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By Alan S. Glos - Cazenovia, New York - USA

Mention the words “Grumman Canoe” and most people familiar with small craft will envision the 17’, heavy duty, aluminum canoe that they paddled about in at scout camp or the boat they rented from a canoe livery to paddle down a river for the day. Using WWII era aircraft technology, they were well built, relatively stable, zero to low maintenance and well suited for the post war population who wanted to get into boating with a minimum of fuss and expense. William Hoffman, a vice president at Grumman Aircraft Corp. and canoe enthusiast, is credited with coming up with the original design concept, and the first boats went on the market in the mid-1940s. They ranged in length from 13’ to 19’ and many of these boats are still going strong fifty or sixty years later. The hulls were constructed of thin aluminum sheets that were stretched to shape over male molds and then assembled with hundreds of rivets that attached the two halves of the hull to an extruded aluminum keel. Aluminum seats, ribs, thwarts and bow and stern flotation tanks finished off the construction. The “standard” models were not all that light, and with all the rivets did cause a fair amount of drag when being paddled. That said, the hulls bordered on indestructible and were the canoe of choice for camps and rental liveries. I paddled many Grumman canoes as a youth, and later owned a 13’ lightweight model. They could be stored outside and uncovered all year and any dings, leaks or popped rivets could be easily repaired with hand tools. I live close to the Marathon, NY plant where Grumman boats were manufactured for several decades, and during a factory tour, I was surprised at how lo-tech the construction was. Rivet holes were hand drilled with electric power drills, and once the hull sections were fabricated, trimmed and drilled, assembly was simply a matter of aligning the component parts with rubber gaskets and riveting them all together. Boats came off the assembly line in a continuous stream and from nearby Interstate 81, drivers could see scores of hulls stockpiled in the storage lot adjacent to the plant awaiting transport to dealers around the world. All in all, this was a very successful design, and thousands of the hulls were manufactured for 60+ years. Over 300,000 boats were built in the three decades leading up to the mid-1970s and production peaked in 1974 with production of 33,000 hulls.) (Striegel, 2007)

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From nearby Interstate 81, drivers could see scores of hulls stockpiled in the storage lot adjacent to the plant awaiting transport to dealers around the world.

In the early 1960s, Grumman bought a controlling interest in Pearson Yachts Company in Bristol, RI and in a bid to expand into the lucrative fiberglass boat market, and somewhere in the late 1970’s, they came out with a 16’ Grumman brand canoe in both fiberglass and Royalex. I happened to see one of the fiberglass hulls at a dealer’s shop, and it was love at first sight. The 16 foot hull was truly a thing of beauty. It was light, stiff with a fine entry at the bow and long flat run aft and no keel. The quality of the fiberglass work was extraordinary, and it was finished off with mahogany gunnels, ash carry yoke amidships and caned ash seats. About the only thing I didn’t like about the boat were the gunnels that looked unnecessarily heavy and overbuilt, but it was the nicest fiberglass canoe I had seen to date. I had to have one, but the price tag at over $1,000 was prohibitive at the time, so my boat-lust dream of owning one went into hiatus.

It was the nicest fiberglass canoe I had seen to date. I had to have one, but the price tag at over $1,000 was prohibitive at the time, so my boat-lust dream of owning one went into hiatus.

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Time marched on, and the Coleman Company came out with their very successful line of Royalex type canoes that sold for $300 or less at K-marts across the country. With their aluminum tube frame and plastic seats, these boats were not going to win any beauty contests, but they were rugged, functional and certainly affordable. I still lusted after the Grumman fiberglass model but found that they were no longer commercially available, and I have to believe that they got priced out of the market by the far less expensive Coleman canoes and clones from other companies. It began to look like a Grumman fiberglass canoe was not to be in my future.

Again, time marched on, and in the fall of 1980, I found myself at the Sail Locker, a little hole-in-the wall sailboat shop in Binghamton, NY. The Sail Locker was owned by Chuck Durgin whose real passion was sailing canoes, and in the back of his store there was a stack of bare, unfinished fiberglass canoe hulls nested together. Closer inspection showed that they were Grumman hulls (be still my heart!) and based on the Hull Identification Numbers, they were built in 1979. I inquired, and Chuck told me that Grumman had discontinued the manufacture and sale of their fiberglass canoes, and he was able to buy up a batch of the bare hulls and components (ash carry yoke/thwart and ready to install caned seats). He had plans to convert one or more of them to “C” class sailing canoes but, yes, he would sell me one! I came back the following week, and for $200 picked up a light blue bare hull, thwart and seats.

