Canoe Outfitting Attachment Weight Bearing Experiment

[Guest]

I am again reminded of an experiment I have too long procrastinated, and in cleaning up the shop shelves found the lengths of wood, vinyl and aluminum gunwale scrap I need to get started.

This will involve sacrificing sundry pad eyes, webbing loops, grommet straps, gunwale tab D-rings and etc.

The Experiment: Attach various connections, 3/16” pop rivets in vinyl gunwale, epoxied screws in wood, gunwale tab inserts under aluminum rail and etc, etc, etc. Hang weights from each attachment point until a rivet or screw pulls out, or a pad eye, webbing loop, grommet strap fails, or some other catastrophe occurs.

That may prove to be an outfitting irrelevant high weight-bearing number, and I expect that webbing loops, washer & nut on a machine screw shank will be all but impossible to break free, possibly deforming the gunwale first.

But, now more than ever, I’m curious about how much total weight each individual attachment would support, and about what fails where and how. Much as I’d hate to waste one, maybe even a vinyl pad D-ring glued to a scrap piece of Royalex and weighs added until something comes apart.

Time to get this experiment going. A hunt through the small outfitting parts box produces a variety of attachment points from simple webbing loops, mini-D-rings, strap grommets and three different style pad eyes.

P4030002 by Mike McCrea, on Flickr

I have (many) pieces of unused gunwale, vinyl with aluminum insert, ash and even some leftover aluminum.

P4030003 by Mike McCrea, on Flickr

Note the shape of the aluminum insert in these vinyl gunwales. Like most vinyl gunwales with aluminum inserts that L shape covers only the top, where seat drop hardware will be suspended, and inwale hull edge, where the gunwales pop riveted in place.

P4030006 by Mike McCrea, on Flickr

Some very few aluminum insert gunwales have a full square-box insert. If you poke your finger up under the deck plate into the open gunwale end you can feel for what is there.

That aluminum insert matters; when pop riveting attachments to the bottom (or side) of the inwale the rivet is only seated through a 1/16” thick piece of vinyl, with no way to install a back up washer on the inside. (There are some specialty blind rivets that flare out further on the mandrel head. Hmmm, I think I have a handful of those)

The test platform is simply a set of 4 foot tall sawhorses, a length of 4x4 and a hanging bucket with a SS carabiner. I just strapped gunwale section in place (close to the attachment point) since the various gunwale sections will be going on and coming off repeatedly as different attachment points are installed in different ways.

P4030009 by Mike McCrea, on Flickr

What I most regrettably do not have are the various discs from the old weightlifting bench; paired 5’s 10’s, 20’s etc for the bar. Long gone, and when I gave that bench away I knew in my bones that I’d eventually have some need for those weights.

For increasing weights the best I can do is a couple sets of steel horseshoes (four shoes each, 1lb 6 oz and 2lb 6oz versions), two 2 lbs weights, two 30lb weights and a 35.8lb cinderblock. Not an ideal weight range selection, but I can incrementally add weight until something fails and get a rough idea.

On to the first test, starting with my favorite DIY tie down point for flotation bags or gear (gear gets tied or strapped to a floor mounted D-ring as well, float bags get a webbing strap), a simple webbing loop with a 3/16” pop rivet hole melted through, attached to the underside of the inwale.

P4030008 by Mike McCrea, on Flickr

Any guesses on how much weight that pop riveted webbing loop through vinyl gunwale will support? Or in what fashion it will fail?

 

[Glenn MacGrady]

In general, I would predict that something at the fixation point will fail -- such as the rivet/screw hole through the gadget material or the rivet itself -- rather than the material of the gadget at the weight bearing point, except maybe for very thin plastic pad eyes. For example, we already know the load bearing strengths of all kinds of webbing.

Perhaps for your next experiment you could test glues that are used to affix things to royalex, poly and composite hulls, such as vinyl D-ring patches, plastic D-ring patches and foam for knee pads and saddles. I've always wondered about the various fixation strengths of contact cement, vynabond, epoxy, and other glues on various hull materials.

 

[Guest]

In general, I would predict that something at the fixation point will fail -- such as the rivet/screw hole through the gadget material or the rivet itself -- rather than the material of the gadget at the weight bearing point, except maybe for very thin plastic pad eyes. For example, we already know the load bearing strengths of all kinds of webbing.

Glenn, that first pop riveted webbing loop was deliberately made as weak as possible so that I could also test stronger variations. What failed on that weakest link webbing loop was still kind of a surprise. That failure and increasingly sturdy webbing variations results coming soon.

One thing I have already learned is that I need to let the weights hang there for a while, at least when up to heavier loads. One heavily weighted webbing loop seemed to hold fine, but when I left it hanging and walked away to do something else it failed after 10 minutes.

A note on poor methodology; all of these failure tests are being performed with the weight hanging straight down, under the inwale. In a real world test of under-inwale webbing loops the stress would be oriented differently, sideways or perhaps pulling the webbing up over the inwale in a capsize.

Beyond that I usually have tie downs or lacing through multiple webbing loops to help share the load; I’m thinking pulling straight down, on a single webbing loop, is an unlikely worst case.

