[Rhodes22-list] Re: HELP!! CB trunk has delaminated!

Tue Dec 7 05:55:44 EST 2004

Lou,

Could you get into your centerboard trunk with a small circular saw blade
chucked up in the flex drive on the Dremel Multitool?  I have a fine tooth
circular saw blade for my Dremel Multitool with a 1 inch OD.  With the close
clearances inside the centerboard trunk & a bare spinning blade, I think I'd
wear a HD glove (preferably Kevlar or chain mail!) on the hand that was
holding the flex drive & you'd definitely want eye protection.  If there is
sufficient room & you think you can do it safely, you could cut thru the FRP
laminate all around the bad area.  Once you have the FRP laminate cut, you
should be able to get behind the laminate with a chisel & peel it away from
the cement.  Once the FRP skin is removed, you will probably be able to
quickly remove the extra bulging cement with the chisel as well.

If it was my boat, before I started cutting, I would try to do some
nondestructive testing to see if there are any other bad areas in the
centerboard trunk.  Look in the Yellow Pages under "Laboratories-Testing"
and also under "Surveyors-Marine".   You are looking for someone that can do
nondestructive ultrasound.  If I were doing this testing, I wouldn't need
anything fancier than a signal generator, the handheld ultrasound transducer
& an oscilloscope.  What you are doing is really just a thickness test.
Good FRP laminate will give a nice clean echo pulse off the FRP/cement
interface at the centerboard well skin & also at the FRP/cement interface on
the outer shoal draft keel skin.  But, you will also get echo pulses off any
delaminations, voids or porosity (either air or water filled), regions of
high density in lead/cement filler, & regions of low resin saturation in the
FRP laminate.  The overall echo pattern on the oscilloscope screen will
probably be very complex.  But, you don't need to explain every little blip
on the oscilloscope screen.  You are really just interested in comparisons
of good/bad areas in the FRP laminate - i.e. areas where the short return
time echo pattern is significantly different than the echo pattern in other
areas of the centerboard well.  An hour of time scanning the interior
surface of the centerboard well could be very revealing, showing areas of
thin FRP laminate, delamination, water intrusion, porosity, & poor resin
saturation.  Then, you could confidently cut out all the bad areas & fix
them.  Around here, there are outfits where I could rent this equipment for
a couple of hours.  Actually, I'd just borrow it from the SVSU materials
testing lab!

Unless an inspection of the centerboard reveals it has some bulges, cracks,
or other flaws, I wouldn't start modifying it.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Lou Rosenberg" <lsr3 at MAIL.nyu.edu>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Monday, December 06, 2004 1:46 PM
Subject: Re: [Rhodes22-list] Re: HELP!! CB trunk has delaminated!

