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Ensign Mast Tuning

Published: Thursday, 08 May 2014 16:39 

Ensign Mast Tuning


by David McClintock


Two factors prompted the request for this article. One was Neil Greenstein's experience in Fleet 9 in mid-September, 1979 of seeing his Jangee, 40, turned from a loser to a winner largely through following the advice of "Moose" McClintock—see Neil's article "Old Ensigns Shouldn't Die." The other was Moose's spectacular sweep of the 1979 Nationals—performed convincingly in both very heavy winds and steep seas and in light airs. His achievement included, among other things, recovering from starting last in the third race after being over early! Gratitude is hereby expressed to Moose for taking the time to tell us other Ensign sailors how he thinks we should tune our masts.—Ed.

There are no mysteries as to how one might set up the rig of an Ensign. However, there are two variables which will determine how you set up your boat. The first is that sails from different sailmakers will differ, so the amount of tension in your rig or bend in your mast must be determined by the sails you have. Second, most Ensigns are fairly old, so most boats have had things changed (mast step, jib tracks, bow fittings) which will make exact measurements useless. Thus, tuning an Ensign is a very exact science requiring a certain amount of "feel" for the best results. There should, and will, be much trial and error before the rig is "perfect", so this article will serve only as a guideline.

To start, all the rigging should be loose and the mast step should be all the way aft. The aft position is merely a starting point, because the important thing is to get the mast standing straight up and down in the boat. In this vertical position, the boat should have slight weather helm. If the boat should develop lee helm, the mast should be raked back to induce a slight weather helm. To tell whether the mast is straight, I usually get off the boat and look at it from a distance. A carpenter's level is also handy.

Once the mast is vertical, tighten the uppers three turns more than hand tight, making sure the tension is equal on either side. The important thing is not to tighten the rig to the point of creating a compression bend to either side. If you think the rig is too loose, you may tighten the uppers more, using the lowers to straighten the mast. However, a mast under compression will not stay in column no matter how the lowers are adjusted, so you may be complicating the process needlessly.

When the uppers are snug, check to make sure the mast is centered over the boat. The simplest method to do this is bringing the main halyard down to the railing on one side, and then checking to see if it hits the same place on the other side. If the main halyard checks out, repeat the process with the jib halyard. This will insure there is no compression bend, and guarantees that the genoa will sheet to the same position on either side.

The next step is tightening the forward lowers, again just a little more than hand tight. The lowers will stabilize the middle of the mast, keeping it in column sideways and preventing it from pumping. The lowers should not induce any pre-bend in the mast because this would flatten the lower part of the main in lighter wind, when the power is needed (the flatter main would also make the leech too loose, which would hurt your pointing ability).

The after lowers should be left slack with about one inch of sag. In heavy air, a tight after lower prevents the bend induced by backstay and mainsheet tension. This will make the main too full down low, which will close the slot between the main and genoa. The fuller main will also make the leech very tight, creating too much weather helm, resulting in increased rudder drag. The aft lowers should not become taut until the main is flattened out. When they become tight, they will help the forward lowers keep the mast supported in the middle.

The headstay shouldn't be tightened any more than the upper shrouds. With the fractional (7g's) rig of the Ensign, too much headstay tension will bend the mast, just as too much backstay tension does. This occurs because the mast is being pulled forward in a place where the mast can flex. To control headstay tension, the genoa halyard offers adjustability with the changes in wind strength. As the wind increases, and luff sag grows, halyard tension will straighten the luff and flatten the genoa, which will help your pointing. It will also tighten the rig and pull against the backstay, making the mast bend. With the added bend induced by the backstay, you have a great deal of control over the draft of the main.

This rig configuration is practical primarily for moderate wind. If your area is used to less wind, it would be better to have a slightly tighter after lower. This will prevent the mast from bending forward, so your main will always be full. On the other hand, if your area is primarily windy, you may want to increase the forward lowers' tension, which will induce pre-bend. This will give you a flatter main all the time, for the windier conditions, and will offer better support in the middle of the mast.

The amount of tension on the uppers may also be different depending on the stiffness of your mast. My mast is very limber, so compression bend occurs very quickly. If the mast is capable of taking more tension without compressing, take it. Keep in mind, however, that every bit of downward load increases as the sail load builds up, so there will still be a point when the mast will begin to bend. The longer it takes to occur, the better your sail shape will be.

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