We spend the last two days taking out all the screws and washers that held the plywood in place while the glue set, and then cleaning things up; filling the hundreds of little screw holes and filleting joints and edges.
The white you see here and there on the hull is a compound of epoxy, fumed silica, and glass micro-spheres. It’s a lot like bondo, except that it’s structural. The generous fillet where the hull and keel meet smooths the shape, but it also provides strength. Fully hardened this putty is like rock (it’s mostly glass) and a bear to sand, so we do as much shaping as possible when it’s soft.
Once of the very best times to do this is when the putty is partially cured. At that stage it’s got the consistency of candle wax, and yields to a Stanley Surform. Much like our using a cabinet scraper on partially cured panels, using a Surform on partial cured fillets is faster, cleaner and gives a better result than waiting till it’s hard enough to sand and going at it with a power-tool.
Getting at it while the fillets are still soft means Saturday work for me, but tomorrow’s the first day of rehearsal for the Spring show my daughters’ ballet school puts on, so I have to drive to Bridgehampton anyway. Two birds, one stone. Winning!
After the hulls are touched up the seems get two course of biaxial fiberglass tape, then a complete skin of 6 oz glass cloth. Then each hull gets coated with a special fairing blend of epoxy and phenolic micro-balloons. I don’t know why, but a putty made from phenolic micro-ballons is easy to sand; which we will, giving the hulls their final shape.
Filling hundreds of screw holes sounds tricky- if you miss one, does the boat sink?Report
Tedious, but not tricky. The holes 1) dead-end in the stringers; 2) will be covered in glass cloth, epoxy and fairing compound 3) are small enough not to sink a boat, but large enough to be noticable and addressed. All in all, very low stress.
Last Spring I launched S/V INTEMPERANCE with one of her unused thru-hulls open. What a gieser that made! Have not worked out all of our plumbing arrangements, but am working towards no thru-hulls on Mon Tiki
One big difference between the the two boat:
S/V INTEMPERANCE was one continuous interior, a 7,000lbs lead keel trying to find the center of the earth. Left unattended, a 1 inch hole would sink her in a matter of minutes.
Each of Mon Tiki’s two hulls is subdivided into 5 separate water-tight compartments, an Mon Tiki gets her stablity by being very very wide, not from a keel. Even with one compartment completely compromised, she would still float on her lines.
Neither way is better, just different. S/V INTEMPERANCE had a positive righting moment up to 135 degrees; once a catamaran goes past 90 degrees, they go over and stay over.Report
Microcapsules. I’m looking at Rubitherm RT27Report
Very interesting!
FWIW, the barney I have for my cine camera is made with a material that turns the camera sound into heat. when it gets too hot it looses it’s ablitiy to supress sound.Report
Yeah, it’s a weird little molecule, RT27. Here’s moreReport