Builders' Forum Archives
Re: cutting darts?
Posted by Howard on Oct 22, 2005
the best way to envision a dart would be like trying to wrap a piece of paper around the corner of a box.
if you tried to push the paper around the three sides coming into the corner, a section of the paper is going to "pop out" and not lay flat (unless you fold the paper in on itself). if you take a scissors and cut from the edge of the paper sticking out and into the corner of the box....this is a "dart". once you do this you can now lay the paper flat around the corner without "folding" the paper.
another way to visualize this is take a circular shaped piece of paper and try to fold it around a corner of a box with the center of the circle on the corner of the box. again you get wrinkles. but if you take the round piece of paper and cut a radius in it (cut from the edge to the center). if you put the center on the corner of the box, you can now get the paper to wrap around the corner with no wrinkles. again...that cut from the edge to the center...is what is meant as a dart.
so when you translate this now to the boat...you lay the cloth over the hull...and pull it tight. around the corners, where the bottom of the hull meets the bow and stern, you will not be able to get the glass to lie flat (it will wrinkle like the box corner discussed above). you cut the dart from the edge of the glass to the corner in order to avoid the glass from wrinkling/having to fold over on itself. once you cut the dart, you can get the glass to lay flat. when you do this you will get some areas with double glass...this is ok...but you do not want to fold the glass cloth.
a last point on cutting the darts. don't cut them until you have filled the weave with epoxy on the centre of the boat..sides and bottom. (when you do your glassing. you work from the centre of the boat towards the ends) the reason for waiting to cut them is that as you apply epoxy to the glass the boat...its position will shift slightly...so you cannot determine exactly where to cut the darts until you have gotten right down to the ends wetting out the epoxy.
In Response to: cutting darts? by Eric Swenson on Oct 22, 2005