The hull was fresh out of the mold. When the hull was laid up at the Pearson plant, the fiberglass mat and resin overlapped the top of the mold and formed a right angle flange that I would eventually have to trim off, but this flange helped to maintain the shape of the hull until wood gunnels could be attached. The sidewalls of the hull were thin, but the bottom of the hull appeared to have a half inch or so of foam or balsa wood for stiffness and flotation, and the hull was light, stiff and beautiful to look at. To finish the boat off, I would need to fabricate and install gunnels, flotation tanks at the bow and stern, and install the seats and thwart.

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The sidewalls of the hull were thin, but the bottom of the hull appeared to have a half inch or so of foam or balsa wood for stiffness and flotation, and the hull was light, stiff and beautiful to look at.

White ash (Fraxinus americana) would be the best wood for the gunnels. Well seasoned ash is an excellent material for gunnels and would match the ash seats and thwart, but none of the lumber yards in the area carried ash in the 17’ length that I needed, and I did not want to scarf shorter pieces together. Finally I located a man in the area who restored old canoes as a hobby and he said he has some ash boards that he would be willing to part with. I visited his shop near Cato, NY and ended up buying one 18’ white ash plank. It was just what I wanted but it had just been cut and rough sawed a few weeks before I bought it, and it was as green as the beer on St. Patrick’s Day. Undaunted, I carted it home. At the time, I had access to a nice wood hobby shop at the college where I work, and I planned the plank down to ¾” thickness and then ripped the planned plank into 7/8” pieces. I got eight pieces out of the plank and figured that planned and ripped, they would season faster with air exposure to all four sides of each piece. I was amazed at how flexible these 18’ long pieces were, and I stowed them in the rafters of my garage and waited for the better part of a year before I could move to the next phase. The cost of the plank was $20, so I was still in bargain budget mode.

When the wood was sufficiently air cured, I inspected each piece carefully. I had to reject a few of the eight pieces owing to twists, warps and other imperfections, and at least two of the rejects ended up as high priced tomato stakes in the following summer’s garden. The others were flawless with no knots, burrs or punky areas and ready to go.

The original Grumman gunnel design was almost flat and looked a bit like a racer with a minimum of freeboard. I liked this look, but decided to modify it slightly by curving the gunnels up slightly at the bow and stern. As there was plenty of spare freeboard that came with in the bare hull, I also added an estimated inch of freeboard compared to the original specifications. To position the outer gunnels, I simply laid one against the bare hull the then “C” clamped in at intervals and made adjustments by eye until I arrived at the desired shape. When I was happy with the shape, I scribed a line the gelcoat of the hull and removed the clamped gunnel section. The next step was to mask up the area below the scribed line with 2 inch masking tape (to catch the epoxy resin run-out.) I then carefully sanded the blue gelcoat off the inch or so above the line to get a better resin bond and then glued the oversized ash gunnel section to the topsides with WEST epoxy resin thickened with chopped cotton thickener to about runny peanut butter consistency. “C” clamps at about 16” intervals held the gunnel outwall in place. To insure a good bond, I then drilled small holes at about 6” intervals from the inside of the hull and into the gunnel section and inserted ¾” long temporary pan head screws. With the clamps and temporary screws, I got a nice even resin run-out top and bottom, and I carefully wiped up the resin on the bottom to make sure it didn’t end up staining the gelcoated topsides. When the resin was partially cured, I removed the masking tape and cleaned the area with a rag dipped in acetone to remove any remaining resin or tape residue.

To position the outer gunnels, I simply laid one against the bare hull the then “C” clamped in at intervals and made adjustments by eye until I arrived at the desired shape.

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When the cure was complete, I transposed the dimensions at 12” intervals along the other topside, laid the next gunnel section on these hash marks, scribed a line and installed the second outer gunnel the same fashion described above. When both outer gunnels were installed and the resin was completely cured, I then rough sawed off the scrap fiberglass and flange off the topsides about ¼” above he top of the gunnels and removed all of the temporary pan head screws.

