I expect that is exactly right with regard to the stretching. I looks, and this is just from looking at the photos, like the top rear sections of the main float and most of the fuselage on the “duck”, for example, were probably overlapping strips of aluminum riveted to formers. But that front section of the main float where it joins the fuselage, the cowling sections, and underside of the fuselage just behind the engine - those must surely have been formed by stretching around some kind of mold, don’t you think? Do you, perchance, know of any texts or someplace where that could be looked up? Considering the time period that looks like pretty sophisticated fabrication to me - practically a manufacturing breakthrough. It would be interesting to know more about how that was done. Its impressive that they could put in that many rivets on a float that would repeatedly take such a hammering and still apparently not develop leaks.
For all the dissing that’s gone on regarding aluminum canoes over the years its easy to overlook what a technological advancement would have been necessarily employed to make a shape like a canoe. I’m glad they did.
Stretching is a little stretch use of the word. It is a process similar to stamped used in steel. Often canoes are two halves joined in the middle/keel, to a “tee” bar. Two rows of rivits highlife this joint.
Stamping stretches flat sheets into 3D shapes. As I recall the metal is also hardened. Here is a description. https://gearjunkie.com/boats-water/canoe/canoes-a-natural-history-in-north-america
Not sure how ground breaking the stamping process is for aluminum as opposed to steel, but stamping dies are very expensive to make. Using the same die for both halves surely helped on the cost.
I’ve owned one of these for about 50 years now and paddled it a lot for the first 30. As a kid I enjoyed building stick and tissue model airplanes and so was interested in aircraft. Because I paddled, Grummans in particular interested me.
I’d always assumed it was stamped (drawn? stretched? There probably is a correct term, though I don’t know it…) with a large press on a mold of some sort, rather like steel was, though perhaps with some “tweeks” to allow for differences in the materials. Overstreet’s post got me to wondering when that process might have first been developed. It must surely have been before WWII because Grumman was making large compound curved pieces - like those pieces on the “duck” - since at least the 30s. And, of course, though they may have been the largest they weren’t alone. Other aircraft companies, and car companies for that matter, were doing the same with steel, and perhaps aluminum also, for quite a while prior to that.
Post WWII seemed late, though maybe not. I wasn’t sure. The thing that caused me to wonder was the scale and the power of the press (presumably hydraulic) needed to make a piece of the size of those floats and fuselage parts - or a canoe. Gad - think of the expense of the pressing dies that Grumman must have made to manufacture all those parts for all those aircraft they’ve produced. Makes a canoe seem almost laughably simple - but its still a perfectly usable marketable product after all this time.
Thanks, Kevburg, for that link.
PS: Has me now wondering how they made the compound curves and riveted steel hulls of the 19th century four-masted steel hulled windjammers…and steamers. That would require similar compound curves in metal on a much much larger scale. It must have been done without presses.
Years back when I started my trade at Pratt and Whitney machine tool, this was a main customer. The machines we made for them had 20’11" travel on 2 axis, and 7’ on the third, and were used to create the punches and dies used for automobile bodies. Later on I got into fabrication, and in a nutshell, don’t recall “stretching” but we did “roll” turbine engine cases, using a turret lathe with a wheel in place of a cutting tool to press material into a die. Craziest operation imo was forming I beams into semi circles, 3 rolls, beam in between, kept applying more tension and decreasing the radius. Something you didn’t want to be near if things went south. https://www.autodie-llc.com/
And it looks like seven ribs? Mine ( a 78 standard weight) has three. This was a topic of another recent thread. I wonder what model year this is and is it the standard or a lighter weight model with extra ribs added for extra strength? Shoe keel or the usual “T”…
And Daggermat - thank you. That was more what I was wondering about.
I guess the question of the historical development of that technology is more a matter of fairly idle curiosity to me. I doubt anyone else has much interest. Its like campfire conversation, you know. There are tangents that don’t necessarily need to be followed through on, at least not in great depth.
Somehow the lines on the Grumman canoe don’t look like the work of Robert Hall…
An amazing man - just look at where his designs started and ended. (And, like Daggermat, he did have a pretty strong connection with Pratt & Whitney through the years…)
It is my understanding that Grumman Engineering prototyped their canoes in 1945, They were first produced in production starting in 1946, which would have an “A” in the serial number. Yours looks like a 1948 as denoted by the “C”. Your canoe, assuming I have this right, is the lighter model with .003 thickness aluminum and it is 17 feet long.
50-C-3-17
50 = production number or the year, could be production number for that model for that year
C = the year 1948…A is 1946, B is 1947. It seems like the number/letter scheme went up to G which is when Grumman moved to Marathon, then the numbering scheme changed.
3 = .003 thickness
17 - 17 foot long canoe
Here is the tag off of my 15 foot canoe from 1947, with standard .005 aluminum, Notice mine has a “B” in the serial number.
.003 and .005 thickness? Nah…that’s human hair thickness. Reference, 16 gage is .062 thickness (1"/gage # = thickness in thousandths of an inch)…here, just found this, maybe the 5 stands for .050"…then again, nah, as the 3 would equate to .03", way thinner than the 16 gauge I’m thinking the canoes were formed from, and 18 gage for the .05, material possibly being thinned out by the stamping process.
