Some of the new coring material (divinicell??) is supposed to address the balsa/foam issues.
Anyone with specific knowledge?? Neil Andersen Rock Hall, MD 21661 484-354-8800 ________________________________ From: CHARLES SCHEAFFER via CnC-List <cnc-list@cnc-list.com> Sent: Friday, September 17, 2021 10:39:29 AM To: Stus-List <cnc-list@cnc-list.com> Cc: CHARLES SCHEAFFER <cscheaf...@comcast.net> Subject: Stus-List Re: Balsa core history That's a great story about Pearson starting the end grain orientation. I wonder if that's 100% true. I'll bet several others would have thought of that as well. Anyone who works with wood knows the compression strength is best when wood grain is oriented that way. Honeycomb cores are end grain oriented for the same reason. I read an article I can't seem to find again, that compared balsa to foam as coring and they determined the balsa was better; stronger bond because the end grain wicks up resin, lower cost, better for the environment too, as it's a renewable source. Coosa board has better water resistance but it's so much more expensive; it comes in sheets that add to shipping costs. ContourKore Balsa is a series of cut squares, attached to a scrim that can be rolled so it packs into a smaller package and ships for less. I used balsa to replace wet core on my boat. Some of the wet balsa still had a very strong hold on the fiberglass, and I had to use a chisel to pry it loose and an angle grinder to smooth the remnants off. Pretty amazing stuff. Chuck S On 09/16/2021 6:21 PM Lisle Kingery, PhD via CnC-List <cnc-list@cnc-list.com> wrote: FWIW, this prompted me to take a look at the book "Heart of Glass: Fiberglass boats and the men who made them": and some info on Balsa is on p122, "Balsa Core. The Baltek Corporation was the exclusive supplier to powerboat builders of balsa planks for stiffening hull sides and bottoms. When balsa was originally supplied in lengths with the grain running longitudinally, Pearson had problems with water migrating away from the point of entry at the deck hardware fasteners, causing delamination. Everett Perason recalls that "We were using pieces 3 feet long by 1/2 inch thick by 2 inches wide. We had some leaks at the fittings, which didn't make any sense. So I started stacking this stuff up and cutting it on the bandsaw and making end-grain balsa. I was doing that on Constitution Street when Alex Lippay and Bob Levine came in from Baltek. They said "What are you doing". I sadi "I got to turn this stuff the other way to stop the water from spreading. They said "Jeez, this is what we should be doing." I said "You're right". That's how Contourkore started. They took the end-grain idea and made samples that we evaluated. They came up with a method of putting scrim on it and so forth. In hindsight, I should have applied for a patent. I think we were probably one of the first to use Contourkore, as early as 1963 in a race boat hull. THe new product was brought to market in 1963 and 1964, with Pearson as one of the its first few users and most vocal supporters. Indeed, in 1981, Pearson sank a 2-square-foot basl cored panel in Narragansett Bay, attached by change to his dock. After three years he removed the panel from the water and had it analyzed. The results? No water penetrated the balso more than 4 mils." Best, Lisle On Thu, Sep 16, 2021 at 4:23 PM CHARLES SCHEAFFER via CnC-List <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> wrote: "Balsa core" gets some bad press and I was interested in how it came into boating, especially C&Cs. After some research, I learned: Making things with a core was first used by Egyptians three thousand years ago. Veneers of precious wood over a core of cheaper wood extended the use of precious materials. The practice was lost in the middle ages and re-imagined in the 1700's when furniture makers wanted to make things from scarce woods. Later in the 1920's and 30's, balsa core was being harvested in Equador by a French company trying to market it in France in the 20's and 30's. The Jewish French owners fled the Nazi takeover and emigrated to the US. Their balsa was later used by DeHaviland in England to build the famous Mosquito two engine bombers in 1941. Dehavilland built over 7700 of these 400+ mph planes using two Spitfire engines each. They used a plywood vaneer over an endgrain balsa core. https://www.youtube.com/watch?v=JTsnMKzmdWs&t=613s The balsa industry lost a market after WWII but in the 70's, they convinced fiberglass boat builders to use balsa core and Hatteras sportfishing yachts were their first big client. Almost all boat builders eventually started using balsa soon after, including C&C, Pearson, Santana, Cape Dory, Columbia, Catalina, Hunter, Olsen, Saber, Schock, J-Boats, Beneteau, Jeanneau, as well as all the power boat builders, too. https://www.company-histories.com/Baltek-Corporation-Company-History.html Core comparisons: https://www.cruisingworld.com/how/inner-layer-core-materials-sailboat-construction/ I personally think C&C did an industry leading job to perfect the process using fiberglass and balsa core to build a lightweight and strong structure, but that is better covered by John Kelly Cuthbertson or others with more personal knowledge. Chuck Scheaffer, Resolute, 1989 C&C 34R, Annapolis Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
