- To determine the width of the boom tent, I measured the distance between the center of the boom and the bottom wire on the lifelines and multiplied by two. The length was simply the length of the boom itself. We have an aluminum toerail that I planned to use to tie and tension the tent once I laid it over the boom, but I needed strong points in the boom tent to attach the tie-downs.
- Starting from the tack, I measured the needed length along the luff of the sail. By incorporating the grommets that were at regular intervals along the luff (and removing the slugs), I already had strong points on one side of the boom tent to use for tie-downs.
- I measured the width of the tent out from the luff and marked a dot every foot or so. By connecting the dots with a straight edge, I had a cut mark for the other side of the tent.
- After double-checking my measurements, I made the cut and hemmed the raw edge. This particular sail had a fairly flat cut, so I simply used the foot of the sail as the other short end, with the added bonus that the large grommet at the tack worked as a strong tie-down point.
- I now had three edges of my big rectangle complete. The clew had too much reinforcement to do much with (quite heavy and near impossible to sew), so I cut it off, effectively squaring off the fourth side.
- Instead of installing new grommets for tie-downs along this newly cut side, I simply cut off another length of luff from higher up on the sail, making sure the strip was wide enough that it would overlap by a few inches, and sewed it right along the edge, running three lines of stitches for strength and durability.
- Instead of working from a straight edge, this time I measured out from the center, drawing a capital I that was as tall as I wanted my awning long. This would be the centerline that ran along the pole.
- I measured and drew the top and bottom lines to the correct lengths, and then connected the four corners to create the outline of the awning.
- Since this was a much smaller piece of material, the tie-down attachments didn't need to be quite as robust; a loop of strong webbing, well sewn at the corners, would be good enough.
Most industrial-strength sewing machines with a walking foot can handle sailcloth and other heavy fabrics. Sailrite, Juki and Adler machines are popular options, as are older Pfaff and Singer models. The sewing machine you choose will depend on your budget, the projects you have in mind, and your available storage space. According to Sailrite's Matt Grant, a straight stitch is strong enough for sailcovers and boom tents, but a zigzag stitch is important if you also plan to mend sails, as it distributes the stress better across overlapping seams.
Sun exposure for a given project will inform your choice of thread. "We use a 200-denier PTFE or Teflon thread because it's impervious to UV or any chemicals, and lasts the life of the fabric or even longer," says Mark Hood of Hood Marine Canvas and Training. V-92 polyester thread is also a good option, adds Grant. Jeff Serrie of Island Marine Canvas notes that nylon thread is less expensive, but should be reserved for interior upholstery projects that won't have any UV exposure.
You'll need a sharp-point needle in the 20- to 23-gauge range to punch through sailcloth. Increase the gauge if you're planning to sew through more than a few layers. Serrie says you should use a heavier thread and increase the tension on your sewing machine when switching to a larger needle.
Sailcloth is tough stuff, so you'll need a large, sharp pair of scissors to cut patterns. To get through multiple layers and reinforced panels, try a razor blade.