what to do with the deck.

Discussion in 'Boat Design' started by whitepointer23, Dec 30, 2014.

  1. whitepointer23

    whitepointer23 Previous Member

    I have just purchased a 35 ft ketch. Beautiful boat but deck is leaking everywhere. It has an old cracked coating on it which is about 3mm thick. When I lifted some of it up it just peels away but underneath there is a nice plank deck. The wood looks good but the black compound in the seams is dry and broken. Can I clean and recaulk the deck then oil it. Would this fix the leaks. I just wonder why they put the other stuff on top. The deck planks are an aussie hardwood not teak. I will put some pics up later this week. I have sanitred to put on but I would prefer the timber deck uncovered.
     
  2. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    Sounds like fun WP,
    someone prolly put that goolygum on there to try to seal the deck.... it might b something like emerclad... or another brand of rubbery membrane coating, emerclad went thru a bit of a phase around 10-15 years ago as a fix all slip resist deck paint or might be something else, reall don't matter cos it B No Good....
    If you want to fix the deck you need to strip it, check for rot & repair then rake, caulk & pay the seams. You can get oakum & Jeffries No 2 "marine glue" from Drive Marine at Beverly Hills, call first as I'm not sure what they hold in stock, there's also some one up the back of Newcastle that sells oakum, also there's a firm around Milperra? that sells road pitch....for cheapa.. proviso that you'd need to blend a "brittle" pitch with a plasticised crack repair one to get the properties you want, sometimes on "some" seams the toolable durabond will do on margins but will need a top up as some solvent loss & shrinkage occurs... mask for that stuff too as really sticky!!!
    You can make caulking rakes from files, just heat & bend the tang either across the flat of the file or with the flat thru about 80-85 degrees, some heat gunning can help get the old pitch soft, for tooling off the poured pitch a bent scraper is good, blackwoods stock them.

    Jeff.
     
  3. whitepointer23

    whitepointer23 Previous Member

    Thanks jeff. I live down on the gippsland lakes. Its a bloody 14 hour flight to beverly hills just for oakum.:D. I have the caulking gear but I was hoping to rake the seams and sikaflex them. Do you think that will work. The boats ex sydney. Designed by one of the barbers but I don't know the builders surname. His first name was bill and he built it for himself and owned it from 1958 to 2009. Double ender called fairwinds does that ring any bells with you. Being a sydney boating socialite I thought you may have come across it before.
     
  4. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    Nice part of the world, had a drive along the coast there a couple of months back. Boat don't ring a bell. As for the seams..... sika can work but you still have to caulk & you'll need to get rid of all of the pitch back to timber to bonding area in seams & use primer such as the sika prime or we often use everdure. Mask the seams about 1.5mm outside the edges then prime....wait..... sika & tool off with measuring end of a steel rule then next day peel the tape- use the 3m green but buy from panel/spray supplier should only be around $4 a roll then... later you can sand in the edges. One thing, if you're improving the condition of a deck they get drier... truly.. more later.
    Jeff.
     
  5. whitepointer23

    whitepointer23 Previous Member

    Thanks jeff. Great info.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The black goo was probably polysulfide, which is the right stuff on a laid deck. If the deck is leaking, especially if sheathed, you obviously have two issues, one is the sheathing breaches, but the other is the old deck condition, which will likely be a combination of loose fasteners and spent seam compound.

    If the fasteners holding the laid deck to the beams and/or their holes are allowing the planks to move, no amount of goo in a tube is going to help. The same is true about a sheathing over a working deck. There are two trains of thought on this, the first is to perform a traditional repair on the laid deck, the other is to repair/replace the deck with plywood and a sheathing.

    The traditional repair is simply reefing out the seam compound, restoring the fastener holes (if necessary) and refasten, then pay the seams again with fresh polysulfide. This works, but is messy, tedious and you'll still have a leak prone deck.

    The modern approach is to either remove the old laid decking and replace it with plywood or overlay the decking with plywood, then sheath with fabric. This method can save an old deck, if it's fairly sound, just loose fasteners and shot caulk. You'd glue and screw the plywood over the deck planks, then sheath. A plywood deck adds a lot of stiffness and rigidity to the deck, far more than a laid deck and it's water tight.

    The usual mistakes owners make is to not use polysulfide in the seams and not refasten soon enough, to prevent the fastener holes from reaming out, as the planks "pant" underway, which rots the holes. Also sheathing a laid deck generally doesn't work, unless you employ a high elongation fabric like Xynole or Dynel. Even these fabrics can shear, if there's a lot of movement. Sheathed plywood decks are the bullet proof way to have a deck.
     
  7. FAST FRED
    Joined: Oct 2002
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    FAST FRED Senior Member

    If you chose the cover with ply route , do spend the extra and use EPOXY when covering it .

    A nice DIY is to pencil the shape of the no skid on the deck, then get COARSE cotton mosquito net. The strff to stop B-52 not no see ums.

