Twisted double braid

[AndyOz]

I have five lines on my boat (two halyards, three sheets) which are double-braid and have a 2:1 purchase via a block, and tensioned via a winch.

They all suffer from a build up of twist, and eventually the resulting friction from the block swivelling means I have to unfasten and rerun them.

Any tricks on ways to prevent or minimise the twist?

And what causes the twist in the first place? Is it the winch initial wraps? Or the rubbing against the winch skirt turning the line as it is tensioned?

It's more important than you might think, as that twist really builds up on a long passage, and I'd rather not be rerunning lines at sea.

[thinwater]

Originally Posted by AndyOz

I have five lines on my boat (two halyards, three sheets) which are double-braid and have a 2:1 purchase via a block, and tensioned via a winch.

They all suffer from a build up of twist, and eventually the resulting friction from the block swivelling means I have to unfasten and rerun them.

Any tricks on ways to prevent or minimise the twist?

And what causes the twist in the first place? Is it the winch initial wraps? Or the rubbing against the winch skirt turning the line as it is tensioned?

It's more important than you might think, as that twist really builds up on a long passage, and I'd rather not be rerunning lines at sea.

Yup, pretty annoying. There can be many causes, and combinations of causes.

1. Coiling tails. It is really easy to add twist, even if you mindfully try not to, and every time the line is eased, some of that twist is sucked into the tackle. Either figure eight coil (does not need to be pretty, just no induced twist), or reverse every other turn (too much work for anything but heavy cables and hoses, which don't figure eight coil well), or flake into a bag. A plain store coil is deadly.
2. Yes, winch skirts can be a factor. Also turning blocks. But not usually the whole cause.
3. Swivel blocks. Replace every block that does not 100%, absolutely need to swivel with a fixed block. Also, most swivel blocks can be locked. If all you need is a little motion, add a shackle. By fixing the blocks the twist is forced back out of the tackle when it is pulled in. Very, very few blocks actually need to be swivel blocks. Do they actually move through a large range of angle?

Fix 1 and 3 and see if that doesn't solve it.

[AndyOz]

Ah, magic. Thanks.

Seizing wire around the swivels, this could (I repeat, could...) be the first ever 5 minute boat job.

I owe you one.

As an aside, I'm paranoid about coiling. One of my more fastidious skippers insisted that lines be flaked twice, once from the winch end to get rid of twists and tangles, then flaked from the tail end so they'd run out true. He wasn't always right, but he was about that. Or if coiled, figure-eight and a hitch that doesn't pass through the coil.