inwale like is done with C1 race boats. Of course then you have the issue of mounting your seat. Sitka spruce for gunnels is a good choice. You can use hollow wood tubes instead of solid wood for thwarts (maybe use bamboo). Deck's are optional too or can be small. You can use cedar or balsa for stems and just use inner stems. Gil Gilpatrick's method does not use stems at all. A more rounded boat design with a thinner beam will be more structurally sound so the limits can be pushed a bit more with your other materials. Wood kayaks routinely use 3 oz glass outside only. A longer boat requires more material. If your really want to go light you can even get rid of the wood and use carbon fiber...Remeber all canoes are compromise and there are trade offs you get by pushing the limits. I think 35-45 pounds should be a reasonable and achievable goal for a 16'6" Redbird cedar strip canoe with usable durability.

Here is an article by John Winters on estimating the weight of a finished cedar strip canoe. http://www.greenval.com/weight.html

Jay Morrison (who I think is a member of this builder's forum) has a good website paddlinglight.com. Here is a great article from him. http://www.paddlinglight.com/articles/l ... -tripping/

And here is an article about a 12 pound Wee Lassie canoe built in Austrailia from balsa wood with all the limits pushed. http://www.storerboatplans.com/Balsacan ... canoe.html

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Patricks Dad
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Re: How light could it be?

Post by Patricks Dad » Wed May 29, 2013 4:35 pm

One minor comment. The Jim Morrison article referenced is on Bryan Hensel's website (Paddlinglight.com).
Randy Pfeifer
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Canoe_builder
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Re: How light could it be?

Post by Canoe_builder » Wed May 29, 2013 5:15 pm

Thanks for the useful replies!

I mistakingly wrote the length of the canoe.... I plan to build the redbird, at 17' 6", according to plans.
I'm looking for a fast/easy paddling canoe, that can hold a moderate amount of gear, and still be relatively stable in the water. So far the Redbird seems to fit the bill pretty well, but would be open to suggestions to other models as well. Preferably a Bear mountain design since they are a local business that I would like to give business to...

Ideally I'd like to build it as light as possible. It will just be used for flat water paddling, mostly in Algonquin park, so it doesn't have to be super tough, but it could still encounter some rocks, or submerged logs from time to time. I'm comfortable sacrificing some strength to lessen overall weight. I want something that will be possible, preferably comfortable to portage for long distances with a well loaded pack on my back.

If I could get close to 40 lbs I'd be super happy....but maybe that's not realistic. Hoping it is though!

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Jim Dodd
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Re: How light could it be?

Post by Jim Dodd » Wed May 29, 2013 6:57 pm

Vacuum bagging would save a lot of resin.

If I really wanted to save weight without sacrificing durability, that would be my course of action.

Jim
Last edited by Jim Dodd on Thu May 30, 2013 5:12 pm, edited 1 time in total.
Keep your paddle wet and your seat dry!

HuffDaddy
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Re: How light could it be?

Post by HuffDaddy » Thu May 30, 2013 11:06 am

Sorry for giving the credit to Jim Morrison instead of Bryan Hensel for the website. Thanks for correcting that. It's a great website.

If you are not committed to the RedBird but are looking for a good Tripper, you are opening another can of worms... I have never paddled the RedBird. I have the Freedom 17 and love it. It's fast and will handle my wife and I and a weeks worth of gear. Between the 2 of us, we are 300 pounds and pack light. Look on the plans at displacement and weight to immerse. Try to estimate your total load. An overloaded boat can get you into trouble, so I think try to stay close to the displacement weight of the design for your total load.

Another great canoe is the Kipawa designed by John Winters. It's fast and quite and a real pleasure to paddle. My dad built one. I'm sure Bear Mountain Boats will still sell you a kit for it so you can keep the business local - the kit and amount of lumber will be similar no matter what boat you build. I think most of the cost of the plans goes to the copy right holder anyway...

Good luck. Post some Pics when you get it done. I'd be interested to hear your modifications and final weight too.

