Tuning a Sailboat Mast

When the boat yard stepped my mast a couple of weeks ago, they just connected the rigging components and made sure nothing fell down. That’s fine – that’s all I expected them to do. Like any other normal people, they wanted to make sure that all was well and secure, so they tightened the rigging wire pretty tight. This isn’t necessarily an optimal set-up, so I did a bit of research on tuning the rig, and today put my knowledge into practice. My on-line reference is found here: theriggingco.com/2014/02/03/how-to-tune-a-sailboat-mast/

Tools required.  Simple mechanics:  lightly hold the shroud above the turnbuckle with the locking pliers, turn the adjuster with the screw driver.

First of all, I was surprised with how easy this is. It’s not complicated. The basics are this:

  • Get the mast perpendicular to the deck
  • Get the mast straight from bottom to top (“In column”)
  • Tension port and starboard cap shrouds so that the mast stays in column and perpendicular
  • Tension lower shrouds evenly from port to starboard, ensuring that they don’t induce bend in the middle of the spar
    • lowers should not be as tight as cap shrouds
    • lowers should just tight enough to not be slack and floppy when they are the lee shrouds
  • Tighten forestay and backstay, inducing as much rake or bend desirable
  • Generally, forward rake adds lee helm, aft rake adds weather helm
  • Because Watkins 27s have a fair amount of weather helm with any significant degree of heeling, it may be best to keep the mast perpendicular or even forward of perpendicular

So the first step is to establish a port-starboard reference, then loosen all the wires so that they are noticeably floppy. I did this by measuring three feet up from the deck at the cap shrouds and marking with masking tape. I marked where the jib halyard landed at that reference on the starboard side, then compared it to the port side.  The marks were within an inch of each other. I pulled the rig slightly to port, then tightened p&s cap shrouds evenly after that, sighting up the mast track frequently to check the column.

High-tech method: port and starboard shrouds measured and marked with masking tape.

After the initial tensioning, I found that the very top of the spar bent off to starboard ever so slightly. I corrected this with more starboard shroud tension, then checked in-column status again, and found that there was no mid-spar bulge.  That meant that I could continue tensioning the lowers evenly. Once done, I moved to the fore- and back-stays, and attempted to simply keep the mast perpendicular to the deck. This something I’ll have to check at anchor, as there is a great deal of visual interference at the pier. Finally, a sailing expedition in moderate winds will be necessary to fine-tune tune the rig and confirm proper tension on the lowers.

This was remarkably easy (I’ve always thought it would be difficult. . . ) and I found that the forces involved were very logical and straightforward. All in all, it took about an hour, or slightly less to do this.

And she's ready for the fine tuning  under way.

Rick Bailey

Rick Bailey sails the Chesapeake Bay with his wife, Ruth, on a Watkins 27 coastal cruiser. Rick is retired and writes the "middlebaysailing" blog (http://middlebaysailing.wordpress.com).

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