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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Deck Lifting at Shrouds

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ct95949
Captain

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Aruba
300 Posts

Initially Posted - 04/22/2007 : 11:43:35

Recently I noticed a slight upward bulge of the deck at each lower shroud eyebolt. In the cabin at eye level it was much more visable and pronounced. Placing a straight edge on the cabin ceiling in front of the eyebolt I measured a 5/32" gap or lift in the deck that extended 5" forward and aft of the bolt where the deck went back to being straight. There are no cracks or seperation above or below.

The obvious answer would be that I put too much tension on the lowers but with the adjustable backstay tight I'm measuring only 27- 28 on the small Pro Loos gauge which would be less than 10% of breaking strength for 5/32" cable.

I have a binder full of mast tuning info starting with Bill Holcomb's version. I only use the Loos gauge as a rough guide and to get both sides equal and the last time I tightened the lowers was to remove slack on the leeward side when sailing upwind.
Has anyone else had there deck lift like this or have any ideas on how to remedy the problem?
Thanks, Craig

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 04/22/2007 12:33:27

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 04/22/2007 : 11:50:25

Sounds more like a chainplate problem than a shroud tension problem to me.

Edited by - on

ct95949
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Aruba
300 Posts

Response Posted - 04/22/2007 : 12:08:24

There is no lifting at the upper shroud chainplates, only at the lower shroud eyebolts which are securely fastened to the deck. I should also mention that these are the upgraded 1/2" eyebolts that use a smaller and thinner ( for some reason

) backing plate that is also bent upward with the deck.

Edited by - on

ClamBeach
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3072 Posts

Response Posted - 04/22/2007 : 14:47:45

IMHO: The plywood coring in the deck around the chainplates has probably rotted out due to water intrusion. It is a common malady on C25's along with many other sailboates with wood cored decks. No core = no strength.

If this is the case, you'll have to re-core that area. This takes some doing but is not an overwhelming task for small areas.

Edited by - on

ct95949
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Aruba
300 Posts

Response Posted - 04/22/2007 : 15:25:26

Clam-
When I replaced the old eyebolts 3 years ago the core looked sound. I did the oversize hole and epoxy routine so there shouldn't have been any intrusion since then. I suppose water could have entered from another source but I wouldn't think that would happen at all four locations. The deck is not spongy or showing any other signs or rot, in fact I've replaced quite a bit of hardware and found very little core damage.

Edited by - on

Leon Sisson
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USA
1893 Posts

Response Posted - 04/22/2007 : 16:14:39

Craig and Lorri,

When I upgraded my lower chainplates, I reused the larger original aluminum backing plates. Checking my aft lowers with a 2' straightedge, I'm seeing about 3/32" deflection in the liner on one side, and maybe 1/32" to 1/16" on the other side. Laying the straightedge on deck shows similar results. I know my deck core is good. I don't tune with a Loos gauge, but I shoot for medium tension, and fine tune the leward shrouds while sailing on a beat. From your description, it sounds like somewhere between nothing to worry about, and a little too much tension on the lowers.

-- Leon S.

Edited by - on

Frank Hopper
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Pitcairn Island
6776 Posts

Response Posted - 04/22/2007 : 16:28:06

It is hard to believe that these could allow the deck to deform, they look like they would spread the load enough that it would not happen.

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ct95949
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Aruba
300 Posts

Response Posted - 04/22/2007 : 18:26:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Leon Sisson
 Craig and Lorri,

When I upgraded my lower chainplates, I reused the larger original aluminum backing plates. Checking my aft lowers with a 2' straightedge, I'm seeing about 3/32" deflection in the liner on one side, and maybe 1/32" to 1/16" on the other side. Laying the straightedge on deck shows similar results. I know my deck core is good. I don't tune with a Loos gauge, but I shoot for medium tension, and fine tune the leward shrouds while sailing on a beat. From your description, it sounds like somewhere between nothing to worry about, and a little too much tension on the lowers.

-- Leon S.
<hr height="1" noshade id="quote"></blockquote id="quote">
Thanks Leon.
I'm sure my deck is fine and I was hoping that someone would say the deflection was no big deal but it's just enough to bug me and since the problem is wider than the old backing plates I was planning on doing something like Frank has pictured.
Frank, is this what you've done on your boat to correct a similar problem, is that aluminum or stainless and is it 2" or 3" angle?
Thanks, Craig.

Edited by - ct95949 on 04/22/2007 18:31:51

bear_tm4
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USA
143 Posts

Response Posted - 04/22/2007 : 21:50:43

Iam pretty sure you can get them at CD, I was looking on line and saw somthing similar tonight, My boat has them instaled all ready, Hope that helps....I fear the same thing you do...although I have ne evidince to suggest it, other than water showing up in odd places, like my one of my cabin lights...I cant seem to find a place its coming in. I re-bedding stanchions hoping that will find the source. we will see. Good luck
Bear

Edited by - on

atgep
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Response Posted - 04/22/2007 : 23:08:56

I dont think I would worry too much. Your boat is going on 30. The newer boats came with the large aluminum angle. If you are concerned, get the biggest angle you can fit in there. The deformation could have happened years ago from a overzealous shroud tightning.

Tom.

Edited by - atgep on 04/22/2007 23:11:22

ct95949
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Aruba
300 Posts

Response Posted - 04/22/2007 : 23:33:36

Since the original plate was 3" wide I thought of using 3" angle about 12" long to span the deflection though it seems like it would be a little obtrusive in the cabin. I've never seen the angle backing plates offered as replacement parts for our boats, I'll have to search.
Thanks all for the input.

