How to repair the deck at the centerboard turning block on a F28/F33

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1

Posted by Barry Stellrecht (yak@…>)

Hello, Vladimir (and other F33/F28 Owners)

I’ve got another one of those F33’s with deck problems where the centerboard
turning block goes through the deck. (I’ve also got deck problems elsewhere
which I’m repairing…so far, all very small areas except for between the port
winch & rope clutches that will probably be a square foot or two when I finish
digging out to fix it.)

Anyhow, now that I’ve got the headliner down I can see how that block works, and
re-constructing the deck around it looks to be an interesting problem that I
would appreciate ideas for…mine has the lower deck skin and balsa cut out in
a ~5inch circle around that block, with a SS backing plate that has a socket
which fits inside a SS compression pipe going down toward the centerboard with
the pennant running inside it. The bottom of the post sits on a large U-shaped
piece of fiberglass inside the trunk which has a tube going thru to stop it
dropping out near the top and some sort of pin going through it at the bottom.
(I haven’t seen the bottom one since I don’t wanna deal with taking the board
out this time!)

Up on the top, there are a couple (slightly rotting) donut-shaped pieces of
plywood above the backing plate. When the block takes the load of the board,
the deck flexes, and the ply compresses until the compression post takes up the
load.

So far my repair ideas are:

  1. Reinforce the top skin of the deck with extra layers of biax cloth & epoxy,
    out as far as the rotten core goes (probably another inch or two beyond the
    existing hole. (I could dig out more core than just what is failed here)

  2. Replace the balsa around with something sturdier (probably plywood except at
    the edge where it might get water exposure at the bolts and pennant
    hole–thickened epoxy there.

  3. Build up the bottom skin a bit too around this area. This can go out a bit
    further than the replaced core…perhaps six inches out?

  4. Try to shim up the compression post somehow so it will take the load before
    the deck flexes. (Right now I’ve just bent a bit of 1/8" steel wire/rod around
    the joint as a stopgap measure while I’m hauling the board up/down to do bottom
    paint on it & the trunk.

For those of you with this problem, what have you tried/considered and how did
it work?

Thanks,

Barry

vladimir_ud wrote:

There is a block on cabin top. it’s turning point for the line for
lifting centerboard. This block supports all weight of the plate. I
have seen four F28-33 boats. All had fiberglass cracked, core
saturated around this block(Mine boat included)

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

2

Posted by Herman and Gail Schiller (hschiller2@…>)

If I understand this correctly, the lower skin, and the balsa core
above it, have been removed. If I was doing this fix, I would then
deeply taper the edge of this area to make it look like an
upside-down pie plate. After this, I would replace everything with a
solid lamination (forget replacing the core; this is a really
high-load area, which reminds me of the winch that lifts the 600
pound keel on an S-2 7.9 meter). To tie it in with the existing
laminate, I’d use epoxy resin. Adding some laminate to spread the
load further won’t hurt (Your number 3). Adding enough of this
locally can act to integrate the deck with the compression
post. It’s a good thing there’s a headliner to conceal all this
surgery. The fun comes with keeping the wet laminate up there until
it cures. I would do this with multiple layers, one or two at a time
with fast-curing resin/hardener. When the lamination gets firm, it’s
time for the next few layers of glass… Takes patience, and lots of
disposable gloves.
Best of luck, Herm

At 05:31 PM 8/5/2008, you wrote:

Hello, Vladimir (and other F33/F28 Owners)

I’ve got another one of those F33’s with deck problems where the
centerboard turning block goes through the deck. (I’ve also got deck
problems elsewhere which I’m repairing…so far, all very small
areas except for between the port winch & rope clutches that will
probably be a square foot or two when I finish digging out to fix it.)

