Another silly shop experiment, which I know a few folks here enjoy.
I have long been curious about how much weight different canoe outfitting attachments would hold. With shelter-in-shop time, and a variety of attachments in shop stock, a long awaited experiment was in store.
A dozen different attachments, installed different ways; pop riveted, screwed through vinyl, wood and aluminum gunwales, pop riveted through holes drilled in Royalex or glued directly to the RX.
Thousands of pounds of weights suspended over the course of 10 days; I discovered that incremental weights each need to hang for a while to reach their eventual failure point. Some failed quite slowly, most failed quite loudly when hundreds of pounds of weights crashed to the floor.
I have been outfitting canoes for a couple decades now, and like to think I have gotten better at it, but have never seen comparative attachment numbers, even crude as mine are. I was comforted by a few things, learned a few things I will always do, discovered a few things I will never do again and found some surprises.
Wayyyy too long and 100+ photo heavy to repost; the full experiment is over on the CanoeTripping.net DIY board. (Admins: I hope it is OK to redirect like that. Please let me know if I have overstepped)
Brief as I can make a photo-less summary of that 9 day project; not sure the cut & paste formatting will appear on a CCR post.
Attachments, Failure Weights, How Failed and Suppositions as to why things failed.
Nylon webbing pop riveted through vinyl gunwale, 30lbs Webbing pulled through 3/16” rivet head
Nylon webbing with fender washer pop riveted through vinyl gunwale, 60 lbs 3/16” Rivet pulled out of vinyl gunwale
Poly webbing pop riveted through vinyl gunwale, 70 lbs Webbing pulled through 3/16” rivet head
Poly webbing with fender washer pop riveted through vinyl gunwale, 80 lbs 3/16” rivet pulled out of vinyl gunwale
Thoughts and suppositions: Webbing loops need a washer under the pop rivet. OK, I already knew that. Thin nylon webbing will pull through a washer more easily than thick poly webbing. No surprise there either. 3/16” pop rivets through thin (1/16” thick) vinyl gunwale will pull through the gunwale between 60 and 80lbs. The thicker/sturdier the webbing the more weight it held, perhaps because the weight was less likely to pull sideways, bending and sheering the pop rivet.
Grommet strap pop riveted through vinyl gunwale, 114 lbs 3/16” rivet pulled out of gunwale
Thoughts and suppositions: OK, not a fair comparative test, the weights were pulling on the grommet strap sideways, not straight down. It definitely takes more weight to pull a pop rivet from a vinyl gunwale in that orientation. I am still impressed that the grommet strap itself held 114lbs
Nylon pad eye with dual pop rivets through vinyl gunwale, 163lbs One of two 3/16” rivet pulled out of gunwale.
Thoughts and suppositions: Two pop rivets are better than one. And I’m more a fan of those nylon pad eyes than ever; those are where my swivel snap Surf to Summit back bands are attached.
Weird plastic webbing connector (no pop rivet, hung via webbing), 95 lbs Plastic broke
Thoughts and suppositions: I dunno, whatever that skinny thingamadoodle was made of it held an impressive amount of weight. I only used it because I had one in the parts box. The type of plastic, nylon, derlin, etc obviously makes a strength difference.
Plastic Cable clamp pop riveted through vinyl gunwale with 3/16” pop rivet, 41.4lbs Plastic clamp broke
Thoughts and suppositions: Way more weight than I thought one of those would hold. The elongation before failure should have been no surprise.
Spray cover stud and mini SS D-ring pop riveted through Royalex sheet with 1/8” pop rivet, 124.5lbs Rivet broke
Spray cover stud and webbing loop with 1/8” pop rivet on Royalex sheet, 171.5lbs Rivet broke
Thoughts and suppositions: Wow! A lot more weight than I would have predicted using a 1/8” pop rivet. Backing up spray cover studs is now a given.
Mini SS D-ring with 1/8” pop rivet affixed to aluminum gunwale, 82.5 lbs Rivet broke
Webbing loop with 3/16” pop rivet on aluminum gunwale, 55 lbs Rivet broke
Thoughts and suppositions: Note the reduction pop rivet failure weights. I believe the aluminum gunwale helped sheer the aluminum pop rivet. And that was pulling straight down; pulling sideways might be even worse.
I tried using 3/16” steel pop rivets once. That was a nope with my hand pop rivet gun; I couldn’t even begin to squeeze them closed. I have a box of 24 left, 3/16” dia X 3/8” long, large flange steel. Free to good home.
Under-inwale D ring plastic tab with 3/16” pop rivet, 151lbs Plastic tab tore.
Thoughts and suppositions: Again, seriously stronger than I would have thought. A decent solution for under aluminum gunwales.
Eye screw in wood gunwale, 76.5lbs Eye screw hole straightened out (long before weight limit was reached)
Thoughts and suppositions: The eye screw loop straighten out, probably starting at 50lbs or so. Kinda predictable.
Cable clamp screwed in wood gunwale, 51.5 lbs Plastic clamp broke
Thoughts and suppositions: The elongation was comical to behold, but even those winky attachments held more weight than I anticipated.
Webbing loop screwed in wood gunwale with cup washer, 282.5 lbs Webbing tore through cup washer
Webbing loop screwed in wood gunwale with flange washer, 320 lbs Webbing tore through flange washer
Thoughts and suppositions: Those both held a lot of weight. Flange washers helps. Better webbing would have helped as well. Dabbing epoxy in the screw holes made no difference, except that I couldn’t back the screws out when done.
Pad eyes screwed in wood gunwale (with smaller screw heads), 146 to 157 lbs Screw heads pulled through nylon pad eyes
Pad eye screwed in wood gunwale (with larger screw heads), 300+ lbs Nothing failed, I just gave up, although that pad eye was bent like crazy.
Thoughts and suppositions: Size does matter, at least when it comes to screw heads in nylon pad eyes. Again, nylon pad eyes, with two pop rivets or screws, will hold a tremendous amount of weight. Also Mike will give up at 300lbs weight and call it good.
Vynabond and hard plastic D-ring on Royalex sheet, 127.5 lbs Hard plastic pad popped off cleanly
G/flexed hard plastic pad D-ring on Royalex sheet, 226 lbs Hard plastic pad broke free, taking some vinyl RX skin with it.
Thoughts and suppositions: Hard, rigid plastic pads adhered to flexible Royalex do not make for a good combination. I’m thinking there is a reason those hard plastic D-ring pads fell out of use in favor of more flexible vinyl pad R-rings
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