Edited by - ct95949 on 04/22/2007 23:41:38

Frank Hopper
Past Commodore

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Pitcairn Island
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Response Posted - 04/23/2007 : 07:43:15

Mine is stock but I thought it was also what is included in the upgrade kits.

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 04/23/2007 : 09:51:06

My '85 also had the aluminum angle extrusions--almost certainly stock, and I think longer than Frank's. Catalina probably went to that after seeing exactly what you're seeing.

Edited by - Dave Bristle on 04/23/2007 09:52:11

esailor
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Response Posted - 04/23/2007 : 11:17:19

Is this deflection common on our older models?

Edited by - on

tinob
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Response Posted - 04/23/2007 : 12:17:34

My '83 has the same angle support as Frank's picture depicts.

Val on the hard DAGNABIT, #3936, Patchogue, N.Y.

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Sloop Smitten
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1181 Posts

Response Posted - 04/23/2007 : 13:27:09

Craig,
My 78 does not have this bulge. If you are following Bill Holcomb's tuning guide I doubt you created this problem. It could have been from a previous owner however. If you are confident the hull core is sound I would put some support plates in extending past the bulge areas and go sailing. I usually set my lower stays to just tight enough to remove any sag in them when they are on the lee side of the main. Then I balance them out with the Loos gauge. Sounds like what you are doing also.

Edited by - on

Dave Bristle
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Djibouti
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Response Posted - 04/23/2007 : 15:25:08

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Sloop Smitten
 I usually set my lower stays to just tight enough to remove any sag in them when they are on the lee side of the main. Then I balance them out with the Loos gauge. Sounds like what you are doing also.<hr height="1" noshade id="quote"></blockquote id="quote">
That's pretty tight, IMHO. My leeward aft lower almost always waved in the breeze on a beat. Some racers run a lot looser than I did, to be able to control the bend under way.

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Sloop Smitten
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Response Posted - 04/23/2007 : 17:34:23

Dave,
I imagine there are a lot of differing opinions on this subject. Using the technique I described they are still looser then the setting indicated with the instructions that came with the Loos gauge. I use to have them loose as you describe but I found a shroud dangling one day where the constant motion had loosened one of the lock nuts and the turnbuckle had backed off. I still have the original style closed turnbuckles. I would not run them as loose as you suggest without converting to open face turnbuckles that can be wired in place. Even so, since I don't race and I don't have an adjustable back stay, I don't see where leaving them looser would provide that much benefit.

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ClamBeach
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3072 Posts

Response Posted - 04/23/2007 : 20:05:17

A bit of deflection on the bottom doesn't bother me... I think a bit of crush is normal.
An upward bulge in the deck surface makes me think something's wrong.

Edited by - on

ct95949
Captain

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Aruba
300 Posts

Response Posted - 04/23/2007 : 22:37:33

Clam-
That's a good point. I didn't measure the top deflection but it looks less than the underside and I know cavities do exist between the deck and the interior liner that a bolt will crush if not filled solid first.

Couldn't find the angle plate at CD, can they still be ordered from the Catalina factory? I can get the material, cut and drill it no problem but I would like to know what the factory engineers had in mind.

Edited by - ct95949 on 04/23/2007 22:59:50

ClamBeach
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Response Posted - 04/24/2007 : 09:22:36

"Couldn't find the angle plate at CD,"

Looks to be a piece of 3/8" aluminum angle stock. 1x3? Easy to cut, easy to drill, betcha if you can't find a piece of that material at a local metals supplier or hardware store in your town it's available on the web.

Edited by - on

Leon Sisson
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USA
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Response Posted - 04/24/2007 : 10:14:00

I'd look into using flat backing plates. They're less obrusive, and don't obstruct the shelves near as much. Quarter inch plate should be plenty stiff enough. If the plate flexes ever so slightly under heavy load, that's not such a bad thing. Someone more fanatical than me might even suggest tapering the plate towards the edges, or stacking two thinner plates, with the one against the fibeglass being larger (in surface area) to help distribute the load.

-- Leon S.

Edited by - on

tinob
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Response Posted - 04/25/2007 : 10:48:07

Craig,

What happens when you loosen the stays in question?

Val on the hard DAGNABIT,#3936, Patchogue, N.Y.

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John Mason
Admiral

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USA
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Response Posted - 04/25/2007 : 12:23:32

If I were putting in angle backing plates, I'd drill a row of holes along that lower edge. Might be handy to hang stuff from.

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Leon Sisson
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Response Posted - 04/25/2007 : 16:40:49

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Mason
 If I were putting in angle backing plates, I'd drill a row of holes along that lower edge. Might be handy to hang stuff from.
<hr height="1" noshade id="quote"></blockquote id="quote">How about getting some scraps of perorated aluminum toe rail, such as some Hunters use? Install it upside down, and weave shock cord between the toe rail holes and the fiddle on the shelf behind the settee.

-- Leon S.

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ct95949
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Aruba
300 Posts

Response Posted - 04/25/2007 : 23:15:44

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tinob
 Craig,

What happens when you loosen the stays in question?

Val on the hard DAGNABIT,#3936, Patchogue, N.Y.
<hr height="1" noshade id="quote"></blockquote id="quote">
I haven't yet, but I'm guessing most of the deflection will remain.
I think I'll be using 3" x 1/4" channel, stronger and not as obtrusive as angle. I found a shop that stocks a wide range of metals in every dimension.

Edited by - ct95949 on 04/25/2007 23:19:36

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