I’m building a Mill Creek 13 and I glassed the exterior hull with 6oz e-glass and also glassed the interior with 4oz s-glass. Just curious if the strength is about equal for both sides. I will still use 6oz e-glass on the bottoms of future builds for increased thickness for abrasion resistance. BTW the additional weight of the interior glass was just under 3lbs.
Doug
hi doug,
with respect to tensile strength (think how much weight a strand could hold) 4 oz of s glass is roughly equal to 6 oz e glass.
as you mention, there are other properties/strengths….so the thicker layup is nominally more abrasion resistance.
in my builds i routinely just build all in 4 oz s glass and take the weigth savings. where i have concerns about abrasion, i usually will use a small rub strip. while a thicker layer of epoxy is more abrasion resistant than a thinner layers, raw epoxy and s glass or e-glass are not really effective against any real abrasion like running up a beach or ramp more than a dozen times …before it will abraid through….hence the rub strips i will use right on the keel at the bow and stern knuckles.
h
Thanks for your reply Howard. I’ve been using s-glass more and more wanting to do what you are doing trying to save weight. It seems like an even trade 4oz s-glass to 6oz e-glass on paper I just wanted to make sure I wasn’t doing something I’d regret later. I know I don’t need to glass the interior of my yak anyway but I just wanted to. Other than adding weight <3lbs it’s a lot of bang for the buck strength wise. I also agree with a statement you made before that saving weight is by the Oz. I would like to do what you are doing on my next build and see how light I could go. Always another hill to climb!
Howard, who do you use as a source of 4oz S glass? Also do you apply rub strips on before or after the full layer of glass. I am starting a new boat for my wife and was wondering which order is best. Thanks David
Hi David,
i have sourced my S glass from a place called Sweet Composites. https://sweetcomposites.com/ . They were a local small business here in Maryland but it looks like they may have relocated to North Carolina recently.
i do my rub strips with dynel fabric and graphite infused epoxy after the glass is applied…same basic construction as the clc kit…but as usual with me, i really try to keep them small and only where they are needed.
one advantage of the light boats i build (i have three sub 30 lbs boats i regularly paddle) is that they are easy to pick up…..vs feeling like you need to drag them. i also am attentive to my cockpit coaming size to so i ensure my coaming length is such that i can sit first and pull my legs in.
when i launch the boat, i place the boat in shallow water, straddle the boat, put my butt in, then retract my legs and paddle off without touching the bottom….and reverse the process on the way in. so i don’t typically run the boat up on to the land but pull it into the shallow, step out, and pick the boat up…and place it above the waterline or right to the car. again, a light boat makes this relatively easy.
like everything, fwiw, glass is getting more expensive but i found for my strip builts, that i could buy 60 inch wide cloth from Sweet which, with some careful cutting, almost always allows me to get an inner and and outer sheathing of the hull or deck from one piece of cloth the length of boat. so a 15 foot boat could be built with only 30 feet of cloth (or 60 feet of ~ 30 inch wide cloth). i carefully keep most of my scraps and use them to glass smaller parts.
another item that i buy from Sweet which they stock is 2 oz e glass. which is useful for glassing a bulkhead or other piece that sometimes we would just paint with epoxy. it’s super light and does not use any more resin then an epoxy coat….but really adds strength. i will, often, also use it for interiors where they simply specify overcoating with epoxy.
h