Stitch and Glue Questions
Posted: Dec 20th, '11, 12:58
I am building a rowing dingy using the stitch and glue technique. It is my own design and meant to be cheap, easy to build, and LIGHT WEIGHT.
LIGHT WEIGHT is paramount because I have to carry it up and down the beach to use it. Trust me. An extra two or three pounds seems insignificant when you are carrying the thing down to the water, but when it comes to carrying it back to the truck after a long row those few pounds really matter! Along those same lines the boat will only be in use for brief periods and will live out of the water at other times; probably in my back yard on saw horses when its not on the lumber rack of my pick-up truck. No inside storage; hence the cheap and easy to build parameters. This thing is going to live a tough, probably short, life! The hull must be water proof enough that the wood doesn’t soak up moisture while in use or when exposed to occasional rain or snow, but it does not have to resist water intrusion through osmosis from prolonged periods of sitting in the drink or from water sitting in the bilge.
Most stitch and glue boats specify a layer of fiberglass cloth over most of the exterior of the hull. They also spec a layer of fiberglass cloth on at least part of the inside of the hull, particularly the bilges. In this way it is like cored hull construction. The glass gives it strength and the plywood acts as the core. I can already tell that I do not need these cloth layers for panel stiffness or strength. Since it’s a dinghy the panels have small spans and loads will be light, so the “naked†plywood has sufficient strength on its own. Also I am not going offshore or doing surf rescue so a hull failure wouldn’t be life threatening. So I am intending to omit the two layers of cloth and avoid the added weight of the resin and fairing compound they would require. However I still need to fill the grain of the wood and to create an effective water barrier suitable per the aforementioned parameters of use.
Some Stitch and Glue boats use West Epoxy and roll it all over the hull even where there is no cloth as a sealant and water barrier. I suppose that would work but it seems excessively thick and heavy. Instead I am considering using some sort of epoxy coating inside and out, like a barrier coat or a thick epoxy primer or epoxy paint. Maybe even West thinned down with MEK or some other suitable solvent.
I have no experience with barrier coats or epoxy paints. Has anyone got any input as to what might do a nice job? Ideally it would be relatively thin so it flows and levels like a paint, but be just thick enough to fill the fine grain of the plywood and perhaps also fill the small holes left by the stitches (1/16 inch dia.) It would either leave a nice smooth finish, or could be easily sanded to one for a final color coat.
Any input would be much appreciated.
Thanks and Merry Christmas!
Peter
LIGHT WEIGHT is paramount because I have to carry it up and down the beach to use it. Trust me. An extra two or three pounds seems insignificant when you are carrying the thing down to the water, but when it comes to carrying it back to the truck after a long row those few pounds really matter! Along those same lines the boat will only be in use for brief periods and will live out of the water at other times; probably in my back yard on saw horses when its not on the lumber rack of my pick-up truck. No inside storage; hence the cheap and easy to build parameters. This thing is going to live a tough, probably short, life! The hull must be water proof enough that the wood doesn’t soak up moisture while in use or when exposed to occasional rain or snow, but it does not have to resist water intrusion through osmosis from prolonged periods of sitting in the drink or from water sitting in the bilge.
Most stitch and glue boats specify a layer of fiberglass cloth over most of the exterior of the hull. They also spec a layer of fiberglass cloth on at least part of the inside of the hull, particularly the bilges. In this way it is like cored hull construction. The glass gives it strength and the plywood acts as the core. I can already tell that I do not need these cloth layers for panel stiffness or strength. Since it’s a dinghy the panels have small spans and loads will be light, so the “naked†plywood has sufficient strength on its own. Also I am not going offshore or doing surf rescue so a hull failure wouldn’t be life threatening. So I am intending to omit the two layers of cloth and avoid the added weight of the resin and fairing compound they would require. However I still need to fill the grain of the wood and to create an effective water barrier suitable per the aforementioned parameters of use.
Some Stitch and Glue boats use West Epoxy and roll it all over the hull even where there is no cloth as a sealant and water barrier. I suppose that would work but it seems excessively thick and heavy. Instead I am considering using some sort of epoxy coating inside and out, like a barrier coat or a thick epoxy primer or epoxy paint. Maybe even West thinned down with MEK or some other suitable solvent.
I have no experience with barrier coats or epoxy paints. Has anyone got any input as to what might do a nice job? Ideally it would be relatively thin so it flows and levels like a paint, but be just thick enough to fill the fine grain of the plywood and perhaps also fill the small holes left by the stitches (1/16 inch dia.) It would either leave a nice smooth finish, or could be easily sanded to one for a final color coat.
Any input would be much appreciated.
Thanks and Merry Christmas!
Peter
