Mast pocket shrinkage

> 10 years ago
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pirrad
pirrad
SA
850 posts
SA, 850 posts
2 Jan 2016 7:35pm
Had several attempts at getting more downhaul on my 6.7 (2010) Severne O/drive today before getting on the water knowing I would be powered to the max at 23-28 knots. Didn't look right and came in to downhaul some more after hour and half sailing but decided against going out again as the wind was building and need some fuel in the tank for tomorrow.
Before derigging I had a go at downhauling some more and gained 3cm without much trouble, sail looked a lot more like it should.
My thoughts are that the mast pocket, left salty from previous use and stored for quite a while shrinks and wont stretch within reason to get desired downhaul (gave mast pocket a good rinse when I got home, and if at that location next time I rig I will give it a pre-rigging soak under the shower before rigging)

AM I right or dreaming?

( used to have the same opinion a few years back with the Gaastra GTX's )
decrepit
decrepit
WA
12872 posts
WA, 12872 posts
2 Jan 2016 5:55pm
Luff pocket and rope friction are reduced when wet.
I had some sails that were almost all cross cut shaped, so there was no extra shape in the luff curve. This meant that the mast was very tight against the pocket before full downhaul could be achieved. Even though there wasn't a lot of mast bend getting full downhaul took a lot of effort.
I used to pre wet the luff pocket before rigging, it made things much easier.

Ian K
Ian K
WA
4169 posts
WA, 4169 posts
2 Jan 2016 6:43pm
i think Decrepit has got it. A lot of the work (Force times distance ) of down hauling goes into friction. If the system was frictionless the tension in the rope would be the same regardless of whether you were putting on more downhaul or letting it off slowly. It seems to me that once you've got that cleat undone the tension while letting off downhaul is noticeably less.

It always puzzled me that the old NP RS slaloms took a lot to downhaul but the mast didn't seem unusually curved? I thought maybe the bend was biased and unnoticed in the stiffer lower section? Maybe the luff material just stuck to masts? I used to use a silicon spray on the mast to make down hauling a bit easier, but water is probably a better idea.
ikw777
ikw777
QLD
2995 posts
QLD, 2995 posts
2 Jan 2016 8:54pm
Sometimes I wet my downhaul line to make it a bit easier to downhaul the sail when rigging. It works very well.
Sputnik11
Sputnik11
VIC
972 posts
VIC, 972 posts
2 Jan 2016 10:00pm
How cold was it?

Brien
Brien
NSW
172 posts
NSW, 172 posts
2 Jan 2016 10:10pm
It is more than likely the webbing that is often folded over to protect the stitching on the vertical seam in the luff sock that has shrunk.
pirrad
pirrad
SA
850 posts
SA, 850 posts
2 Jan 2016 9:43pm
Sputnik11 said..
How cold was it?



20 ish degrees, according to willy weather temp graph, forecast was 23.
Tardy
Tardy
5337 posts
5337 posts
3 Jan 2016 8:02am
I think your onto it..I leave a few sails at my mates place in WA and only use them ones a year .in his hot shed ...the ones I don't wash are as stiff as a board ..maybe use some fabric softness ..on the sail cloth pocket ?
Mastbender
Mastbender
1972 posts
1972 posts
12 Apr 2016 5:26am
I normally allow my sail to dry before de-rigging it, beer time, so when I release the down haul, the mast pocket can't shrink because it's already dry.
But when I re-rig it, it's hard to down haul because of some friction in the pocket, but mostly with the down haul line and base extension being dry.
Like mentioned before, I pour some water on the down haul line only, as well as the base, easy rigging is the result. Even salt water will work if you only have a little drinking water, or beer even.

At least you weren't asking about mast shrinkage.
Faff
Faff
VIC
1417 posts
VIC, 1417 posts
12 Apr 2016 8:36am
Formuline (dyneema) rope.
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