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Mainsail

» Posted on 16 Jul 2012

In a previous article on staysails I described some of their types (large light-weather staysails, heavy-weather staysails – working jibs, etc.). In a discussion on the mainsail, I will focus on one sail, which should serve us for the widest possible range of winds. As the text below is intended for a wider group of readers, I will not get into the topic of light-, medium-, and heavy-weather mainsails because it is an issue for a small group of readers i.e. professional sailors. Most sailors have to deal with one mainsail on the boat and therefore can only use the sails available on a particular boat. The first thing you encounter when putting up the mainsail is the bolt rope in the luff and the foot. Since I can remember, 99% of mainsails have been attached to the mast and boom by means of a bolt rope. This was always associated with problems of chafing on the corners and excessive shrinkage of sail edges as a result of use of an improper bolt rope.

 

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Chafing appears in the head, tack or clew of a sail i.e. in places that perform the hardest work in the mast or boom profiles. After some time, these places become dirty at best, and often begin to chafe, after which they break away from the sail. In the case of racing sails, such attachment of the mainsail to the rigging is justified due to the “leakage” of air and consequently weaker thrust.

In recreational sailing, we don’t need to worry about this aspect. On a boat, there are so many factors allowing for enhancing the speed of a sailboat, so that it is fine to attach the mainsail to the mast using slides, which will make handling the mainsail easier while increasing its lifespan. Inserting the mainsail into the mast sailtrack requires two people – one heaves in the halyard, the other inserts the bolt rope into the sailtrack.

In case of slides, one person is always enough. When the mainsail is outside the sailtrack, the person first puts all the slides in the sailtrack, blocks them with a stopper so they do not fall out, and then heaves in the halyard. Then we can drop and put up the mainsail with no restrictions (provided that the slides will fit the sailtrack – and will not jam).

 

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In case of mainsails with the area of 30 – 40 m², sliders with plastic clasps can be used with no problems. This is a most appropriate system, although it would seem that plastic slides will crack. Nothing could be more wrong! Firstly, there are a lot of these slides (spaced every 50 – 60cm), and secondly, when one breaks it is because there was an unexpected “event” in this section, which caused an increase in the force pulling out the sail from the track to the limit.

And now:

    • In the case of a metal slide, the eyelet is likely to be torn out along with the bolt rope from the luff
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    • If it was a mainsail without slides, the sail could tear near the sailtrack
    • If plastic slides and snaps are used, one of these elements will crack first
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The conclusion?

Cases a) and b) result in a visit to a sailmaker’s shop for repairs. It is possible to fix this on one’s own, but it will not look good, and the guarantee that our repair will be sufficient is smaller.

In case c) the repair comes down to taking out a spare slide or snap from the secret compartment, replacing the defective element and sailing on! (Where the wind??).

I leave the comparison of time, cost and troubles associated with the repair to the readers. Foot of the mainsail is a place of a lot of confusion, erroneous approach, and the recipe is very simple – the foot of the sail should be free, running outside the boom. We often encounter a situation where the customer after picking up their mainsail and installing it on the boat calls us with disapproval in his voice: “Gentlemen! And where is the bolt rope for the the foot of the sail? Such a mistake!”

After a week of sailing the same customer calls us and confirms that our justification for this solution is completely right and that he already likes it. This situation occurs frequently … and what is our justification?

 

  • There is no sail in the boom – there is nothing to get damaged, there is nothing to repair, there are no additional costs
  • Of course, the mainsail is attached to the boom by the tack and clew of the sail. These places are always made with operation in difficult conditions in mind, due to the large forces acting there as well as chafing, and so nothing should happen there for a long time
  • the notion that the bolt rope at the foot of the sail sustains the boom over its entire length is wrong – the supporting force is only present at the point of attachment of the clew. When a bolt rope is used, it only closes the space between the boom and the sail for the escape of air from the lower part of the mainsail. How much air really escapes that way?

In the case of recreational sailing, you can skip this question, because this is not the way to increase the speed of your sailboat.

On the racing Omega class sailboats, where we use this solution, there is not an element which decides about victory, it does not bother anyone, and in some moments it even helps. It helps when you want to work with the foot of the sail when sailing. The lack of a bolt rope causes that the clew moves itself towards the mast when the mainsail is loosened on the foot, and when heaving it, there is no bolt rope resistance in the boom or stretching of the bolt rope itself.

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Andrzej Kiełsznia