Mast pumping?

[syvictoria]

Our mast does this too. Initially we tried much of that suggested above, including getting the rigger back! No result I'm afraid, although it has maybe reduced a little I think. Whilst it used to keep me awake at night (both in terms of noise and worrying!) we've now learned to live with it.

 

[simonfraser]

Mine is calming down with age

 

[dunedin]

Suspect there are a number of different symptoms that the OP could be experiencing.

A thrumming noise in the rigging is quite common, and a topping lift or halyard on the boom end can be a cause.

Interesting the vortex shedding one - not sure how you recognise that as not been aware of it.

We have found an issue with the furled jib roller pumping, or moving around quite violently in some strong winds. Have tried winching the jib sheets very tight which does help sometimes.

Also on a mast with only one set of shroud plates and no baby stay, the whole mast can start flexing very slightly in harbour in a full on gale. Winding on the hydraulic backstay tensioner slightly to increase pre-bend helps stop any mast flex, but does increase rig wire whine.

 

[Travelling Westerly]

Suspect there are a number of different symptoms that the OP could be experiencing.

A thrumming noise in the rigging is quite common, and a topping lift or halyard on the boom end can be a cause.

Interesting the vortex shedding one - not sure how you recognise that as not been aware of it.

We have found an issue with the furled jib roller pumping, or moving around quite violently in some strong winds. Have tried winching the jib sheets very tight which does help sometimes.

Also on a mast with only one set of shroud plates and no baby stay, the whole mast can start flexing very slightly in harbour in a full on gale. Winding on the hydraulic backstay tensioner slightly to increase pre-bend helps stop any mast flex, but does increase rig wire whine.

The noise I can cope with, its the physical movement of my bed that I cant, its like flying on a magic carpet through some serious turbulence!

OK I may have dramatised the above but seriously the bed feels like its jumping up and down, 1 to 2 bumps a sec on average ?. I do wonder if it can damage the boat but if others suffer the same issue then I guess not?

 

[syvictoria]

I do wonder if it can damage the boat but if others suffer the same issue then I guess not?

+1. My rigger said not to worry and that it wouldn't cause damage.

 

[dunedin]

The noise I can cope with, its the physical movement of my bed that I cant, its like flying on a magic carpet through some serious turbulence!

OK I may have dramatised the above but seriously the bed feels like its jumping up and down, 1 to 2 bumps a sec on average ?. I do wonder if it can damage the boat but if others suffer the same issue then I guess not?

So can you see the mast itself physically moving? Is the jib furler moving around? Both?

 

[Habebty]

I have spent quite a long time playing with babystay tension to try to overcome the problem. Unfortunately unsuccessfully. With forward bow of about half the mast fore and aft thickness, 2-3 inches, the pumping quite regularly exceeds this figure. Any more bow than that is too much for the mainsail.

I wind halyards in a spiral below the spreaders but this does not make a huge improvement.

Blimey...
Would some "parking" runners tensioned from the baby-stay tang led back aft help?

 

[peter gibbs]

You'll have to excuse me if I have the term wrong but it seems to fit the issue I'm having at present and extensive googling came up with "mast pumping".
Basically just had a recent rig tune and inspection, all OK, but during windy evenings the mast and rigging seems to pump which is then transfered down to the aft cabin and my bed! Now I can see where some responses/replies may go but keeping it fairly clean does anybody know how I can stop it? I don't remember this happening before the tune up but my memory may be failing me.

Thanks

Apart from being disturbing this is not good news for your lovely vessel. As others have said, it's a condition arising from tensions, often a lack of mid mast support. Working the lower stays should assist, turns applied equally either side., I would be surprised if adjusting top stays would make any appreciable difference. Naturally none of this would have been apparent when tuning under other conditions. In twenty years of ownership I have only once submitted to tuning - exciting and almost irrelevant to subsequent experience. I keep my rig tuned myself, it's no state secret. No pumping!

PWG

 

[Travelling Westerly]

So can you see the mast itself physically moving? Is the jib furler moving around? Both?

No not really because it mainly happens when Im in bed and the wind gets up. You dont feel it in the saloon, its only felt in the aft cabin where the backstays lead to. If I go outside and "pump" the backstays it replicates the movement in the aft cabin. I can see the inmast foil bumping around when I do this but cant see the mast move.

Interestingly, I set up my removable inner forestay yesterday and tensioned it, the wind got up and you could feel the pumping in the saloon for the first time. Not sure if that means anything? I have removed it now

 

[dunedin]

No not really because it mainly happens when Im in bed and the wind gets up. You dont feel it in the saloon, its only felt in the aft cabin where the backstays lead to. If I go outside and "pump" the backstays it replicates the movement in the aft cabin. I can see the inmast foil bumping around when I do this but cant see the mast move.

May help to get warm clothes and go shine a bright torch at the rig whilst it is happening. Possible you may get a pleasant surprise and discover neither mast nor jib foil are moving significantly, hence probably only an annoyance.
Equally if something is moving around significantly I would want to get to the bottom of the cause and stop it.

 

[Dan Tribe]

A trick that sometimes works for me is to hoist my heaviest mooring warp and wrap it round the last below the spreaders.. Not always successful, but worth a go. You sometimes see spiral fins on skinny chimneys for the same effect.