Perhaps for your next experiment you could test glues that are used to affix things to royalex, poly and composite hulls, such as vinyl D-ring patches, plastic D-ring patches and foam for knee pads and saddles. I've always wondered about the various fixation strengths of contact cement, vynabond, epoxy, and other glues on various hull materials.

I’ll meet you part way, not even half way. I have no poly or composite canoe hull material to sacrifice. I do have a supply of large Royalex squares and will use some of those. I have at least one oddball through-hull attachment (SS mini-D-ring to back up a pop rivet stud on snap riveted spray covers), and some crude, old school D-rings.

I would like to test modern vinyl pad D-rings, using both G/flex and vinyl adhesive. But - very big but – while I don’t mind trashing some 25 cent attachments in the name of curiosity, a Northwater double D-ring vinyl pad runs $8, and I’d want to test pads with a nylon D and a stainless steel D. $16 in D-ring pads destroyed is too rich for my Scot’s blood. $32 if I tested vinyl pads with both Vynabond and G/flex. I don’t see that happening.

Never fear, I have some less expensive tests in the D-ring arena. I still have two of the old style rigid plastic D-ring covers, the 2” x 5” rigid plastic ones with the molded D-ring hump in the middle. And a couple of beefy 2” SS D-rings that fit in that pad hump. I never liked that style pad, and suspect that the adhesive will pull free, maybe tearing the vinyl skin off with it, before the thick plastic pad or massive D-ring fails.

And I’ll make a cheapie DIY D-ring or two, laying webbing over a D-ring and epoxying glass atop the exposed webbing ends. I need to lay those up soon so the adhesives have time to cure before the weights go on.

This could take a while working my way through various gunwale materials and attachments, but makes a wonderful shelter at home experiment and, now started, my curiosity is higher than ever.

Thanks for the kick start Jim; I’ve never seen those numbers, or even guesstimate approximations, and this could be fun. Coming this spring, McCrea Breaks Everything.

Thanks Jim Dodd!

 

[Dan Cooke]

The direction of force applied I believe should mimic the use. Failure after time was most likely due to creep of the webbing from such a pinpoint force applied from the rivet. A washer on top of the webbing would assist in reducing creep. Fun exercise in trying to understand strengths of attachments. So many variables and small scale samples of testing that I doubt anything more than general conclusions in the end will be attained; but a fun exercise non the less. If you ever want more roylex I have the middle of a roylex canoe in the back yard free for the taking.

 

[Dan Cooke]

With the Plastic (if made from Nylon) loops they will be less prone to fracture if they have been immersed in water for a day. If delrin plastic the chlorine can lead to stress cracking. Also Temperature will have effect on the strength and creep of the plastic hardware. Then there is the coefficient of thermal expansion that will change the loading of the fasteners as the base and the attachment piece will change size as there is temperature changes.
It is all sooooo confusing- too much confounding properties to try to separate in my mind.

 

[Guest]

The direction of force applied I believe should mimic the use. Failure after time was most likely due to creep of the webbing from such a pinpoint force applied from the rivet. A washer on top of the webbing would assist in reducing creep.

Dan, I’m too dense, and too cheap, to mimic various possible forces on attachment points. You nailed the failure point with that initial weakest-of webbing-loop installation.

I typically put a washer over the webbing and have now done those tests, including using thicker, sturdier (poly cam strap) webbing. Better webbing and washer both make a difference, and together make a huge difference, even on a single pop rivet point.

DougD cut up some squares of old RX hull for my future experimental use last year, and that future is now.

Back to breaking things. Gawd this is fun.

 

[Guest]

Webbing loops through vinyl gunwale test failure weight.

The pop riveted webbing loop held 30lbs for a few seconds, and then failed in a surprising way. I thought the mandrel head would pull through the vinyl gunwale. Instead the (cheap nylon) webbing pulled through the rivet head, even with a hot nail head melt and sealed 3/16” hole

P4040012 by Mike McCrea, on Flickr

That begs two more tests with the pop riveted webbing loops in vinyl gunwale. Trying the same nylon webbing with (admittedly way oversized, couldn’t find a right sized one) fender washer over the rivet head, to spread the load on the webbing.

P4040014 by Mike McCrea, on Flickr

Held firm at 46lbs, held at 54lbs

P4040016 by Mike McCrea, on Flickr

Held firm at 60 lbs with the two 30lb dumbbells in the bucket.

P4040018 by Mike McCrea, on Flickr

I was about to start incrementally adding weight to the bucket when I took a phone call in the office. Long call; 10 minutes in I heard a crash. The rivet had, with time, pulled out of the vinyl gunwale channel.

60lbs per vinyl gunwale pop rivet using a fender washer on the rivet head? That’ll do, but I guess I’ll need to let the weights hang for a while. Could be an excellent time consuming shelter-in-place project, this may take a week to complete.

But, in for a penny, how’s about trying that with some better quality webbing.

