Light but Strong – Building Cedar Strip Canoes for Wilderness Tripping

Before describing how I built a tripping-tough cedar strip Osprey at 35lbs, let’s first put my biases and assumptions on the table in plain view so you can decide whether you want to share them or not. In my observation, there tends to be two distinct types of people who build wooden canoes – paddlers and woodworkers. I enjoy the building process very much because I like the challenge of solving problems and figuring out new methods and because I prefer the look and feel of a wooden boat but my woodworking knowledge is very basic. Stone-age is more like it. The last thing I had built before canoes was a birdhouse in grade six! I took a strip-building course. What I discovered was that the woodworking was actually the easy part (errors can usually be easily redone or fixed) but that laminating the fiberglass to the hull with epoxy is stressful and that mistakes could be near catastrophic. I still feel that way. Fortunately, I had inherited my grandfather’s hand tools and maybe a few of his skills. Hopefully my attention span is longer than his was as Gramps was missing several fingertips by the time his woodworking career was over.

The point is that I am a paddler, not a woodworker. This means that the techniques I use are well within your capabilities no matter what your experience. This also means that in choosing building materials and methods I have been willing to sacrifice appearance for lower weight, better function and efficiency on the trail. Maybe you are not. Oh yes, I get a lot of compliments on my boats and take pride in doing precise work but use of interesting hardwoods (heavy) for visual effects is not in my boat building vocabulary. However, as I learn more about wood I am interested in finding ways of enhancing appearance without sacrificing weight.

I do a lot of whitewater group trips in Royalex boats but my preference is for exploring remote lakes and streams in Canadian Shield country either solo or just my wife and I. Although we travel extremely lightly, the necessity of doing numerous long portages and having limited time means that the weight of the canoe has to be reduced to an absolute minimum while still being reliable where help is very far away. Even while carrying a small pack in addition to the canoe, my load is sometimes less than hers at the beginning of a trip. Which is probably fair because she is as strong as I am or maybe it’s just that she complains less. Anyway, our experience is that light weight gear and canoes enable us to travel long and far over rough terrain and still be comfortable and enjoy ourselves but it also means that you need skills and you need to be careful. If this approach does not sound crazy to you (and to some it does) read on.

I built and have paddled for a total of eight seasons two boats that I would consider light enough for portaging comfortably with gear over long distances, i.e., 2000-5000 meters. They are: a 15′ Bob’s Special tandem at 38lbs and a solo Osprey, also 15′ at 35lbs. The Osprey is considerably tougher than the Bob’s Special although, unlike the Bob’s, it is made of three sixteenths inch strips instead of the standard one quarter inch. A couple of times we have pinned the Bob’s in a bouldery class I rapid – hey, stuff happens! The glass was cracked and delaminated at the point of contact with the rock but the wood was undamaged – nothing a few strips of duct tape couldn’t seal until we got home. The Osprey, being six inches narrower and with a rounder bottom, is an inherently stronger and stiffer shape. Nevertheless, I decided that the Osprey needed to be made more strongly than the Bob’s. And, oh yeah, I put on 25 personal pounds since I built the Bob’s after taking an, umm, extended time out from distance running. Also, 3/4″ x 2″ western red cedar (WRC) seat frame for the wider span of the Bob’s bow seat became inadequate. Don’t ask how I know this.

The basic philosophy I took to building these boats was to look for every possible source of weight saving. “Take care of the ounces and the pounds will take care of themselves”, is my motto. I was confident in questioning traditional building methods and materials from the point of view of years of wilderness tripping experience. And if I built too light and it broke, it would be a good excuse for building another one. Oh, and no I was not interested in going the “Wee Lassie” route. I very much respect the late nineteenth century lightweight tripping approach of Nessmuk and his ten and a half pound Sairy Gamp built by Henry Rushton for tripping in the Adirondacks but Nessmuk was a very small man and we need boats that will handle food and gear for a couple of weeks on big, cold lakes with three foot whitecaps.

I find that the canoe weights quoted by most designers and sellers of plans tend to be a little bit optimistic if they assume using standard methods and materials, i.e., one quarter inch WRC strips, ash stems and trim and 6oz fiberglass inside and out. Using the standard techniques, I calculate that the Bob’s would have come out at about 55lbs and the Osprey would have been about 50lbs plus a removable yoke which I avoided having to mess around with by integrating a small sculpted yoke into the front cross piece of the seat frame. A saving of 15-20lb of canoe weight is very significant on long tough portages.