Anyhow, now that I’ve got the headliner down I can see how that
block works, and re-constructing the deck around it looks to be an
interesting problem that I would appreciate ideas for…mine has
the lower deck skin and balsa cut out in a ~5inch circle around that
block, with a SS backing plate that has a socket which fits inside a
SS compression pipe going down toward the centerboard with the
pennant running inside it. The bottom of the post sits on a large
U-shaped piece of fiberglass inside the trunk which has a tube going
thru to stop it dropping out near the top and some sort of pin going
through it at the bottom. (I haven’t seen the bottom one since I
don’t wanna deal with taking the board out this time!)

Up on the top, there are a couple (slightly rotting) donut-shaped
pieces of plywood above the backing plate. When the block takes the
load of the board, the deck flexes, and the ply compresses until the
compression post takes up the load.

So far my repair ideas are:

  1. Reinforce the top skin of the deck with extra layers of biax
    cloth & epoxy, out as far as the rotten core goes (probably another
    inch or two beyond the existing hole. (I could dig out more core
    than just what is failed here)

  2. Replace the balsa around with something sturdier (probably
    plywood except at the edge where it might get water exposure at the
    bolts and pennant hole–thickened epoxy there.

  3. Build up the bottom skin a bit too around this area. This can go
    out a bit further than the replaced core…perhaps six inches out?

  4. Try to shim up the compression post somehow so it will take the
    load before the deck flexes. (Right now I’ve just bent a bit of 1/8"
    steel wire/rod around the joint as a stopgap measure while I’m
    hauling the board up/down to do bottom paint on it & the trunk.

For those of you with this problem, what have you tried/considered
and how did it work?

Thanks,

Barry

vladimir_ud wrote:

There is a block on cabin top. it’s turning point for the line for
lifting centerboard. This block supports all weight of the plate. I
have seen four F28-33 boats. All had fiberglass cracked, core
saturated around this block(Mine boat included)

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

3

Posted by Barry Stellrecht (yak@…>)

That last bit was wishful thinking…I hoped that the lower skin & core was
removed, but once I took the compression post out I discovered that the plywood
was just below the lower skin…and it had got wet enough to delaminate once I
took the bolts out. Above that, the core was all wet and mostly rotten. (When
it took a load as I was cranking the board up to paint the trunk around it, it
squeezed out nasty water like a sponge!)

Since I’ve got a boat-work vacation scheduled, I’ve just taken out all the core
right around the block’s backing plate, and I’m gonna let it dry for a while and
remove what has to go…then replace and reinforce it.

As for the upside down fiberglass work, after the bow pulpit, two fwd
stanchions, and a variety of smaller holes where screws from below had migrated
water up, we’re getting pretty good at it…and we may do the rest of the
stanchions and the other “easy” holes from the grab rails, the rope clutches,
the winches, and the turning blocks going to the masts and CB on deck, to really
get in practice! (Actually I should say that Margaret is getting good–I mostly
grind and she mostly does layups while I mix epoxy and wet out cloth)

And yes, the headliner will conceal all the stuff I do, although once it is
sealed up and ground smooth, it will look about as good as the original did.

Barry

P.S. Anybody else have thoughts on how to better handle this load? Or would
the balsa cored deck have taken it before it got wet/rotted?
Herman and Gail Schiller wrote:

If I understand this correctly, the lower skin, and the balsa core
above it, have been removed. If I was doing this fix, I would then
deeply taper the edge of this area to make it look like an
upside-down pie plate. After this, I would replace everything with a
solid lamination (forget replacing the core; this is a really
high-load area, which reminds me of the winch that lifts the 600
pound keel on an S-2 7.9 meter). To tie it in with the existing
laminate, I’d use epoxy resin. Adding some laminate to spread the
load further won’t hurt (Your number 3). Adding enough of this
locally can act to integrate the deck with the compression
post. It’s a good thing there’s a headliner to conceal all this
surgery. The fun comes with keeping the wet laminate up there until
it cures. I would do this with multiple layers, one or two at a time
with fast-curing resin/hardener. When the lamination gets firm, it’s
time for the next few layers of glass… Takes patience, and lots of
disposable gloves.
Best of luck, Herm

At 05:31 PM 8/5/2008, you wrote:

Hello, Vladimir (and other F33/F28 Owners)

I’ve got another one of those F33’s with deck problems where the
centerboard turning block goes through the deck. (I’ve also got deck
problems elsewhere which I’m repairing…so far, all very small
areas except for between the port winch & rope clutches that will
probably be a square foot or two when I finish digging out to fix it.)