Webbing cut from a length of (way-too-long, and I don’t use straps on boats anyway) poly cam strap, folded together with a 3/16” melted hole and a no fender washer, pop riveted on same section of vinyl gunwale. The Scotch tape is just to keep the ends even, and my fingers away from the hot nail head when melting the holes.

The rivet head pulled through the poly webbing at just under 70lbs. Took only a few seconds to fail this time, I was barely a step away.

P4040021 by Mike McCrea, on Flickr

In for two pennies; Thule cam strap webbing with melted hole and fender washer. Failed at 80 lbs, but it took a few minutes and the rivet pulled through the gunwale.

P4040024 by Mike McCrea, on Flickr

That (may) end the pop riveted webbing loops through no-insert areas of vinyl gunwales. It appears that simply using a washer helps prevent the webbing from tearing free, and helps prevent the pop rivet from pulling through the vinyl gunwale.

70 or 80 lbs per spaced webbing loop will do for me. I would still like to test poly webbing loops on the end of thwart and yoke machine screws, but think I’d need a much bigger weight platform, and maybe an old Chevy engine block and four or five cases of beer to get to the failure point. I’m taking donations.

Next up, some of the molded nylon attachments. I’m thinking they will fail sooner than the webbing loops, but I’ve already been surprised by the results a couple times.

P4040027 by Mike McCrea, on Flickr

 

[Guest]

On to the plastic and nylon attachments, starting with another oft-used favorite, a nylon pad eye (or strap eye).

http://topkayaker.com/index.php?main_page=product_info&cPath=2_133&products_id=137

P4050002 by Mike McCrea, on Flickr

Adding weights, adding weights, still adding weights. That is all the weights I have, 114.5lbs. And they’ve been hanging for a half hour in anticipation.

P4050005 by Mike McCrea, on Flickr

Screw it; until I build a platform to start stacking multiple cinder blocks 114lbs will have to do. Even I do not lean back that heavily on a back band, one of my attachment applications for those nylon pad eyes in an open canoe. And there are two pad eyes supporting the weight bearing straps of the back band. 228+ lbs leaned against the back band isn’t likely.

P4050004 by Mike McCrea, on Flickr

Weights removed, the pad eye and pop rivets look no different, nothing budged.

That no-failure testing is no fun, time to try some perhaps flimsier nylon/plastic stuff.

Next up, a grommet strap. OK, they not all the attachment points are 25 cents, but I use grommet straps in both open boats and decked canoes. I need to know.

http://topkayaker.com/index.php?main_page=product_info&cPath=2_74&products_id=898

P4050007 by Mike McCrea, on Flickr

The sideways hung gunwale made some creaky noises starting at 85lbs, and I left it hang at that weight for a long while. No fail; time to add some big boy weights.

Adding, adding, adding. Waiting, waiting, waiting. At 114 lbs the pop riveted grommet strap finally failed. It somehow missed the cushion under the bucket and made quite the crash.

P4050010 by Mike McCrea, on Flickr

My son came in to check on me “Are you OK?” Had I known he was coming to I could have laid on the floor with a barbell on my neck, moaning piteously.

The failure point was the pop rivet pulling through the vinyl gunwale. I think I’m good with grommet straps, especially on decked boats where I can back up the pop rivets

P4050012 by Mike McCrea, on Flickr

The grommet strap is fine and I can reuse it after drilling out the busted pop rivet.

Time for some really flimsy stuff. I’m not sure what this actually is, probably something I cut off a tent. What the heck.

P4050015 by Mike McCrea, on Flickr

I’m thinking it won’t be the pop rivet failing this time.

Well dang, I am again surprised. That is 46lbs hanging from that flimsy POS, although there is no pop rivet in play, I just wanted to see what the weirdo D-ring would hold.

P4050018 by Mike McCrea, on Flickr

On to the big boy weights again. Seriously, how the heck is that flimsy looking piece of plastic holding 60lbs? I waited. I waited a long dang time. No crash.


P4050021 by Mike McCrea, on Flickr

OK, I know that seemingly flimsy thing will fail eventually, and I got nothing but time. Adding more weight dammit.

Son of a. . . . . 95 freaking pounds to finally fail that seemingly flimsy attachment. The weight eventually broke the slender webbing pass through. dang, that is some amazing nylon or plastic. But note, there was no pop rivet to fail first, just webbing tied around the 4x4.

P4050022 by Mike McCrea, on Flickr

I got one more weight test in me today, the flimsiest thing I can imagine, a plastic cable clamp. Specifically a cable clamp with a boat outfitting sized 3/16” pop rivet hole; the pass though hole in the other two hardware store cable clamps beside it are too small to fit the pop rivet through. Buyer beware.

P4050024 by Mike McCrea, on Flickr

This one better fail quickly, I’m getting tired of hoisting cinder blocks and 30lb barbells.

P4050026 by Mike McCrea, on Flickr

Jeeze Louise, even that cable clamp held 41.4lbs before the plastic cable circle broke.

P4050028 by Mike McCrea, on Flickr

Those nylon or plastic attachment points will each bear a surprising amount of weight, the bigger failure point is the 3/16” (aluminum) pop rivets.

