Mast Pumping / Vibrating

[Ocean Girl]

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]

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

[Sailmonkey]

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]

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

[Bash]

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.

[GordMay]

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?

[HHNTR111]

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]

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............_/)

[Cheechako]

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?

[sailvayu]

Do you have a roller furling jib up?

Wayne Canning, AMS

[Ocean Girl]

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]

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]

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

[s/v Moondancer]

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]

These Ladies are always speaking to us....