I have heard to grind a v grove in the crack and mix resin and cabosil to fill them.....does that really work? It looks like on most of mine it would be just as easy to grind the whole spot down and throw some cloth on them. Do you think a single layer of cloth is adaquate? Also I have read to drill a small whole where the crack terminates to keep it from growing.......should I do this too?  Do you drill all the way through the glass...or is the idea to just drill half way through ,or??? I will try to put up a pic or 2 of what I am fixing. Also.....other that the flame itself...is propane heat a bad idea when doing glass....its only mid 40's here this week. I worry about all the humidity assocated with propane heaters.

+1 on what Ralph said. Also you will probably need more than one layer of cloth to properly fix the crack. I personally would grind it deep enough to get at least one layer of mat and a finish layer of cloth preferably  either deck cloth or  a 5-6 oz cloth. As far as the Propane heat is concerned I would stay away from it, If you are using epoxy resin a fast hardener is more than sufficient for  the  temp range. I have been using the epoxy resin from Tap Plastics and am very pleased with the results I have been get

http://www.tapplastics.com/shop/product.php?pid=27&    for the resin.

http://www.tapplastics.com/shop/category.php?bid=6&    for the glass


RC

another valid point^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
if there is a bulk head under that stress crack it will come back until you fix the bulk head.

any part of the bulk head (wood) that is touching the hull will cause cracks.