C-Forum

How vulnerable to UV is the red seat belt webbing that Mohawk uses in its saddle systems? Wondering how many years I've knocked off that piece's lifespan from having to store the boat on an outdoor rack this season...

right side up?!

UV destroys not only webbing but royalex, plastic gunwales, and PE as well. The amount of damage is not readily apparent until it is too late but color fading of the webbing is one indicator that it is being affected.

I suspect that unless you left the seatbelt webbining in direct sunlight for a long time, it would be fine. I have seat belt webbing from my first whitewater canoe (almost 20 years now...) that has been used on and off the entire time and exposed to the elements for a lot of that time. It's fine, maybe a little less flexible than originally. Also, the original breaking strength of webbing probably exceeds the needed strength (not to mention the strength of the bond of the D-ring to the royalex) by several (if not many) times...

When you consider the requirements for material that is part of a "life-safety" device in a car, our uses are puny in comparison. If the material is not cut or seriously abraded, it should be functional until the foam, vinyl, and royalex are crumbling to dust.

Shep

Thanks. Sounds like not much to worry about. The boat is stored upside down.

I'm not too worried about the Royalex - the local university has dozens of Royalex boats, some 20+ years old, that have been stored outside for their whole lives. Their vinyl is faded, but they continue to survive beginners smacking them into rocks...

Shep wrote:When you consider the requirements for material that is part of a "life-safety" device in a car, our uses are puny in comparison.

Agreed. And I've never even thought to worry about parking my car in the sun and having the UV degrade the seltbelts, until just now. Then I wondered if auto glass blocks the UV rays...Then I stopped wondering because I never worried about it before and I have better things to do.

Abrasion and other wear will kill the webbing much faster than UV damage, and it'll take a lot of wear before that happens anyway.

I'm pretty sure auto glass does block UVs - that's why my "transitions" lenses in my glasses don't get dark behind the wheel but they do outside.

I don't have the link or source for this corroborating evidence, but Black Diamond has pull tested the old tat cut down from climbing anchors after it has baked in the direct sun for unknown seasons. Although there is thought to be serious concern surrounding UV degredation, these samples reliably test at surprising strengths.

If i have time I'll try and find a link to this data, but it was upward of 80% of the original strength, and if I remember right, the tests did not result in breaking strengths statistically different from the original spec.

That said, I store all of my ropes in climate controlled environments and replace my slings and nylon before I retire my 'biners. For boats, I would expect roylex to fail before any webbing, and the Mohawk seatbelts to fail once they've been worn through, nibbled by rodents, and run off a 60 footer.

--Z

Royalex is skinned with vinyl. "Plastic" gunwales are vinyl. Vinyl is the most UV resistant plastic commonly in use. Customers do not need to worry about vinyl. If you want to put 303 on it, go ahead, but you don't need to.

"Poly" kayaks and canoes are more easily damaged by UV, but damage occurs slowly. Modern boat poly includes UV inhibitors.

Straps. Nylon straps are more rapidly damaged by UV than polyester straps. But I've never had a Nylon strap fail because of sun exposure.

If the vinyl skin gets scraped off the ABS of your Royalex canoe, you'd better keep that ABS protected with 303 or paint. ABS exposed to UV can be made brittle and weak. However, it doesn't happen so fast that you can't deal with it.

I have had nylon straps fail from prolonged UV exposure, but not on a boat. The nylon straps in question held an extension mirror onto the rear view mirror housings of my truck which is usually parked outside.

Polyester is nearly impervious to UV exposure. That is why they make car and truck seat belts out of this material. It also has less stretch than nylon.

Yeah, I'm shopping for some polyester rope right now. Never wears out, but I lose it at put-ins, take-outs, hanging raft guides......

Gonna bring a climbers point of view to this.

As a climber I place a 4 year lifespan on Nylon no matter its use (whether daily or locked in a dark closet). Obviously visual and physical inspections would trump this. There have been studies by several gear manufacturers on life span of cordage and webbing. Black Diamond equipment does a great job of testing equipment and I think they really get off on finding ratty webbing and hooking it up to the hydraulic press. From studies I've read they have found that many times old tattered webbing left outside at climbing areas (used often times as rappel anchors at tops of routes) tested stronger than anticipated. But the golden rule is, "if there is ANY doubt, don't use it...period". If you don't trust your gear, replace it. Simple.

Now in the boating world (I've been both an open-boater and C-1 boater for 10 years+) webbing used for thigh straps, grab loops, etc, don't truly constitute "life support" devices (especially compared to the uses they were designed for, ie climbing). The OP mentioned using automotive seat belt material. This is used in the climbing world but is folded and sewn into a tube form to make 1 inch tubular webbing. Fold a seatbelt in half and it looks just like this webbing. I would suggest that if you have any doubt about anything (serious discoloration, cut or tears of more than 50% of width, or just plain OLD and funky) replace it. Odds are though even if the webbing is discolored but contains no tears it will still withstand the weight needed to hold you in your boat.

Now for cordage used for rescue applications. This can and will see extreme loads. I'd put the 4 year rule into play on this equipment. A Z-Drag can multiply forces and chew up gear in a hurry.

A great article that may still be around is titled something like, "Comparative Strength Test of Cordage". Google it and it should come up (probably on the Black Diamond or Fish Gear website). If you're a gear geek like me you will find it fascinating. If not you will be bored silly!

Sorry for being so long winded...

-Rod Thomas
AMGA Certified Rock Instructor
Can be found upside down in a river

Found the Cordage study.

Here is the link:
http://www.fishproducts.com/tech/High_Strength_Cord.pdf" onclick="window.open(this.href);return false;


Enjoy!

granola1861 wrote:... This is used in the climbing world but is folded and sewn into a tube form to make 1 inch tubular webbing. Fold a seatbelt in half and it looks just like this webbing. ...

Not sure what your seat belts look like, but mine are not similar to tubular webbing at all. Except that they are both woven from thread. Just seems every one I can remember is constructed by what I believe is termed bar stitching (no - not bar tacking), with visible lateral 'bars' running running parallel down the entire length of the piece. While tubular webbing is only one such bar. Yes - the company line is to replace-replace-replace. However ... inspection and knowledge of your gear's history is more key. Number of falls, length of rope out, etc.

You are absolutely correct to worry about leading climbing, and sharp end falls with minimal rope belayed...

However the forces we are dealing with are near inconsequential, you could cut a piece to within a 1/2 of an inch (maybe 1cm) of it's life, and it would hold an upside down paddler. The primary reason for wide webbing in our usage is not it's breaking strength, but rather in it's comfort and our ability to make it stay in place.

Can and do appreciate the lesson - and IMHO every boater should have reliable anchors and a prusik loop(s). My airbag over-straps are usually installed to be easily removable, just in case. However this guys outfitting is perfectly fine, for many a year to come. (Just another climbers perspective)