Hello Gardner Have you tried using Nida Core ?  I have my reservations about it especially below water line but it is vary cheap compared to Nida Core and It might be possible to use it in some parts of boat.  Next winter I may do some test myself just for curiosity sake, who knows I may decide to use it. It is listed in the LBI fiberglass sight.   Happy sailing.   George Kuck Chestertown, Md.   PS. I put the nets on my TT 720 today and only have a few items left to do before putting boat in water.  Should be in water sometime next week.  --- On Fri, 6/12/09, gardnerpomper <gardner@networknow.org> wrote: From: gardnerpomper <gardner@networknow.org> Subject: [harryproa] Re: AirCell tested and fails (I think) To: harryproa@yahoogroups.com.au Date: Friday, June 12, 2009, 6:26 PM Hi, I have posted some more photos into the Aircell Testing phot folder of this group. I redid the tests with 1" corecell. My results were: 1) hammer test - smashed foam, broke fiberglass, delaminated. I think this test was excessive 2) hand sledge against wood block hit 10 times hard - no effect. Slight indentation on top side, no delamination on either side. Much better than Aircell in this test I then added another test, which was to put the panel on the floor, climb up on the table and drop the hand sledge (about 5 lbs) from as high as I could reach. I figure this is a 10' drop. 1) Aircell - dented, no delamination 2) Corecell - dented, no delamination They both seem to be pretty equivalent on this test. I think this highlights that if you are going to toss sledgehammers onto your deck, you should probably have more than 1 layer of 18oz fiberglass on the topside. Not sure if it tells me anything else. I think the other test that I should run is to have a bigger panel, supported on either end and jump up and down on it over and over. The problem is that is a very expensive test. Shipping on all this material is running at 20% (or more) of the purchase price. I wish there was a place around where I could get it. So far, I am 400 miles from each of 3 sources. Comments are welcome, as always. - Gardner