Wondering if anyone has any good/bad points or advice about sail thread weight and type.
Going to be restitching the seams on my jib and main, showing some fraying and general wear.
I do have two industrial sewing machines and have been making/repairing kitesurfing kites and gear for a few years. Not sure if the 40 wt serafill thread will be strong enough for sails.
boats a wharram tiki 30.
Haven't used the Serafil thread myself so can't comment on its strength or UV resistance. For my 4oz & 5oz Dacron sails I use the V69 Dabond, for 6-7oz sailcloth I'd go with a V92 thread and anything heavier then that I'd use V138 thread. See
www.sewingmachinesaustralia.com.au/shop/buy-accessories/sewing-threads/coats-dabond-uv-treated for more info.
have ordered some dabond v138 black and white,will see how it goes and report back on ease of use, Give me a few years and can report on longevity as well!
Select to expand quoteandycass said..
have ordered some dabond v138 black and white,will see how it goes and report back on ease of use, Give me a few years and can report on longevity as well!
Not sure how heavy duty the sails on your tiki 30 are but I'd say the v138 thread will outlast your sailcloth. 
V69 would have been ample. V138 is going to add a lot of weight and slow you down!
I probably should have added a smiley face! V69 is more than ample for a 30 footer. V138 is going to stand proud of the cloth a bit. Just a quick look in my sewing room and the heaviest thread I have is V92.
Definitely.
I used some v138 to sew a new boltrope on a 5 oz sail only because I ran out of v92 and couldn't find a local supplier. Yes it is definitely more visible then v69 at twice the thickness but it also has a breaking strain above 10kg so it makes up in performance and withstand longer UV exposure before breakind down if you don't mind the heavy duty look. Would look even better if used in a neat zigzag pattern in a color that also stands out, like Navy Blue or Crimson Red on white sailcloth. 
Btw, do you know of any online local supplier of V92 ?
www.sewingmachinesaustralia.com.au/shop/buy-accessories/sewing-threads/coats-dabond-uv-treated
They don't list V92 on the website, but I've bought it from them several times.
I find that V69 only lasts a couple of years or less of continuous exposure in Qld. Maybe not so important for work on sails, but for covers I always use V92 or V138 to maximise UV performance.
Yes, Tenara does seem to be the ultimate, although I haven't found a reasonably-prices source in AU. Apparently you do need to go to a fair bit of trouble to set the machine up to use it.
Our local canvas shop has told me they charge an extra few hundred dollars for anyone who asks for Tenara, just to cover the setup PITA. On the other hand, from the shop's point of view, it's in their best interests to discourage customers from using Tenara because they'll never get a re-stitch job. I think the re-stitches are a pretty reliable source of recurring income.
Select to expand quoteRamona said..
I have found using straight stitch instead of zig zag on my sail cover it has lasted much better. I have been using a boat trailer winch strap for years I stitched with v69.
On winch straps you should try v138 , has over 10kg breaking strain and will outlast the v69 a few times over. Or else try some v207 in the Speedy Stitcher, should last the life of the straps.
I used v138 on my front tramps on the cat and despite being full time in the sun , salt water spray and walked on for the past 2 years they still look as good as the day I fitted them.
just got the cones of 18 wt/v138 thread and ran some scrap canvas through the machine went well once i put a fence post in for a needle. I reckon the extra weight and wind drag will slow me down, at least i can use the surplus thread for spare rigging! It looks like rope compared to my usual 60wt or 40 wt thread. Definitely will outlast my sails, probably outlast me too.
Select to expand quoteandycass said..
just got the cones of 18 wt/v138 thread and ran some scrap canvas through the machine went well once i put a fence post in for a needle. I reckon the extra weight and wind drag will slow me down, at least i can use the surplus thread for spare rigging! It looks like rope compared to my usual 60wt or 40 wt thread. Definitely will outlast my sails, probably outlast me too.
Apart from the thread showing, the holes will have quite an effect with the sun shining through when you gaze up to admire your handy work.
Size 20 needles should be sufficient for up to 4 layers of 7-8 oz cloth. For corner patches I need to go up in needle size to a 22 and all the way up to a 24, although by then I have to use brute force instead of the motor and may take a few goes to get the needle through the material. It is only after that method no longer works that I change to a Speedy Stitcher.
I have an old Singer treadle sewing machine with the same needle as my industrial Singer machine. With the belt twitched up tight this will drive through about 4mm of cloth with ease. The industrial machine balks at it. Only straight stitch though. Impressive bit of engineering from the early fifties.