Sorry, I put an extra zero in there. It should be .03 and .05 thickness. As best I know, they made canoes in .032 (lightweight), .05 standard, .o65 (white water/shoe keel model), .08 (livery model)… I don’t claim to be an expert. This is just what I have read in other places.
thanks to all that reply with a few exceptions, I own this 72 year old canoe that is unbelievable great shape and I have no use for it, its my understanding that this was the 50th canoe built in 1948 the lightweight model a friend looked at it and said the rivets still have the plastic around them, the plastic he tells me was from the installation process, my question is wahts this thing worth and who might want to own it? I would love to see it with someone that wants it
In your shoes I think I’d clean it up with a chore boy sponge (sparing any stickers that my still be clinging), and ask about $250 or $300 and be reluctantly willing to bargain it down to absolutely no less than $150.
If possible I’d try to get it before buyers of a community of modest (mostly no garages) lakefront, possibly summer only, properties - where outside storage would be a real plus to the buyer and where portaging or whitewater usage wouldn’t matter much.
It would be great if you could find someone who really appreciated the role that boat, and vintage, played in US canoeing history, but there aren’t many such people and they probably already have one. You might try contacting Marathon/Grumman and see if they know of collectors or even canoeing museums (there are some - one in Spooner WI, for example) that might be interested. Your boat represents a real piece of canoeing history, but finding others who appreciate it as such, and be willing to pay extra for it, is a real long shot.
If its any consolation, I bought my current one in 78 for $400. Yours would have sold for much less in 48. How many things can you own and resell 72 years later for more than was originally paid?
And my apologies if my going off on a Grumman non-canoe tangent was a problem for you. No offense was intended.
@PJC You know that $400 in 78 is worth at least 4x that today, right? I bet that the price in 48 was far higher compared to income than your’s was in 78
Comparing the purchase price to what it can be sold for today without considering inflation is not fair at all.
But do you think it would be wise to suggest, using mine as an example, that (4X$400=) $1600 is a reasonable starting point asking price for a 43 year old Grumman? Or that it is reasonable to apply that approach to the valuation of anything used? Heck, lots of folks think, as is the situation with a new car, there’s a pretty major (~20%?) loss in simply driving it off the lot. So maybe a 43 year old Grumman in great condition should start at (0.8X$1600=) $1,280 because I took it home sometime during Jimmy Carter’s administration and its still in near perfect condition?
No, that wouldn’t fly at all… too many good brand new boats could be had for that or less. And Grumman 17s in particular were made in huge numbers and many last a looong time - so the used supply is high compared to demand. The value of a used Grumman 17 (unlike a Rushton, Chestnut, Peterborough, etc.) in good condition is utilitarian regardless of vintage. Alas.
If I were going to sell my Grumman today I think I’d start at about $250 or $300 and reluctantly bargain it down to absolutely no less than $150 - because with luck that’s about what I think the market might bear. I’d be disappointed selling at that price, it would be a nostalgic loss to me, but I don’t think I could reasonably do much better financially. And I’d suggest the same to a friend unless they could find some more profitable niche market to sell to. Or to LimoGreg.
And afterword I’d probably try to console myself by saying I paid $400 and got a decent percentage of that back after many years of enjoyment.
man o man, what a shame this super cool history loaded 72 year old canoe is only worth the cost of dinner and drinks? What a bummer I was excited as its story began to come to light but now I feel it was a waist of time, think I will give it to my nephew or something hardly worth trying to preserve anything or the hassle of selling this thing, very sad
Well, I’m with you and in about the same boat - so I hang on to mine. And I do still use it. Its great for trips with kids or first timers. And I use it on the rare occasions when I have to haul a really heavy load or if I might be carrying stuff that would damage a glass or royalex canoe - like for river clean-ups. In fact, I used mine first one cleaning up a local pond with classmates on the very first Earth Day…
You know, there was quite a long period of time around the turn of the century when canoeing was a really really big thing. Everybody did it. There were all manner of canoes - courting canoes, sailing canoes, … It got displaced as a popular pastime by bicycling. Canoeing would probably have died out (or nearly so) as a popular activity if it hadn’t been for the comeback after the war made possible by that humble, sturdy, affordable, Grumman 17 std. like you have. (BTW, I looked it up and new 17 stds. are going in the neighborhood of $2,000 - its a sin that the used value is so low.)
I suggested what I would try for if I was selling - but I’m no dealer. Perhaps I’m wrong… try asking more. What could it hurt? You might get it, and if you do congrats to you. And maybe try giving the Marathon/Grumman company a call or Email. I bet they’ve seen other cases similar to yours and might be able to offer more help than I with regards to where a better selling price might be found…
How did you come by it? Do you use it? If not, might you? Perhaps there are some trips to be taken with your nephew to see if the paddling bug bites him?
I need to take off now and won’t be back for a bit…but I need to make it to an appointment.