Here are the basic specs for materials of the two canoes. Then there are some details on where the methods or materials depart from the standard approaches.

The Light and Strong Cedar Canoes

Bob’s Special

Hull – one quarter inch western red cedar strips, heavily sanded, no stems (Gil Gilpatrick method); glue – Lee Valley gap filling; decks – WRC; gunwales – WRC, one piece three quarter inch x 1 inch with routed centre groove, epoxied, no screws; seats – WRC frames with hand woven plastic cane, epoxied to hull with cleats, no hardware; yoke – sculpted cherry, epoxied, dowelled and screwed to gunwale; fiberglass – three and one quarter ounce per square yard open weave satin fiberglass, one layer inside and outside; epoxy – West System with 207 hardener, one “B” kit; varnish – one liter spar varnish.

Osprey

Hull – three sixteenths inch WRC strips lightly sanded, WRC inner stems, no outer stems; decks – WRC; gunwales – WRC, one piece three quarter inch x seven eighths inch”, epoxied, no screws; seat – ash frame with hand woven plastic cane, sculpted yoke forms front cross piece of seat, epoxied to hull with cleats, no hardware; thwarts – two, WRC epoxied and screwed to gunwales; glass – three and one quarter oz tight weave satin glass inside and out, an extra layers on outside football; epoxy – West System with 207 hardener, one “B” kit; varnish – one liter spar varnish.

Light and Strong Methods for Cedar Strips

Hull

Some folks like to say that most all of the strength of the modern wood strip method is in the glass and epoxy. This isn’t strictly true; the hull is technically a wood/glass composite with both materials working together. Going too light with either is going to cause problems depending on the weight of the paddlers and how the boat is going to be used. Remember, there is light, there is ultra-light and there is stupid-light. If it doesn’t get you home it was too light.

I weigh about 175lbs. The hull of the Osprey is quite adequate for me because I take care to get into and out of the boat without over-stressing the hull which, when done improperly when the boat is grounded, is much more likely to seriously damage a light boat whether made of wood or Kevlar than bumping a few rocks. The three sixteenths inch strips and an extra layer of three and one quarter ounce glass over the outside football and one layer inside works well for me. If you weigh under 150lbs, you could get away without the extra layer on the outside football but this would save only about a pound and a half or so. If you weigh over 175lbs, you ought to add an extra layer of glass to the inside football as well and if you weigh substantially over 225lbs and like to stand on one foot in your canoe you should stick with the standard one quarter inch strips and 6 oz glass or take swimming lessons and invest in a good pair of hiking boots because one day you will end up walking, not paddling out of the bush. Fortunately, you large folks can still build a 40lb Osprey since much of the savings in my method comes from the gunwales and trim.

A word on stems: To save weight and get a very fine entry line, I used the stem-less construction method on the Bob’s. This requires rather painstaking joining of the strips at the stems. It also resulted in the stem moulds being extremely difficult to remove on completion of the hull. I do believe Gil Gilpatrick when he says that the stem-less ends of his boats are adequately strong for real tripping and I like the clean look of the boat with no stem sticking up inside. However, the extra work involved in this method is not worth the weight saving, in my opinion. While it might be worth doing if using standard ash inner and outer stems, probably about two pounds worth, the alternative, which was employed on the Osprey is to use WRC for inner stems and forego the outer. By the time the cedar stems are shaped to accept the strips and then tapered on the inside of the hull, the pair weigh about 8oz. What I do strongly object to, from a tripper’s point of view, is the standard practice of planning the hull to accept an outer stem, weakening the hull in a critical area by thinning the contact between inner stem and hull. Instead of an exterior stem to take tripping abuse, I created thin skid plates of cedar-dust thickened epoxy applied to the hull and then sanded fair. If necessary, they are easy to repair or replace.

Gunwales

As I see it, heavy, over-built wood gunwales on wooden boats are a holdover from the days before Royalex hulls and vinyl gunwales when canvas/cedar rib and plank canoes were the only boats available for serious whitewater as well as flat water tripping. These boats had to be strong enough to provide at least a faint hope of it remaining in paddlable condition after a mild wrap. This type of gunwale on a strip canoe is based more on tradition rather than function. I own a forty-five year old Canadian Canoe Company cedar rib and plank canoe and I like the way it looks and paddles. It’s just a tad heavier than I care to carry over the 5305 meter Dickson-Bonfield portage in Algonquin Park. If you prefer traditional looking gunwales, fine, but they are not needed for the requirements of flat-water tripping.

