Conference unifix::sailing

    It would help to have a picture of your headboard assy to know exactly
    how things fit together, but in general:
    
    -	I would avoid butt gluing solid wood to endgrain plywood, especially 
    	in an area that has already proven subject to water problems.
    
    -	I would expect to cut off somewhat more than 1" if you have rot
    	already - the slightest delamination is good for at least that and 
    	probably more unless you are very lucky and caught the problem very
    	early.  Figure on cutting at least to the depth of the screws for
    	the first pass, then 1/2" increments until you are sure of solid
    	lamina.
    
    -	What about replacing or modifying the headboard ? A new piece, grooved 
    	to accept the edge of the ply will allow a good glue surface, the
    	strength of a tenon joint, the opportunity to caulk/seal well, and a
    	good place to use screws from underneath a right angles to the ply
    	and headboard. _________
    				|   __________
                                V   |        | <----headboard
                                    |___     |
    			-----------.   |     |
           Plywood----->___________:   |     |
                                    ___|     |
                                    |________|
                                     |
                                    /_\ <---screw from under through
    					    plywood and back into head-
    					    board - very sturdy when
    					    joint glued as well with good
    					    resourcinal (sp?) glue.
    
    Only disadvantage is that you would have to expand width of headboard
    by amount of ply cut off + depth of groove (at least 3/4").
    
    Since all boarders will invariably grab the most convenient place to swing
    from, this could maintain their convenience and save you having to do the
    job again in the future.
    
    Good luck,
    
    R.

    The profile in .1 is not far off from what is looks like today.
    
    Here is what it is like in actuality:
                                  _______ Teak Headboard
        		    _____/
                            |   |
    			    |	|	
    ?<==== Area of delam.=| |   |
    ========================|   |
    ////////////////////////|  _|
    \\\\\\\\\\\\\\\\\\\\\\\\| / |
    /////////////////<========  | <---Screw Hole
    \\\\\\\\\\\\\\\\\\\\\\\\| \_|
    ========================|   |
                            |   |
                            |	|
    			    |	|
    === > fiberglass        -----
    \\\ > plywood
    
	
    Proposal is to rout back the delaminated area and fill with a solid
    piece of wood and epoxy in place along with screws from the top and
    bottom through the fiberglass.  Essentially this would give a new
    nailer to screw the head board onto.  We do not know how deep the
    delamination goes but we would try to clean out as much as possible.   
    
    I agree with the butt gluing concerns that is why I am suggesting we
    secure by screwing from the top and bottom, through the glass.  	
    
    One of the problems I see is the ability to clean out the plywood to a
    sufficiant distance back from the edge with out cutting the fiberglass
    liner underneath.  The liner is a molded pan in the shape of the PH
    which we really don't want to mess with.  
    
    I like the idea of a mortise type joint though.  Could we do the same
    thing by screwing and gluing strips on the top and bottom to the
    existing headboard and using this to add the extra security?  Sort of
    creating an artificial mortise?  
    
    
    Thanks for the reply,
    
    Brian
    		                             

RE: .1 & .2,

Is it worth taking the best features from each suggestion and combining 
them?  

A)  Rout/gouge/clean out the rotted ply, leaving the molded fiberglass to
receive a replacement piece.  (If the roof is curved, then it might be 
easier to build up a lamination designed to slip right in, rather than 
bending a straight piece.)  This replacement piece could be wide enough 
that when fully seated and bonded to solid ply in the roof, it will
project 3/4" or so beyond the edges of the fiberglass.  

B)  Dado a new headboard piece to receive the piece above, which then 
functions as a sort of spline in the PH roof/headboard assembly.  If roof
curvature isn't too much, it might be possible to introduce enough
curvature to a solid piece by fitting it first to the (curved) dadoed
headboard, then fitting this sub-assembly to the roof.  Getting a solid
ply-to-spline joint might be difficult this way, however. 

J.

    Brian,
    
    Aha, the light dawns on Marblehead!  I should have detected the
    operative word "core" in .0.  Anyway, sandwich construction presents a
    solution which depends less on the strength and water-tightness of a 
    butt glue.
    
    If you can get routed out cavity clean/dry/straight enough, go ahead
    with your butted strip, but I would still suggest resourcinal glue 
    rather than epoxy.  Most important: CLEAN AND DRY.
    
