Tech Team - Fine-Tune Systems

    Mainsheet Fine-Tune Systems


    Here's a look at fine-tune systems for mainsheets. Despite the rather fancy-sounding title, fine-tunes are not just for tweaking, they are mostly about ease of sail handling and power.

    Fine-tune_system_160x200In the simplest sense, a fine-tune is a second purchase that attaches to the end of the main purchase of the mainsheet. Here's a good example:

    As the fine-tune is operating on the end of the main purchase, you multiply the two purchases together. In the case of this illustrated system, the gross purchase is 6:1 and the fine-tune is 24:1. The fine-tune only operates for the length that is made available by the setup of the gross purchase. Usually, one pulls the gross purchase on first and then uses the fine-tune to apply more power.

    Why are fine-tune systems useful?

    First, you can pull the mainsheet on harder to control the leach. This might enable you to set the sail better or by intentionally over-sheeting, point higher (but sail slower). Second, using the fine-tune to ease the sail from fully trimmed makes the process of easing, bearing away, or even dumping the main a bit less dramatic. You can take the power out of the sheet with the fine-tune and then ease more with the main purchase of the system, reducing the risk of the sheet being jerked from your hand or of your hand being pulled into the cleat.

    Jibing with a fine-tune system

    The one way that a fine-tune can be a bit of a hazard is during a jibe as the flying block in the fine-tune could potentially hit someone if the jibe is not fully controlled. For this reason it is sensible to pull the fine-tune block-to-block when sailing downwind (don't forget to let it out before rounding up to sail to windward).

    Using a fine-tune gives you extra sheeting power without miles of extra line. Extra power means extra control, and more control makes the environment in your cockpit safer. Here are some other examples of mainsheet fine-tune systems. Hopefully, one is suitable for your boat!


    Key points to take away…

    • Fine-tunes are not just for tweaking, they are for ease of sail handling and power.
    • Fine-tunes enable you to pull the mainsheet on harder.
    • Fine-tunes make easing, bearing away, and dumping the main less dramatic.
    • Always pull the fine-tune block-to-block when sailing downwind.

    For specific questions about fine-tunes relating to your boat, or anything else! Feel free to contact us at

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