However, you might be a member of the wooden boat school that paddles serious whitewater. You may build your hulls extra tough with spruce on the bottom and lots of 6 oz glass and then a generous coat of graphite-thickened epoxy for strength and slipperiness. Stronger gunwales would then also be in order. Aside from the fact that your 16′ tandem stripper now weighs about 70lbs, for serious whitewater tripping, I prefer to go Royalex because if you like to push the envelope, sooner or later bad stuff will happen to your boat. It happens to me quite frequently. Royalex and vinyl can survive horrendous wraps and live to float you home. Wood will not. Period. So let’s assume that you are going to be using your stripper for flat water tripping with just the occasional swift or class I that you couldn’t possibly end up in a wrap. Right!

When considering building the Bob’s, I had not heard of anyone make gunwales out of one piece of cedar but figured it would be worth a shot since the pair would weigh about 3lbs and could be simply epoxied on to the hull instead of using a couple of pounds worth of screws to attach four pieces of ash weighing at least 8 or 9 lbs. I cut a groove about five sixteenths inch wide and a half inch deep in the centre of the three quarter x one inch gunwale and glued it over the hull using thickened epoxy. I then injected epoxy into any gap between gunwale and hull. This results in a completely sealed gunwale, eliminating a common source of rot. Another benefit of the method, in addition to avoiding the agony of installing all those screws, was that the more flexible cedar gunwales could be held in place without a million clamps, using masking tape only. This was enabled in part because I had removed an inch of shear from the stems when starting to strip to reduce windage since we are quite light and don’t need the extra freeboard. A design with more extreme shear such as a prospector would need clamps or weight applied until the epoxy sets.

Obviously there are drawbacks to this gunwale method that, depending on your tripping style, may offset the up to 7 or 8lb weight saving. If you are the sort of paddling barbarian who enjoys rolling your canoe over on rocks, the soft cedar gunwales will soon get quite dented and gouged beyond the “character” stage and well beyond your desire to keep sanding and re-varnishing them. You could try harder spruce or cherry to save significant weight over ash but I can’t guarantee that it will bend easily enough to avoid the need for clamping. Similarly, if you plan on snapping your gunwales at some point, you might want to avoid altogether the labor of separating them from the hull with a chisel. Or just take them off with a jigsaw and make do with canoe about an inch shallower. Careless paddlers may want to start with a canoe an inch or two deeper than the design calls for, it’s really quite easy. OR you may want to treat your equipment as if your life depended on it because in some circumstances it might. But seriously, after paddling the Bob’s for some time I had no hesitation in using the same method for the Osprey, even making the cedar gunwales an eighth inch shallower. They are plenty stiff and strong enough for flat-water paddling.

Seats

Now of course one of the few good reasons that you need fat, strong gunwales is to hang the seats … that will support fat … So, you can see the problem with light gunwales that protrude from the hull by less than 1/4″. So, I decided to epoxy and dowel the seats to one-inch deep WRC cleats epoxied to the hull. A lot of measurement and a bit of fussing to get the mating angles right but the result is a very clean, functional look with no heavy hardware dangling in the way. Again, if you plan on breaking your seats at some point this method may not be for you. The plastic cane is extremely durable and resistant to environmental degradation while it looks like the natural product. Another plus of seats fixed to cleats is that, unlike hanging seats, they act as structural members of the hull, stiffening it considerably.

The fixed Osprey solo seat was constructed of ash with a sculpted ash yoke forming the front crosspiece. Cherry would have been strong enough and saved a little weight but I already had the yoke and I was able to use thinner ash stock due to its greater strength. Cutting square spaces into the rounded yoke for the sidepieces was a bit of a challenge for me but patience with a sharp chisel resulted in a fairly professional looking job. A bigger challenge was making sure that the irregular shape could be nicely caned. All I can say is: think about it – a lot. Plan, measure, measure some more, check the plan, measure some more and then cut. Making the seat took about 20 hours total including the caning, about 15% of the time needed for the whole project. But it eliminates the need for a removable yoke. Using cleat instead of being hung with bolts gives a cleaner look, and besides, with skinny gunwales there would have been no place to attach it. And you do not want to do a 3000-meter portage with the edge of a standard seat on your neck.

