Mast Pumping / Vibrating

Ocean Girl · 29-10-2009, 08:31

In the slip during a wind gust my mast vibrates. I have tuned the rig, my friend the rigger has re-tuned the rig..?? The vibration is enough to shake my windex. I have checked all the tangs and chainplates, but will again when I have the time (I work long hours - ugh

).

It did not pump before I replaced the bowsprit, which is very odd considering the bowsprit was rotten and the forestay had no support. The new bowsprit is a replica, except it is a bit thicker and longer, the j-measurement has not changed.

Tune the rig again? Should I put in a little more rake?

Thanks,
Erika

DaveC · 29-10-2009, 08:46

My first thought would be maybe the rig is a little too tight at the top compared with the lower shrouds? I tend to keep all mine (uppers and lowers) a little loose since I'm not racing (not flopping around loose, but not real tight). Makes it easier on everything. If you're going to be in a rolling sea then maybe tighten it a bit...

I'm not an expert rig-tuner, however.

-David

GordMay · 29-10-2009, 09:15

Damping or muting:
Was the old sprit so rotten that is couldn’t transmit vibrations to the boat, or hold enough tension for the rig to vibrate?

Sailmonkey · 29-10-2009, 08:55

Mine does the same thing, shakes the whole boat in a breeze at the slip. Our boats are rigged the same and I have not found what's wrong either.

steve_hendry · 29-10-2009, 09:01

It might be as simple as that the new bow sprit is elastic, while the rotten one would have damped down the vibration.

Bash · 29-10-2009, 09:03

given that this problem didn't exist with the old sprit, the first thing I'd recommend checking is the dolphin striker. the source of your problems may be the longer sprit, which means the tension on the stricker is critical.

HHNTR111 · 29-10-2009, 09:18

The rig on my old boat, a Contessa 35, sometimes vibrated in a breeze while anchored or moored as well. Often I found that simply adding or letting off the hydraulic backstay pressure helped. Sometimes, it is just a harmonic that can be eliminated with a little change like that.

delmarrey · 29-10-2009, 09:19

Do you have an adjustable backstay. If so, loosen it up during wind storms in port.

Mine will actually sing and I can change it's tune using the hydraulic back stay.

Also a topping lift and halyards can affect the rig. Just experiment with your lines until you get the results you want or can live with............_/)

sailvayu · 29-10-2009, 09:30

Do you have a roller furling jib up?

Wayne Canning, AMS

Cheechako · 29-10-2009, 09:21

It's really not uncommon for a boat to have the mast start harmonic vibrations under certain conditions, is the problem more mast pumping or more just rigging vibration? Try putting some bungee cords accross the shrouds and uppers tieing all three together on both sides about 7-8 ft up. If the mast pumps, buy a nylon strop, put it around the mast and pass a halyard (spinnaker?) down through it and then forward to the front of the boat... thus supporting the center section of the mast. also, if the prevailing winds do this, have you tried just turning the boat around in the slip?

Ocean Girl · 29-10-2009, 10:34

Thanks for the input, I am sorry but I have to run to work! but did want to quickly add that her bowsprit is the same but heavier, no roller furling. I will try to re tune.
She isn't just humming, she is pumping. It moves the whole boat and I worry about the stress that is doing to the rig fittings. One thing I didn't check was the compression post...gulp, if it is soft that could be why she wont stay tuned. Late for work, thanks for the replies
Cheers,
Erika

RTB · 29-10-2009, 10:48

Mine does the same thing. You may be referring to our little storm last Monday....winds 50+ according to our marina manager, and I was on my boat wondering if my new docklines would hold!

imagine2frolic · 29-10-2009, 13:03

I found releiving the tension on the mainsheet relieved me of the pumping. Something is too tight somewhere.........i2f

s/v Moondancer · 29-10-2009, 14:46

One very windy night in a marina in Scotland I thought I was sleeping in a violin and it turned out to be the topping lift/main sheet tension that turned the topping lift into a very tight violin string being plucked by the gale.

RTB · 29-10-2009, 14:58

These Ladies are always speaking to us....

29-10-2009, 08:31	#1
Ocean Girl Registered User Join Date: Jun 2009 Location: Kemah, Texas Boat: Cape Dory 30 cutter s/v Ocean Girl Posts: 860	Mast Pumping / Vibrating In the slip during a wind gust my mast vibrates. I have tuned the rig, my friend the rigger has re-tuned the rig..?? The vibration is enough to shake my windex. I have checked all the tangs and chainplates, but will again when I have the time (I work long hours - ugh). It did not pump before I replaced the bowsprit, which is very odd considering the bowsprit was rotten and the forestay had no support. The new bowsprit is a replica, except it is a bit thicker and longer, the j-measurement has not changed. Tune the rig again? Should I put in a little more rake? Thanks, Erika

29-10-2009, 08:46	#2
DaveC Registered User Join Date: Oct 2009 Location: Melbourne, Florida Boat: Cape Dory 28, Alaina Posts: 7	Too tight? My first thought would be maybe the rig is a little too tight at the top compared with the lower shrouds? I tend to keep all mine (uppers and lowers) a little loose since I'm not racing (not flopping around loose, but not real tight). Makes it easier on everything. If you're going to be in a rolling sea then maybe tighten it a bit... I'm not an expert rig-tuner, however. -David

29-10-2009, 09:15	#3
GordMay Registered User Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 12,582	Damping or muting: Was the old sprit so rotten that is couldn’t transmit vibrations to the boat, or hold enough tension for the rig to vibrate? __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?"