Anyhow, now that I’ve got the headliner down I can see how that
block works, and re-constructing the deck around it looks to be an
interesting problem that I would appreciate ideas for…mine has
the lower deck skin and balsa cut out in a ~5inch circle around that
block, with a SS backing plate that has a socket which fits inside a
SS compression pipe going down toward the centerboard with the
pennant running inside it. The bottom of the post sits on a large
U-shaped piece of fiberglass inside the trunk which has a tube going
thru to stop it dropping out near the top and some sort of pin going
through it at the bottom. (I haven’t seen the bottom one since I
don’t wanna deal with taking the board out this time!)

Up on the top, there are a couple (slightly rotting) donut-shaped
pieces of plywood above the backing plate. When the block takes the
load of the board, the deck flexes, and the ply compresses until the
compression post takes up the load.

So far my repair ideas are:

  1. Reinforce the top skin of the deck with extra layers of biax
    cloth & epoxy, out as far as the rotten core goes (probably another
    inch or two beyond the existing hole. (I could dig out more core
    than just what is failed here)

  2. Replace the balsa around with something sturdier (probably
    plywood except at the edge where it might get water exposure at the
    bolts and pennant hole–thickened epoxy there.

  3. Build up the bottom skin a bit too around this area. This can go
    out a bit further than the replaced core…perhaps six inches out?

  4. Try to shim up the compression post somehow so it will take the
    load before the deck flexes. (Right now I’ve just bent a bit of 1/8"
    steel wire/rod around the joint as a stopgap measure while I’m
    hauling the board up/down to do bottom paint on it & the trunk.

For those of you with this problem, what have you tried/considered
and how did it work?

Thanks,

Barry

vladimir_ud wrote:

There is a block on cabin top. it’s turning point for the line for
lifting centerboard. This block supports all weight of the plate. I
have seen four F28-33 boats. All had fiberglass cracked, core
saturated around this block(Mine boat included)

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

Yahoo! Groups Links

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

4

Posted by Herman and Gail Schiller (hschiller2@…>)

I hate plywood as reinforcing (or in this case, a shim) because of
the enormous amount of end-grain showing at the edges ( a natural
sponge). If you’re going to put back wood; there are alternatives
that don’t soak up water, like Starboard. Or laminate two (and only
two) layers of something rot-resistant like white oak or teak. The
lamination will prevent splitting, and still not as much end-grain
showing (I’d also thoroughly seal the end-grain with epoxy resin). Herm

At 05:11 PM 8/7/2008, you wrote:

That last bit was wishful thinking…I hoped that the lower skin &
core was removed, but once I took the compression post out I
discovered that the plywood was just below the lower skin…and it
had got wet enough to delaminate once I took the bolts out. Above
that, the core was all wet and mostly rotten. (When it took a load
as I was cranking the board up to paint the trunk around it, it
squeezed out nasty water like a sponge!)

Since I’ve got a boat-work vacation scheduled, I’ve just taken out
all the core right around the block’s backing plate, and I’m gonna
let it dry for a while and remove what has to go…then replace and
reinforce it.

As for the upside down fiberglass work, after the bow pulpit, two
fwd stanchions, and a variety of smaller holes where screws from
below had migrated water up, we’re getting pretty good at it…and
we may do the rest of the stanchions and the other “easy” holes from
the grab rails, the rope clutches, the winches, and the turning
blocks going to the masts and CB on deck, to really get in practice!
(Actually I should say that Margaret is getting good–I mostly grind
and she mostly does layups while I mix epoxy and wet out cloth)

And yes, the headliner will conceal all the stuff I do, although
once it is sealed up and ground smooth, it will look about as good
as the original did.