The Osprey seat had to be placed so that it was high enough off of the bottom to ensure that the top of my head would be clear of the hull when portaging but as low as possible for a stable centre of gravity (I almost never kneel when paddling flat-water and in any case the Osprey is best paddled more or less even-keeled while sitting). For me, this resulted in the bottom of the front edge of the seat (the yoke) being about nine and a half inches from the bottom of the boat. People with very long necks or big heads (not I, of course) might find that this arrangement will not work very well. It is very important in this narrow boat that your centre of gravity not be too high.

Yoke and thwarts

The sculpted yoke on the Bob’s had to be reinforced with a single screw through the gunwale on each side as well as dowels and epoxy. It seems that the spreading force exerted when using V straps attached to grab loops through the decks to car-top the canoe was enough to pop the yoke from the gunwale. No problems have occurred post-application of the screws. This is a highly leveraged force that would never normally be encountered in a tripping situation. Similarly, the two thwarts in the Osprey have a brass screw in each end.

Fiberglass

I am astounded that many highly skilled boat builders (far more skilled than I) appear to accept conventional wisdom on what weight and quantity of glass is required to sheath their craftsmanship. Ok, I’m not really astounded; I just wanted to say that to get your attention. Certainly if you are building boats for strangers who may lack the skills or the proper respect for their equipment it makes sense to use 6oz glass with maybe an extra layer over the football for good measure. But if you will be the careful paddler, subject to the weight limits mentioned above, three and one-quarter ounce glass will do the job. I used an open weave satin glass from RAKA Marine in Florida for the Bob and a tight weave satin glass from RAKA for the Osprey. Couldn’t seem to find it in Canada. One of the advantages of satin glass is its low profile. It takes significantly less epoxy to fill the weave. This saves both weight and cost. On a boat the size of the Osprey using three and one quarter ounce glass will save almost two pounds in glass and at least three pounds of epoxy. On the Bob’s I did not need to fill the weave of the inside lamination beyond the wet out coat, filling with varnish instead. On the Osprey I rolled a few more ounces onto the inside to fill the weave figuring that it would get more wear and tear. No problems with de-lamination of either canoe in spite of plenty of knocks..

The tight weave satin glass may be stronger ounce for ounce but since it moves less freely on the bias, it tends to develop stubborn wrinkles more easily around the chines and at the gunwale when wetting out (like you really need more stress at this stage!) In order to minimize this problem, the extra layer of glass on the outside of the football doesn’t have to be wider than about 18″ tapering to zero at the bottom of the stems. This really stiffens the boat and adds some impact resistance too.

Epoxy

While I have used East System and System III for minor boat repairs and other applications, so far I have used only West System with 207 hardener for strip canoe building. My impression is that once builders get used to how an epoxy handles, they get pretty reluctant to try others and I’m no different. However, I find West to be a bit too viscous for wetting out glass easily and from what I have read and discussed with other builders, high quality 100% solids epoxies such as MAS, System III Clearcoat, or RAKA may be the choice for my next boat. In addition to faster and easier wetting out of the glass, my impression is that there may be a good argument that less viscous epoxies penetrate the wood better, making a stronger bond. In any case, I would not even consider cheaper epoxies that generally contain solvents. In addition to the inconvenience and hazards of working with materials containing solvents, the cost saving over the life of the boat is trivial considering that a well-built boat will probably be passed on to your heirs. Besides by using these light weight techniques, you should be able to build a boat such as the Osprey with only one “B” kit of West or equivalent, saving a couple of hundred dollars for the usually recommended second kit, some of which will sit in the cans until you manufacture an excuse to build another boat. Hmmm, “But Honey, I hafta build another boat or this expensive epoxy will go to waste!”

Since people are always curious, both boats cost about Can 900$ in materials. Cutting your own strips would save about $200. I had the strips cut to my specifications since I do not own a table saw (yet). Probably why I still have all my fingers. How much damage can you do to yourself with a random orbital sander?!

Without going into all the details, these are the main features of my approach to building light but strong woodstrip canoes. If you are looking for a very light weight boat for real tripping and enjoy the look and feel of wood, going this route beats the heck out of spending $3000 on a Kevlar boat, in my opinion. And if I can build them, you can too. All it takes is patience.

Now the next boat is going to be radically different… A fifteen foot solo that will come in under 30lbs, be stronger, cheaper to build, less labor intensive but possibly stronger and prettier, too. There is always a better way if you look for it.

Editor’s Note: Jay’s last boat came in at 32lbs. It turned out that the manufacturer’s stated weight of the plywood panels was a little optimistic.