 

[Glenn MacGrady]

You're not finished are you? This is better than Netflix. Would you please test other crucial canoe tripping fun stuff: a wine bottle cork, a beer pop top, and a bra strap buckle.

 

[Guest]

You're not finished are you? This is better than Netflix. Would you please test other crucial canoe tripping fun stuff: a wine bottle cork, a beer pop top, and a bra strap buckle.

dang you Glenn, beers are precious in these shelter in place times.

P4070018 by Mike McCrea, on Flickr

I’m just getting started. No weight testing today, I needed to do some prep work on the next test pieces, including:

Pop riveting a piece of Royalex in the aluminum gunwale channel; several of the attachment points go on or under the aluminum inwale.

Installing the stud for a snap riveted spray cover through a piece of Royalex, and backing it up with a stainless steel mini D-ring instead of just a washer. Eh, crap, I should install a snap rivet stud backed up by a webbing loop and washer. So many possible variations.

Affixing webbing loops, pad eyes and cable clamps to the underside of some wood gunwale pieces. Two doohickeys in each piece of wood gunwale, one just tightly screwed, one tightly screwed with some G/flex in the holes.

Installing three variations on hull mounted D-rings on RX scrap, two of the old-school hard plastic pads; one adhered with G/flex, one with Vynabond, and a DIY webbing, fiberglass and epoxy D-ring.

And some other silly crap to be revealed later.

Tomorrow, while I am waiting a day or so for the adhesive to fully set up, I have an idea for a better weight bearing platform, something I can stack cinderblocks on. I still want to know how much weight it takes to fail that pad eye pop riveted in vinyl gunwale (more than the 114lbs it successfully held).

I’m not sure if my current max weights of 114lbs will fail the D-rings, and I have a lot of cinder blocks.

 

[Matt C]

I spent two years in the Materials Engineering lab at Eastman Kodak Company early in my career; you are bringing back many fond memories Mike!

 

[Alan Gage]

Once when I was trying to measure the breaking strength of some thin pieces of wood I found the best way to record the weight was to stand on a digital scale, zero it out, and then start pushing on the wood by hand. I'd just look down at the scale while pushing and note the highest reading I saw before failure. Things could get exciting with a sudden failure at 200 pounds.

Alan

 

[Odyssey]

Interesting how gunnel integrity seems more an issue than fastener strength.

 

[Guest]

I spent two years in the Materials Engineering lab at Eastman Kodak Company early in my career; you are bringing back many fond memories

Matt, I truly enjoy undertaking these crude shop experiments, and am innately curious about things where I have never seen any data.

The oil, epoxy and etc finish on wood gunwale experiment took 4 ½ years to complete.

https://myccr.com/phpbbforum/viewtopic.php?f=49&t=40923

A sailing magazine replicated that finish test a few years later, with far better scientific methodology and I was pleased to see that one of my top choices was one of theirs.

With prep work, cure time and various impact and abrasion abuses & inspections the initial skid plate testing stretched out over a month.

http://www.canoetripping.net/forums/...stance-results

Sometimes one experiment leads to another. That skid plate materials testing resumed nine months later with different materials (Dynel sleeve), different epoxies and lay up techniques.

http://www.canoetripping.net/forums/...ion-experiment

I learned some new-to-me things in those experiments, and verified things I had believed true without empirical evidence.

Once when I was trying to measure the breaking strength of some thin pieces of wood I found the best way to record the weight was to stand on a digital scale, zero it out, and then start pushing on the wood by hand. I'd just look down at the scale while pushing and note the highest reading I saw before failure. Things could get exciting with a sudden failure at 200 pounds.

Things can get loudly exciting when a bucket full of horseshoes and barbells suddenly crashes down and misses the cushioning pillow I have on the concrete shop floor. Unlike the sudden failure with wood strips I have discovered that I need to allow each incremental weight load to hang for at least a few minutes, and wait longer with heavier loads. Testing each attachment point takes a goodly while.

The heaviest weight load so far has been has been (edit) 163bs; any guesses? I had to build a bigger platform and get more weights.

Interesting how gunnel integrity seems more an issue than fastener strength.

Brad, I’m actually a day or two ahead on testing, but haven’t yet tried anything affixed to the aluminum or wood gunwale pieces.

Once everything I have prepared has been tested to failure I will post a TLDR summation of each attachment type, the weight at which it failed, and how/what failed.

 

[Odyssey]

My money's on the metal. Aluminum box design gunnels are probably the winner. Material and structure. Just a guess.
Another guess is that boat builders had different ideas in mind for gunnel purpose not associated with attachments.

ps - But let me just say I am disappointed no-one has offered up a section of their kevlar carbons. Those are truly beautiful but are they strong? In the name of science, people. Don't make Mike turn into some kind of Victorian era grave robber looking for boaty anatomical specimens. We've all seen his Dr Jekyll side, and goodness knows that's nice enough. Let's not push him too far.

 

[Guest]

I needed to do some prep work before the next phase of testing, starting with making a fresh supply of webbing loops. I’ll need a few more, and like to have a small supply on hand. Once the putty knife and nail are hot it only take a minute to seal cut the webbing to length, tape the ends together and melt a perfectly sized 3/16” pop rivet hole (point end of a 20 penny nail).

