Turnbuckle at base of mast

[msenko]

On my 1987 C34 with a keel stepped mast there is a turnbuckle inside the cabin with one end bolted to the cabin top and the other end attached to the mast.

The book that came with the boat does not really address the function of this turnbuckle.

Does anyone know its purpose?

Thanks,

Mike Senko

S/V Puffin

[pklein]

It keeps the deck from flexing and therefore permits the boot that covers the hole in the deck where the mast goes down to the keel to remain relatively stable.  It also makes the deck less bouncy when yoy walk on it. :eek:

Phill Klein
Andiamo #977
Montrose Harbor - Chicago

[dpenz]

It's a structural fastener.  There is a compression load from the mast applied to the keel.  There are tension loads from the stays applied to the sides of the boat.  These forces would tend to bend the sides of the boat inward and the cabin top would bow upward.  With the cabin top restrained from upward movement, it acts as a compression member to hold the sides in place.  There would otherwise need to be a stiff beam in the cabin top to handle these forces, and that beam would reduce headroom.

[msenko]

Thanks for the information. I wish Catalina would give more information on its function.

A follow up question, are there any guidelines as to how tight to make it?

Mike Senko
Everett, Wa.
#495 Puffin

[Ron Hill]

David Penz is correct. Anytime that I have a question I go back to Catalina and ask David Graas or Gerry Douglas.  David usually replys back the next day, Gerry when he gets a chance.

I always call and talk to the Manufacturer - "the horses mouth". You need to be careful about answers from the internet, as you don't know which end of the horse is speaking!   Ron

Ron, Apache #788

[Stu Jackson]

Re:  question of how tight.

We just had new standing rigging installed, and the mast was pulled.  We have been out sailing a few times since, and have heard a sharp, intermittent "cracking" noise coming from what I've been able to track down from the mast partner (where the mast goes through the deck).  

I originally thought it was only the new wood spacers which were getting "used to their new homes."

After reading this thread, it occurs to me that perhaps the mast turnbuckle down below is not tight enough, because perhaps the cabintop is flexing, since the noise only occurs when we're close hauled.

I'll try tightening it up a bit and let you all know what happens.

Stu

[Stu Jackson]

Folks,

Like everything else in boating, it sometimes takes a bit longer, but here's the update:

My last post mentioned that I'd report back to you on the results of the tightening of the turnbuckle.

Cory said, "Why just figure you have to tighten it, maybe it should be looser.  You guys always tighten things, and then they break!"  Good thought.

When next hard on the wind, I tried loosening the turnbuckle.  Same noise, maybe even worse.

Good news, the rigger had left the cotter pins out of the shafts.  "Maybe we're onto something here," I thought, "Hmm, they may really need an adjustment, so that's why they left the cotter pins out for me to put in when I'm "done" tuning the rig."

Still on the wind, I tightened.

Dagnabbit, no change.  Enough of that for this particular day.  Nice sail, though.

So, as another excuse to go sailing again, I explained that I still had to go sailing again, to finally figure out the right turnbuckle tension.  Beats changing the oil.

Of course, by this time I had the new roller furling gear installed and was working on THAT system's tension, too.

Good news: I was able to figure out the differences in the "above decks" vs. the "below  decks" tensioning that I had to accomplish.  One was all upstairs, the other was down below, with a noise that sounded from all over, like it was coming from a series of broaching whales, some of whom sounded like they were able to fly.

Next time out was a beautiful day, with our new flat cut 85% jib (yes, you folks who wish for wind should move here to San Francisco, we have plenty to spare) and a reefed main, Aquavite and I sailed up past Alcatraz and towards Sausalito into a building early afternoon breeze.

CRACK

Get wrench out and tighten turnbuckle.

CRACK

Tighten some more.

crack

One half a turn more.

c   r   a   c  k

Quarter turn more.


Blessed s i l e n c e.

Of course, this was just too easy, so I went up and danced on the cabintop, jumped down from the mast step, swung off the rigid vang and generally made a fool of myself pounding on the cabintop while no one was watching (they were too busy avoiding broaches on a reach in 25 to 30 knot winds).

I tacked, again and again.  The noise never came back.

I tried sailing downwind - no "adjustment" noises.

Gybed, tacked, motored, sailed - every position to torque the bloody thing, and it was soooo  
q u i e t.

I actually looked UNDER from below to make sure the wedges hadn't popped overboard.  Still there.

I did my usual docking (we have an "upwind" berth in our marina:  they call it upwind because the marina's head is in a certain downwind direction, and their definition of upwind has NOTHING whatsoever to do with the prevailing westerly wind which is abeam from starboard), so I put some more "gee, I sure am glad I learned that trick that  WD40 gets off hull black marks" black marks on the portside, tied and tidied her up, thankful that we'd solved the problem, and had had a wonderful sail.  

Locked the boat, remebered the recycling material, and headed up the dock for the car and home.

As I reached the top of the gangplank, I turned and looked back with a smile of accomplishment for a job that was successful and required at least two trips to the boat, and sailing her to boot.

I smiled and sighed.

And so did she:  c    r    a    c    k

(More like just a little creak, really, and hard to describe while typing, but significant enough to know that she knew that I knew that she knew, etc.)

One last time for old time's sake, we both thought.

I think we've got the new roller furling tensioned properly, but we'll have to go out again to check it out.

Stu