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Old 09-04-2009, 05:24 AM   #1
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Just started out on a run for the chesapeake from New Bedford, MA... all was well, going along nicely on a beam reach with a beam sea... a bit rolly but nothing to worry about... that is until I realized that with each roll the mizzen mast was rotating about 5 degrees each way... watching this for a while I finally looked up and realized that the reason is the weight of the wind genny and radar which as the boat rolls side to side turn the mast a bit one way then the other.... is this something to worry about... This is the mizzen on my pearson 365 for those who aren't familiar with my boat.... it's deck stepped but I've actually never had the mast off so I'm not sure how securly it is seated.... is it safe for my mizzen to have this slight rotation?

we're postponing and about to put in at a port of refuge due to this... I'll talk to the previous owner in the morning and hopefully get some more info on the stepping arangement....

all input greatly appreciate... with any luck this is not something to worry about and we just get a good nights sleep and then take off again tomorrow.
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Old 09-04-2009, 06:47 AM   #2
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Pearson_365.jpg

Is this Ketch similar to yours ?

Is the mast circular in section at the base?

What is it stepped into ? eg tightly into a metal receiver which is "fixed" to the deck

Below deck, is the mast supported on a pole or a bulkhead ? Can you see any problems there?

The 5 degrees movement , what does that measure at the front of the mast - in parts of an inch? (5 degrees on a 6"diameter mast, off the center line would only be something like 1/4" movement either way)

Are the mast's shrouds nice and tight ?

Does your Ketch have a triatic stay ?

Hard to give 100% good advice - other than to suggest:

Take the mizzen sail off.

Either take off the Boom or lash it fast out of the way

Then brace the Mast by cleating with additional line to midship cleats

The mizzen main's halyard to be winched down tight on the opposite side to where the boom has been lashed and cleated off

Check the movement by drawing a vertical line down the mast and continuing it forward for an inch on the deck.

And carry on.
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Old 09-04-2009, 08:46 AM   #3
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Yeah, I did pull dwn the sail and lash the mast to the sheet winches, we are now safely at anchor... looking more closely at it now that the boat isn't bucking around it appears that the mast is vey slightly out of balance sitting mostly on the starboard edge of the base... it pivots on this but only slightly, less than 1/4 inch but enough for me to notice when I was sitting in the cockpit and cought the wiggle out of the corner of my eye... I'm not sure actually how the mast is stepped, I've never had it off... it's not in a receiver, looks like it's just sitting on a plate but you can't push/wiggle it off the plate so I'm guessing the base of the mast is a receiver accepting an insert from the plate....

the step is strong, it's braced below deck in the engine compartment to the keel, I do have a triatic stay...

in the morning I'll try and balance the rigging a little better and still definitely plan to talk to the previous owner just to get his insight... will keep you all posted on how things turn out.
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Old 09-04-2009, 07:39 PM   #4
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Hello there. Sounds like you'all are having some interesting times. Sounds like you've gotten it temporarily under control as well.

The load of your radar and wind generator is likely to be normally countered nicely by the wind loading on the mizzen sail and likely you're unloading the sail with each roll and thus seeing the movement due to the not-well-stayed add-ons to the mast.

The problem could be as simple as you not having the shrouds and stays adequately tightened and balanced. When we first launched our schooner, we motored the boat about 25 miles (15 open ocean) while only partially stayed--importantly we only had a halyard on the foremast as a fore stay, a rather loose triatic and freshwater stay going from the foremast aft to the main mast (which was much better fore-and-aft stayed with the gollywobbler halyards going foward and the two running backs going aft). We happened to exit Mission Bay in surf and the fore-and-aft loading of the partially stayed foremast was frightful to see. After seeing the masts shivering like jello as we plunged into wave troughs, hubby quickly tightened up the temporary forestay pulling the masthead forward and tightening up the rig sufficiently to not have to worry about it for the rest of our trip.

Your freshwater stay/ spring stay (technically only we schooners have triatic stays ) and the aft staying of the mizzen may not be up to snuff for the task of dealing with the added weight of the radar and wind generator. Some ketches have more than one spring stay in order to transfer loads to the main mast. Further, if your mast is unduly flexible, you may benefit from changing the spreaders or adding jumpers for the equipment loading or even x-spreaders. Hard to figure without seeing the situation. If, when the radar and wind generator were added, a thoughtful analysis wasn't performed she may be inadequately stayed.

Several times here on the CL, I've recommended that folks invest in a copy of Brion Toss's Rigger's Apprentice. You can find it new and used online and besides having great info on how to tie various knots, do rope and wire splices, it is a wonderful reference for learning about dealing with all sorts of rig-related issues.

