shaking mast

[rogerconwy]

We have a Van de Stadt Pioneer 10, 32 foot and recently,after 3 years of ownership the mast has begun to vibrate. This only happens when in marina, wind speed approx force 3-4 from the beam. It is as if the whole mast is shaking. The rigging has been re-tensioned as per Seldon book so the mast is not loose or too tight. Anybody else had a similar problem and what is the fix.
Also just bought a Dell laptop and want to download weather via Nasa SSB receiver, what do I need as the laptop is running on Windows XP.

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[Robin]

Maybe the vibration is coming from a tight halyard or the topping lift?

Re the Nasa/laptop. There is Weatherfax and RTTY (telex) software available to download as either demo or shareware. The usual connection now is via a simple jack plug lead from the extension speaker socket of the SSB radio (I assume the NASA has this?) to the phono input on the laptop. We have SEATTY software which will do RTTY and Weatherfax, it is excellent and cheap to register just $29 I think, if you like it (free trial as shareware). We also have demo versions of JVComms32 which also does fax and RTTY/Navtex, it leaves a small repeated 'demo' pattern on the pages, mostly ignorable until registered about £50 I think. Another is Mscan, good but V expensive to register and the demo screen is pretty well blotted out and lines deleted fron RTTY. All the above run on Windows XP on my laptop.

I think the sites are SEATTY www.dxsoft.com
JVComms32 www.pervisell.com

Otherwise theyare easily found with a search.

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[Ric]

Do you have in-mast reefing? The slot for the sail can turn the mast into a giant organ-pipe. If the windspeed is at a certain value, you can get standing waves in your mast which can really vibrate the mast.

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[sailorman]

we have the reverse.
when @ anchor / on mooring we get a "humming" noise on occasions, have checked everything, u name it ive checked it again & again & again. could be worse could be @ work!.

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[daveking]

the humming is coming from your topping lift

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[kds]

I Agree with Dave - tie an old towel round the topping lift a metre or so above the boom end.
Ken

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[smb]

One cold night in Newtown Creek at the start of last season I went on deck 3 or 4 times in the space of an hour to cure the humming from the topping lift. There is nothing I did not do to that blasted piece of rope.

On the last visit I solved the problem quite simply. I lifted the boarding ladder out of the ebb current. No more tuning fork.


Steve



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[temptress]

we get a 'humming'' in the mast in about F2 fron the topping lift but only if the Kicker is tight. It took us months to find ths out!!!!

<hr width=100% size=1>Temptress of Down
Southsea Marina
Hants
UK

 

[boatmike]

All of the correspondents are right for different reasons. Think of your vessel as a violin (or double base if it is a large one!) The mast is the neck, the rigging (all of it) represents the strings, and the hull and deck are the soundboard or body of the instrument. Either the wind (or even the tide in some cases, re the guy with the boarding ladder) sets up a vibration. If this is in tune with, or a harmonic of, the length of a halyard, topping lift (common culprit) or other part of your standing or running rigging the first thing that happens is that that member starts to vibrate in sympathy. If, as sometimes happens this "note" is the same, or a harmonic of some other part of the boat, that will be set off also. Soon the deck, which is directly attached to the end of the mast which is receiving all this "music" starts to vibrate as does the sound board of the violin.......(very rarely happens with keel stepped masts in my experience) My own boat is a catamaran and therefore has a very big sound board. I can work up quite a symphony sometimes on a summer evening!
And I also agree re the solution. First find out which bit is causing the original sound by walking around the boat and grabbing hold of bits in turn. You may not hear it above deck though. Get crew below to yell out when it stops. Then you have to damp it by whatever means at hand. If it's topping lift, yes, hang a wet towel around it as far up as you can reach. If its a stay, the same might work. but routing a halyard over the offending stay and winching it in a bit does it for me.
When you have found it and fixed it be aware that the next night in a different anchorage a different wind strength will set something else entirely going and you may have to start all over again!
Earplugs, or several stiff scotches are then called for......
Sleep well.........


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[AndrewB]

Abominable Dr Phibes

If my yacht is moored with the wind blowing across deck at a certain angle, the stop holes make my extending spinnaker pole sound. Three distinct notes, presumably one for each hole, something like a deep pan-pipe or a windy organ. Outside, it can only be heard right up close to the pole, but is much clearer inside the cabin. At first we thought the boat was haunted - think Vincent Price in "The Abominable Dr Phibes" (which would have been a good name for her). As it happens only occasionally it wasn't until after more than a year we discovered the cause.

Actually the sound is quite pleasant and soothing, the notes changing slowly from one to another to produce different plantive melodies. So we've let it be.

 

[MedMan]

An eloquent explanation of an age-old problem.

You can often see the offending halyard/control line vibrating once you have got used to what to look for. Alternatively, just touch your finger on the likely culprits as you walk round the deck - you will certainly feel which one is vibrating. Next to the topping lift, our most frequent offenders are the spinnaker halyard and spare genoa halyard, both of which have their snap-shackles clipped to the toe-rail.

I find the simplest solution is just to slack of the offending line a touch and change its resonant frequency. More difficult with the topping lift as the weight of the boom creates the tension, hence the wet towel trick.

<hr width=100% size=1><A target="_blank" HREF=http://www.yachtretreat.com>http://www.yachtretreat.com</A>

 

[boatmike]

Re: Abominable Dr Phibes

I'll swop you for my Jimmy Hendrix..........

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[sailorman]

i have a solid kicker / strut & use the main halliard as topping-lift. its not that, i have tried everthing, all halliards,back stay, felt all standing rigging ( light finger test @ 02.00 hrs).
its intermitant & annoying

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[ponapay]

I have had the same problem with a Nic38. It was definitely the mast, which is keel stepped. It occured only with winds over force 5 and from most directions but started later from astern.

My solution was less tension in the cap shrouds. The vibration appeared to show only above and below the lower shrouds and less cap tension seemed to remove it.

Hope that helps.

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[sailorman]

that could be an answer i have double spreaders & the caps r as tight as a ducks
whats-it.
i cant find any vibes @ deck level

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[AndrewB]

Your Jimi Hendrix for my spinnaker pole?

Er ... is that "Purple Haze"? /forums/images/icons/cool.gif

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[Chris_Robb]

Everyone has focused on vibrating rigging - not shaking mast. I believe that the Pioneer has all it rigging in line with the mast attached to the main bulkhead on which the mast is stepped. The mast therefore has no real fore and aft support as there is no babystay or lowers providing a for and aft restraint. I have seen masts rigged like this sheak quite violently. Is this the problem you are getting?

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[boatmike]

Re: Your Jimi Hendrix for my spinnaker pole?

Yeah! How did you know! Unfortunately it's the Rolf Harris version.......

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[rogerconwy]

Thanks for the info on NASA SSB, but it is not the standing or running rigging causing the shaking

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[rogerconwy]

I think I've sorted the problem. Spoke to Seldon Masts and they are aware of this problem, their man reckons the culprit is wind induced vibration. Aerodynamics really but the wind flows around the mast at certain angles which create lift, hence vibration. They sell an anti vibration strip at 3 pounds prt metre, just fasten to halyard and hoist in the sail track. Haven't had beam winds as yet since fitted as now in Caribbean on an Atlantic delivery. Will let you all know if it works, if not I will take it back to Seldon and stick it ...............

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