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Detentioning lower shrouds moved support beam in cabin

LeifThor

Member II
1972 E35-2
I recently needed to stress check a lower shroud.

I loosened the lower shrouds, and found the support beam in the cabin between mast and hull had moved slightly making it so the head door wouldn’t close. Compression plate recently replaced there’s no sag whatsoever.

I screwed up and when I loosened the shrouds DID NOT remove tension from the boom vang.

Anyone have any ideas how to fix this? It moved about 1/4in but shows no change in position at the top or bottom of the post, and the post isn’t bowed, its straight perfect. Very confused...



help
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
The down force of the spar, when shrouds are tight, goes to the plate on the cabin top, then thru the cabin top layers of glass, plywood, or sometimes a steel plate, then to the mast support post (which may be in two places if the opening to the forward cabin has a bridge beam....
and then to whatever is below that support system and the bottom of the hull or appropriate cross beam or "floor".
One place that sometimes get overlooked is the part under the post, i.e. the material under that section of sole. There may have been plywood or a hardwood piece under there originally, set in poly mush.
After 40 years it's not unusual to have to rebuild that lowest part on any boat from any builder.

Aside: "stress checking" a part of the standing rig is a new term to me. We replace the wires after 20 years, and many sailors are much more conservative yet.
 

LeifThor

Member II
Thanks for responding Loren!
Every Ericson I’ve looked at has had some level of mast sag except this 35-2 I bought. When I bought it, the compression steel plate under the mast and just under the deck glass had water intrusion and rusted and expanded 1/2 in tearing apart the glass pushing the mast up, but the compression under the plate had held steady, a thing I found impressive compression stability wise.

Because of this I didn’t want to fix something that wasn’t broken, even though as you mention the compression post below the sole is exposed to possible rot or any number of non visible things to reduce its strength.

I just want to add for relevance-
New rigging
New compression plate
Rigged and performed exceptionally
At no time while mast was off or after when new rigging was tuned did the post move.

It only moved (or the head door moved going the other way??) after I’d detensioned the lowers WHILE forgetting to detention all forced pulling the boom downward.

How to fix this though is the big question...
 

steven

Member III
Can you be more specific on what seems to sag and in what direction?

The lowers mainly are to hold the mast in column, but there are side effects.
The tension in the shroud pulls upward on the deck.
And the fwd chain plate anchors below the deck to a bulkhead (discussed in another recent thread) which pulls down on the deck down and up on the bulkhead.

Relieving the tension on the lowers might have moved the beams and bulkheads without involving the mast support.

--Steve
 

LeifThor

Member II
Can you be more specific on what seems to sag and in what direction?

The lowers mainly are to hold the mast in column, but there are side effects.
The tension in the shroud pulls upward on the deck.
And the fwd chain plate anchors below the deck to a bulkhead (discussed in another recent thread) which pulls down on the deck down and up on the bulkhead.

Relieving the tension on the lowers might have moved the beams and bulkheads without involving the mast support.

--Steve
I solved it by tensioning the forward lowers and then tensioning the rear lowers to a slightly less tension. Door closes fine now:)
 

LeifThor

Member II
I came to that conclusion because the beam shift led one way by detentioning the lowers while there was still tension from the boom vang. So to get it to shift the other way I figured tensioning from the other side might do it. Worked like a charm.
 
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