P4060002 by Mike McCrea, on Flickr

Those are 6” long pieces of webbing, so 3” long folded over. Pop riveted to the underside of a vinyl gunwale those leave 2 inches of webbing loop exposed for easy tie down/lace through, and they can be turned sideways 90 degrees to vanish under the inwale.

The most important part of making the sealed holes in webbing is finding the just-right sized nail (or nail head) to use. It’s worth trying a couple different nails to find a head that melts a perfect/tight 3/16” hole through the doubled over webbing; no sense having a bigger, sloppier hole that might more easily pull out through the rivet head or washer. I made a couple of webbing loops to accommodate 1/8” pop rivets as well (pointy end of a finishing nail)

Thicker, heavy duty poly webbing is trickier to melt a sealed hole; the nail/head needs to be really hot, so hot the hole tends to melt a little larger than the head, and leaves a bead of gooey melt perimeter. If you are quick about it you can melt the hole and stick a fender washer and rivet through while the goo melt is still hot, and mush things down flat.

Before I can test attachments on/under the piece of aluminum gunwale I needed to pop rivet a sheet of Royalex in the gunwale channel. The RX should look familiar to Doug, and the aluminum gunwale regrettably familiar to Chip.

Yes Chip, this is a piece of the aluminum gunwale we used to re-rail the RX Mad River Fantasy. “We”, that is aluminum gunwale with a channel sized for a composite canoe. We forced it onto a Royalex hull.

Not recommended; it took three of us, several wide blade putty knives to slide along betwixt the gunwale channel and hull and considerable pounding on the top of the gunwale with a rubber mallet. Many colorful words were spoken, but we only dented the aluminum gunwale in one especially recalcitrant area towards the sheerline rise and curve.

I used the thinnest piece of scrap RX I had, widened the length of the gunwale channel, and it was still a struggle. I would like to try installing the new anti-crimp two-piece aluminum gunwales someday. As soon as I find a cheap Blackgold Bell Rob Roy with rotted gunwales. That’s the plan.

I slid the under-gunwale D-ring tab below the inwale edge, and pop riveted a webbing loop on as well. And pop riveted a mini D-ring and webbing loop atop the inwale edge as well; the mini D-rings use a 1/8” pop rivet, the others are the usual 3/16”.

P4060004 by Mike McCrea, on Flickr

The brass spray cover stud a couple inches down from the edge is backed up with a SS mini D-ring. Those mini-D’s are good quality stainless steel; I bought some similar SS attachments from Wenonah that rusted to heck in a year or two, without any salt water exposure.

These “stainless steel” (my-arse!) things.

P2170545 by Mike McCrea, on Flickr

I liked the 1” webbing pass through concept, but that is some ugly, rusty (not) stainless steel. I cut all of those fugly rusty pieces out, leaving the plastic tab intact, and ran a length of high strength Dyneema Zingit cord through the plastic tabs

The SS mini D-rings have fared far better, even with some salt water exposure.

P4060007 by Mike McCrea, on Flickr

Before I test weight those pieces I need to back up another stud with a webbing loop & small washer.

P4070008 by Mike McCrea, on Flickr

Time to “prep” some wood gunwale attachments. I am not a fan of things screwed into wood gunwales, for a variety of reasons, starting with the ugliness of metal or plastic doohickeys on attractive wood gunwales.

But I’ve seen it done, even folks using eye screws for float bag lacing in wood railed canoes. Despite hating the crude look of eye screws in wood gunwale, this is a test, this is only a test; I got eye screws and lots of seasoned wood gunwale scrap.

I hear Glenn and others softly chanting in the background “slotted wood gunwales”. I guarantee you I lack the skills and pre-planning measurement to located thwarts and seat drops necessary to make slotted rails.

If need be I would drill lacing holes through the hull every 6 inches and run a length of cord in-out-in-out along the bow and stern sidewalls below the gunwales, so I have cord inside the hull every 6 inches near the sheerline to tie onto. Not a fan of through-hull float bag lacing left in place; I don’t use float bags often enough, and that permanent through-hull lacing is awkward with gear or even on empty boat day trips.

The prep work needed on the ash gunwale pieces is simply that I plan to screw in two-each sample attachments, with and without G/flex in the screw hole. Those leftover pieces of ash gunwale have been stored inside for 20 years and should be 100% dry. No idea if the epoxy will make a difference, but I needed to mix up some G/flex for the D-ring pads.

P4070009 by Mike McCrea, on Flickr

While the G/flex was out I used it to epoxy one of the hard plastic pad D-rings to a sheet of Royalex, and adhered the other one using Vynabond. I was loath to open that NIB tube of Vynabond, but once again, I want to know. Let the Vynabond set up for a few minutes, hit it with a heat gun, laid the pad in place and weighted it. EDIT to be clear: thin coat of Vynabond on both surfaces, allow solvents to flash off, hit both surfaces with a heat gun, press together. Putting Vynabond on just one surface won't do crap.