>    Roger,
>   I soon realized that I would never want to use a Sawsall on the
> trunk!  A drill to pierce the thin layer of  FRP that has bulged
> outward and then a few taps w a strong wood chisel would do ..  The
> manufacturer didnt lay up any glass mat there .
>
>   Lou
>
>
>
>
> >   I now realize that a sawsall on just one side of the trunk might
> >give me enough room and then all I have to do is re seal and re
> >glass the trunk but that is still alot of work compared to doing
> >just the board.
> >   My initial measurements on the trunk told me that I only needed
> >about 1/16" more clearance total to make the board move freely.
> >  I have also thought about adding a emergency release on the top of
> >the cap . Basically a spring loaded  rod attached with a rubber
> >piece that contacted the back of the board that would help it
> >release if it got stuck during the season. What do you think of that
> >idea?
> >
> >more info later,
> >Lou
> >
> >>GBI did not build the early Rhodes 22's in-house.  Instead, the
construction
> >>was out-sourced to a number of contract boatyards.  The quality of
> >>construction at some of these boatyards was not of a very high standard,
> >>which is why Stan eventually started building his own boats in-house.
This
> >>is also why GBI will not recycle & warranty Rhodes 22's from this era.
My
> >>fearless hypothesis regarding the problem with your centerboard trunk is
> >>that the FRP laminate was too thin &/or of poor quality.  Water has
leaked
> >>into the cement thru this questionable FRP laminate.  Over time, this
water
> >>has reacted with the residual Portlant cement & expanded to give you the
> >>bulge we observe today.
> >>
> >>My initial reaction is that you are going to have to grind away the bad
FRP
> >>laminate in the centerboard well + some cement.  Then, you are going to
have
> >>to rebuild the walls of the centerboard well with new FRP laminate.
Ugh!
> >>
> >>Let me think about this problem a little more?
> >>
> >>Roger Pihlaja
> >>S/V Dynamic Equilbrium
> >>
> >>
> >>----- Original Message -----
> >>From: <steadilsr at verizon.net>
> >>To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
> >>Sent: Sunday, December 05, 2004 9:11 PM
> >>Subject: [Rhodes22-list] Re: HELP!! CB trunk has delaminated!
> >>
> >>>  Roger, Todd , Peter T and all Rhodies:
> >>>   Need advice on pics being posted.
> >>>
> >>>   After pulling out the stuck CB last week I decided to use my dremel
tool
> >>>  attached to a flex shaft & 120grit sand minidrum to shave about 1/16
" of
> >>the
> >>>  fibreglass away which is bulging out into the upper trunk.
> >>>  During the wk I carefully measured the CB thickness using two
straight
> >>edges
> >>>  for references I meas the distance btw the edges along the length of
the
> >>>  board.
> >>>   i then cut strips of plywood conforming to those depths as test
sticks.
> >>I
> >>>  used those depth sticks today to measure how much glass i was
trimming
> >>away
> >>>  with the dremel.
> >>>   Its diff to photograph but my trunk  as it has 2 apparent sections
of
> >>depth.
> >>>  The upper trunk where the lip is sealed with the neoprene and the
lower
> >>>  section which opens to the sea.  My lower section is not bulging and
there
> >>is
> >>>  plenty of room, but the upper is too tight.
> >>>   After sanding the head of the board down I was able to drop the
depth
> >>stick
> >>>  in and moved on to the middle of the board.  The section to the rear
of my
> >>>  pivot was tighter and soon I foung my wall had cracked and the glass
> >>crumbled
> >>>  away revealing the dry cement.  I know how to patch the hole with
epoxy,
> >>but
> >>>  now I cannot sand the walls with out risking similar problems.
> >>>   I am posting my pics for reference and will have more next week.
> >>>   Any advice welcomed.
> >>>
> >>>   note: Even if a surveyor had told me not to buy this boat due to a
stuck
> >>cb,
> >>>   i think i would have gone agains his advice due to the condition of
the
> >>hull
> >>>  and other parts.  I am still convinced my boat will sail this summer!
> >>>  Lou
> >>>
> >>
> >>
>
>>--------------------------------------------------------------------------
--
> >>----
> >>
> >>>  Name: 16 w ruler CU..jpg Type: image/jpeg Size: 135840 bytes Desc:
not
> >>available
> >>>  Url:
>
>>http://www.rhodes22.org/pipermail/rhodes22-list/attch/200412/05/16wrulerCU
..
> >>jpg
> >>>
> >>
> >>
>
>>--------------------------------------------------------------------------
--
> >>----
> >>
> >>>  Name: Str down trunk no dam vi.jpg Type: image/jpeg Size: 134960
bytes
> >>Desc: not available
> >>>  Url:
>
>>http://www.rhodes22.org/pipermail/rhodes22-list/attch/200412/05/Strdowntru
nk
> >>nodamvi.jpg
> >>>
> >>
> >>
>
>>--------------------------------------------------------------------------
--
> >>----
> >>
> >>>  Name: MCU  galley flr.jpg.jpg Type: image/jpeg Size: 138460 bytes
Desc:
> >>not available
> >>>  Url:
>
>>http://www.rhodes22.org/pipermail/rhodes22-list/attch/200412/05/MCUgalleyf
lr
> >>.jpg.jpg
> >>>
> >>
> >>
>
>>--------------------------------------------------------------------------
--
> >>----
> >>
> >>>  __________________________________________________
> >>>  Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> >>
> >>
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> >
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