    Spray starch and iron the net , lay it on the deck and trace the design you want.

    A thin ,thin, thin layer of epoxy paint will have the deck looking like a fine factor job.

    Almost no cost , you have to paint the deck anyway.
     
  8. whitepointer23

    whitepointer23 Previous Member

    Thanks par and fred. I went up there today and forgot my phone so no photos. Hopefully I will get some tomorrow. The plywood sounds quick compared to recaulking but I do like the look of a plank deck if it can be fixed with no ongoing problems. This sanitred system that came with it looks easy but it feels like I am just hiding the problem for a while. Am I correct or is sanitred as good as the testimonials say.
     
  9. whitepointer23

    whitepointer23 Previous Member

    Also the plank deck areas are quite small . The ply cabin tops cover most of the topsides. So I would not need much ply if I went that way. What thickness ply. 1/4 or 3/8 ?.
     
  10. FAST FRED
    Joined: Oct 2002
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    FAST FRED Senior Member

    What thickness ply. 1/4 or 3/8 ?.


    Thickness doesnt matter as much as the number of plys, if you wish to add some structural stiffness. 5 ply not 3 ply if you can.

    You can seal the ply to the old deck with common roofing tar.

    Use galvanized ring nails to hold it to the decking under.
     
  11. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    What Par wrote is spot on, I would suggest removing the old planked deck altogether and replacing it with plywood/ dynel or xynole/epoxy. You will end up with a lot better job than putting ply over the old deck. Its going to be a bit of work no matter what you do so might as well do it right. Your existing planked deck is likely at least 3/4" so if you laminate 2 x 3/8 layers with epoxy staggering the joints yo will have a much stronger deck than the original ever was and watertight forever and if you stick with a light color paint it will be much cooler inside and out than the planked deck. I have actually done all 3 methods Par mentioned and imho trying to save an old planked deck is an exersize in futility, and the ply overlay is not as easy as it might seem as the deck has been worn/sanded away unevenly over half a century and needs to be flattened off so the ply will lay down properly as well as you usually have to do repairs also.
    While completely replacing the deck is obviously more disruptive to the interior it allows you to do repairs and paint the deck frame while its all open, you can also mark out the deck frame on the 1st layer of ply, then pre paint it before putting it down. Imho in the long run it will also be the quickest as long as you just get stuck in and rip the old deck up without trying to save anything.

    Steve.
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'd agree with Steve, in as much as ?replacing" the deck with plywood, but there's some catches. I've been asked to do this sort of thing several times and one of the main concerns is the look on the inside of the boat. The laid decking often has beaded edges on the under side, which does look nice and difficult to replicate if using plywood.

    I've used plywood "bead board" as an initial layer, to simulate the laid deck look on the inside of the boat. Over this bead board, I'll use more plywood, which offers a double layer for better stiffness and water tightness, because staggered seams don't need to be scarfed.

    This is major surgery and a lot aren't willing to commit to this evasive of an approach, but it is the best way to go, both from a water tightness and hull stiffness point of view.

    Simply screwing plywood over a worn out deck isn't going to do much, unless special attention is made to insure the fasteners holding down the plywood also fall deeply into solid beams.

    The cheapest course of action is simply fixing the deck in a traditional fashion. Naturally, you'll still have a laid deck that will probably leak in short order, but this is the nature of the beast. The next cheapest would be to make repairs to the laid deck and sheath it over with something (Xynole). This will accept the movement, yet keep it water tight. Lastly, some form of plywood overlay or wholesale replacement of the deck will cost the most, but offer the most as well.
     
  13. whitepointer23

    whitepointer23 Previous Member

    I can't see the need to rip up the deck. So far what I have looked at is in good condition apart from leaking seams. I understand what you are saying steve but that is a lot of work. I will most likely recaulk to restore plank tension and maybe sheath it later with the products i use in my waterproofing business. I will get some pics today so you can see what the deck looks like.
     
  14. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Some pics would be great WP.
    Ply will do a great deck & acts like a continuous lodging knee but I'd hold off too unless the existing deck has unseen secrets- leaking decks can have rot within the seams & to beam intersections. Putting stuff back how it was is a great fallback strategy = original fabric. With a ply overlay it might be straightforward if there's no bulwarks & associated stanchion- edge treatments & sealing are critical with ply & agree if you need to go that way all ply would be better than the overlay.
    Try & get the deck dry before you caulk, aussie hardwoods change size with moisture content quite markedly, so if you improve the overall condition, the MC drops & the planks loose some pressure & grip from the caulking material- obviously narrower planks thats less issue & side decks that are narrow prolly don't matter, at times on larger jobs we'll stop deckwash for a while in the targeted area & will also sneak up on condition by recaulking every other plank then come back to the leftovers.... You can get a moisture meter that will serve for comparative purpose for 30-40 bucks at supercheap.
    Jeff
     

  15. whitepointer23

    whitepointer23 Previous Member

    deck pics

    2 pics
     

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