Constrictor Clutches

Mar 23, 2025
25
Catalina 250 Lake Somerville
I was researching which clutches to add to the mast of my Catalina 270. It seems that many experienced sailors have switched from Spinlock/Lewmar/Garhauer/etc to "Constrictor Clutches" (invented by Cousin Trestic and manufactured by Ronstan?). Are these constrictor clutches still in production? Are they still in use? Why aren't they more popular? Most online retailers are out of stock of them and/or don't have any reviews on them. If I can source them, are they a good choice for a halyard clutch mounted on the mast? Can I use them on a mast or do they need to be mounted on a flat surface?

Thanks
 
Mar 23, 2025
25
Catalina 250 Lake Somerville
Currently the halyard is led from a turning block at the mast base, to a turning block on the cabin top, to a clutch on the starboard side by the cabin top winch. The problem is that there is a lot of extra friction that makes the mainsail unnecessarily difficult to raise. It has to be slowly winched up. When I’m on a port tack, the starboard winch has the working jib sheet, so I have to run the main halyard back to the starboard cockpit winch, which I cannot turn 360 degrees because the lifeline is in the way. So raising the mainsail is unnecessarily slow and laborious. For more background: I always 1) cut the motor 2) raise the jib before the main, 3) then raise the main last. My reasoning for doing this is because I can’t raise my main without heading upwind, and while I believe most people motor into the wind and raise their mainsail first, I like to be practiced at raising my sails without a motor. Another Catalina 270 owner changed his rigging by terminating the main halyard at the mast (and he added a small winch on the mast for this purpose). He said the main halyard was far easier this way. I often take large groups of family, and when the cockpit it crammed, I think it would be an advantage to have more lines terminated midship.

Would a cam cleat have any advantage over a clutch? I guess it is cheaper, simpler, and easier to maintain, but it can’t release under a heavy load like a clutch can. I like having the ability to drop sails very quickly when necessary.
 

PaulK

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Dec 1, 2009
1,390
Sabre 402 Southport, CT
You might be amazed at how fast a loaded cam cleat can be released when it needs to be done. Raising the main on a Catalina 250 (or 270) should not require winching it up all the way. Your slot may need cleaning and lubricating. Having someone jump it at the mast helps on our boat too. We hoist the main first with the motor running because it helps keep us headed into the wind and we can see where we're going.
 

colemj

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Jul 13, 2004
575
Dolphin Catamaran Dolphin 460 Mystic, CT
The advantage of constrictor clutches are that they are easier on the rope, can be used with bare dyneema, and can be gradually released to allow small adjustments of the line. None of these are of much advantage for a main halyard that gets raised and stays static in a clutch, then dropped. Unless you are using bare dyneema for a main halyard.

The disadvantage of constrictor clutches are the amount of mounting space they require. This will likely be an issue on a mast.

You can make your own constrictor clutches. Like everything involving single braid dyneema, it is really simple. You just thread the halyard through a length of dyneema inserting it a few inches from one end of the dyneema and exiting a few inches from the other end of the dyneema. Fix the end of the dyneema facing the direction the halyard end (the end you pull), connect the other end of the dyneema to a bungie cord and fix the end of the bungee cord so that the dyneema is stretched out. Also connect a pull rope to that end of the dyneema.

When you pull the halyard, the dyneema is bunched up and allows the halyard to pass through it, but when you stop pulling the halyard, the dyneema grabs it like a Chinese finger trap. To release or let out a bit of the halyard, you pull on the pull cord, it slowly starts to bunch up and let the halyard slip.

Mark
 
May 17, 2004
5,642
Beneteau Oceanis 37 Havre de Grace
I always 1) cut the motor 2) raise the jib before the main, 3) then raise the main last. My reasoning for doing this is because I can’t raise my main without heading upwind, and while I believe most people motor into the wind and raise their mainsail first, I like to be practiced at raising my sails without a motor.
Getting occasional practice to know it’s possible is good, but you’re probably introducing a lot of friction by trying to hoist the main when it’s not straight into the wind and fully luffing. Before you go moving the termination to the mast I would try raising the sail while motoring into the wind to see if that works more easily. Make sure the sheet is fully eased too - you don’t want to have any tension or pull at all on the luff. I’d also experiment by going to the mast and just trying to raise the sail from there, even if you can’t cleat it there. That will tell you how much friction the blocks are really adding, versus how much may be from a dirty track or your hoisting technique.