    Re cutting into liner, glass is harder than soggy plywood, so any cut
    into liner should be minimal as long as some care is taken.  Standard
    router bit may be hard to find of appropriate length, so maybe round
    rasp or milling bit in a drill will do the same.  Must be very sharp
    and have as many flutes as possible.  After cleaning out wood, sand or
    otherwise rough up inside of "bread" pieces to provide good adhesion.
    By the way, a non-carbide bit will dull almost immediately upon contact
    with fiberglass.
    
    Slather replacement strip well with glue on top, interior and bottom
    edges and slide into cavity.  Clamp well at 6"intervals after assuring
    that strip is fully inserted and tight to routed edge of ply.  You want
    to end up with as tightly compressed a sandwich as possible.  Trim new
    strip even with edge of fiberglass.  When clamping, use strips under
    clamps to prevent marring and spread clamping pressure.
    
    This is where I would agree with .3 re dado joint.  Get new piece of
    teak and dado to accept full sandwich as in .1.  Glue well and screw
    from underneath.  Adding strips to current headboard, with screws to
    hold strips to headboard and screws to hold headboard to ph will mean a
    lot of screw holes, each of which must be watertight, and you are ulti-
    mately ending up with the same problem of endgrain-inserted screws sub-
    ject to the high torque of swinging gorillas.
    
    By enclosing entire sandwich in well sealed dado joint, you have
    strength, water resistance and no exterior screw holes.  For extra
    security, fewer seams to calk as well.  Plus (personal view), it would
    look better and more professional.  Again, rough up FG along edge
    within dado to assure good glue surface.
    
    Whatever you end up doing, its going to be a PITA job while you're doing 
    it, but well worth it afterwards.
    
    Again, good luck,
    
    R.
    

re .2:

Yikes, what a poor design! Unless the headboard to cabin roof joint is 
extremely strong, I'd expect chronic problems.

re others:

I'd not recommend resorcinal glue for this repair. Resorcinal is
primarily for bonding wood to wood, and it has little gap filling
ability. You must bond to both the wood core and to the fiberglass inner
and outer skins. You'll be very lucky to get a good fit between a wood
filler piece and the fiberglass skins. The reference I looked at says
that resorcinal will bond to fiberglass, but I'm dubious. Certainly
experiment before committing yourself if you do use resorcinal. 

However, this sounds like an ideal application for epoxy with filler. 
I'd somehow remove the old, rotten core and then fill the gap with epoxy 
putty made with high density (high strength) filler. The Gougeon 
Brothers of WEST fame sell high density filler. You can also epoxy bond 
the screws holding the headboard on. This would make a very strong, 
rot-proof repair. Even if the headboard to cabin joint fails again (it 
is likely to given the design), no rot or real damage will occur, 
especially if the screws don't penetrate the wood core. According to 
tests done by the Gougeon Brothers, the screws will fail before the 
screws pull out of the epoxy. Using epoxy putty will also be much faster 
and easier than trying to shape or laminate a wood filler strip. The 
weight you save using wood will be totally insignificant. If you do use 
wood, still consider epoxy bonding the screws. (If you haven't yet boat 
the Gougeon Brothers boatbuilding book, I'd suggest you do so -- I've 
found it most useful. It describes epoxy bonding hardware in great 
detail and has the test-to-failure data.)

'Taint nothing wrong with using plastic to repair plastic boats!

Alan

    Ditto on Alan's epoxy comments in the previous reply!   Most
    of us don't have the joinery skills required to get away with using 
    resorcinol (sp?).  You need extremely good dry fit to use this glue
    successfully.
    
    You might also try a product called 'Git Rot'.   This is designed to
    stabilize mild wood damage due to delamination and rot.  It's a two
    part compound that is designed to saturate wood, turning it into a
    solid block of 'petricized' wood.   I believe, to use it, you simply
    drill a series of small holes into the damaged area then insert the
    Git Rot (in your case probably with a syringe).  This could restore the
    core integrity.
    
    
    Combine this with the rabbited trim board replacement design (so 
    eloquently described previously) and you might have a solid permanent
    repair without so much joinery.

    No, it is not the worlds best design especially considering the loads 
    this piece takes.  The holding power of screws in plywood is terrible
    in plywood on the endgrain as well.  It is the only over head hand hold 
    available.  In speaking with my partner, we both agreed that the repair 
    would have to be strong since it will be virtually impossible to keep 
    people off the PH roof and from using the head board as a hand hold.  
    
    From all of the much appreciated advice it seems the place to start is 
    with cleaning out the damaged core as much as possible and letting the
    rest dry out thoroughly.  The molded liner is ribbed so the damage
    cannot be that far back.  We can also see sound wood where the bolts
    from handrails along the sides of the PH are through bolted from the
    top.  The question of how to fill the gap still remains though.  
    