Barry

P.S. Anybody else have thoughts on how to better handle this load?
Or would the balsa cored deck have taken it before it got wet/rotted?
Herman and Gail Schiller wrote:

If I understand this correctly, the lower skin, and the balsa core
above it, have been removed. If I was doing this fix, I would then
deeply taper the edge of this area to make it look like an
upside-down pie plate. After this, I would replace everything with a
solid lamination (forget replacing the core; this is a really
high-load area, which reminds me of the winch that lifts the 600
pound keel on an S-2 7.9 meter). To tie it in with the existing
laminate, I’d use epoxy resin. Adding some laminate to spread the
load further won’t hurt (Your number 3). Adding enough of this
locally can act to integrate the deck with the compression
post. It’s a good thing there’s a headliner to conceal all this
surgery. The fun comes with keeping the wet laminate up there until
it cures. I would do this with multiple layers, one or two at a time
with fast-curing resin/hardener. When the lamination gets firm, it’s
time for the next few layers of glass… Takes patience, and lots of
disposable gloves.
Best of luck, Herm

At 05:31 PM 8/5/2008, you wrote:

Hello, Vladimir (and other F33/F28 Owners)

I’ve got another one of those F33’s with deck problems where the
centerboard turning block goes through the deck. (I’ve also got deck
problems elsewhere which I’m repairing…so far, all very small
areas except for between the port winch & rope clutches that will
probably be a square foot or two when I finish digging out to fix it.)

Anyhow, now that I’ve got the headliner down I can see how that
block works, and re-constructing the deck around it looks to be an
interesting problem that I would appreciate ideas for…mine has
the lower deck skin and balsa cut out in a ~5inch circle around that
block, with a SS backing plate that has a socket which fits inside a
SS compression pipe going down toward the centerboard with the
pennant running inside it. The bottom of the post sits on a large
U-shaped piece of fiberglass inside the trunk which has a tube going
thru to stop it dropping out near the top and some sort of pin going
through it at the bottom. (I haven’t seen the bottom one since I
don’t wanna deal with taking the board out this time!)

Up on the top, there are a couple (slightly rotting) donut-shaped
pieces of plywood above the backing plate. When the block takes the
load of the board, the deck flexes, and the ply compresses until the
compression post takes up the load.

So far my repair ideas are:

  1. Reinforce the top skin of the deck with extra layers of biax
    cloth & epoxy, out as far as the rotten core goes (probably another
    inch or two beyond the existing hole. (I could dig out more core
    than just what is failed here)

  2. Replace the balsa around with something sturdier (probably
    plywood except at the edge where it might get water exposure at the
    bolts and pennant hole–thickened epoxy there.

  3. Build up the bottom skin a bit too around this area. This can go
    out a bit further than the replaced core…perhaps six inches out?

  4. Try to shim up the compression post somehow so it will take the
    load before the deck flexes. (Right now I’ve just bent a bit of 1/8"
    steel wire/rod around the joint as a stopgap measure while I’m
    hauling the board up/down to do bottom paint on it & the trunk.

For those of you with this problem, what have you tried/considered
and how did it work?

Thanks,

Barry

vladimir_ud wrote:

There is a block on cabin top. it’s turning point for the line for
lifting centerboard. This block supports all weight of the plate. I
have seen four F28-33 boats. All had fiberglass cracked, core
saturated around this block(Mine boat included)

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

Yahoo! Groups Links

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

5

Posted by Alan Kusinitz (akusinitz@…>)


Sometimes I use epoxy and mix in large amounts of silica. If
you put enough silica in (and you need a lot) it is like a putty and holds
shape (which I haven’t found to be the case with other fillers) and can be put
on the bottom of something and it won’t ooze or fall out. You can smooth it
before it hardens so there’s really no sanding or you put cloth or matt over
it. I’ve done it this way for some repairs in relatively small areas of the
deck rather putting balsa back in.
Alan F-33 Hull #51 1982.



