[Rhodes22-list] Tuning a Sailboat Rig

[mweisner at ebsmed.com]

I found, at the BoatUS website, what appears to be a very nice explanation
of the process of tuning the rig that does not require the use of Loos
gauges or advocate over tightening.  It should be very useful to any Rhodie
as it seems to employ logic similar to Stan's.

 

The link is:
https://www.boatus.com/magazine/2019/april/tuning-a-sailboat-rig.asp

 

The linked story is reproduced below for convenience.

 

Mike

s/v Wind Lass ('91)

Nissequogue River, NY

 

 

Tuning A Sailboat Rig

By Mark Corke

If your sailboat seems slower, follow our how-to on tuning your rig for
optimal performance.

Spring is a time of prepping your boat for the coming season. While
powerboaters fine-tune their engines, sailors should consider fine-tuning
their rigs. Doing it yourself may seem intimidating, but it shouldn't be.
Anyone reasonably handy can do it in a few hours. The reward is easier and
faster sailing throughout the coming season.

Let's start with the basics for new sailors. With a few exceptions, a
sailboat mast is held up by a series of stainless-steel wires. But those
wires also perform several other equally important functions. When a
sailboat is at rest and there is no wind blowing, the stress on these wires
is very light with almost all the load downward toward the keel. However,
when the boat is sailing and heeled over in a fresh breeze, more stress is
placed on the wires and they have to work harder to hold the mast upright
and stop it from bending.

The wires that prevent the mast from moving from side to side are called
shrouds, and the ones that prevent fore and aft movement are called stays.
The larger and taller the mast, the greater the load, and the number of
shrouds and stays required. On a typical cruiser, say up to about 35 feet,
there will generally be one forestay, one backstay, and two shrouds on each
side.

To get the best performance from your boat and sails, the rigging needs to
be set up correctly - often called "tuning the rig." The rig should be tuned
with the boat in the water on a day with little to no wind. You'll also want
to be away from wakes and other boats that can rock your boat. To start, the
turnbuckles for the stays and shrouds should be hand-tight only. This is
sufficient to hold up the rig but places no strain on anything - yet. Lay on
your back on the boat's foredeck and sight up the front of the mast. It
should be perfectly straight with no bends or kinks. Next, tighten the lower
shrouds - these are the ones that do not go all the way to the top of the
mast and often attach to the mast at the base of the crosstrees (the two
horizontal spars at the upper ends of the topmasts).

You'll need a large screwdriver to rotate the turnbuckle, and a wrench to
hold the shroud fitting and prevent it turning as you tighten. Give a couple
of complete turns on either side. Have a helper release the main halyard and
keep a little tension while you pull down the end that normally attaches to
the mainsail until it just touches the top of the toerail adjacent to the
chain plate. Have your helper cleat off the halyard, then swing the halyard
over the boom and check the measurement on the other side. They should be
the same. If not, adjust the turnbuckles until they the measurement is equal
on port and starboard.

Adjusting and tuning a sailboat rig will often bring benefits such as easier
handling and better performance.

Next do the same for the cap shrouds, these are the ones that go to the top
of the mast, but note that due to the length of the shrouds, it is easy to
bend the mast to either port or starboard. With the shrouds adjusted, sight
up the mast one more time to ensure that it is still straight.

Next comes the fore and aft adjustment, which is made with the backstay and
forestay. Masts should be plumb or lie back slightly. It should never rake
forward. A good starting point is to tighten up the forestay and backstay a
little over hand-tight. Use the main halyard as a plumb bob. Cleat off the
halyard so the free end is just clear of the top of the boom and let it
hang. If the shackle on the end of the halyard hits the mast, the mast is
likely too far forward, so slacken off the forestay and tighten the
backstay. Adjust a little at a time until the end of the halyard hangs free
- 4 or 5 inches is a good starting point.

You'll need to install cotter pins into the turnbuckles to prevent them
loosening over time, but before doing that, take the boat for a sail when
the wind is blowing about 10 knots and see how everything works. With the
boat on a beam reach, note the tightness of the windward shrouds. If they
appear slack, they will need to be adjusted up. If the boat is hard on the
tiller or wheel and tries to turn into wind, the mast has too much aft rake,
so you'll want to slacken the backstay and tighten up on the forestay a
little. If the bow wants to turn away from the wind, the mast is too far
forward, so you'll need to move the mast back a little.