Subject: Re: [harryproa] Re: Building methods / materials |
From: "Rob Denney" <harryproa@gmail.com> |
Date: 4/11/2008, 10:05 AM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
On Fri, Apr 11, 2008 at 9:00 PM, Mike Crawford <jmichael@gwi.
>
> In an unrelated note, I've read that kevlar does not do well with
> abrasion against sand, so some builders cover it with glass if a boat is
> ever intended to be beached. I don't know enough about the topic to have an
> opinion.
>
> - Mike
G'day,
Kevlar is amazingly good at resisting abrasion. A few years ago, John
West, a kevlar/foam/
mooring buoy. The external kevlar and the foam were removed pretty
quickly, the internal kevlar was still watertight after a couple of
hours.
The problem with the stuff is that it goes fuzzy when abraded and
there is noway to get it smooth. Hence the layer of glass so you
don't sand through it, either on the beach or during fairing. It is
also very hard to cut and has peculiar, and low, compression
properties. A bit stiffer than fibreglass and as strong as carbon on
a weight for weight basis. As a last resort safety item, a layer of
kevlar on the inside has a lot going for it.
regards,
Rob