Installation of the inner gunnel section was easier, but the sections had to be pre-cut carefully and beveled at the ends so they formed a mitered joint at the bow and stern where the starboard and port inner gunnels met. Once the sections were cut to final shape, I dry fitted them on the inside of the hull and drilled holes at 12” intervals from the outer gunnel, through the fiberglass shell and slightly into the inner gunnel sections. I then countersunk the holes and again dry screwed the inner sections in place with flat head brass wood screws. When everything fit properly, I masked up the inside of the hull, attached the gunnel sections with thickened epoxy and screwed the assembly together using the wood screws as clamps. Using a plug cutter, I then made plugs from a piece of scrap ash, and drove the plugs into the countersunk holes with a little unthickened epoxy. The last step was to clean off the excess resin run out on the bottom with acetone solvent.

When all the epoxy had cured, I belt sanded the top of the gunnels with a 100 grit belt so the fiberglass edge was sandwiched between the outer and inner gunnels and then rounded over the edges of the gunnels with a router and 1/4” diameter round over bit. I left the inner gunnel square on the bottom, but with a sharp block plane, I beveled the underside of the outer gunnel so it was full sized where it joined the fiberglass hull but a little thinner on the outer edge. This bevel reduced the weight a little and was esthetically pleasing. Hand sanding down to 220 grit sandpaper finished off the gunnels. With the finished gunnels in place, I was amazed at how stiff the topside of the hull became.

Installing the thwart and seats came next. I cut the thwart to size and bolted it onto the underside of the inner gunnel exactly amidships. I used two flat head 3/16” stainless steel flat head bolts without epoxy. Canoe thwarts are easily broken (mostly through clumsy moves in the cockpit!) and I figured if I ever had to replace it, not having it glued in place would make the retrofit easier. Also not gluing the thwart to the gunnels allowed for a little flex without the risk of cracking the gunnels or the thwart.

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Installing the thwart and seats came next. I cut the thwart to size and bolted it onto the underside of the inner gunnel exactly amidships. I used two flat head 3/16” stainless steel flat head bolts without epoxy.

The caned seat assemblies that came with the purchase were wider then the inside of the hull, and before fitting them, I had to determine where I wanted them positioned fore and aft. I scaled the locations from an advertising brochure photo and a friend’s 16’ canoe. I then sawed the seat frames to the proper width and installed them using 3/16” flat head stainless steel bolts with 3/16” inside diameter copper tubing as spacers. Again, I looked at the advertising brochure photo to get an idea how deep each seat needed to be set into the hull knowing that I could always use longer or shorter bolts if it turned out that the seats needed to be higher or lower. As luck would have it, the location of the seats seemed good right from the start and no adjustments were necessary.

Now the only remaining fabrication that remained was making the flotation tanks in the bow and stern. Again, looking at the advertising brochure photo, I scaled the approximate size of the tanks and made them out of metric (about 3/16” thick) marine mahogany plywood. To get the right shape for the vertical and horizontal panels I made cardboard templates and kept trimming then until I got the right shapes. I epoxied the horizontal panel to the underside of the “v” in the gunnels and then covered the top of the panel with 3 oz. fiberglass cloth and WEST epoxy resin. This added strength and helped to insure a water tight fit. I then fabricated a ¾” by ¾” piece of mahogany with rabbets and limber holes to join the horizontal panel to the vertical panel. I attached the vertical panel to the sides of the hull with epoxy resin and 2” fiberglass tape, and then covered the panel with epoxy resin and fiberglass cloth. As a final step, I installed a drain plug in the bottom of each tank and a 5” inspection port on the vertical panels and then placed a plastic bag inside each tank filled with Styrofoam packaging “peanuts” just to make sure the flotation tanks would function even if damaged or holed.

I finished the bare wood with Interlux spar varnish and painted the bare fiberglass interior and new vertical tank panels with Pettit two-part, grey epoxy paint. The combination of the light blue hull exterior and grey interior went well with the blond ash wood and mahogany components.

The boat finished out at about 65 lbs., not ultralight by canoe standards but lighter than most 16 footers and yet heavy enough not to be blown all around in a brisk cross wind. True to my predictions, the boat had good manners and paddled easily in the flat water conditions it was designed for. It also adapted well to the subsequent addition of an outboard motor mount and my little 1.2 h.p. outboard motor. I still think about adding a “C” class sailing rig with leeboards and a Laser style sail but maybe that will be another story for another time.

[Read about the history of the Grumman aluminum canoe, “Paddling a Canoe to Success”, Lawrence Striegel, Staff Writer, Newsday.com, 2007]
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