Steve,
Mast pumping is when the middle of the mast moves fore and aft as the boat hits
waves or is subjected to sudden puffs. Pumping is minimized by babystays or
running backs. Running backs are lines or wires attached at stress points on
the mast which then run aft to a purchase or winch to allow tensioning or
relaxing.
First, a primer on some generic rig types.
1. Mast with split lower shrouds. Upper shroud attaches to point on deck dead
abeam of mast then carries upward to spreader(s) then to top of mast. Fore and
aft lower shrouds attach to points on deck forward and aft of upper shroud
attachment.
2. Mast with inline shrouds and swept back spreader(s). All shrouds are
attached to same point at deck somewhat aft of mast. Spreaders are angled aft
from mast.
3. Mast with inline shrouds and straight spreaders. All shrouds are attached
to same point at deck dead abeam of mast. Spreaders are straight, not angled.
OK. In configuration 1, the middle of the mast is stabilized by the lower
shrouds. This configuration rarely pumps unless the lower shrouds are loose.
In configuration 2, the mast is bent by tightening the shrouds. The tension on
the shrouds pushes forward on the spreaders resulting in the middle of the mast
being pushed foreward. These rigs are somewhat subject to pumping. You may or
may not see babystays or running backs.
Configuration 3 is most subject to pumping. With inline shrouds and straight
spreaders, there is nothing to stabilize the middle of the mast fore and aft.
If the mast extrusion is bendy, it will bend back and forth, hence pumping.
Dennis C.
Touche' 35-1 #83
Mandeville, LA
>________________________________
> From: Stevan Plavsa <[email protected]>
>To: [email protected]
>Sent: Thursday, October 18, 2012 10:19 AM
>Subject: Re: Stus-List Dyneema baby stay
>
>
>What exactly is mast pumping?
>The early 32's seemed to not come with baby stays but I believe the later ones
>did. I've also read that the 32 is "prone to mast pumping" but I don't know
>what that means :)
>I have an idea, but I don't really know. Mine is an early one with no baby
>stay. However, there is a funny little attachment point (female, threaded,
>~1/2") on the floor inside the vee birth that I have no idea what it's for,
>maybe related, maybe not.
>
>
>Thanks,
>Steve
>C&C 32
>Toronto
>
>
>
>On Thu, Oct 18, 2012 at 10:34 AM, Morgenstern, Keith E CIV SEA 08 NR
><[email protected]> wrote:
>
>This may come across as pedantic....but have you ever tried to cut
>>dyneema?
>>
>>That stuff is *hard* on knives.....I have a Spanish steel bladed (like
>>they use for swords), and I can only make 1 splice before it's time to
>>reshapen.
>>
>>I've switched to utility knives, and go thru at least 1 blade (usually
>>both tips) every splice.
>>
>>So..yeah, it's "fabric" in the sense that it's not metal, but It's
>>insanely resilient and tough.
>>
>>For babystay, I'd switch in a heart beat, if I hadn't replaced it with
>>wire only a few years ago before I was hooked on spectra.
>>
>>And that's the new name for my next rock band: "Hooked on spectra"
>>
>>-Keith
>>
>>
>>-----Original Message-----
>>From: Pat Nevitt [mailto:[email protected]]
>>Sent: Thursday, October 18, 2012 9:11
>>To: Law Office of Craig Meyerson; [email protected]
>>Subject: Re: Stus-List Dyneema baby stay
>>
>>I have a 29-2 that has a baby stay on it. The stay normally stays
>>shackled to the mast base except in heavier air when I run the shackle
>>to a ring in the center of the deck. The stay is cable to a series of
>>blocks that give me 4:1 purchase and aline that runs back to the cockpit
>>through a rope clutch. Whether you need it or not depends on how much
>>wind you get. Here on the Chesapeake I rarely use it. During the race
>>last Sunday however with winds at 16-19, gusts to 24, we put it on when
>>going upwind and it really helps flatten the mainsail. With the setup I
>>have it is really easy to release the clutch to take the tension off the
>>shackle and then run the shackle back to the mast for the downwind run.
>>I don't know about using Dynema. The thing that bothers me about that
>>is that at the end of the day, it is still fabric and something sharp
>>can cut it and destroy it.
>>
>>Pat Nevitt
>>Patriot
>>C&C 29 MKII
>>Galesville MD
>>
>>
>>On Thu, Oct 18, 2012 at 7:40 AM, Law Office of Craig Meyerson
>><[email protected]> wrote:
>>
>>
>> I installed a traveler track from the mast base to the forward
>>most point on the deck I wanted the baby stay to reach on my old C&C 34.
>>Put an adjustable car on the track controlled from the cockpit. Used
>>dyneema for the stay. Downwind adjusted the car aft to get out of the
>>way for dip-pole jibing and aft pole adjustment. Worked very well.
>>Should be helpful for end to end jibing too. The dyneema was on its
>>fourth season when I sold the boat.
>>
>> Baby stay reduces mast pumping upwind, so I would not remove it.
>>
>>
>> Craig Meyerson
>> C&C 115 Souvenir
>>
>>
>> From: dwight veinot <[email protected]>
>> To: [email protected]
>> Sent: Wednesday, October 17, 2012 6:28 PM
>>
>> Subject: Re: Stus-List Dyneema baby stay
>>
>>
>> Won't be much easier
>>
>> Dwight Veinot
>> C&C 35 MKII, Alianna
>> Head of St. Margaret's Bay, NS
>>
>> -----Original Message-----
>> From: CnC-List [mailto:[email protected]] On Behalf
>>Of
>> [email protected]
>> Sent: October 17, 2012 10:10 AM
>> To: [email protected]
>> Subject: Stus-List Dyneema baby stay
>>
>> Hi,
>>
>> I am looking for a solution to help make my baby stay more
>>easily removable.
>> I presently have a standard 1x19 SS cable turn buckle set up,
>>and I plan to
>> install a pelican-like hook attachment. I have a colleague who
>>is
>> replacing his SS lifelines with Dyneema line. This got me to
>>think about
>> using Dyneema for the baby stay. Does anyone have any
>>experience in using
>> a Dyneema solution for any rigging arrangements?
>>
>>
>> -
>> Paul E.
>> 1979 C&C 29 Mk1
>> S/V Johanna Rose
>> Carrabelle, FL
>>
>>
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>>10/16/12
>>
>>
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>>
>>
>>
>> _______________________________________________
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>>
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