
When you order a kit from them it comes in a box with almost everything you need to make your sail. Pre-cut panels, patches for the corners, hardware, leather including a needle and thread to handsew the leather on and a multi-page instruction manual that is a combination of boilerplate and things specific to your sail. Not included is a setting tool for the spur grommets, though they will happily sell you one.

Not necessary but helpful is their proprietary sewing machine, in this case an LSZ-1. I bought this one when I was getting ready to sew Marianita's sails, previously i had used an old but potent Necchi BU that struggled a bit after 5 or 6 layers of sailcloth. Still have the Necchi but I do like the added power of the LSZ-1. A good pair of scissors, I have three very nice left-handed Ginghers in different sizes but the little thread snipper sees a lot of use.

Corner patches come cut, labeled and stapled together.

They get basted together with double-sided tape.

Then basted/sewn onto the main panel. Sailrite says one row zigzag or two rows straight stitch. My process is to start with the three or four corner patches and fill in from there. Included in the paperwork is a diagram of the sail with all the pieces so you can sew "accessory" bits like reef points in the middle of a panel while it is relatively small.
Comment