Subject: Re: [harryproa] Re: Water migration in honeycomb?
From: Gardner Pomper
Date: 2/5/2009, 8:52 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

Hi,


I am also drifting a little from the topic, but how do you join full sheets of honeycomb when making a big panel? Do you route out the edges and epoxy in a foam strip? Or something else?

- Gardner

On Thu, Feb 5, 2009 at 8:38 AM, Mike Crawford <jmichael@gwi.net> wrote:


  Oh, and while this may be redundant for most on the group, I thought I'd add a comment on sealing techniques for anyone who hasn't been using them.

  There are two that we (and our boatyard) use, depending upon the size of the penetration:

  a) For small holes, overdrill the hole size, fill the hold with thickened epoxy, let it cure, and then drill the proper hole through the center of the solid expoxy section.

  b) For larger holes, drill out the proper sized hold, then use a router with a bit that fits in between the skins to rout out 6mm of core material, fill with thickened epoxy, and let it cure.

  It's also possible to use a hybrid method on larger holds for extra security.

       - Mike




Gardner Pomper wrote:

Hi,


I don't know if anyone is watching the KSS forums, but I got Derek to give a little more detail on the test he did where he sees water infiltration into honeycomb. It was a sample with unsealed edges, put in boiling water for a minute, the doused in cold (not ice) water. He immediately got water in 3/4 of the cells. He let it sit for a day, by which time all except 3-4 cells had water in them, meaning that water migrated between cells even after cooling.

This seems to be a test of what would happen if the skin was broken, or some cut (cleats, hatches, etc) was not sealed completely. If water does migrate in honeycomb, might we be better to restrict its use to the hull sides and maybe the bridgedeck, which does not get as much water exposure or hardware mounting?

Derek didn't specify a manufacturer he tested. I have a sample of Nidacore I am going to try this on. Maybe we could see if it is true of all the different varieties.

Any thoughts? Is this serious or just a reason to be extra careful sealing holes in the honeycomb?

Thanks,

- Gardner Pomper
York, PA


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