From:
FreedomOwnersGroup@yahoogroups.com [mailto:FreedomOwnersGroup@yahoogroups.com] On
Behalf Of Herman and Gail Schiller
Sent: Thursday, August 07, 2008 7:39 PM
To: FreedomOwnersGroup@yahoogroups.com
Subject: Re: [FreedomOwnersGroup] How to repair the deck at the
centerboard turning block on a F28/F33

\




I hate plywood as reinforcing (or in this case,
a shim) because of
the enormous amount of end-grain showing at the edges ( a natural
sponge). If you’re going to put back wood; there are alternatives
that don’t soak up water, like Starboard. Or laminate two (and only
two) layers of something rot-resistant like white oak or teak. The
lamination will prevent splitting, and still not as much end-grain
showing (I’d also thoroughly seal the end-grain with epoxy resin). Herm

At 05:11 PM 8/7/2008, you wrote:

That last bit was wishful thinking…I hoped that the lower skin &
core was removed, but once I took the compression post out I
discovered that the plywood was just below the lower skin…and it
had got wet enough to delaminate once I took the bolts out. Above
that, the core was all wet and mostly rotten. (When it took a load
as I was cranking the board up to paint the trunk around it, it
squeezed out nasty water like a sponge!)

Since I’ve got a boat-work vacation scheduled, I’ve just taken out
all the core right around the block’s backing plate, and I’m gonna
let it dry for a while and remove what has to go…then replace and
reinforce it.

As for the upside down fiberglass work, after the bow pulpit, two
fwd stanchions, and a variety of smaller holes where screws from
below had migrated water up, we’re getting pretty good at it…and
we may do the rest of the stanchions and the other “easy” holes
from
the grab rails, the rope clutches, the winches, and the turning
blocks going to the masts and CB on deck, to really get in practice!
(Actually I should say that Margaret is getting good–I mostly grind
and she mostly does layups while I mix epoxy and wet out cloth)

And yes, the headliner will conceal all the stuff I do, although
once it is sealed up and ground smooth, it will look about as good
as the original did.

Barry

P.S. Anybody else have thoughts on how to better handle this load?
Or would the balsa cored deck have taken it before it got wet/rotted?
Herman and Gail Schiller wrote:

If I understand this correctly, the lower skin, and the balsa core
above it, have been removed. If I was doing this fix, I would then
deeply taper the edge of this area to make it look like an
upside-down pie plate. After this, I would replace everything with a
solid lamination (forget replacing the core; this is a really
high-load area, which reminds me of the winch that lifts the 600
pound keel on an S-2 7.9 meter). To tie it in with the existing
laminate, I’d use epoxy resin. Adding some laminate to spread the
load further won’t hurt (Your number 3). Adding enough of this
locally can act to integrate the deck with the compression
post. It’s a good thing there’s a headliner to conceal all this
surgery. The fun comes with keeping the wet laminate up there until
it cures. I would do this with multiple layers, one or two at a time
with fast-curing resin/hardener. When the lamination gets firm, it’s
time for the next few layers of glass… Takes patience, and lots of
disposable gloves.
Best of luck, Herm

At 05:31 PM 8/5/2008, you wrote:

Hello, Vladimir (and other F33/F28 Owners)

I’ve got another one of those F33’s with deck problems where the
centerboard turning block goes through the deck. (I’ve also got
deck
problems elsewhere which I’m repairing…so far, all very small
areas except for between the port winch & rope clutches that
will
probably be a square foot or two when I finish digging out to fix
it.)

Anyhow, now that I’ve got the headliner down I can see how that
block works, and re-constructing the deck around it looks to be
an
interesting problem that I would appreciate ideas for…mine has
the lower deck skin and balsa cut out in a ~5inch circle around
that
block, with a SS backing plate that has a socket which fits
inside a
SS compression pipe going down toward the centerboard with the
pennant running inside it. The bottom of the post sits on a large
U-shaped piece of fiberglass inside the trunk which has a tube
going
thru to stop it dropping out near the top and some sort of pin
going
through it at the bottom. (I haven’t seen the bottom one since I
don’t wanna deal with taking the board out this time!)