P4070011 by Mike McCrea, on Flickr

With both hard pads adhered down I covered them with pieces of wax paper and added some weights to help hold them down flat. In vinyl pad D-rings I use sandbags and some intermittent hard roller action.

Time walk away time from that sheet of RX. For how long I do not know. At least a couple days to allow the Vynabond and G/flex to fully cure? Longer? I’m in no rush.

I would dearly like to have tried this with vinyl pad D-rings. I’m curious about the hold of the stitching through the webbing and vinyl pad, but I’m not wasting any of those at $8 a pop.

P4070012 by Mike McCrea, on Flickr

Since I had the Vynabond out another experiment seemed in order. I took a piece of intact RX and laid a small puddle of Vynabond on it, lightly scarred through the vinyl skin in another area and puddled some Vynabond there as well, both covered with wax paper to help trap some solvents. Might have to try that “Solvents ate my canoe” with a scrap of minicel and puddle of Contact Cement as well.

P4070014 by Mike McCrea, on Flickr

And finally, the DIY D-ring, overkill constructed. Over long length of thick webbing with a 1” metal D-ring in the center, laid on a coat of epoxy (already getting age dark West 105/205 Fast hardener) on the Royalex, laid the webbing webbing on that coat, top coated that with epoxy, covered the webbing with longer pieces of 2” E-glass tape, wetted out that out , covered with peel ply and hard roller compressed a few times.

I know that when the peel ply comes off that will be one of the sloppiest DIY webbing D-rings I have ever laid. The webbing is far longer than need be, 6” has proven plenty, I made way too much epoxy and I didn’t tape out a perimeter to provide nice straight epoxy lines. Aesthetics don’t matter in this test, but I have the same “How long to wait question” (105 & Fast hardener, not G/flex)

Yeah, I still had leftover epoxy, once again painted on the ends of the impervious-to-nature sawhorse legs.

P4070017 by Mike McCrea, on Flickr

There has to be 10 coats of leftover epoxy or epoxy paint on those sawhorse feet. Alien archeologists will dig them up in 10,000 years and wonder WTF.

BTW, a lesson learned. That set of sawhorse had a 30 years of white house paint spilled on the crossbar. I had some white EZ-poxy paint left in a pan and on the roller. That stuff is too expensive to waste, might as well roll it out on the sawhorse crossbar.

Uh, no, bad idea. I rolled that epoxy paint onto the entire crossbar, including the top. Every dang time I set a boat on those sawhorses it left white marks on the hull. Really hard to get off white marks. After a half dozen hulls with white hash marks I took a belt sander to the top and removed that stuff.

 

[Guest]

I can weight test the five attachment points on the aluminum gunwale/Royalex piece while I wait for the epoxied stuff to cure.

First, I need a new weight table. Some of the coming attractions may be impossible to break or pull out with the current 114lb limit in a hanging bucket. And I still want to know how much weight that unfailed nylon pad eye in vinyl gunwale will hold.

Skip the too-small hanging bucket, I used another couple cam straps and suspended a wide board as a weight platform. FWIW the platform and cam straps adds another 12 lbs

P4080001 by Mike McCrea, on Flickr

Brought in a few more cinder blocks, a second 38.5lb block and a 52 ½ lb version. Plenty more where those came from; I will break everything.

P4080003 by Mike McCrea, on Flickr

Adding weight, waiting. Adding weight, waiting. Adding weight.

P4080002 by Mike McCrea, on Flickr

That pad eye through vinyl gunwale held 151 lbs for a couple of minutes while I was fetching more weights. Ooops, I forgot the 12lb weight from the platform; the pop riveted pad eye held 163lbs.

P4080005 by Mike McCrea, on Flickr

What finally failed? One of the pop rivets pulled out of the vinyl gunwale.

P4080007 by Mike McCrea, on Flickr

I am stunned at that weight bearing capacity; at a never-seen-any-numbers guess I would have thought a pad eye, pop riveted through the non-insert part of a vinyl gunwale, might hold 50 or 60 lbs, but I had no previous idea of what a single pop rivet would hold.

P4080008 by Mike McCrea, on Flickr

With the rivets drilled out the pad eye still looks like new. That’ll do pad eyes, that’ll do.

Next up, assorted things attached to aluminum gunwale or through a Royalex sheet.

 

[Guest]

My money's on the metal. Aluminum box design gunnels are probably the winner. Material and structure. Just a guess.

That would have been my guess as well. “Would”, past tense; I have discovered some surprising things about attachments and aluminum gunwales. Let’s just say that aluminum gunwales and aluminum pop rivets do not always work and play well together.

But let me just say I am disappointed no-one has offered up a section of their kevlar carbons. Those are truly beautiful but are they strong? In the name of science, people. Don't make Mike turn into some kind of Victorian era grave robber looking for boaty anatomical specimens. We've all seen his Dr Jekyll side, and goodness knows that's nice enough. Let's not push him too far.

My boaty anatomical specimen intention had been to drive up to Blue Mountain Outfitters and look through the lazy susan outfitting parts bins for other objet d’tachment. I know there is stuff in those parts bins I haven’t yet tried. I’m not taking the weight station sawhorses away just yet; I might mail order some BMO stuff.

