Light weight Canoe

Redbird Bernie · Post by **Redbird Bernie** » Sun Oct 17, 2010 5:26 pm

Hi everybody, it has been a while since I've been on this forum.

I built a Redbird some 3 years ago but don't use it much because of size and weight. It is a little too heavy for me to handle alone, due to a bad back, and when my wife helps me she struggles to lift it onto the car top. What I'd like to build is a shorter ultra light canoe that is not tippy and can carry 2 people or be used solo. Our combined weight is under 300 pounds and the canoe would be used for short day trips in clear water.

A 25% reduction in weight can be achieved using 1/8 inch thick strips instead of 1/4 inch. Further reductions can be had by switching to balsa or other light wood, 4 ounce cloth, laminated scuppered gunwales, canvas seats etc. But, will this make a safe and durable canoe?

Composite airplanes are made of a dense foam covered over by criss cross layers of cloth and epoxy. According to my research wood is the only way to go because foam is not flexible enough for use on canoes. Is this really true?

Glen Smith · Post by **Glen Smith** » Sun Oct 17, 2010 5:42 pm

What is your target weight and length?

Redbird Bernie · Post by **Redbird Bernie** » Sun Oct 17, 2010 7:04 pm

Hi Glen, hearing from you is like meeting an old friend. Your suggestions and postings helped me a lot when building my Redbird.

My primary consideration is to minimize weight which should certainly be under 40 pounds if I am going solo. Length is secondary around 13 feet or less as long as it is not unstable or tipsy with 2 people.

Moonman · Post by **Moonman** » Sun Oct 17, 2010 9:38 pm

Bernie - take a look at this link:

http://www.smallboatforum.com/PDFfiles/ ... Canoes.pdf

you can also lose a lot of weight by cutting down on trim thickness.

moonman.

Rick · Post by **Rick** » Mon Oct 18, 2010 8:32 am

Redbird,

...under 40 pounds if I am going solo. Length is secondary around 13 feet or less as long as it is not unstable or tipsy with 2 people.

A 13' tandem canoe will most likely be a poor choice especially with two paddlers... it may float two, but it will be unsafe in waves and performance will feel like a submerged log.

In cedarstrip, you could go with the 15' Bob's, a traditional choice for good solo performance together with enough tandem capacity. I don't know whether you could keep the weight under 40 pounds.

If you have a bad back, there are light tandems being made now that could make things much easier... for instance, Swift's Algonquin 15' weighs as little as 34 pounds. Being designed by David Yost, paddling should be a pleasure, solo or tandem - getting it on and off the vehicle won't be a problem.

http://www.swiftcanoe.com/canoe/classic/algonquin15.htm

Redbird Bernie · Post by **Redbird Bernie** » Mon Oct 18, 2010 11:42 am

Moonman, I appreciate the link. Don Wilkinson’s experience with 1/8 inch thick strips and 4 ounce cloth seems to indicate that it can be done safely. His sliding bow seat design is interesting too.

I wish I could easily calculate the portion of a boat’s weight that is due to planking. If I knew the area of the planking on my Redbird, I could then estimate the amount of weight reduction from using 1/8 inch strips instead of ¼ inch. My assumption is that it would not be more than 25%. If that is the case, then a 60 lb Redbird with 6 oz cloth would end up weighing 45 lbs. But will the thickness reduction significantly affect the structural integrity and durability of the hull?

I found this link on building with Balsa wood. I was not aware that epoxy has a tendency to delaminate on Balsa.
http://www.storerboatplans.com/Balsacan ... canoe.html

Rick, thanks for your input. I believe that the Bob’s Special weighs around 45 to 50 lbs. It is on my list if I can figure out a way to get the weight down. As far as manufactured boats are concerned, the light ones are pricy and no where near as pretty as strippers. Beside, it is more fun to build then to buy.

Glen Smith · Post by **Glen Smith** » Mon Oct 18, 2010 1:37 pm

I built a 12 foot canoe using 3/16" strips and a single layer of 4 ounce cloth inside and out. It tips the scale at 29 pounds so you can definitely build something to meet your needs.

vann evans · Post by **vann evans** » Mon Oct 18, 2010 6:40 pm

for what it's worth---
I built a 15' Freedom. I weighed it a couple of times during the build. The complete hull (strips only-no glass or epoxy or trim) only weighed half of the finished total. the fiberglass/epoxy and all wood trim equaled the weight of the hull.

I have also considered building a tandem lightweight. I agree with the earlier post about minimum length around 14'6" or 15'. I think using the 1/8" strips, lighter trim and 4 oz cloth would save about 35% of the weight. 40 pounds is a good goal, but I bet 45 is closer to reality.
Keep us informed as to what you do.

Vann Evans

willo · Post by **willo** » Mon Oct 18, 2010 8:00 pm

To cut down on weight I think that you need to think outside the box. Trim adds a lot of weight to the total. If you use lighter woods there , a lot of weight can be cut. 3/16 " strips are as thin as I would be comfortable with cedar strips. My present build is with 3/16 " strips - and 6oz. cloth , I am using no hard wood except for seats and thwart. I am predicting a weight in the mid thirties. I really don't believe you need to sacrifice over all hull strength to get a 15 footer under 40 #.One of these days I will get back at it and will know for sure. I have already built one Ranger at 40# so getting this one under should be easy.

