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Balsa cored hulls

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Old 04-28-2008, 09:01 AM
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good stuff!

Airex? What is it? Who makes it? Does it absorb moisture?

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Old 04-28-2008, 09:28 AM
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The grain doesn't alternate. The grain is oriented at a right angle to the sheet. The face of the sheet is the end grain. Balsa (supposedly) won't absorb water because if its cellular structure. Here's a pic-

So why "Checker Board" effect? I know this stuff is manufactured or should I say harvested,cut and put back together guessing for construction purpose it conforms to shape easier?

I'm not saying because it's in my boat it has to be the best, I can say the hull side and deck integrity is impressive. I have this thing about smacking the side of hull's at boat shows and can notice interesting differences in builds.
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Old 04-28-2008, 09:29 AM
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Baltek makes Airex. Foam is usually used in hull sides where the forces aren't as great.
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Old 04-28-2008, 09:37 AM
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So why "Checker Board" effect? I know this stuff is manufactured or should I say harvested,cut and put back together guessing for construction purpose it conforms to shape easier?

I'm not saying because it's in my boat it has to be the best, I can say the hull side and deck integrity is impressive. I have this thing about smacking the side of hull's at boat shows and can notice interesting differences in builds.
It allows it to be laid across contours. It has a material bonded to only one side. That's the top. The bottom squares will open from each other to allow them to go over the curves and contours.

Baltek is truly impressive structurally. It provides a high rigidity to weight ratio. It used to be boats like Cigarette were laid up with lots and lots of fiberglass layers to get the strength and rigidity. Composite core construction came from the areospace industry. The theory is best explained in an example- Take two pieces of steel... they're both the same length and weight. One is a solid bar, one is an "I" beam. The bar will be equally rigid in all directions of force whereas the "I" beam will be much stronger in the one direction it's intended to be loaded in, the flange face. On an equal-strength basis, the "I" beam will be substantially lighter. Coring a composite provides the same effect. The top and bottom skins are the flanges of the "I" beam and the core is that center rib.
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Old 04-28-2008, 07:39 PM
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You mean like Bertram, Hatteras, Broward and such? That's funny because rotten cored decks are really common in those boats.

How can so many people be doing it wrong?
I guess they installed the self-rotting brand. Look one has to ask how the water was allowed to saturate the core in the first place and these same people should then avoid Plywood/ply rot like the plague for scantlings since the grain orientation as we know would allow the entire member to be water logged.



Hatteras??? http://www.yachtsurvey.com/boatrevie...terasINTRO.htm

Viking also has no problem with Balsa.

I thought Browards were Aluminium.

Bertramís problems were from the engineering and installation.
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Old 04-28-2008, 07:52 PM
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good stuff!

Airex? What is it? Who makes it? Does it absorb moisture?

Thanks
Swamp if you have a Harley then it has an Airex core.

No it does not absorb water in any measurable amount.

It has the highest Peel strength of any cores I have used.

The cell structure can be deformed 60-80% without damage.

It is PVC Foam and a great one at that.

BUT there is a thermal issue that one should be aware of like DO not use in a Dark deck in the sub tropic summer sun.

However I have built race boats from it in the ME where it gets to a comfortable 135 F in July and august.

And it is not cheap.
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Old 04-28-2008, 08:09 PM
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Best stuff I ever worked with

I've worked with Airex, Klegcell, Baltek and lots of other core materials. But my hands down favorite is Nida Core. Its light weight, doesn't rot, good tensile strength and good stiffness. Only down side is you have to be real good at your bonding skills. Your laminates will delaminate from it if you do a trashy job.
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Old 04-28-2008, 09:09 PM
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I've worked with Airex, Klegcell, Baltek and lots of other core materials. But my hands down favorite is Nida Core. Its light weight, doesn't rot, good tensile strength and good stiffness. Only down side is you have to be real good at your bonding skills. Your laminates will delaminate from it if you do a trashy job.
Just went to their website they have a nice selection of material nowadays and it seem's they are up on infusion also.
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Old 04-30-2008, 08:02 PM
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It allows it to be laid across contours. It has a material bonded to only one side. That's the top. The bottom squares will open from each other to allow them to go over the curves and contours.
If your covering a concave surface the scrim goes outward towards you. If its a convex surface the scrim goes inward away from you.
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