Wooden spar tuning

[traderhank]

After reading the various posts about tuning the rigging, it seems that the tensions applied to the shrouds and stays maybe too much for a wooden mast. Am I correct, or should the tension on the rigging be different (as in less)?

[Ian McColgin]

This is a practical rather than an engineering answer.

Wooden masts are most associated with often older wooden boats. But good boats are designed and built in harmoney. For example, a beamy old ketch likely has a sail plan of lower aspect than modern rigs - inherantly less stressed. Even some fairly lofty rigs, imagine an older Rhodes in the 40' range, are lower stress because the hulls heel more readily than many modern great flair go-fast sleds.

So, while compression strain in unlikely to harm the mast, there's no reason to overstress the rig or wring out the garboards. When tuning older boats, I get the mast(s) centered athwartships and with about the rake that appears right for the design, with a firm "hand taught" on the turnbuckles at the shrouds and a bit firmer on the backstay and jib stay. To adjust the highest shrouds, I use the simple old way of bumping a halyard rail to rail to measure when the truck is centered. Then I do the aft lowers to have the mast in colum under that, and lastly the foreward lowers.

Then off for a sail in a moderate or fresh breeze (Force 4 to 5, wind say 15 to 20 kt). The leeward shrouds will be slack and the mast may sag off a bit to leeward. I tighten from the weather side, no more than one turn at a time, tack by tack, usually ending up with the final adjustments devoted more to getting any lateral bend out. I'll also drop sail a couple of times to do the halyard bump making sure the truck is still centered - which it usually is as I take the same number of turns on the screws on each side some stuff happens.

The goal is to end up with the mast remaining in colum on each tack with just a sense of unloading but not real rattling about on the leeward side.

This approach is slow and not too scientific but my life in older wooden boats has me trying to be as nice to the rig as possible and it makes the tuning process a proper consumation to the spring courtship.

G'luck

Ian

[Russ L]

Hi Hank,
The tuning posts (and Brion's video) are excellent sources of reference. They are contingent on the shrouds and mast specs being proper. There is no practical loading difference on a metal mast vs wood mast in the same application. Mast loading is a function of righting moment, so at 30 degrees of heel you have the same "mast loading" regardless of material. To tune for less loading on a wood mast means you would need to adjust your sailing habits to account for lower loading, thus your boat will not perform as she should.
The move to different mast materials is largely performance (less weight)or manufacturing (less skill, reliable supply, cheaper) concerns.

Cheers, Russ

Originally Posted by traderhank

After reading the various posts about tuning the rigging, it seems that the tensions applied to the shrouds and stays maybe too much for a wooden mast. Am I correct, or should the tension on the rigging be different (as in less)?