 

[vyv_cox]

Apart from being disturbing this is not good news for your lovely vessel. As others have said, it's a condition arising from tensions, often a lack of mid mast support. Working the lower stays should assist, turns applied equally either side., I would be surprised if adjusting top stays would make any appreciable difference. Naturally none of this would have been apparent when tuning under other conditions. In twenty years of ownership I have only once submitted to tuning - exciting and almost irrelevant to subsequent experience. I keep my rig tuned myself, it's no state secret. No pumping!

PWG

My rigging is tuned to perfection, methodology is all on my website. When checked with a Loos gauge the tensions were exactly what they should be. Pumping is a known problem with my boat, it seems very little can be done about it.

 

[Travelling Westerly]

May help to get warm clothes and go shine a bright torch at the rig whilst it is happening. Possible you may get a pleasant surprise and discover neither mast nor jib foil are moving significantly, hence probably only an annoyance.
Equally if something is moving around significantly I would want to get to the bottom of the cause and stop it.

Good advice which Im passing on to the boss as we speak. She is getting her foulies at the ready.
The thing I cant get my head around is that I dont remember this happining before the last rig tune. Im waiting to see what the rigger comes back with. Perhaps the slight mast bend was not so bad after all!
Cheers

 

[dunedin]

Good advice which Im passing on to the boss as we speak. She is getting her foulies at the ready.
The thing I cant get my head around is that I dont remember this happining before the last rig tune. Im waiting to see what the rigger comes back with. Perhaps the slight mast bend was not so bad after all!
Cheers

Good segregation of roles

Your point about loss of slight pre-bend could be a factor - certainly putting some bend on helps with ours, but a very different semi-fractional rig and no in mast furler. And as others have said, other factors also.

 

[bignick]

Another thing to consider is the stability of the heel. If the riggers have increased mast rake then the compression forces may all be going through the aft corner of the heel, rather than distributed across the length. This will reduce stability of the mast and increase its propensity to move. See if you can push the lower part of the mast forward at shoulder level.

 

[richardbrennan]

I too understand pumping to be an unwanted inversion of the mid section of the mast and I am suspicious it has only happened since your rig tune. I suffered from this problem, but when out sailing. I took the boat to Martin Leaning at Port Solent and they discovered the upper intermediates were over tight preventing sufficient pre- bend in the mast. After they had retuned the rig, the problem was solved. I also fitted a backstay tensioner as belt and braces.

 

[Quandary]

Its an inmast Selden set up, mast head, twin spreaders but not swept back at all. The back stay splits into 2 sections and both have turn buckles so adjustable I guess. There is a baby stay as well.
The mast had prebend in but the new riggers said it should not have any as its an inmast unit. It was after their tune up that it started pumping - alot! I've written an email to them so awaiting their reply.
One thing I did seem to find on Google was others who had the same issue suggested the rig was to tight. If I took half a turn off each turn buckle on the whole rig would that be a safety issue?

It sounds to me that in his efforts to avoid any prebend in your mast that the rigger may have set up the rig a bit slack rather than too tight, If there is no backstay adjuster other than turnbuckles you could try tensioning by pulling the two parts together with a bit of line the next time you have the conditions where it occurs. If that stops it you can rig a tensioner to be used at bedtime, Easing the turnbuckles half a turn is unlikely to make any difference to anything.
I am not certain that vortex shedding would be the problem because if it was you should have experienced it occasionally before the rig tune.

 

[johnalison]

My impression is that it is commoner on older masthead rigs than modern ones, which are more likely to be properly rigged. We have a 19/20 rig with double spreaders that are not swept. Mast flogging is not a big problem but occasionally occurs with a moderate wind from the beam. I sometimes see a small triangle hoisted on the forestay to allay a similar problem but a mast is harder. I have seen people hoist a fender halfway up to break the vortex but haven’t tried it myself. I believe that spirals are built into tall structures for the same reason, and although I haven’t tried it, it looks as if the spiral winding described above might be successful, but presumably less so with double-spreaders.

 

[differentroads]

I used to have a similar problem with my 10m deck mounted masthead sloop in winds of 30kn+. Its disappeared (touch wood) since I converted to a cutter (inner forestay usually mounted but not tensioned up unless I'm off sailing) and adjusted the mast rake forward to reduce weather helm and removed the prebend (which tensioning the inner forestay puts back in.) Of those changes, I don't know which had the effect on the 'pumping' sound and sensation (I appreciate that technically mast pumping is a very specific phenomenon and the problem experienced by the OP and me could be from other causes.)
I had tried the tips above to reduce vortex shredding. They changed the wind speed or angle that caused the problem but didn't eliminate it.
I used to worry about the risk that whatever was causing the sound and movement could work harden the rigging or fittings. But if someone with Vyv Cox's knowledge and experience isn't red flagging it, I'm not going to stress about it (foregive the pun.)

 

[TernVI]

To be completely vague and general, there are 3 ways of avoiding resonant effects:
Remove the excitation
Alter the tuning of the resonating body
Introduce 'loss' or 'damping'

Which isn't directly helpful, but sometimes adding some bungee cord across the shrouds or even mast to backstay. might be worth a try.
See how the mast or wires are moving and take energy out of them.