Controlling Lines—Cleats, Clutches, and Jammers

Posted on Monday 27 April 2009

There was a sailor asking me about his mainsheet setup on an on-line forum, and was thinking of using line clutches or line jammers for his mainsheet. I tried to explain that this was both unwise and dangerous. A line clutch or line jammer can take too long to release—and in the case of a main sheet, could result in a knockdown or broach.

Dealing with Dynamic Lines

Dynamic control lines, like sheets generally need to be released fairly quickly in an emergency. The best type of line control mechanism for dynamic control lines are cam cleats or clam cleats. Both clam cleats and cam cleats allow you to easily release the lines being held by them by lifting the lines upwards, out of them.

Cam cleats are often used for sheets and other dynamic control lines, since they can easily be incorporated into blocks, while still allowing fairly easy control of the line. Clam cleats are generally used for smaller lines, and are often seen on dinghies and on sails, where they’re used for leech lines.

Controlling Static Control Lines

Halyards, boom vangs, outhauls, topping lifts and furling lines are relatively static lines, since they aren’t generally adjusted very often. These are probably best controlled using line clutches or line jammers. However, line clutches are better than line jammers for heavily loaded lines, since some line jammers, as well as some poorly designed line clutches, can be difficult to release under load. Spinlock line clutches have this problem.

The best line clutches, in terms of performance and price, are probably the Lewmar line clutches. The use a different mechanism than most of the other line clutches, and seem to cause the least amount of abrasion to lines, as well as give you the most control when easing a heavily loaded line. However, the Lewmar line clutches have the narrowest working range, so your choices of line used are far more limited by them. One important point, if you use Lewmar line clutches—unlike most other brands, the handles on the Lewmars flip open towards the winches, not away…. if you’re used to most other brands, you might end up mounting the line clutches backwards, like my friend Craig did.

Cleats, Clutches and Jammers—What They Look Like

Spinlock PowerCleat
Spinlock PowerCleat
Good for many different kinds of lines, but can only deal with relatively low loads. They can substitute for cam cleats, or lightly loaded line clutches. Unlike a line jammer, the Spinlock PowerCleat has a positive release mechanism.

Cam Cleat
Cam Cleat
Good for sheets and other control lines that need to be released quickly. Often integrated into fiddle blocks and other block and tackle setups. The plastic jaw versions tend to be kinder to the line, but the metal jaw versions usually are more durable.

Clam Cleat
Clam Cleat
Good for sheets and other control lines that need to be released quickly, only for fairly small lines. Often found on sails for leech lines.

Jam Cleat
Jam Cleat
Often used with genoa sheets… not quite as quick to release as cam cleats or clam cleats. These are often used in place of regular cleats, which aren’t being discussed here, but don’t require a cleat hitch to hold the line under normal conditions. For safety’s sake, a cleat hitch should be used if extra security is required.

Line Clutch
Line Clutch
Best choice for halyards and other relatively static lines. Usually available in single, double, and triple forms.  Line clutches generally have the highest load capacity of all the line control devices.

Line Jammer
Line Jammer
Good for halyards and such, but often have a problem being released under high loads. Line clutches are a bit more sophisticated and a better choice for heavily loaded lines.


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