Originally Posted by smurphny
It also tends to start shredding the thread if you try to go too fast through a lot of layers. I have found that oiling the thread helps with this. A #19 or 20 needle also is a must to avoid thread breakage in thick material.
I'm pretty new to this stuff so maybe the terminology I'm using is wrong.
I haven't made any sails and don't really intend to but I have done quite a bit of my own canvas work. I'm using a "bonded polyester" thread that is really strong and doesn't fray, is this standard/normal?
I have found it sometimes breaks if there were too many layers or if one layer is leather. So I bought needles that are intended for leather and have an "anvil" head or so the sewing shop called it. It cuts cleanly through multiple layers including leather and using the bonded polyester thread, it sews through just about anything.