A hot awl through a sail sounds like a risky stroke. Take care that the rest
of the sail doesn't melt - or worse!! Check the sail material - natural
fibres are less likely to melt of course. Fine cloths, as for spinnakers are
almost certainly polyester or nylon and would sizzle if touched with a hot
tool. Lightweight working sails may go the same way.
A sailmaker's needle or any bodkin of larger size, eased between the threads
of the weave would do the job.
However, there's the alternative of commercially produced adhesive tell-tales.
Usually a sticky circular patch about 2cm diameter with a piece of wool strand
perhaps 15cm long. Mine are coded port and starboard.
Make your own with wool and adhesive tape. If it's removeable tape you can
try different locations. Rolling the sail oftem breaks or removes the wool
but without damage to the sail.
Bruce Longstaff
Verwood, Dorset GB