Good luck in getting things settled in better form

fair winds,
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Old 09-04-2009, 08:39 PM   #5
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I do in fact have a copy of the riggers apprentice, great book,

Spoke with the previous owner today, the 365 Ketch mizzen mast is effecively a socket which accepts a solid aluminum post that is part of the mast step, the post is about two feet tall and also an oval to fit the mast... the little bit of wiggle I'm getting is not uncommon to this boat apparently but he has never heard of a mizzen mas step failure. I tightened the stays right down hard (harder than I usually would, keepin things well balanced) and it seems to have solved the problem.... so we are under sail again... now that we've lost most of a day we don't have time to run for the chesapeake so it's back to the old fall back of puttering down the long island sound... pleasant sail, much less busy than I had expected.

thanks for all your help as always,
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Old 09-04-2009, 10:53 PM   #6
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Quote:
Originally Posted by atavist View Post
I tightened the stays right down hard (harder than I usually would, keepin things well balanced) and it seems to have solved the problem...
I'm thinking you're talking about shrouds not stays...if so...you know to tighten the lowers (that go to the spreaders) more than the ones that go all the way to the top of the mast--right?

I'm also thinking it's your fore-and-aft staying not being adequate for your (over) load of gear up there that's the root problem. So, hope you'll think about that and might come up with an intermediate backstay or something useful to deal with this longer term. Uh, I don't even see a backstay on the pic that MMNETSEA posted but figure I must be mistaken. There's a backstay for the mizzen, right?

Take care
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Old 09-05-2009, 01:16 AM   #7
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yeah sorry, shrouds...

as it happens though, the ones that go to the top of the mast are the ones that go to the spreaders and then there are a set of lowers that connect beneath the spreaders.... I make the ones that go to the top via the spreaders the tightest.... the manual for the boat says to make the for and aft stays "tight" and the shouds "tight enough to keep the mast from moving under sail"... it's a 1978 manual... what can ya do...

for backstays I have running backstays, and for a forestay the mizzen has only a triatic... er "fresh-water stay"?
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Old 09-05-2009, 01:37 AM   #8
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When you have time check the Mizzen's chain plates ; especially on the inside. If you find any sign of rust , worth removing the bolts one by one, to see what shape they are in .

Not forgetting the Foremast's plates.
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Old 09-05-2009, 04:02 AM   #9
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LOL "tight" enough, huh?

If you have no way of measuring rig tension, and you're just trying to get everything tighter it's safest to tighten up the lowers and then tighten up the longer shrouds a lesser amount. When all is said and done and if you can measure rig tension you'll eventually have the longer shrouds tighter than the shorter ones--but it's easy to induce a bend in a mast by tightening up the shrouds that go all the way to the top without having the lower shrouds tight first.

Fresh-water stay...well...that's also a schooner term I think that stay is technically called a "spring stay" on a ketch--but since it can function like the fresh water stay on the schooner, it might be called the same thing...

I'd sit down (sometime when you're windbound or something) and figure out the loading for the mizzen with all that "extra" on it. Sit down with the Rigger's Apprentice and go through it. You'll likely be happy that you did and you'll learn whether you're properly stayed for the extra loads.

Good luck!
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Old 10-12-2009, 12:49 PM   #10
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Tightening the rigging just to solve the mast rotation problem can lead to excessive mast compression. As long as the mast stays in column, it won't be noticeable until it receives some side loading under sail or when you roll or heal. Excessive mast compression can result in deflection of the mast step (deck beam ) in the absents of the compression post or chainplate attachment points. Usually evidenced by cracks in the gel coat. Also damage can be cause aloft in the tangs and mast attachment points. Worst case is to have the mast explode under compression load. This happens when the unsupported panels of the mast (between shroud attachment points or spreaders) bow out of column, and down she comes.

A little Story (short version): The ketch "Cloud Nine", out of Southwestern Yacht Club, SD., was demasted during the TransPac to Hawaii race (early '60). She was a fine wooden Kettenburg 38. During the passage, the owner would go around and tighten the lee shrouds without regard to the effect and compression load. As a result the main mast exploded 200 miles from Diamond Head. It also took out the mizzen as well, loosing the whole rig. The crew salvage as much as they could and were eventually towed to port by the USCG. She was hauled out and inspected before deck shipping back the San Diego. The compression load had also been transferred to the keel (maim mast was keel stepped) and through the planked hull structure to the chain plates, resulting in the planking seams being opened up on the windward side.

I would recommend you look at the torsion effect the wind generator is having on the mast. Standard radar mounts are generally in close enough to not have much lever effect. You don't mention what type and type of mount your wind generator has.

My thoughts (and ramble). FWIW.

Steve
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