Conference unifix::sailing

I would use marine plywood since I don't know how well paint or 
adhesives adhere to pressure-treated plywood. The chemicals in 
pressure-treated wood also attack most fasteners -- I think you must use 
galvanized fasteners.

I'd also change the design. As long as the hatch isn't varnished, you'll 
have better non-skid if all the strips are the same thickness. I'd throw 
away the narrow strips and make enough wide ones to cover the hatches. 
I'd epoxy glue and screw (from underneath) the strips to the plywood 
substrate. If the plywood is fully coated with epoxy, it won't rot. You 
could either butt the strips together (edge glue) or leave a gap about 
3/8 wide (ta da! the width of the narrow strips) and use black seam 
sealant in the gaps (ie, the look of a traditional laid deck). If the 
wide strips have cupped badly, you might have to replace them with new 
teak decking. 

No matter what you do, this isn't a quick and easy project. Probably 
not cheap, either.

    I bought some pressure treated plywood for a project around the house. 
    It doesn't seem very suitable for boatbuilding.  Too many voids and not
    enough plies.  Alan's suggestion about marine ply is the way to go.  A
    beauty like St. Kilda deserves the best - the 5 ply all mahogany stuff. 
    If the engine cover is also the pilot house floor, then definitely go
    with the most substantial material that'll fit.  That area did look
    like it had taken its share of wear over the years.
    
    On screwing the finish flooring up from the bottom.  If the teak strips are
    1/4" - 1/2" thick (usually they're thinner) that's not a lot of material
    for the tapered end of the screw to hold on to.  Also, as the floor
    wears, the there's the risk of exposing those pointy screws to delicate
    bare feet. **ouch**  I'd suggest putting them in the usual way with
    bungs to cover.  It shouldn't take too many fasteners.  Epoxy should
    provide the real adhesion and waterproofing.  Forget about painting the
    plywood.  The paint's adhesion is less than that of epoxy.  
    
    To keep the hinges out of the way when you've relocated them to the top
    of the cover, try mortising them into the floor.  I think there are
    hinges designed for this type of installation that present a flat
    unobtrusive surface (no protruding pin).
    
    - gene

    I'd recommend against using pressure treated plywood. Cutting PTL is
    very hazardous if you inhale the sawdust. You'll have to do any
    cutting, drilling, or filing outside with breathing protection. You
    don't want that stuff in your house. 
    
    Besides, if you join and overcoat everything with epoxy the results
    will be extremely water resistant. An undercoat of epoxy is a great
    base for a natural polyurethane finish.
    
    Send away for the West System boat building and fiberglass repair
    manuals. It's the best $4 I ever spent.
    
    Paul
            

    I agree with Alan that pressure treated buys you nothing, but
    headaches.  The chemicals in pressure treatead wood are to kill insects
    that eat it underground when it is wet.  It doesn't prevent it from
    getting wet.  There is some viscosity to it so dryrot is delayed, but
    the main reason is insects.
    
    Use a good quality marine plywood.  Not exterior, but Marine.  There is
    a difference.  I also agree that the conglomeration of wood strips
    seems like a little over kill for a non-skid surface, but it could be
    that my mind and you discription don't match.  I'd do a basic plywood
    surface and add strips (expoxied and screwed) to it the were the same
    level. As long as they don't get varnished they'll be a good non-skid.
    
    I ahve several books that could help you with this if you'd like to
    borrow them.  Just let me know.  
    
    Regards,
    Jeff
    
    

    Well it's another case of learn by spending!  I went out and bought the
    PT prior to using the combined wisdom ofthe SAILING community.  Too
    impetuous I guess.  Yes, the hatch is a conglomeration of strips like 
    this:
    
    ========||=========||========||========||   Viewed from the end
    
    --------||---------||--------||--------||
    |       ||         ||        ||        ||
    |       ||         ||        ||        ||
    |       ||         ||        ||        ||   Viewed from the top
    |       ||         ||        ||        ||
    |       ||         ||        ||        ||
    |       ||         ||        ||        ||
    
    
    I will reconsult with my partner to see where he wants to go.  I think
    it might be best to skip the thin strips and fill with whatever the
    traditional caulking is on teak decks.  Hopefully this will fly.
    
    Thanks for the suggestions, I appreciate it.  
    
    Brian

re .5:

>>> I think it might be best to skip the thin strips and fill with 
>>> whatever the traditional caulking is on teak decks.  

Oakum and pine tar, I believe. Worked well on the deep water square 
riggerers. For a modern caulk, try black Sikaflex 231.

    I went for the black seams in between the teak boards.  I asked at
    Jamestown Dist. what would be a suitable material for this.  Sikaflex
    is NOT recommended for deck seam sealing per the manufacturer's
    instructions.  I opted for a couple of tubes of Boatlife one part deck
    caulking.  The two part sutff sounds like a real pain to mix and
    prepare for with all of the priming required etc.  I should have one
    section complete by the end of this weekend.  
    
    Brian  

    I have gotten to the point where I have almost completed on of the
    hatch sections.  I applied the caulking last night and must say that it
    is just about the messiest job I have ever undertaken.  Could be that I
    am just clumsy myself but the stuff is gooey.  When all was said and done
    though it looked nice.  Alot of material is wasted in the process
    though since you essentially need to overfill the void in order to
    insure it all gets in there.  To keep the clean up to a minimum I taped
    both sides of the seams so any excess would squish over onto that
    instead of the wood.  It made clean up much easier.  I way under estimated
    the amount of caulking needed.  The two tubes I bought were supposed to
    be good for all three sections.  I barely made it through onesection!  
    This is getting really expensive.  I also wish I was getting paid by the 
    hour for it.  Now for the finishing touches.  
    
    I was able to salvage all of the boards from the original hatch as the
    cupping was very slight and everything can be sanded smooth.  Instead
    of using brads to fasten them in place, I used Epoxy and some bronze
    wood screws.  Now I need to figure out how to fill all of the screw
    head countersink holes.  They are too shallow for bungs. My
    understanding is 0.12" minimum for depth is needed to insure they stay
    put.  Is this true or will a shallower bung work? I used #4 screws so the 
    holes are not large and I was thinking of filling with a colored wood 
    putty but not the caulking.  Suggestions?    
    
    A sanding tip for anyone with a large vise and a belt sander.  I mounted 
    my belt sander upside down in my Black and Decker mega expando vise.  I 
    was able to run all of the slats over the belt (while moving) in assembly 
    line fashion.  It made for a real slick makeshift sanding table.  I 
    wouldn't wear long or loose clothing or hair while trying this though.    
       
    Thanks,
             
    Brian

    West System epoxy mixed with low density filler has a nice light brown
    wood-like color. Maybe you can use it to fill your screw holes.
    
    Paul

re .9: 

Epoxy is quickly damaged by the UV in sunlight (booo!).

    Not when overcoated with a UV blocking polyurethane (Yeah!!!)

    The hatch will not be covered with anything other than possibly teak
    cleaners and oil.  So if UV is a concern, it looks as if that way is a
    no go but thanks for the suggestion.  BTW I asked in the Home_work file
    about pressure treated lumber and fastener corrosion.  There does not
    seem to be any correlation since any number of fastener types are used
    including brass and bronze.  Good news for me in that I used what I
    bought but I readily admit I probably should have gone with the Marine 
    grade material instead.  Learning, always learning....
    
    Back to the depths of my basement where my hatches are planning... ;-)