    The PH has a slight curve to it which may not be conducive to sliding a
    piece of wood in there, solid or plywood.  The pieces I can see were
    all kerfed to allow for the slight bend over the span of the roof so I
    guess we could do the same.  We may run into a problem with getting a
    clean surface to butt against with the old plywood as well as leading
    to potential rotting problems again in the future.  The epoxy would
    cure both of those I guess.    
     
    The curve of the PH will also make replacing the headboard with a new 
    piece of teak challenging if we were to rabbet it out to accept the PH 
    edge.  Not to mention the expense of a teak plank of the dimensions 
    needed.  Partner says: "we use the old piece".  The joiner work on the
    headboard is really amazing in and of itself as it was pieced together
    from three separate boards tongue a grooved together in a complicated
    way.  Seeing as how this condition has lasted 20 years or so I'd say we 
    are pretty lucky to be addressing this at this point.   
    
    I will be tackling the clean out this weekend and will post results
    here.  Thanks again for all of the replies.  
    
    Brian

    It's going to snow this weekend Brian.  No boatwork should be started
    before its time.  8^)
    
    Let me suggest a kluge that might reduce the tendency of the PH trim
    board to be used as a pull up bar.  How about cutting down the height
    of the peice so it doesn't potrude quite as high past the level of the
    PH roof?  Leave maybe just enough to get a fingertip hold on so
    passengers can stabilize themselves when moving around.  1/4" should be
    enough.  The idea is to reduce the lever arm length on the attaching
    screws which will still be subject to tension along their length.
    
    To take this idea to its extreme, you could reduce the trim board to
    just a cometic cap to cover the end grain of the plywood.  Then attach
    a piece of teak toe rail to the PH roof just in front of the trailing
    edge.  This could be through bolted right through the roof.  It could
    still be close enough to the end of the roof to provide a solid hand
    hold.   
    
    Enjoy.  I'm sure you'll have a swell time this weekend.
    
    - gene

    Maybe I should go skiing instead Gene?  In search of the elusive
    perfect bump run?  Not a bad thought at that.  Hmmmmm..... 
    
    The back of the headboard has a series of twist lock fasteners used for
    the canvas cover that goes over aft coach roof and covers the open end
    of the PH.  We need some height here to provide the attachment points. 
    You have pretty much hit on the problem though.  The headboard does
    tend to get used as a mon

    Yea.  Bumps.  Snow.  Too soon for it to end.  Hard to get psyched on the
    boat when it's 20 deg out.
    
    Here's a even simpler/cheaper kludge.  Put some teak knees between the
    forward edge of the PH trim and the PH roof.  Bolt the knees down into
    the roof and screw/bolt the trim to the knees.  Four or six of these
    should do the job.  This will get around the problem of trying to cut
    or rabbet any curved pieces to match the shape of the PH roof.  If
    there's enough clearance below, between the trim and the PH ceiling,
    you could put a few knees on the underside as well.  This could almost
    eliminate any load on the screws into the plywood end grain.
    
    Although it may take a while in this cool weather, I'd try drying out
    the plywood and doing the West Epoxy delam cure that's described in
    thier pamphlet.  If there's any kind of integrity left in the plywood,
    that's the easiest way to go.  If you can transfer the load on the trim
    to another member, all the plywood has to do is take up space and keep
    water out.
    
    If it's of any interest, I have a box of teak scraps that might be good
    knee candidates.
    
    - gene

    Well, the dirty work is out of the way here.  I removed the coring
    material to a depth of about 2.25".  I used a power saw with a carbide
    tipped blade to chew the coring out.  I would not recommend using a
    skil saw for this type of work,  the owner's manual certainly didn't
    list it as one of the uses!  It took several passes and the wood was 
    quite damp still though it had dried out appreciably.  The delamination 
    was limited to the edge, back about 1.00" or so.  With the wood being
    real wet, it did not cut very well and ripped rather than got chewed
    up.  Safety goggles were a definite must.  I really should have had a
    full face shield.  At any rate, I made a nice uniformly deep cut with a
    nice smooth surface to butt the new wood against.  I used a chisel to
    clean up any rough areas and to get into the corners where the blade
    did not reach.  I think we will epoxy and screw the new coring to the
    existing material prior to attaching the head board.  Next week,
    assembly!  
    
    Brian