Snowman · Post by **Snowman** » Mon Oct 18, 2010 9:37 pm

Have a look at this article - http://www.paddlinglight.com/articles/l ... -tripping/

I can probably give some marginally useful information of how to wind up with a heavy canoe (my self design build came out at 63 lbs). You can deduce some steps of how to get a lighter canoe :smile

I am sure that Bryan Hansel can provide some excellent insight.

I too dream about my next build as a lightweight.

Keep us informed of how you make out.

Moonman · Post by **Moonman** » Tue Oct 19, 2010 9:54 pm

Hi Bernie,

There are a lot of ways to reduce weight and a determined search on the various forums will help with pointers. If you want to get to 40 pounds, I think you can do it but you'll really have to watch the weight on every step. Also, plan and calculate likely weights of various components of various woods/epoxy use etc. If you email Steve Killing, I'm sure he would give you the skin square footage of the Bob's (or whatever Bear Mtn. boat you want to build). With that info you can fairly accurately predict weight gain/loss depending on strip thickness. Western Red Cedar is about 22-23lbs per cubic foot. You can use lighter wood for rails and trim - butternut is really nice, great grain etc but much lighter than its cousin walnut. Spruce (sitka is best) and pine is also good. jay Morrison built his 35lb Bob's with cedar rails. You can use cherry and shave down the dimensions. Calculate everything. John winters has an article on the Green Valley Boats site re. calculating boat weight (dealing with fiberglass and epoxy). If you are using 1/8inch strips you don't have much room for sanding or miss aligned strips. You could try 3'16" thick on the bottom and 1/8" between the bilge and shear. Everything is a trade off in terms of weight versus strength, but if you already have the Red Bird, you can go as light as you can and baby the boat. If it breaks, fix it or build another! :eyebrows

moonman.

Redbird Bernie · Post by **Redbird Bernie** » Wed Oct 20, 2010 11:39 am

Hey guys,

Glen is your 12 footer your own design? How stable is it in the water? It looks great for kids but a bit light and tight for two adults.

Snowman, I too had found the article by Jay Morrison and hope to study it more when time permits.

Don Wilkinson ( http://www.smallboatforum.com/PDFfiles/ ... Canoes.pdf ) writes about his experience building an 18’5” canoe that came in at 45 lbs using 1/8” strips and 4 oz cloth.

I also found quite a bit of information on NorthwestCanoe.com for estimating skin area and boat weight. I am ashamed to say that I never looked at a canoe skin as a number of adjacent trapezoids. Here is an excerpt from that site:
“Use a flexible dressmakers tape to measure the working edge of each building form. Add the length of two adjacent forms, divide by two and multiply by the station spacing. You just calculated the area of a trapezoid. Now, divide by 1296 (square inches per square yard) and add the square yardage together to calculate the total surface area of your canoe.
Fiberglass absorbs one ounce of resin by weight; hence, it takes six-ounces of epoxy to wet out one square yard of six-ounce fiberglass. So for example: eight square yards of surface area will require 48 ounces of catalyzed epoxy to wet out the fiberglass. Naked cedar drinks up three-ounces of epoxy per square yard. That brings your estimate to 72-ounces. In addition, plan eight-ounces of thickened epoxy to fill minor voids (give or take – depends on how tight your hull is and whether you build with or without staples).
If you come up short, look at the floor. If the floor is clean, look for shinny areas, fiberglass floating on top of pooled up epoxy. Find and relocate the excess epoxy rather than catalyzing another batch and going for the heavyweight championship.”

I am looking forward to doing some arithmetic to see if this falls in line with Vann’s observation that ½ the weight is in the strips.

Glen Smith · Post by **Glen Smith** » Wed Oct 20, 2010 12:23 pm

Hi Bernie, yes it is my own design but highly influenced by the Chemaunis from Carrying Place Canoes. It is a great little canoe which I use either solo or with my daughters.
If you insist on high initial stability, you might want to go with something a bit wider.

I think the Bob's built at 14' using 3/16" cedar, careful selection of trim materials and dimensions and 4 ounce cloth would produce a highly satisfying and lightweight canoe for your requirements.

PS: Where are you located in Illinois?

Redbird Bernie · Post by **Redbird Bernie** » Wed Oct 20, 2010 1:17 pm

Hi Glen, your 12 footer is gorgeous. The double diamond detail is a particularly nice choice and adds class to the design. It seems like shorter hulls look better with slightly more busy detail.

As it turns out I've been thinking about the Bob's all along. In fact I already have the forms ready to plot on AutoCad. Hadn't though about reducing it to 14 feet. Good idea!

I live in a northwest suburb of Chicago north of O'Hare airport.

Glen Smith · Post by **Glen Smith** » Wed Oct 20, 2010 1:42 pm

Actually, I copied the accent strip off John Caldeira, it was too hard to resist.

I have a friend who lives in Peoria, drove down to see him last year for the first time in 42 years!!!

Hadn't though about reducing it to 14 feet. Good idea!

Go for it!