It would be interesting to read the failure weights and whys for the custom carbon & etc attachments people have DIY’ed, all it takes is a couple of sawhorses, a suspended platform and sufficient weights.

 

[Guest]

On to the piece of Royalex and aluminum gunwale. Y’all be wondering how I am going to affix that to the 4x4 support and carabineer hang the weights.

Easy; a second 4x4 on the tall sawhorses, with the Royalex sheet atop and the attachment points suspended close in between. I’ll use the same weighing station supports when I get to the D-ring pads.

P4080012 by Mike McCrea, on Flickr

Starting with what I think (been wrong several times already) may hold the least weight, the snap rivet stud in the Royalex sheet, affixed with 1/8” pop rivet, backed up with a mini SS D-ring backing.

P4080013 by Mike McCrea, on Flickr

Well, I know it holds the 12lb platform, and I can start adding horseshoes and 2lb weights to that.

And once again adding, adding, adding.

P4080014 by Mike McCrea, on Flickr

Removing the smaller weights, adding cinder blocks, waiting, adding more cinder blocks. That single 1/8” pop riveted mini D-ring behind stud held 124.5 lbs for a couple of minutes before the rivet broke. Once again, far more than I would have guessed.

P4080016 by Mike McCrea, on Flickr

The SS mini D-ring is undamaged and un-deformed, back in the outfitting parts box for future use. I got those mini D-rings from Cooke Custom Sewing to back up the snap rivets on one canoe. Wish I had done all of the other spray covers that way, and guess I need to get some more; I had but two left.

Seems like an appropriate time to weight test the SS mini D-ring pop riveted through the aluminum inwale flange. Having an idea of the rivet strength I think I can skip the smaller weights and start with a cinder block.

That mini D-ring through aluminum gunwale failed at 82.5lbs; the rivet broke. I thought for certain I’d need to haul in more cinder blocks.

P4080017 by Mike McCrea, on Flickr

Not really sure what to make of that reduced result; my guess is that the sharp aluminum gunwale edges helped shear the rivet; it was impossible to seat the rivet with the gun head fully flush, the inwale flange wasn’t wide enough. Rivets seated at an angle or otherwise poorly seated are always likelier to fail.

P4080019 by Mike McCrea, on Flickr

The SS mini D-ring was again unblemished.

Next up, the webbing loop and small washer backing up a snap rivet stud on that piece of Royalex.

Back to adding weights. Gawd this would be easier if I had some kind of hanging scale that recorded the last incremental weight added before failure. That still wouldn’t eliminate the wait-time-for-eventual-failure aspect.

P4080021 by Mike McCrea, on Flickr

Finally, after a wait time as I went out to fetch more cinderblocks, it failed at 171.5lbs. I am beginning to appreciate that wait time, those dang cinder blocks are getting heavy.

P4090026 by Mike McCrea, on Flickr

What failed? Again, the 1/8” pop rivet. The stud, webbing loop and washer are all intact.

P4090027 by Mike McCrea, on Flickr

I am kinda hoping some stuff starts to fail more quickly, humping hundreds of pounds of weights around the shop is starting to get old.

With a beverage consumption respite for my aching back it was on to the webbing loop pop riveted through the aluminum inwale flange, and the slotted under inwale pop riveted D-ring tab, both with 3/16” pop rivets.


P4090029 by Mike McCrea, on Flickr


The webbing loop with 3/16” pop rivet sheered with a horseshoe clang at only 55 pounds. I am back to thinking that the sharp aluminum gunwale do no favors to an aluminum pop rivet, the webbing loop may have allowed the pop rivet to hang more angled than something rigid, helping break the pop rivet

P4090032 by Mike McCrea, on Flickr

Finally - I have had enough cinder block and barbell toting for a day – the only thing left on that piece of Rx and aluminum gunwale was the under-inwale tab plastic D-ring, installed with a 3/16” pop rivet.

I admittedly hoped that this one would break before I had to hoist too many cinderblocks and barbells. Uh, no, that flimsy looking plastic tab held 151lbs before it failed.

P4090039 by Mike McCrea, on Flickr

What failed was the thin plastic under-inwale tab.

P4090041 by Mike McCrea, on Flickr

I’m thinking those under-inwale tabs are a good choice with aluminum gunwales.

Note that I only had one of those under gunwale D-ring tabs on hand, and had previously drilled a 3/16” hole through the tab just below the pop rivet installed area. I expect that a virgin tab would support considerably more weight. I work with what I got.

That was enough for one day. By tomorrow the G/flex, 105/206 and Vynabond will have had a chance to cure, and I can move on to the wood gunwale screwed-in attachments, and D-rings epoxied and Vynadonded on Royalex.

Next up, wood gunwales with four different attachment points.

 

[Guest]

On to the attachments screwed into wood gunwales

P4090001 by Mike McCrea, on Flickr

Starting with the eye screws, the one without G/flex in the screw hole first.

