Big Catamaran, Big Drop 'Test',....WHAM !!

brian eiland · Jul 5, 2013

The following quote is taken from a piece of literature (manual) that was utilized by the NidaCore company as a sales pitch in support of their PP honeycomb core product.

A customer of the NidaCore Corp, in the Caribbean islands had a 65' commercial charter boat, cored entirely with NidaCore polypropylene honeycomb (less the hull bottom), including hull sides, deck and superstructure. It was scratched and water damaged on a coral reef during a major hurricane. The insurance copany agreed to write off the boat on condition that customer takes boat out of service and does not attempt to repair it. The charter boat operator agreed to dismantle the boat and discard of it.

Using one of the marina's cranes, they hoisted the 50,000 lb boat 50 feet in the air and dropped it onto a concrete parking lot, hoping that they would be able to collect the pieces and discard of them in the dumpster. To much of their astonishment the boat remained completely intact, with no visable structural damage. They repeated the procedure continuously for a couple of days to no avail. Finally to accomplish their mission they had no other alternative than to rent a chainsaw to cut the boat into pieces.

Although somewhat of an extreme example, it clearly indicates the superior nature of a 'resilient' cored-sandwich construction in boats. The increase in impact strength as compared to single-skin laminates is better demonstrated if one sees the core as a shock absorber that evenly supports the outside skin from impacts and protects the inside skin, while still having enough elasticity maintain the bond line between the core and the skins. Experience shows that although sandwich construction is not completely punture proof, it significantly increases skin penetrating puncture resistance.

The more brittle cross-linked PVC and SAN foams would simply crumble and shear under a sever impact whereas polypropylene honeycomb cored structures would be locally damaged, however the core structure would be intact, and cells, although elongated would still keep their structure and shape, ready to absorp or withstand more impacts and compressions.
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There are no other specifics supplied,...such as name of vessel, charter organization, island location or marina where this was carried out, what hurricane, etc. And it may have occurred before wide spread info dissemination by the internet came into being?

Is there anyone with any more knowledge as to the details of this 'event' ??

Capt Ralph · Jul 6, 2013

Sounds like a Sales Pitch to me. I would also think the parking lot surface (concrete) would be damaged.

brian eiland · Jul 30, 2013

OK here is the latest info I can uncover. This was sent to me by a gentleman working for nidacore division of 3M

I'm not sure which "drop test" he's referring to. If it is Janot Lemaire's catamaran, it was not a test. The vessel was torn from it's mooring during a hurricane (I believe in the Bahamas because that's where he called me from to order more core and told me what had occurred). The vessel sat on a reef and chewed up the keels and then beached at some resort.

The owner of the resort wanted the vessel cleared off the beach immediately. Janot brought in a crane and spent quite some time (he said three days) picking it up 15 feet off the ground and dropping it to try to break it up. He said it just bounced so they finally resorted to cutting it up with chainsaws.

Mr Lemaire built quite a fleet of these Seminole Cats for Club Meds as well as some others for customers in the Middle East. They had a reputation for being a very tough boat.

Any other info would have to come from Janot Lemaire. I have not seen him in at least ten years. He moved to maybe Guadalupe and then possibly Tahiti where his brother was operating some boats. Everything I know of it was related to me by Janot in that phone call. I believe that was around 1993 or 94
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I found these photos of one of his vessels,...I believe the one in the Bahamas

kiffa · Nov 29, 2013

Janot was just in my office and I have sent him the link to this post, I think the latter story is correct and his boats are very well built, there is still one operating here that has stood the test of time. I hope he gives some more input soon.

karo1776 · Nov 29, 2013

Brian... many years ago... now 32... a company my brother and I owned experimented with a cored graphite skin structure for wings (aero not water). The idea was to allow an internal mechanism change the wing shape and also as impact improvement for small stones kicked up on landing a takeoff landing.

Anyway, we experimented with several layup designs all with resin contents of 27-32% resin (epoxide) to skin material (less core) mass. We found that thin carbon composite skins with a polyethylene foam core of about 4-8 lbs per cubic foot were very good... now what was interesting is it was extremely impact damage tolerant and had good rigidity for the use... note these core thicknesses were in the range of 0.1" to .2" for reference.

Now later some work was done with similar materials for survivability proposes... very good to its limits.

What was strange was the flexible core would transfer the impact loads and protect the skins from localized impact damage...

JUST LIKE YOU TALK ABOUT HERE... !

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Big Catamaran, Big Drop 'Test',....WHAM !!

brian eiland Senior Member

Capt Ralph Senior Member

brian eiland Senior Member

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kiffa New Member

karo1776 Senior Member