Fw: [Passport] Re: After Rebedding Chainplates
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Bill Schmidt
Apr 25, 2013, 2:50:08 PM4/25/13
to Passport Owners, Ian Macrae
Oops! I hit the delete button instead of the send button. It's hell to get
old.
B.
----- Original Message -----
From: "Bill Schmidt" <bi...@windwitch.com>
To: "Ian Macrae" <versin...@gmail.com>; "Passport Owners"
<Passpor...@googlegroups.com>
Sent: Tuesday, April 23, 2013 6:44 PM
Subject: Re: [Passport] Re: After Rebedding Chainplates
> Ian et al: I've said this before, many times before: The plywood is cheap,
> construction grade plywood, not marine grade and only used as a form for
> constructing the "real" knees made of fiberglass. The REAL problem is
> either a Bob Perry design problem or a Wendell Rankin, builder problem,
> depending upon who you want to believe, or both. Either way the problem is
> that the fiberglass knee tears away from the hull. Perry states (lately)
> that the design called for the knee to tab into/thru bolt into a bulkhead
> that Rankin didn't use/build. We went to Tom Wiley, when this problem
> happened to Wind Witch, for a separate redesign (and subsequent
> construction). He told us, through the boat yard, that the problem was a
> design problem---something that BP has had issue with for a long time.
> Compounding this revelation (or whatever) has been that knees for the
> upper and middle shrouds were not built systematically to the same specs.
> There were "long knees" and "short" knees. The boats with "short knees"
> (which appear to be made on forms really intended for the construction of
> the knees for the forward and aft shroud chainplates) seem to be the ones
> that fail or have failed first. I am not aware of any boat where the
> smaller knees forward and aft on the lower shrouds have ever failed. They
> leak as often as any and, if rot were a problem, I would think that we
> would have seen some of these being a problem too.
> There have been many different solutions used on boats over the years.
> "Trial Run" has a stainless steel belly band running from port to
> starboard attaching to the knees on both sides. The knees of Wind Witch
> are very long, massively thick and fenestrated. They are made of S-fiber
> roving (whatever that is) and have no voids for puddles. In 25 years, they
> have never leaked nor needed rebedding except for when we replaced all the
> chain plates in Mazatlan in 2006 when we redid the teak decks. On
> Wildflower (I think) the problem was solved by attaching a turnbuckle to
> the chainplates and to a pad built lower down on the hull, then taking up
> a tension. I am sure there are other solutions used as well. God only
> knows which is best.
> With regard to when to retension after rebedding, I really don't think
> it matters. Those shrouds and chainplates flex and shake recurrently when
> sailing and tacking. So long as you don't use a rigid cement or caulk, I
> doubt it matters. Think of how many sailboats are constructed and how long
> it usually is before they are finally fitted with a mast. Long time, long
> time.
> Billy Manana
> ----- Original Message -----
> From: "Ian Macrae" <versin...@gmail.com>
> To: "Passport Owners" <Passpor...@googlegroups.com>
> Sent: Tuesday, April 23, 2013 4:28 PM
> Subject: [Passport] Re: After Rebedding Chainplates
>
>
>> My thought is to reconnect right away. Applying pressure after it
>> cures might mean it would be too stiff to adapt to the new pressurized
>> position. Let it cure under pressure and in its final resting spot.
>> This question about when to tighten might be like the debate about
>> which is better, a Ford or a Chevy.....For trucks, obviously a Chevy
>> or GMC!
>>
>> The workers just got done cutting out the two knees for my top and mid
>> shrouds, the port and starboard (obviously). Inside the fiberglass
>> "triangle" that is visible when you take the trim box off were two
>> wooden triangular pieces of 1/2" (or close to 1/2, I didn't actually
>> measure it) plywood. They weren't glued together, just held together
>> by the fiberglass and the chain plate bolts. It was obvious that
>> water had gotten into the wood, as there was rot and mold. Trying to
>> imagine the mechanism of the failure that allowed my deck to be pulled
>> up, I'm thinking that as the wood rotted it stopped giving structural
>> support and rigidity, and the load transferred to the fiberglass that
>> surrounded the now rotten wooden triangles. Then the fiberglass
>> started flexing and working which led to its disintegration. I have
>> to say that there was not really that much rot, but apparently enough
>> to cause the whole thing to fail. And before the failure it wasn't
>> obvious to me or my rigger (who had installed new shrouds in December)
>> that there was a problem. There were a few water stains around the
>> knees, but nothing that would cause alarm bells to go off. Even after
>> I found the deck pulling up, there was nothing really dramatic to see
>> around the fiberglass knees....a few little cracks and broken threads
>> of fiberglass and some separation of wood along the bulkhead and
>> underside of the deck area.
>>
>> So, make sure you keep those little plates around your chain plates
>> well caulked at all times!
>>
>> Ian
>>
>> P40, Freyja, #49
>>
>>
>>
>>
>> --
>> --
>> Passport Owners Association http://passportyachts.org
>> To post to the group, use "reply all" or send email to
>> Passpor...@googlegroups.com
>> To reply to just the author, just use "reply:
>> For more options, go to
>> http://groups.google.com/group/PassportOwners?hl=en
>> ---
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>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>
>
> --
> --
> Passport Owners Association http://passportyachts.org
> To post to the group, use "reply all" or send email to
> Passpor...@googlegroups.com
> To reply to just the author, just use "reply:
> For more options, go to
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> ---
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>
>
>
old.
