How much is downhaul tension at race sails?
Severen sail has 4 pulleys ,8 lines..my proximation is when pull rope around 50kg so mulitply 8 it is around 400kg?

choco said..

This calibration only works for original Ezzy mast..but even same masts are slighlty differents in stiffnes,so this system works only for one mast that was used when calibration was made..

Downhaul tension (load cell) is function of mast stiffnes and sail luff curve.
I you put diffrent mast and use " Ezzy downhaul system" and align line with mast end,sail will gat completly different shape.
So i think is better visual leech loosnes option with min and max dot at head..

Sail at video has RDM mast and little luff curve ,tension is 159kg, so it seems my proximation of 300/400 kg for race sails is OK..
That is huge force at sail materials!!

choco said..

hotlap said..

choco said..

This calibration only works for original Ezzy mast..but even same masts are slighlty differents in stiffnes,so this system works only for one mast that was used when calibration was made..

Downhaul tension (load cell) is function of mast stiffnes and sail luff curve.
I you put diffrent mast and use " Ezzy downhaul system" and align line with mast end,sail will gat completly different shape.
So i think is better visual leech loosnes option with min and max dot at head..

Sail at video has RDM mast and little luff curve ,tension is 159kg, so it seems my proximation of 300/400 kg for race sails is OK..
That is huge force at sail materials!!

I posted the video so you may get an idea about sail tension load, don't overthink things, just enjoy sailing.

i cant sail anymore

hotlap said..

choco said..

This calibration only works for original Ezzy mast..but even same masts are slighlty differents in stiffnes,so this system works only for one mast that was used when calibration was made..

Downhaul tension (load cell) is function of mast stiffnes and sail luff curve.
I you put diffrent mast and use " Ezzy downhaul system" and align line with mast end,sail will gat completly different shape.
So i think is better visual leech loosnes option with min and max dot at head..

Sail at video has RDM mast and little luff curve ,tension is 159kg, so it seems my proximation of 300/400 kg for race sails is OK..
That is huge force at sail materials!!

But if you use another mast you can re-calibrate the trim guide by setting the downhaul to the medium setting on the dots on the leech then moving the guide to match on the Velcro. I've had several Ezzy sails now and each one matched dots to guide without moving the guide. Even after 100 sessions it still matches, the material doesn't stretch over time. I think its its a simple and effective trim guide, much easier than looking at the leech if you have uneven ground, gusty winds moving the sail around. I think the x-ply on Ezzy sails makes it harder to spot exactly where the looseness is, whereas on a monofilm sail the material is more supple.
If you use a flex top mast then looking at the dots on the leech wont help because the head will get too loose for the shape around the boom.
Ezzy sails have a lot of shape through seaming, they dont rely on downhaul tension to achieve the correct shape as much. I reckon my Naish Redline freerace sails needed twice the downhaul load of my Ezzy Lions, possibly more. I had to use a winch.

275-450 POUNDS.

presume 4:1 would place greater load strain on rope than 6:1 , ? .... so poss to break downhaul easier ?

???? So why not pick up Panducah for using the same British/American units in the preceding post? Anyway to be technically pedantic tension should be measured in newtons. Type "275 pounds in newtons" into google.

Back in the days of big downhauls you'd find a wet sail easier to downhaul than a dry sail. Or spray the mast with a silicon lubricant.

(Is that Mr Ezzy himself measuring tension in pounds in the second post? It's OK then)

PhilUK said..

hotlap said..

choco said..

This calibration only works for original Ezzy mast..but even same masts are slighlty differents in stiffnes,so this system works only for one mast that was used when calibration was made..

Downhaul tension (load cell) is function of mast stiffnes and sail luff curve.
I you put diffrent mast and use " Ezzy downhaul system" and align line with mast end,sail will gat completly different shape.
So i think is better visual leech loosnes option with min and max dot at head..

Sail at video has RDM mast and little luff curve ,tension is 159kg, so it seems my proximation of 300/400 kg for race sails is OK..
That is huge force at sail materials!!

But if you use another mast you can re-calibrate the trim guide by setting the downhaul to the medium setting on the dots on the leech then moving the guide to match on the Velcro. I've had several Ezzy sails now and each one matched dots to guide without moving the guide. Even after 100 sessions it still matches, the material doesn't stretch over time. I think its its a simple and effective trim guide, much easier than looking at the leech if you have uneven ground, gusty winds moving the sail around. I think the x-ply on Ezzy sails makes it harder to spot exactly where the looseness is, whereas on a monofilm sail the material is more supple.
If you use a flex top mast then looking at the dots on the leech wont help because the head will get too loose for the shape around the boom.
Ezzy sails have a lot of shape through seaming, they dont rely on downhaul tension to achieve the correct shape as much. I reckon my Naish Redline freerace sails needed twice the downhaul load of my Ezzy Lions, possibly more. I had to use a winch.

One point u mentioned is that the material doesn't stretch over time. This is for sure depended on the material mix but for most of the materials used in sails I think this is not true. From my experience and also from material theory the material gets worn off over time. Creep occure on fiber reinforced polymers too. Maybe this effect does not mainly drive the change in sail feeling. From my experience sails generate a different feeling during the first sessions and after a couple of 100 sessions or a couple of years. Laminate sails as past S1 Pro Versions hold the initial feeling much longer than sails with Dacron panels around the mast. Did someone has the same experiences?