Poly sail.

I'm currently fitting a SOT for sailing and intend on making a poly sail. I know everyone hates poly sails, but it will only be a test bed, once I have the right size, shape, plus all the other bits and pieces sorted, I'll be making a dacron sail. My question is how do you stick polytarp together for mast sleeve, etc. Have tried before using different glues, but none worked.



I've previously fitted a 12' and a 16' canadian with sails (cut from old mirror sails) but want to avoid wasting good dacron on mistakes.