{Stus-List} runniers and baby stays

cscheaffer at comcast.net cscheaffer at comcast.net
Wed Mar 28 00:21:18 EDT 2007

Dear Charlie,

I would ask your sailmaker that question.

My PO removed the baby stay also on our 34R and I have checked with UK sails and the spar maker Offshore Spars and they agree it is OK.  You will see a definite improvement in mainsail power if you tension the runners in anything over ten knots TWS.  Hull speed will surge 1 or maybe even 2 knots.  The change is measurable and immediate.  The runners straigten the mast increasing draft in the main.  We use a bungy cord tackle to pull the untensioned runner/checkstay forward to the chainplate and it retracts effortlessly.  We sail in the ocean and have not seen any problem with pumping.  This boat's three spreader rig is supposed to have some rake and prebend which I am still tweaking, but you are right.  The chainplates are about six inches behind the mast partners, but the rake allows for the spreaders to be fairly straight.  Of further interest, this rake and prebend also causes the lower diagonals to act as "aft lowers", limiting how far the lower mast can bow forward.

1990 C&C 34R
-------------- Original message -------------- 
From: cenelson at aol.com 

All right--my head is spinning between backstays, baby stays and running backs. Here is another question.

My 1995 C&C 36XL/kcb masthead boat came with an adjustable babystay and running backs and a 3 spreader rig. In 2004, my local sailmaker, a former crew on an Americal's Cup challenger in 1972, looked over the rig carefully in preparation for a new set of carbon sails to race her in Charleston Race Week.

It was his opinion that my spreaders were slightly aft of athwartships and that the babystay was an unnecessary complication to the boat's standing rigging. Accordingly he recommended removing the babystay entirely but keeping the runners in place (but not routinely used) to stabilize the mast in the rare pumping situation in the NC sounds.

He built the sails accordingly and presumably discounted any serious forward mast bend in his sail design. I have only rarely used the runners in heavy air when I could see the mast moving fore and aft. 

Is he all wet/wrong about this?  If so and the sails were designed without consideration of the babystay, would reinstalling the babystay foul up the shape of the carbon sails designed without it in mind?

Truth be told, I do not miss the babystay--dealing with the masthead kite on this boat is already tough enough without remembering to remove/reinstall the babystay at every windward/leeward mark!

Fun indeed!!

Charlie Nelson
Water Phantom
C&C 36XL/kcb

-----Original Message-----
From: gcutter at odu.edu
To: cnc-list at cnc-list.com
Sent: Tue, 27 Mar 2007 8:29 PM
Subject: Re: {Stus-List} running back stays

All these rig questions! Maybe we should write a book....
To add to what Dennis said, they have another function on masthead boats,
one being to stiffen/support (as in pumping) a thin section mast (baby stay
and runners on). Second, when it's really blowing (25+kts) and you really
have the backstay cranked down to tighten up the forestay, to pull some of
the bend back out of the mast (this then applies more tension on the
forestay). The backstay does 2 things on a masthead boat - forestay tension
and eventually (depends on spreader and shroud angles) bending the mast.
But, you can overbend the mast such that the leech of the main is not
supported (imagine the head of the mast being pulled back and down, which
loosens the leech), and so the runner (higher one) and check (lower) stays
pull some of the bend back out of the mast when the rig is really tight.
Fun, eh?

Greg Cutter
Department of Ocean, Earth, and Atmospheric
Old Dominion University
4600 Elkhorn Ave.
Norfolk, VA 23529-0276 USA
(757) 683-4929 - office
(757) 683-5303 - fax
Internet: gcutter at odu.edu
Web Site:

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