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Wednesday, September 9, 2015

Fender Washers--Basically Useless?

In the process or researching an article on backing plates, it seemed worthwhile to actually test some washers. After all, it was the failure of fender washers that led to cracking of my deck and the need to remount the winches.

Not really very flat anymore.... The deck paid the price.

I used a 3/4" pine board as a surrogate for a cored deck and tightened a collection of 1/4" washers untill the first damage to the wood, and until failure. To no surprise, common washers, fender washers, and HDPE were glaring failures, and FRP and thicker metal washers were fine.

This looked fine to start, but within hours it started to bend and within 24 hours is was bent worse than the SS fender washer. This could lead to a hidden failure if not monitored (1/2" HDPE)


(click to enlarge table)

And then there is always the matter of what happens in wet places. Though I like aluminum for ease of fabrication, I also know its limitations.

This bow cleat is a little shaky.

2 comments:

  1. Again, your practical test results are pretty revealing. But you've created more work for me - now I'm nervous about all my fittings that are anchored with big washers.

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  2. Me too. The secondary winch anchors took 18 years to fail, very heavily loaded in solid glass. The primary anchors, in cored deck, did not take nearly so long.

    But I have a whole stack of cone-shaped fender washers in my scrap pile, witness to what can happen.

    Personally, I have gone to a combination of 1/8" aluminum for light-duty and dry locations, and 1/4" FRP if damp or very heavy duty. I have not purchased a fender washer in 10 years--I've learned that they are useless, maybe even dangerous,.

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