1600 stitches per minute isn't going to help when you need to sew really heavy stuff like the corners of a sail.
For that, you need a machine that's slow, but has a ton of torque.
If you can find one in good condition, a Viking Husqvarna like this one is better suited for sewing sails
as it has a high/low gear
The machine in this link also has needle up/down capability, a real plus when turning corners.
BTW, I service
machines for a living and although this machine is not mine, my wife used to have one exactly like it.
Royal Red Husqvarna Viking 6460 Sewing Machine | eBay