B.
----- Original Message -----
From: "Bill Schmidt" <bi...@windwitch.com>
To: "Ian Macrae" <versin...@gmail.com>; "Passport Owners"
<Passpor...@googlegroups.com>
Sent: Tuesday, April 23, 2013 6:44 PM
Subject: Re: [Passport] Re: After Rebedding Chainplates
> Ian et al: I've said this before, many times before: The plywood is cheap,
> construction grade plywood, not marine grade and only used as a form for
> constructing the "real" knees made of fiberglass. The REAL problem is
> either a Bob Perry design problem or a Wendell Rankin, builder problem,
> depending upon who you want to believe, or both. Either way the problem is
> that the fiberglass knee tears away from the hull. Perry states (lately)
> that the design called for the knee to tab into/thru bolt into a bulkhead
> that Rankin didn't use/build. We went to Tom Wiley, when this problem
> happened to Wind Witch, for a separate redesign (and subsequent
> construction). He told us, through the boat yard, that the problem was a
> design problem---something that BP has had issue with for a long time.
> Compounding this revelation (or whatever) has been that knees for the
> upper and middle shrouds were not built systematically to the same specs.
> There were "long knees" and "short" knees. The boats with "short knees"
> (which appear to be made on forms really intended for the construction of
> the knees for the forward and aft shroud chainplates) seem to be the ones
> that fail or have failed first. I am not aware of any boat where the
> smaller knees forward and aft on the lower shrouds have ever failed. They
> leak as often as any and, if rot were a problem, I would think that we
> would have seen some of these being a problem too.
> There have been many different solutions used on boats over the years.
> "Trial Run" has a stainless steel belly band running from port to
> starboard attaching to the knees on both sides. The knees of Wind Witch
> are very long, massively thick and fenestrated. They are made of S-fiber
> roving (whatever that is) and have no voids for puddles. In 25 years, they
> have never leaked nor needed rebedding except for when we replaced all the
> chain plates in Mazatlan in 2006 when we redid the teak decks. On
> Wildflower (I think) the problem was solved by attaching a turnbuckle to
> the chainplates and to a pad built lower down on the hull, then taking up
> a tension. I am sure there are other solutions used as well. God only
> knows which is best.
> With regard to when to retension after rebedding, I really don't think
> it matters. Those shrouds and chainplates flex and shake recurrently when
> sailing and tacking. So long as you don't use a rigid cement or caulk, I
> doubt it matters. Think of how many sailboats are constructed and how long
> it usually is before they are finally fitted with a mast. Long time, long
> time.
> Billy Manana
> ----- Original Message -----
> From: "Ian Macrae" <versin...@gmail.com>
> To: "Passport Owners" <Passpor...@googlegroups.com>
> Sent: Tuesday, April 23, 2013 4:28 PM
> Subject: [Passport] Re: After Rebedding Chainplates
>
>
>> My thought is to reconnect right away. Applying pressure after it
>> cures might mean it would be too stiff to adapt to the new pressurized
>> position. Let it cure under pressure and in its final resting spot.
>> This question about when to tighten might be like the debate about
>> which is better, a Ford or a Chevy.....For trucks, obviously a Chevy
>> or GMC!
>>
>> The workers just got done cutting out the two knees for my top and mid
>> shrouds, the port and starboard (obviously). Inside the fiberglass
>> "triangle" that is visible when you take the trim box off were two
>> wooden triangular pieces of 1/2" (or close to 1/2, I didn't actually
>> measure it) plywood. They weren't glued together, just held together
>> by the fiberglass and the chain plate bolts. It was obvious that
>> water had gotten into the wood, as there was rot and mold. Trying to
>> imagine the mechanism of the failure that allowed my deck to be pulled
>> up, I'm thinking that as the wood rotted it stopped giving structural
>> support and rigidity, and the load transferred to the fiberglass that
>> surrounded the now rotten wooden triangles. Then the fiberglass
>> started flexing and working which led to its disintegration. I have
>> to say that there was not really that much rot, but apparently enough
>> to cause the whole thing to fail. And before the failure it wasn't
>> obvious to me or my rigger (who had installed new shrouds in December)
>> that there was a problem. There were a few water stains around the
>> knees, but nothing that would cause alarm bells to go off. Even after
>> I found the deck pulling up, there was nothing really dramatic to see
>> around the fiberglass knees....a few little cracks and broken threads
>> of fiberglass and some separation of wood along the bulkhead and
>> underside of the deck area.
>>
>> So, make sure you keep those little plates around your chain plates
>> well caulked at all times!
>>
>> Ian
>>
>> P40, Freyja, #49
>>
>>
>>
>>
>> --
>> --
>> Passport Owners Association http://passportyachts.org
>> To post to the group, use "reply all" or send email to
>> Passpor...@googlegroups.com
>> To reply to just the author, just use "reply:
>> For more options, go to
>> http://groups.google.com/group/PassportOwners?hl=en
>> ---
>> You received this message because you are subscribed to the Google Groups
>> "Passport Owners" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to PassportOwner...@googlegroups.com.
>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>
>
> --
> --
> Passport Owners Association http://passportyachts.org
> To post to the group, use "reply all" or send email to
> Passpor...@googlegroups.com
> To reply to just the author, just use "reply:
> For more options, go to
> http://groups.google.com/group/PassportOwners?hl=en
> ---
> You received this message because you are subscribed to the Google Groups
> "Passport Owners" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to PassportOwner...@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
>
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