Hello,
One book I would recommend is "One-Off Airex Fibreglass Sandwich Construction" by Thomas J. Johansson. It is a bit dated but a vary good book to get. Note: The foam used at the time the book was written is what is now referred to as Airex R63 "Damage Tolerant foam". Airex is now part of Alcan Corp. and they have many other types of foam in addition to R63. You should be able to find a copy on Amazon.Com
George Kuck,
Chestertown, MD.
--- On Wed, 12/24/08, Gardner Pomper <gardner@networknow.org> wrote:
From: Gardner Pomper <gardner@networknow.org>
Subject: Re: [harryproa] Resin infusing honeycomb?
To: harryproa@yahoogroups.com.au
Date: Wednesday, December 24, 2008, 12:39 PM
Hi,
I apologize. I hit send too early. I am also curious about the fiberglass/carbon. Can I get away with just using fiberglass cloth for the hulls? What weight is used on a Harry? How about a Visionary?
I have also noticed that there are sometimes 2 types of fabric listed under cloth, "regular" cloth and "twill". Is either of them ok for use? Do they both leave the same type of surface finish?
I am also curious about pricing trade offs. From my very inadequate sample of information, I am coming up with sq ft pricing that indicates that the vast majority of materials cost is in the core material. For example, based on the one infusion that I have seen done:
12mm core cell : $3.50/sq ft
Vinyl Ester resin: $1.25/sq ft
Fiberglass 10oz: $0.55/sq ft
Total: $5.30/sq ft
But I saw some 12 oz carbon fiber twill on sale at Noah's for $2.25/sq ft. While 4 times the price of the fiberglass, it only increases the total materials cost by $1.70/sq ft. Might it be worth just using carbon fiber on the whole hull? Or maybe just on one side?
I feel like I am asking a lot of incredibly basic questions. There must be a book or something out there that would help teach me the basics so I would not have to pester people so much. Can someone recommend one to me (purely in self defense <grin>) ?
Thanks,
- Gardner Paper
York, PA
On Wed, Dec 24, 2008 at 12:16 PM, Gardner Paper <gardner@networknow. org> wrote:
Hi,
I am planning on sending off for samples of various core materials to evaluate. My first project with these will likely be a 10' catamaran dinghy, but it is all in preparation of building a 40-50' harryproa. Can you give me some information on what thicknesses I should be looking at for the different core materials. I am currently considering:
core cell
polycore
nida-core
airex foam (for the rounded hull bottoms)
Also, what other core materials might be appropriate? I don't want to deal with balsa, but other than that I am open to pretty much anything.
Finally, what foam are you using for the bows? It looks like your current process is to build flat panels for the hulls up to within about 1m of the bows and then carve the compound shape out of solid foam. Am I correct in that?
Thanks,
- Gardner Paper
York, PA
On Wed, Dec 24, 2008 at 10:03 AM, Gardner Paper <gardner@networknow. org> wrote:
Hi Rob,
I thought you have recently been building with a honeycomb core. Have you been infusing that on just one side at a time, or is it different enough from nida core that you can do both sides at once?
- Gardner
On Tue, Dec 23, 2008 at 9:18 PM, Rob Denney <harryproa@gmail. com> wrote:
G'day,
Glad it went well, George. Infusing Nida is tricky. I would not drill holes in the core, you will use a fair bit of extra resin. George's suggestion would be better. The big problem is the edges. Exposed edges could be tapered using a hot household iron, but joined edges will be messy as you don't want a solid resin edge for weight, bending and stress reasons. A solution would be to taper them both at 45 and overlap them. On big boats, you could leave a gap and join the inner and outer skins. You could also bog the edges before infusing. None of these are ideal. Unless there are labour/time considerations, i would lay it all up wet and bag it. I would also talk to Nida and ask for their advice. It is possible that a thicker layer of scrim would act as a transfer medium
Funny story: I got a phone call yesterday from the guy that bought the
420 sq m/450 sq' Outleader kite. He makes boating movies for a living. He has chartered Brindabella (80' maxi) for Sydney Hobart, sold half the crew positions ($10,000 each!) and because the forecast is for fresh northerlies, wants to fly the kite in the race and film it for a future TV show. Could I come over and show them how to work the kite?
So, I leave here at 0005 on Boxing day, fly to Sydney, get to the boat at 0900 and we cast off at 1100, race starts at 1300. A beat out of the harbour, then bear away, drop the main and hoist the kite. Next stop Hobart. A boat full of kite virgins, including the inevitable few who think they know what they are doing and the world's biggest traction kite. Add in the stress of the race, the on board cameras, a dozen media helicopters, huge spectator fleet and we have the recipe for a flawless display. ;-) I will let you know how it went when i get
back.
regards,
Rob
On Wed, Dec 24, 2008 at 12:31 AM, Gardner Paper <gardner@networknow. org> wrote:
Hi,
I got my first hands on demonstration of vacuum resin infusion from George Kuck of this forum last weekend. Thanks George! He was using core cell and had drilled holes through to allow infusion of both sides of the panels. I an now looking to start trying some samples myself and I wanted to try out nidacore. My question is, can you still infuse both sides at once on honeycomb? I can't tell how big the cells are, but it would seem to me that drilling through might open a couple and you would end up with a big block of resin. Is that ok? I would think it would be a stress point.
- Gardner
York, PA
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