Tech Team - Ratchet Blocks

    Ratchet blocks...they don't just go click


    • Hold sheets longer without cleating
    • Make trimming easier
    • Get greater control

    Ratchet blocks are an essential part of any boat's equipment. But what is it that they actually do? And how does it contribute to your sailing?

    Ratchet sheaveA ratchet block has two essential elements: a sheave that can grip the rope, and a pawl that prevents the sheave from turning in the direction of the load. In use, the block takes part of the load in the sheave's grip and leaves the rest in the user's hand. The amount of load the sailor holds depends on the size and shape of the sheave and the wrap of the line around it.

    The sailor gains two big advantages. First, they can hold the sheet in their hand much longer, making constant trimming much easier. Second, they have much greater control over the line and can ease in a controlled manner without getting pulled into the block.

    You will want to make sure that the sheave grips the line when you want it to, allows controlled easing, and doesn't damage the line. This last aspect is often forgotten as sailors love the positive hold and then wonder why they need to replace the sheet every other week.

    What about turning the ratchet off?

    In light breeze, if there is not enough pressure to pull the sheet through the block, you might want to turn the ratchet off. This is usually straightforward, using a switch located somewhere on the block. However, as soon as there is sufficient pressure, the ratchet should be turned back on so that gusts don't pull rope through blocks rather than pull the boat through the water faster.

    What about automatic ratchet blocks?

    ratchet_ratchamatic.jpgThis brings us to the subject of automatic ratchets, or Ratchamatic® blocks as they are termed at Harken.

    These blocks have a ratchet that prevents the sheave from turning in one direction when the rope has load on it, but allows the sheave to spin freely when the rope is unloaded. This means that the ratchet helps you hold the load when trimming, but does not restrict free movement of the sheet when you want it to run. A perfect example of this is when jibing an asymmetric spinnaker -- as soon as you pull the load on after tacking, the ratchet springs back to engage.

    So why not use Ratchamatics for everything?

    It comes down to preference. Some sailors don't like a Ratchamatic on the Laser mainsheet because the sheet flies out too quickly. Using a standard on/off ratchet adds a little drag and allows movement across the boat in a controlled manner. The more youthful among us might use their athletic ability to move much faster and might prefer the Ratchamatic.

    But it's all sounding a bit racy so far…

    What else can we do with a ratchet block?

    • Mainsheet control
    • Jib furling

    Using a ratchet block in your mainsheet reduces the feeling that if you uncleat the sheet you will get dragged through the blocks. It gives you control. This is at least as important to cruising sailors as it is to the racing folk.

    Using a ratchet block on your jib furling line makes unfurling the sail, especially to a reefed position, a much more controlled and pleasant experience (and frees up the winch that you might have used for the same purpose).

    So, that's what ratchet blocks give you: Control! Holding loads and easing them become much easier.

    The one thing it doesn't do is make it easier to pull in, except in as much as it reduces the energy expended holding the load after each pull.

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