Best material for abrasion resistance

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ks8
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Re: Best material for abrasion resistance

Post by ks8 » Sat Jun 26, 2010 12:14 pm

Really appreciate this kind of info. :) Your input and experiences are appreciated PAR, and don't you dare vanish because a few posts were deleted elsewhere. :)

One thing I would venture to add on the abrasion subject is that where glass is specified for a design here, a builder should use the glass, and then consider if the additional weight of additional materials and epoxy, for higher abrasion resistance than the glass alone, is worth doing. I don't say this for PAR (he knows it far better than I :) ), but for others that have been viewing the abrasion thread. :) The glass when specified here, is a necessary element of panel strength, and Dynel should not be exchanged simply for abrasion reasons. Required structural strength always comes first. Once the spec'd glass is applied and necessary strength per the designer assured, then comes a decision of whether or not to add another type material for abrasion resistance that is more effective than glass, but spec'd glass must remain in the lamination schedule for required panel strength. :)

The details of how much more resin is soaked up by the other cloths is helpful info. If Dynel is being considered for a deck, that does show that it will add quite a bit of weight there, since it goes over any spec'd structural glass. Question becomes whether it is worth the time, expense and weight, knowing it can not be used *in place* of spec'd glass, but only in addition to it. KiwiGrip?

I'm enjoying the info in this thread, some of which I hadn't known or understood in this context before. :D



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Re: Best material for abrasion resistance

Post by lncc63 » Sat Jun 26, 2010 6:04 pm

I second everything ks8 said. I am thinking of adding a Kevlar layer on top of whatever structural glass is specified. The reason I ask is there seems to be an impression that fiberglass boats are superior to wood cored composite boats. Now I know I should look at Xynole or Dynel. Thanks!

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Re: Best material for abrasion resistance

Post by ks8 » Sat Jun 26, 2010 7:42 pm

Personally I need to be sold hard on using anything in addition to the specified glass. By the time I finish adding stuff, I don't think I want to make the boat any heavier with another cloth over the glass unless I'm sailing through logging country and bouncing off logs in the water, perhaps... ? :)

And kevlar is very hard to cut. If a thread of it gets snagged or pulled, it could cause some problems, because it is so tough. I complicate things enough already. :lol: As I said, I need a hard convincing sell before adding another sort of cloth over the spec'd glass, other than just laying on thicker glass, or something like kiwigrip on a deck or sole.

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Re: Best material for abrasion resistance

Post by jacquesmm » Sat Jun 26, 2010 9:28 pm

lncc63 wrote: . . . I am thinking of adding a Kevlar layer on top of whatever structural glass is specified. The reason I ask is there seems to be an impression that fiberglass boats are superior to wood cored composite boats. Now I know I should look at Xynole or Dynel. Thanks!
You can add Dynel or Xynol but if instead you add an extra layer of glass, you not only add resistance to abrasion but strength. A win-win situation.
Dynel or Xynol do not add strength.

And if you add two layers of glass or three, the boat will be way too heavy.
Please do not start with the premise that our boats are weak.
If you search the forum, you will find several stories of our boats who ran aground at high speed or even impaled themselves on underwater obstructions and survived.
In particular, I remember the story of a PH16 that struck an immersed tree at full speed and ran another 2 or 3 miles to the ramp at 25 mph with the stump in the hull without taking any water! Show me a fiberglass boat that can do that.
Please, stop assuming that our boats are not strong enough and need extra reinforcements. During the design, I take in account your possible navigation mistakes.
I design for amateur builders and use large safety margins.
Jacques Mertens - Designer
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Re: Best material for abrasion resistance

Post by lncc63 » Sun Jun 27, 2010 5:49 pm

Point taken Jacques. My apologies if I gave the wrong impression. I know for a fact that the designs here are strong.

Actually, I've done just what you suggested above on my CR13, and it did actually "save" my friend and I when we ran aground once. We ran aground on a rocky shelf when our shear pin broke and the wind and surf pushed us on to the shelf. We were just motoring. We were probably scraping the bottom for at least 10 minutes. The sounds were awful and I was expecting to find water coming in at any moment. When were eventually rescued and the bottom inspected, I found the extra glass layer had held very well. So well in fact that I've not repaired it except for filling the gashes with epoxy.

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Re: Best material for abrasion resistance

Post by ks8 » Mon Jun 28, 2010 12:10 am

There ya go! :D

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Re: Best material for abrasion resistance

Post by wadestep » Mon Jun 28, 2010 11:45 am

During the design, I take in account your possible navigation mistakes.
Priceless. I'm sure in the hundreds (thousands?) of hours I expect to put on my hull, I'll be thanking you in the future. I also thought about increasing the amount of 'glass on the botttom, but afterlooking at the number of total layers along the keel and chines, I'm impressed already.
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Re: Best material for abrasion resistance

Post by ks8 » Mon Jun 28, 2010 12:13 pm

During the design, I take in account your possible navigation mistakes.
within reasonable limits... :?

I had a boat crash picture linked (you've seen plenty before), but I deleted it. Just wasn't right. :|

I did scrape halfway up a rocky shore by the launch ramp at about 4 knots, and slid back down scraping all the way (don't ask... I was entertaining those standing by, yeah, that's it). Had just a few scrapes from it, and none went through the 6 or 9 oz glass (I think its only 6oz). Between the design, the epoxy, glass and VC Performance epoxy/teflon bottom paint... tough bottom.

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Re: Best material for abrasion resistance

Post by jacquesmm » Mon Jun 28, 2010 1:41 pm

AS KS8 says "within reasonable limits".

I run aground more often than most people, my wife hates it but I have done it so often that it becomes second nature to include extra reinforcements in the hull.
One more layer is not a big deal but a very heavy bottom will be a handicap.
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Re: Best material for abrasion resistance

Post by Cracker Larry » Mon Jun 28, 2010 5:22 pm

I run aground more often than most people,
Me too, usually oysters, usually faster than 4 kts 8O With 2 layers of 12 oz biax, I've never even made a scratch 8)
my wife hates it but I have done it so often that it becomes second nature
Mine too. You'd think she'd get used to it by now :roll:

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