29-10-2009, 09:03	#6
Bash Registered User Join Date: Dec 2008 Location: sausalito Boat: h46LE Posts: 690	given that this problem didn't exist with the old sprit, the first thing I'd recommend checking is the dolphin striker. the source of your problems may be the longer sprit, which means the tension on the stricker is critical. __________________ reality is for those who lack imagination

29-10-2009, 09:19	#8
delmarrey Registered User Join Date: Mar 2003 Location: Puget Sound, WA Boat: Choate 40 Posts: 3,928	Do you have an adjustable backstay. If so, loosen it up during wind storms in port. Mine will actually sing and I can change it's tune using the hydraulic back stay. Also a topping lift and halyards can affect the rig. Just experiment with your lines until you get the results you want or can live with............_/) __________________ Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful!

29-10-2009, 08:55	#4
Sailmonkey Registered User Join Date: Sep 2009 Location: Houston, TX Boat: '76 Allied Seawind II Posts: 72	Mine does the same thing, shakes the whole boat in a breeze at the slip. Our boats are rigged the same and I have not found what's wrong either.

29-10-2009, 09:01	#5
steve_hendry Registered User Join Date: Sep 2009 Location: Baltimore, USA Boat: Irwin Citation 39 'Chesagansett' Posts: 21	It might be as simple as that the new bow sprit is elastic, while the rotten one would have damped down the vibration.

29-10-2009, 09:18	#7
HHNTR111 Registered User Join Date: Oct 2009 Location: Rowayton, Ct. Boat: Cambria 46, Starlight Posts: 26	The rig on my old boat, a Contessa 35, sometimes vibrated in a breeze while anchored or moored as well. Often I found that simply adding or letting off the hydraulic backstay pressure helped. Sometimes, it is just a harmonic that can be eliminated with a little change like that.

29-10-2009, 09:30	#9
sailvayu Registered User Join Date: Mar 2006 Location: Wilmington, NC Boat: Irwin 40 Posts: 98	Do you have a roller furling jib up? Wayne Canning, AMS

29-10-2009, 09:21	#10
Cheechako Registered User Join Date: Aug 2006 Location: Skagit City, WA Boat: Fellippi 32 Posts: 2,205	It's really not uncommon for a boat to have the mast start harmonic vibrations under certain conditions, is the problem more mast pumping or more just rigging vibration? Try putting some bungee cords accross the shrouds and uppers tieing all three together on both sides about 7-8 ft up. If the mast pumps, buy a nylon strop, put it around the mast and pass a halyard (spinnaker?) down through it and then forward to the front of the boat... thus supporting the center section of the mast. also, if the prevailing winds do this, have you tried just turning the boat around in the slip?

29-10-2009, 10:34	#11
Ocean Girl Registered User Join Date: Jun 2009 Location: Kemah, Texas Boat: Cape Dory 30 cutter s/v Ocean Girl Posts: 860	Thanks for the input, I am sorry but I have to run to work! but did want to quickly add that her bowsprit is the same but heavier, no roller furling. I will try to re tune. She isn't just humming, she is pumping. It moves the whole boat and I worry about the stress that is doing to the rig fittings. One thing I didn't check was the compression post...gulp, if it is soft that could be why she wont stay tuned. Late for work, thanks for the replies Cheers, Erika

29-10-2009, 10:48	#12
RTB Registered User Join Date: Nov 2008 Location: Texas Gulf Coast Boat: Hunter 36 s/v "FUGUE" Posts: 58	Mine does the same thing. You may be referring to our little storm last Monday....winds 50+ according to our marina manager, and I was on my boat wondering if my new docklines would hold!

29-10-2009, 13:03	#13
imagine2frolic Registered User Join Date: Feb 2008 Location: N.E. Florida Boat: Simpson, Catamaran, 46ft. IMAGINE Posts: 3,160	I found releiving the tension on the mainsheet relieved me of the pumping. Something is too tight somewhere.........i2f __________________ BORROWED! No single one of us is as smart as all of us! SAILING is not always a slick magazine cover!

29-10-2009, 14:46	#14
s/v Moondancer Registered User Join Date: Nov 2008 Location: Grenada and Trinidad for hurricane season Boat: Tayana 55 Posts: 286	One very windy night in a marina in Scotland I thought I was sleeping in a violin and it turned out to be the topping lift/main sheet tension that turned the topping lift into a very tight violin string being plucked by the gale. __________________ Phil "Remember, experience only means that you screw-up less often."

29-10-2009, 14:58	#15
RTB Registered User Join Date: Nov 2008 Location: Texas Gulf Coast Boat: Hunter 36 s/v "FUGUE" Posts: 58	These *Ladies* are always speaking to us....

Thread Tools
Show Printable Version Email this Page
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Mast Pumping - Is This Normal?	Sergy	Deck hardware: Rigging, Sails & Hoisting	10	13-08-2009 21:00
Vibrating Tiller	gbendaly	Seamanship & Boat Handling	8	19-06-2009 14:17
Plumbing / tank pumping question	Cormorant	Plumbing Systems and Fixtures	18	30-01-2009 16:34
head isn't pumping water	Aquah0lic	Plumbing Systems and Fixtures	20	03-01-2009 13:54
Pumping of POO	Therapy	Plumbing Systems and Fixtures	26	24-10-2007 21:11