Currently the halyard is led from a turning block at the mast base, to a turning block on the cabin top, to a clutch on the starboard side by the cabin top winch.
Does the line run from that clutch straight to the winch? I find clutches can add quite a bit of friction if the entrance or exit angle isn’t quite straight.
 
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Mar 23, 2025
25
Catalina 250 Lake Somerville
Awesome input, thanks y’all!

Davidasailor26,
- Good idea on hoisting it from the mast as a test before committing to buying and mounting additional hardware.
- while raising the main, I sail perhaps 45 degrees apparent wind and have the mainsheet completely eased. Friction in the blocks often prevents the boom from swinging out as far as I like, so I usually give the boom an extra push with my hands. The mainsail is not under load while being raised. That is my method. It is much more pleasurable to me to raise the sails without the motor off.
- No it is not a straight shot from the halyard clutch on the cabin top to the starboard winch. You’re right that that is adding extra friction.

As long as the mainsail is not under load, I should be able to raise it to the top (but not very tight) without mechanical advantage. The fact that I’m not able to means that there is friction somewhere. It could be the sail track, sail slugs, or turning blocks. I’m just guessing it is the turning blocks based off of one guys anecdote that it was far easier to raise his mainsail on his 270 from the mast.
 
Jan 11, 2014
12,874
Sabre 362 113 Fair Haven, NY
As others have said, if you need a winch to raise a mainsail on a 25' boat, something is seriously wrong.

Top candidates:

  1. Raising the mast when the sail isn't luffing into the wind.
  2. Dirty mast track and sail slugs. Spiders love mast tracks.
  3. Dirty, worn, or seized sheaves at the mast head.
  4. Dirty, worn or seized turning blocks.
  5. Poorly tuned mast, mast is not in column.
  6. Oversized sail slugs.
  7. Undersized sail slugs, the slug goes sideways in the track and jams.

Start at the top of the list and work your way down. By the time you get to the bottom your problem will be solved.
 
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colemj

.
Jul 13, 2004
575
Dolphin Catamaran Dolphin 460 Mystic, CT

Colemj, does this commercial constrictor setup work on the same principle as yours?
I don't have constrictor clutches, but yes, those work on the same principle as I described a home-made one would. The difference is that the commercial ones have a bullseye terminating one end. Otherwise, you just fix that end of the dyneema in some manner.

Mark
 
May 17, 2004
5,642
Beneteau Oceanis 37 Havre de Grace
  1. Raising the mast when the sail isn't luffing into the wind.
  2. Dirty mast track and sail slugs. Spiders love mast tracks.
  3. Dirty, worn, or seized sheaves at the mast head.
  4. Dirty, worn or seized turning blocks.
  5. Poorly tuned mast, mast is not in column.
  6. Oversized sail slugs.
  7. Undersized sail slugs, the slug goes sideways in the track and jams.
This is a great list. I might just add one more possibility - that a previous owner replaced the halyard with an oversized line that doesn’t run through the blocks smoothly.
 
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Jan 1, 2006
7,534
Slickcraft 26 Sailfish
...Having someone jump it at the mast helps on our boat too...
This is an understatement.
It is the preferred method of raising the main even when the halyard does go back to the cockpit. It is fast and less effort. When the exit block for the halyard is above the height that one can reach up to the person raising can get the long muscles engaged instead of mainly the arms in the cockpit.
 
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Mar 23, 2025
25
Catalina 250 Lake Somerville
- I’m not sure if y’all are reading my posts but, the mainsail is always luffing while I raise it.
- The halyard is the correct size. I just replaced it. 5/16
- it’s a 27’ boat, not 25’. Similar but the extra sail area makes a difference
- the mast collar block feeds into the “deck organizer” turning blocks at a slightly odd angle. Feeding the halyard through two turning blocks and then through a clutch is going to add significant friction. Especially if any of the leads aren’t completely fair.
- all the blocks use plain bearings and turn fine.


This is an understatement.
It is the preferred method of raising the main even when the halyard does go back to the cockpit. It is fas and less effort. When the exit block for the halyard is above the height that one can reach up to the person raising can get the long muscles engaged instead of mainly the arms in the cockpit.
You can use your whole body in the cockpit if you sit on the bench and put your legs against the cabin. Jumping the halyard is effective because you get to use your body weight, but your halyard exit blocks have to be high to do that. Sweating the halyard is effective because you achieve mechanical advantage when applying a lateral load to any line.
 
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