[Public-List] Strengthening Soft Bulkheads.

[Gordon Laco via Public-List]

Hello Jonathan - 

I've been silently reading this exchange... I keep a close eye on SURPRISEs
bulkheads. The only places her plywood is showing trouble is the horizontal
shelf of the lazarettes on both sides of the main cabin, and the edges of
the semi-bulkhead up in the forepeak.  These are degraded by water leaking
in the hull to deck joint, which I am resolved to deal with this spring.

My experience with plywood when it starts suffering the attacks of water is
that it's finished when it starts showing symptoms.   I reckon that's not
good news to anyone, but I believe this to be true.  Once the glue in the
laminate starts letting go, all you've got is a bundle of paper thin veneers
and there's no particular strength in that to bear loads, let alone hold
itself together.

I reckon that an emergency repair can be made by gluing and bolting a
'plate' of some material, be it aluminium, more plywood, or glass cloth and
epoxy, by extending out to healthy wood and anchoring loads to that... But
the creeping crud may be silently working its way outwards from the trouble
you can see so surgery is the sure way to achieve a lasting cure.

And all that, is why I am not going to put off the deck edge repair again
this year...

Gord #426 Surprise


On 2016-01-29, 8:45 AM, "Jonathan Bresler via Public-List"
<public-list at lists.alberg30.org> wrote:

> Noodling on this a bit
> Guessing that
> 
>    - the bolts through the bulkhead resist the upward pull of the shrouds.
>    - the end of the bolt at the chainplate is being pull upwards
>    - the structure of the bulkhead has to resist the upwards pull
>    - the incompressibility of the bulkhead is what provides the resistance
>    - might be good to obtain a piece of G10 that extends the length of the
>    chainplate plus a bit, laminate the G10 to the bulkhead, through bolt the
>    chainplate to the G10 and the bulkhead.
>    - at that point, guessing that it would be the G10 that is resisting the
>    upwards pull rather than the bulkhead, and the G10 is transferring that
>    force to the portion of the bulkhead that the G10 is laminated to.
>    - punkiness in specific small areas of the bulkhead would not matter as
>    the G10 is laminated to a much larger area and that area as a whole would
>    have to fail for the G10 to move.
>    - might be good to do this two shrouds at a time with the chosen pair of
>    shrouds fully loosened.
> 
> Thoughts ?
> 
> Jonathan
> 
> On Thu, Jan 28, 2016 at 6:21 PM, Wes Gardner via Public-List <
> public-list at lists.alberg30.org> wrote:
> 
>> And of course, the disclaimer - only you can evaluate the effectiveness of
>> any repair vs. replacement and as Jeff points out, how well you'll sleep at
>> night. :-)
>> 
>> Sent from my iPhone
>> 
>>> On Jan 28, 2016, at 5:24 PM, Michael Connolly via Public-List <
>> public-list at lists.alberg30.org> wrote:
>>> 
>>> Hi all,
>>> 
>>> The Lorrie Rose has many problems among them bulkheads which are suspect.
>>> 
>>> She has wood-grained Melamine laminated to her primary bulkheads.
>> Tapping with a small hammer in the vicinity of the chain plates produces a
>> hollow sound. I suspect at minimum the laminate has detached from the
>> plywood substrate.  There is relatively little apparent water damage in
>> this area, but there is evidence of water intrusion.
>>> 
>>> I plan to remove the chain plates and peal back or lift off the Melamine
>> where it has delaminated, revealing the condition of the plywood beneath.
>>> 
>>> My question to those on the list is.  If there is no wholesale rotten
>> plywood, i.e., delaminating plies, missing pieces or punky holes but
>> perhaps some soft or tender but intact plywood, would it be possible to
>> consolidate the exposed plywood with some sort of penetrating epoxy
>> product?  Git-rot (R) comes to mind.
>>> 
>>> I would most likely redo the tabbing to the hull and deck.  Perhaps
>> lay-up some epoxy saturated fiberglass cloth to the consolidated surface of
>> the bulkhead. In other words, if the damage is not extensive or covering a
>> large area, can the bulkheads be repaired/strengthened without wholesale
>> replacement?  Has anyone attempted to do this in lieu of replacing the
>> bulkheads?
>>> 
>>> Thanks for your thoughts,
>>> 
>>> Michael #133
>>> 
>>> 
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> 
>