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Catalina/Capri 25/250 Sailor's Forums

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Shroud dilemma/question

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txbigfoot
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USA
194 Posts

Initially Posted - 10/17/2008 : 23:18:12

When I am sailing upwind, I have noticed that my shrouds on the lee side are loose and you can see them dangle in the breeze. I am guessing that I have about 6 inches of slack. Is this normal or do I need to tune the rigging? It does not matter which side of the wind I am on, it is all the same and the amount of slack is even from side to side
Dan

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OLarryR
Master Marine Consultant

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3477 Posts

Response Posted - 10/18/2008 : 08:08:30

That is too much slack. The Technical Tips Section of this Forum has info on mast tuning. Here is the direct link:

http://www.catalina-capri-25s.org/tech/tech25/snkmast.asp

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Nautiduck
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3704 Posts

Response Posted - 10/18/2008 : 16:05:41

You leeward lowers should have some slack but not the uppers. Here is how Arlyn Stewart, arguably the most knowledgeable C250 person anywhere, tunes his rig:

"The 250 has a very different rig than most. The 250 have a modified form of a B&R rig and have no forward lowers. It also has lighter rigging, as it is a lightly keeled boat. It is also an open hull without interior bulkheads. The available numbers just don't fit.

The 250 should be tuned firm but not hard, with the upper shrouds (the aft shrouds that go to the spreaders and then on to the mast head) a good bit firmer than the forward (those just below the spreaders).

I know it would be easier if someone could just yield some numbers but first thing to understand is that the loose gauges often read very different and there are several differing gauges making things even worse. It is better to understand the dynamics of the rig tuning.

What is wanted is a setup that doesn't allow the foresail too much power. To get that the aft lowers should be tuned firm as they are the opposing force to the headstay (though you may be saying...this guy is whacko, the backstay is the opposing force to the headstay... trust me, I'm right about this on the 250.) Tighten them firm but loose enough to allow an inch of deflection when pulling the shroud after grasping it with two fingers at the last finger joints and curling the fingers inward. I know there are those who are thinking this ain't scientific enough... but trust me you will get a feel for it.

The forward lowers should deflect about twice as much as the aft given the same test. If the forwards are tightened too much (equal to the uppers), it will induce reverse (aft) mast bend that is not desirable.

The last stay to tune is the backstay...tighten it only enough to pull it straight where it won't sag into the sail roach. Do not over tighten the backstay as to do so will release some of the tension on the aft lowers. It is the aft lowers that leverage against the raked spreaders that hold the center of the mast forward so over tightening the backstay reduces the ability of the uppers to hold the center of the mast forward... this is why the 250 is not a candidate for an adjustable backstay tensioner.

If after tuning, one feels that in a breeze the headsail has too much power because of a loose forestay and is sagging off too much...then tighten the uppers a bit more.

A simple test is when running hard to windward in a breeze, the leeward upper shouldn't be shaking but the leeward lower should have some slack. If there isn't any slack... then the lowers may be too tight. If the rig is too tight... light air performance will suffer and if it is too loose, then it can be overpowered in a breeze and suffer too much heel and helm pressure.

Of course it goes without saying when adjusting shrouds to observe symmetry. Once the masthead has been centered using a halyard to the rub rail on each side and the mast column straightness has been set by the lowers... any further adjustment of a shroud has to be countered by an equal adjustment on the other side.

Now...once a setup has been achieved that seems good...then one can use a loose gauge and write down those numbers and use them to compare further adjustments and possibly even use them against other similar 250's... but not other boat designs. Keep in mind however that even with the same boat and loose gauge... the gauges may not read the same.

One final point... the 250 is not typical to heavily keeled boats that need a firm tough rig to handle the sail plan opposing the keel. Those boats will groan and strain under a broach whereas the 250 heels over and rounds up and shakes a broach off like it was no big thing. Many a traditional boat skipper will scoff at the light rigging of the 250 thinking it is dangerous... but it's not true... the rigging is very adequate to the boat design.

I've yet to hear reported to this forum an instance of rig failure from overload on a 250. There have been a couple of failures reported but do to snagging the shrouds on other boats or objects."

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.