Balsa experiment, It’s only been one week...

[transomstand]

The balsa fear is grossly over stated imo.

More like total hysteria

[XstreamVking]

If you saturate the balsa it kinda negates the lightness feature of it. Also the resin's weight will not add strength. Better to go light on the saturation and seal with gell after layup IMO.

[LakeFever]

It didn’t really take all that much to seal it up on my build. Most of the balsa was shiny after two coats rolled on. There was some pieces that took 9? Passes or so. Less than 10% was very thirsty. My hull with cored deck and way more 1708 than probably nec came in at 694lbs. Xstream it would be great to know your hulls weight to compare. For those that haven’t seen my build its a 79 vking.

still thinking about running a third round of this balsa test. Cant help myself the curiosity itch gets the better of me

[Mark Poole ModVP]

Boat builder I worked for many years ago bonded the balsa down into two layers of very resin rich chop strand mat. I read some where that the best way was to bed it in a bonding compound that was troweled on. And...that the underside should be 'hot coated' before putting it down.

[LakeFever]

Makes sense to me so thats why i did that on my recore. We placed the balsa sheets over a piece of pipe to open the balsa blocks up and did two very wet coats of resin. We used ATC corebond and troweled that down to the hull and laid the balsa in before the resin kicked. The corebond squeezed up between the blocks and made a very tight void free fit. When we got to the more curvy areas we used more corebond so there would be no voids between balsa blocks. When we had the core fully laid and cured we sanded the entire core smooth and flat then vinylester resin coated the top side until saturated. Then laid 2 layers of 1708 overtop again using vinylester. Further laying more layers of 1708 when running stringers using one piece down, across, and up over the pad and stringers. In the end it looked like a gym floor with a super smooth finish over top. I’m sure it could and has been done better but im very pleased with how it turned out. If anything gets spongy or goes dark i will certainly update my build thread.

[loop]

Thanks for performing this experiment to help people understand balsa better. Balsa is sometimes improperly installed and has had plenty of miserable failures because of it.
when i prepped my balsa coring i took a 4x8 sheet of pegboard and forced it longways between the wheel wells in the bed of my truck. In less than 2 minutes i had a nice large arch to lay it over. Covered it with sheet polyethylene so nothing would stick. Laid the balsa over diagonally so all the blocks were spread apart in both directions. rolled on some slightly thinned vinyl resin then flopped the sheet around a little just to make sure the resin reached all the way to the bottom. Then just let it harden/dry in this position so the blocks wouldnt stick together. Balsa had been stored inside my hose to keep it good and dry. I waited for a day with very low humidity to do the coating since i had already leaned (the hard way) that balsa WILL absorb moisture from the air.
Doing this gave me piece of mind that all the blocks are individually sealed the way they were intended to be. i've seen plenty of balsa work that wasnt sealed this way and theres nothing there to stop water and rot migration from one block to the next. Balsa being open cell, it seems like this should be done before any vacuum bagging also to prevent complete resin saturation of the individual blocks which would completely defeat the purpose of a light weight core material.