Up on the top, there are a couple (slightly rotting) donut-shaped
pieces of plywood above the backing plate. When the block takes
the
load of the board, the deck flexes, and the ply compresses until
the
compression post takes up the load.

So far my repair ideas are:

  1. Reinforce the top skin of the deck with extra layers of biax
    cloth & epoxy, out as far as the rotten core goes (probably
    another
    inch or two beyond the existing hole. (I could dig out more core
    than just what is failed here)

  2. Replace the balsa around with something sturdier (probably
    plywood except at the edge where it might get water exposure at
    the
    bolts and pennant hole–thickened epoxy there.

  3. Build up the bottom skin a bit too around this area. This can
    go
    out a bit further than the replaced core…perhaps six inches
    out?

  4. Try to shim up the compression post somehow so it will take
    the
    load before the deck flexes. (Right now I’ve just bent a bit of
    1/8"
    steel wire/rod around the joint as a stopgap measure while I’m
    hauling the board up/down to do bottom paint on it & the
    trunk.

For those of you with this problem, what have you
tried/considered
and how did it work?

Thanks,

Barry

vladimir_ud wrote:

There is a block on cabin top. it’s turning point for the
line for
lifting centerboard. This block supports all weight of the
plate. I
have seen four F28-33 boats. All had fiberglass cracked, core
saturated around this block(Mine boat included)

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)

Yahoo! Groups Links

–
s/v Flutterby, Freedom 33 cat ketch (becoming a junk rig)



\

6

Posted by vladimir_ud (eremeev@…>)

Here is what I did.

Rot and water penetration was extensive in my case.

I removed outer skin and core on front 1/3 of cabin.
I used marine plywood to build up the core again.
I voted for plywood as a material for a number of reasons, one of them
is that plywood is stronger, and can be a structural material by itself.
I do believe that people tend to overestimate water resistance of end
grain balsa sheets, used in boat building
Anyway, it is a topic for another discussion :slight_smile:

I used 1/4 inch plywood, laminating three layers one at time, bending
them into shape. I used west system epoxy with structural fillers for
bonding. I made sure that every sheet of plywood is coated with epoxy
prior to going into place. Basically, I built very strong arch 3/4
inch thick, going across the cabin. Then I shielded it in fiberglass.
I drilled oversize holes for bolts and outhaul, filled it with
thickened epoxy. Then I drilled right size holes through the epoxy. I
made sure there is no exposed wood left, I tried use as big sheets of
plywood as practically possible so there are no edges for water to
seep in.

It was quite a project, and took me 2 weeks to complete it
structurally. Cosmetically it is not perfect yet, but I’m planning to
paint the boat eventually.

On supporting pole. I have not done it yet, but it is on my list.

The upper small T-shaped part and bottom tube are not fixed against
each other.
I’m planning to drill 1/4 hole through both tubes, tape it and put
short bolt through, locking both parts together.

Vlad
F28CK “Nemo”

7

Posted by geraldfreshwater (freshwater@…>)

Had a similar problem with UK built F33 cat Ketch. Just replaced the wet balsa
with epoxy
filler, whilst I was doing the new headlining. The pennant for the CB comes
through about 7-
8cm from the heads compartment bulkhead, which seems to carry any compressive
loads:
the tube in which the pennant runs does not appear to carry any load, and I can
see no sign
of the coachroof flexing. There is a wooden pad on the deck (solid teak) beneath
the block
which spreads the load a bit, and is at a better mechanical advantage than
something below
the deck, especially since it is cambered. However, what you describe seems
strong enough
for any purpose.

Would putting a bolt through the tube cause chafe on the pennant? Is the tube
wall strong
enough to withstand the shear loads where the bolt goes through?

Gerald Freshwater,
“Castaway”, Shetland Islands