P4090004 by Mike McCrea, on Flickr

So much for my anti-cinder block dreams.

P4090006 by Mike McCrea, on Flickr

I had to go to a cinder block and 24 more pounds of weight before the un-epoxied eye screw finally failed.

P4090008 by Mike McCrea, on Flickr

It hung in there for a while, and it didn’t pull out of the gunwale, the eye simply straightened out at 76.5lbs (or a bit before, I wasn’t paying attention to how it failed as it happened)

P4100012 by Mike McCrea, on Flickr

Knowing that weight 76.5lb limitation I can start with the big cinder block on the epoxied eye screw.

The eye screw with G/flex hole held the 52.5lb cinder block and the horseshoes on the platform. I was ready to add the 2lb weights when I noticed that the eye had already opened almost all the way. Just barely got a photo before things crashed to the floor

P4100013 by Mike McCrea, on Flickr

I didn’t pay attention to exactly when those eye screws started to straight out. Probably somewhere under 50lbs. Screw eye screws, they are ugly, and prone to failure.

On to screwed in place plastic cable clamps. I remembered to look at the attachment this time while I added weights. The plastic cable clamp elongated at under 30 lbs, but still held.

P4100018 by Mike McCrea, on Flickr

The elongated plastic clamp finally broke at 51.5lbs. About the same as eye screws, but less fugly.

Not much reason to weight test the other cable clamp, but it is there and I only need to move the gunwale stock a couple inches to center between the straps. What the heck, if only for comparison sake

Worth the comparison, that cable clamp snapped just under 50lbs.

P4100022 by Mike McCrea, on Flickr

I’m beginning to suspect that the G/flex in the screw holes makes zero difference.

On to the screwed in webbing loops with cup or finish washers, this time starting with the G/flexed screw. Son of a. . . . .201.5 lbs and holding. And I waited a long dang time for something to eventually fail. Nope. Time for more freaking cinder blocks.

After some hang time the webbing finally pulled through the cup washer at 282.5lbs. I could hear it tearing seconds before the crash.

P4100023 by Mike McCrea, on Flickr

The crash broke my 52.5 lb cinder block. At least the pieces will be less weighty to pick up.

P4100026 by Mike McCrea, on Flickr

I was hoping not to repeat that 200lb plus experiment, but the screw that tore through the webbing had a simple cup washer.

P4100028 by Mike McCrea, on Flickr

The no-G/flex screw was installed with a flange washer. Fark me, I got no choice but to do a comparison.

The screwed in webbing loop with flange washer held almost 320lbs, but the failure was nearly instant, with no tearing noises; the flange washer pulled through the screw head.

P4100031 by Mike McCrea, on Flickr

That was using the cheap nylon webbing, I don’t think the washers, flange or cup or flat, matter as much as the webbing. Flange washer and better webbing seems the best possible combination.

I could try that again with some thick poly webbing and wide load bearing flange washers, but my back hurts, and +/- 300lbs is way more than I was expecting with webbing and washers screwed in wood. Single webbing loops at that, extrapolate for a webbing loop every X inches.

I really want to finish up the wood gunwale tests today, but what I have left are the two-screw pad eyes. I have guessed wrong a dozen times in this experiment, but from what the pop riveted version held (163lbs) I’m predicting I’ll need to bring in more cinder blocks to fail those two-screw attachments. Oh joy, more freaking cinder blocks.

Ok, I’m done guessing at weight bearing numbers. The screwed in pad eye was starting to stretch out at 146Lbs and failed at that weight after a few minutes.

P4100034 by Mike McCrea, on Flickr

The second screwed-in pad eye also stretched out and finally failed at 157lbs.

P4100035 by Mike McCrea, on Flickr

What failed? The screw heads pulled through the holes in the pad eyes.


P4100029 by Mike McCrea, on Flickr

Those screw head were a bit recessed in the pad eye hole. Guess I should try that with larger head screws, some pans and some flat heads.

The larger screw heads that stick up a hair above flush on the pad eyes. No epoxy in the screw holes this time.

P4100002 by Mike McCrea, on Flickr

Larger pan heads first. This time I paid attention and watched this time as the nylon pad eye bent further and further.

P4100003 by Mike McCrea, on Flickr

242lbs, and the weights have been hanging for 30 minutes.

P4100008 by Mike McCrea, on Flickr

Adding more weight. That pad eye became seriously elongated, but still held in there.

P4100006 by Mike McCrea, on Flickr

At 294.5lbs I finally heard the crash. Yippie!

No yippies, no joy in Mudville; my weight platform had tilted over and dumped the enormous mess on the floor.

P4100013 by Mike McCrea, on Flickr

It looks like I will not be breaking everything after all. I don’t have the heart to clean all that mess up and restack it on the other pad eye. The pad eye was already insanely bent at 294.5lbs and couldn’t have held on much longer. Or could it?

P4100014 by Mike McCrea, on Flickr

We may never know. I left that second pad eye screwed into the wood gunwale. Just in case anyone wants to swing by McCrea’s Gym and haul cinder blocks around for funsies.

Next up, Vynabond and epoxied D-rings.