Features February 2018 Issue

Undoing Mainsheet Twist

What kind of line do you use in your davit tackle? My lines keep twisting, chafing, and jamming. The ropes run crooked in the blocks no matter how often I restring them,” asks Sailor One.

1. The main sheet tackle runs true with becket swivel locked. 2. A twist-tie locks the swivel. 3. Multi-purchase blocks like these on the dinghy davits love to get twisted.

“Simple. You need a swivel on each of the blocks to let the twist work its way out,” fires Sailor Two.

“No, that’s not it at all,” interjects Sailor Three. “You need to replace that cheap line with some of this top dollar Dyneema line. It never twists like that, and it’s slippery, so there’s less friction.”

All of this sounds logical. Only the swivel advice is dead wrong, and the line doesn’t need to be replaced. They both miss the primary underlying cause completely. While it’s true that every rope likes a good tangle—it’s something deep in their DNA—there is no reason for a tackle to twist if the forces are properly balanced. If the tackle is inclined to twist, the last thing you want to do is enable such misbehavior with a swivel. Instead, use fixed blocks throughout, correcting any major misalignment with an extra shackle. Force any line twist to come out of the last block when the tackle is block-to-block.

Fiddle Blocks. These are always rigged in one plane, using a simple outward spiral pattern. None of the internal blocks should swivel; a swivel there solves nothing and leads to friction. A swivel at one end may be useful, but more often fixed blocks are better.

Double and Triple Blocks. If these are rigged for 4:1 purchase or 6:1 purchase, the problem is nearly always square rigging. An imbalance in forces due to bearing friction, line friction, and sometimes an offset pull on the final exit twists the blocks, cause the ropes to rub and the lines to run crooked in their pulleys. The solution is cross-reeving. Instead of following common sense, winding the lines from right to left in square pattern, lay the blocks at 90 degrees. (See photo #3)

Even if the ropes do rub on occasion, it is more likely they are traveling the same direction, so wear and friction is reduced. If a swivel is required because of the inherent extreme rotation (multi-purchase dinghy lifting tackle loves to get twisted) you can now add a swivel and it should remain well behaved.

Stopping the Spin on Swivel Blocks. Many blocks include a facility for eliminating rotation, generally adjustable in 90-degree intervals. Ronstan blocks can be locked by means of a set screw or special locking washer, depending on the product line. Harken Carbo blocks can be locked at 90-degree intervals.

Even non-locking blocks can be secured either permanently or for test purposes by lashing crisscrossed with anything from cable ties or rigging wire; very little force is actually involved. Take a close look at the swivel and call the factory if all else fails, before buying new blocks.

Other causes. Double braid lines often have a slight construction imbalance, either between the core and the cover or between right and left hand weave. Normally this will settle down after a few dozen hard loading cycles, but it may take as much as a full season. Some lines are worse; Sta-Set Xtra is notorious, due to the core wrap that gives it reduced stretch.

Most single braids and climbing ropes are immune to twisting. Even three-strand rope will settle down given time, although it may require occasionally re-reeving the tackle during the break-in period. Again, with certain applications you may need a swivel to make it run smooth, though never to eliminate twist. However, before running out and buying a new block, try inserting a shackle or a short rope pendant.

Splices, Knots and Line Size. These topics are always contentious—many think a knot looks somehow unfinished—so just a few things to consider:

• Length. The stiffness of the splice may limit the ability of the tackle to go block-to-block.

• Friction. A knot can rub on the lines, increasing friction (generally very minor). Often reversing the knot or using a different knot will solve the problem. Tighten securely and keep the tails reasonably short.

Comments (10)

For real fun, neatly coil the in-boom reefing tails. It will twist up where you can see it. The solution, other than not doing it in the first place, is to work the twist back out with your fingers at the exit. Fun.

I've never understood "neat" coiling. Just lay the line over your hand, which ever way it comes, and secure when finished. I learned coiling with 70M climbing ropes, and once you sort out someone's "neat" coil on a ledge somewhere, you will never let it happen again. Same with power cords. Hoses require special care.

Posted by: Drew Frye | February 8, 2018 1:13 PM    Report this comment

And I thought I was the only one who had this problem! After trying the untwist-the-sheet routine multiple times to no avail on my Newport 28 II, I finally figured out that by replacing the swivel block with a fixed block where the main sheet meets the boom above the traveler made the twisting issue disappeared. Thanks for validating my resolution.

Posted by: Over Budget | February 5, 2018 8:05 AM    Report this comment

And I thought I was the only one who had this problem! After trying the untwist-the-sheet routine multiple times to no avail on my Newport 28 II, I finally figured out that by replacing the swivel block with a fixed block where the main sheet meets the boom above the traveler made the twisting issue disappeared. Thanks for validating my resolution.

Posted by: Over Budget | February 5, 2018 8:05 AM    Report this comment

On my last two boats, Catalina 22 & Catalina 27, with end boom sheeting, I always kept the bitter end secured so it wouldn't twist out. When I sheeted out for a run any built up twist would undo itself. After a few times , the twist was eliminated completely.

Posted by: Scuppers The Sailor Dog | February 4, 2018 2:29 PM    Report this comment

My experience is that when you wind the sheet around a winch three to four times and then move the sheet in or out and then unwind it it throws a Twist in the sheet. So every now and then I have to reave the whole line all the way out to get it straightened out. You would think they would run together and counteract each other but they apparently don't

Posted by: Captchuck | February 4, 2018 10:59 AM    Report this comment

My boat has a fiddle on the bottom, a double on the top, and a separate block on the top to lead to fine tune. It's not clear to me how or if cross reeving could be done. Any ideas?

Posted by: DaveChicago | February 4, 2018 10:18 AM    Report this comment

A few times a season our mainsheet gets loaded with multiple twists in the line, and this results in twists between the blocks. This is caused by some of our neater but inexperienced friends who tidy up our double braided sheets as they would 3-strand rope by putting a half-twist into each coil so the rope hangs in a neat loop. This looks great but introduces twists into the line as it is pulled into the blocks when the boom is let out.

It is important, though counter-intuitive, not to add twists to double-braid when coiling it. Neatly done, the line should hand in a tidy 'figure-8'. Doing so will result in smoother running blocks and fewer tangles.

Posted by: CabinBoy | February 4, 2018 9:24 AM    Report this comment

I have a mainsheet on my Morgan 462 which is composed of two four sheave blocks one with a becket the other with a cam cleat. The only way I could reave the tackle to run smoothly and without binding/twisting was to reave from the becket to the center sheaves then move out to the outer sheaves and then cross over back to the center sheave on the cam cleat lower block. This style of reaving allows for alignment along the centreline of the tackle. This does create a crossover line run but the friction associated with that is minimal. The tackle now runs, comparatively, without effort while under load or not.

Posted by: Mainstreet | February 1, 2018 11:33 AM    Report this comment

No mention was made of walking the mainsheet? Sometimes we find the line twists and causes blocks to turn binding . Walk the line out all the way to the end to relieve this untwisting as you go. Flaking rather than coiling helps in storage.

Posted by: Yachtski | January 22, 2018 10:10 PM    Report this comment

When reeving 4:1 or 6:1 blocks a special pattern is required, hinted to above, but not explained. Google "harken reeving diagrams" for detailed instructions. If you have one of these on davits, they will get tangled eventually; instead of fighting it, pull the rope out, pull the instructions up on your smart phone, and do it right.

Posted by: Drew Frye | January 20, 2018 3:39 PM    Report this comment

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