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Patricks Dad
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Re: How light could it be?

Post by Patricks Dad » Thu May 30, 2013 1:14 pm

The Redbird feels a bit tender when you first start paddling it but you get used to it quickly. It's actually more stable with more weight in it (as you might expect).

The Freedom 17 is also a popular design and is a bit more stable than the Redbird. It's somewhat easier to build than the Redbird but in my opinion doesn't look nearly as nice.
Randy Pfeifer
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HuffDaddy
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Re: How light could it be?

Post by HuffDaddy » Thu Jul 18, 2013 6:17 pm

Here is a link to an article by John Winter's titled, "What will my boat weigh." Do the math to estimate the weight of your project. It's a good read as you can see where the weight comes from.

http://www.greenval.com/weight.html

AlanWS
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Re: How light could it be?

Post by AlanWS » Thu Aug 08, 2013 1:20 pm

One of the most effective ways to minimize weight without sacrifice of strength is to wetout the glass with epoxy, then to cover the wet surface with a plastic film and roll it smooth. After cure, the film is peeled off leaving a smooth surface that needs no fill-in coats. It can be sanded with 360 grit and varnished.

This trick was developed by a guy who called himself Dr. Dichroic. It works particularly well on stitch and glue boats where compound curves don't complicate fitting film to surface. I have used it only in limited areas of woodstrip canoes for applying reinforcing or patches for repair, since the compound curves don't matter for smaller regions.

Other ways to diminish weight include use of spruce or cedar for gunwales, thwarts, and seats, rather than hardwood. I've not seen it done, but these could be made similarly to the hull: hollow, light wood encased with glass. In normal use, the glass under tension would be hidden on the bottom of the seats, so it could be applied only there. Scuppered gunwales provide much more stiffness for the amount of material used, so you can use fewer thwarts. It's probably lighter to epoxy on the gunwales rather than to use screws, but I have not done that.

Rather than hanging seats from gunwales, these can be mounted to blocks epoxied to the hull. This can be lighter, and it allows seats to play the role of thwarts to stiffen the hull. But of course once it's done, adjusting seat height is difficult.

The deck is not really needed, but I would make a lightweight one rather than leave it out.

The more UV protection in your varnish, the thinner the varnish that will protect epoxy from degradation, so use good varnish. System Three WR-LPU is what I've used. I vaguely recall deciding it would provide the same protection in a thinner layer, but I don't know if that's correct.
Alan

Rabbit
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Re: How light could it be?

Post by Rabbit » Fri Aug 09, 2013 6:39 am

one thing i discovered is that you cant rely on things like timber density charts and the like. i just weighed my glassed hull. its a 15ft bob's. i worked out that the hull glassed with no trim except the stems should weigh in at 10kg... it was 14kg. while there was some western red cedar, the hull was primarily paulownia. it's quite a bit lighter than wrc, looks like balsa but stronger and slightly heavier. i used 4oz glass inside and out, with 3 coats epoxy outside and 2 inside. the only weighty bits were the stems which at the time didn't feel all that heavy ... tassie oak for the inner stems is not very heavy, and the spotted gum/marbou are both dense timbers but again didn't feel heavy on their own at the time. i guess at the end of the day it's going to weigh what it weighs. :crying

alick burt
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Re: How light could it be?

Post by alick burt » Wed Aug 14, 2013 12:18 pm

Hi Folks
Just a little point about my experience with the weight of my boats.I made my first Peterborough five or so years ago and never weighed it until a few weeks ago.I use it regularly and often carry it around locks using the yoke.(My record in a day is 14 hrs paddling and seven locks)
I made my seventh Peterborough to the exact same spec and finished it about three weeks ago.I would say the seventh boat looked a lot better in that everything is new and my work particularly with epoxy has improved a great deal with practice.
I was thinking they would be different weights but....
I weighed both boats using bathroom scales balancing them in the middle on a pair of battens and both weighed exactly 35 kilos!
Cheers
Alick :wink

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