Mizzen Mast Pumping and Rocking on Mast Step

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3 years 6 months ago #2551 by William Weigel
Mizzen Mast Pumping and Rocking on Mast Step was created by William Weigel
I am having a consistent problem with my mizzen mast rocking fore and aft on the mast step when pounding to windward. The mast also seems to pump considerably. I have tried tuning the mizzen stays as well as the triatic stay to better stabilize the mast but still have too much motion. Any ideas?

I am thinking of removing the triatic since the primary motion is fore and aft. How essential is the triatic in others experience?

Thanks in advance for your thoughts.

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3 years 6 months ago #2553 by Scott Lee
Replied by Scott Lee on topic Mizzen Mast Pumping and Rocking on Mast Step
Joie we Vivre does not have a Triatic stay.

Is the pumping action occur just when the mizzen sail is raised or any time?

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3 years 6 months ago #2554 by William Weigel
Replied by William Weigel on topic Mizzen Mast Pumping and Rocking on Mast Step
We almost always have the mizzen up so I am not sure if it does it when the sail is down. Not surprising it is most notable when we are in a heavy sea forward of the beam. I am able to see the rocking at the mast step with a 1mm gap at the front of the mast opening and closing as the mast moves. Another tell tale sign is a gray streaking that forms at the base of the mast across the deck if there is also enough salt spray. The gray streaking comes from aluminum oxide wearing off from the relative motion.

The reason I am thinking that the triatic may be part of the problem is that any flexing of the main mast can induce a load to the mizzen contributing to the dynamic loading of the mizzen. I have read the various posts in favor of the triatic so I am reluctant to take it down.

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3 years 6 months ago #2555 by Gerry O'Donoghue
Replied by Gerry O'Donoghue on topic Mizzen Mast Pumping and Rocking on Mast Step
I think I asked this previously, on another forum. Do you have running back-stays on your mizzen. My mizzen had. Look for pad eyes on the deck near the LPG locker aft, on both sides. If you don't, you should rig temporary ones and do a test run. Use a block system, they need lots of tension.

Gerry
The following user(s) said Thank You: William Weigel

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3 years 6 months ago #2556 by William Weigel
Replied by William Weigel on topic Mizzen Mast Pumping and Rocking on Mast Step
We have running back stays rigged with a 3 to 1 block and tackle with a cam cleat. We are able to set them with reasonable tension but of course the leeward stay is loose when using the mizzen. As I mentioned, I observe a gap opening at the front of the mast so my first thought was to try to pull the mast forward more. I tightened the forward shrouds on the mizzen but it did not seem to help much. The forward shrouds connect between the spreader and the mast head. Tightening these pulls the mast out of column and almost seems to amplify the pumping motion. It almost seems that the mast needs forward lower shrouds to more directly oppose the aft lower shrouds at the spreader.

I plan to remove the mizzen next month and inspect the mast step for wear. I also will grind the base of the mast to make sure it is flat. Apart from these measures, I need to figure out the best tuning configuration for the mizzen stays. Finally, I need to decide if I keep the triatic or not. If we follow through on our transatlantic crossing I want to make sure the mizzen is up for the trip!

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3 years 6 months ago #2557 by Gerry O'Donoghue
Replied by Gerry O'Donoghue on topic Mizzen Mast Pumping and Rocking on Mast Step
sounds like the mast is rocking backwards. This would seem to indicate that the triatic is not tight enough. if you remove it the problem will get worse.

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3 years 4 months ago #2588 by William Weigel
Replied by William Weigel on topic Mizzen Mast Pumping and Rocking on Mast Step
I think I have my answer. Joie de Vivre reported to me that their mizzen has forward lower as well as the forward intermediate stays both going to a common chain plate. I also took a look at a Whitby in a local marina (Blue Prince) that has a forward lower but no forward intermediate. I think I will go with the setup that Joie de Vivre has. I plan to add a Schaefer Triangle Plate like this to the chain plate. I will come off the upper corners of the Triangle Plate with 2 link plates to interface with my turnbuckle fork.

Does this make sense to those that I hope will read this?
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