what to do with the deck.

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

  1. whitepointer23

    whitepointer23 Previous Member

    deck pics

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  2. whitepointer23

    whitepointer23 Previous Member

    I put up a couple of pics . This morning I spent 2 hours scraping and lifting the stuff the deck has been covered in . It comes off in big sheets where the water got under it. What I have uncovered so far looks good apart from a couple of spots where the cabin side meets the deck. The bowsprit has a large rotten section where the coating trapped water against it. Oregon dissolves if it stays wet for a while. Whats the best timber for a new bowsprit. Would it be stronger if it was laminated. As far as drying out goes I plan on getting all the coating off and leaving the deck bare until the end of February while the weather is hot.
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's tough to tell, but there does appear to be some rot, which usually also includes fastener issues, such as waste and beam rot around the fasteners. The priority should be to get a good assessment of the over all deck condition, which will likely force your hand in the type of repair.

    Get it clean and dry (tarp it if necessary), then pull fasteners from the worst places, which will be along the margins and around hardware, where bedding and caulk has failed. From the pictures, you're going to have to replace some planking, but you might get lucky and can tidy up with more caulk and some new planks. During this assessment process, figure out how thick the decking is, in the high traffic areas. The minimum thickness for a laid deck to be reliable is 3/8" (9 mm). On your boat the decking should be much thicker, say in the 1" (25 mm) to 1.25" ((32 mm) range, assuming reasonable beam spacing (hell maybe even thicker). If it's thinner than this, it can't be bunged reliably and is usually too weak to do much as structure (laid decks are a structural element). The only time this isn't true is if you plan a heavy sheathing or plywood overlay. By heavy sheathing I mean 36 ounces (1,200 gsm) of fabric as a minimum. This is crab boat heavy, but it does work, assuming the skinny, but still solid laid deck below has a good grip on the beams.

    I saved a deck like this once on an old classic that had been 'glassed over to stop leaks. It had a 1.25" cedar deck, worn down to 1" in spots. The whole deck was pulled up and each piece numbered. Then each plank was planned to 3/4" thick and set aside. Two layers of 1/4" plywood was glued and screwed down to the beams, with overlapping seams, then skinned with two layers of 10 ounce cloth. Lastly the refreshed old deck planks where laid back down, where they use to live, looking new and pretty. This was a classic yacht and the owner wanted to do as much as he could for the old lass, so you'll have to justify how much you want to do, but the above technique is bullet proof, the deck is stronger and it doesn't leak.

    Conversely, you could just refasten the existing deck with the next size up screw, fixing what you absolutely need to fix and push some fresh goo into the seams as you finish. It'll look nice and it'll retain most of it's patina, but it'll still be a leaky old laid deck that isn't very strong either. Use 2 part polysulfide in the seams. One part polysulfides are available, though not as durable as the 2 part. Don't let costs or anyone else, convince you that polyurethane will do just as good a job, because it doesn't.
     
  4. whitepointer23

    whitepointer23 Previous Member

    Thanks par. I have found a bit of rot along the cabin side but the bulk of the deck is solid so far. But I haven't seen the port side yet. I do like the ply deck idea the best but the bow area will be a big job. There are 2 anchor winches and several fittings plus the bowsprit but that has to be replaced anyway. At the end of the day as much as I like the plank look strength and elimination of further issues takes precedence over fancy looking decks.
     
  5. whitepointer23

    whitepointer23 Previous Member

    I got put off my idea of using my waterproofing membranes today when I saw the damage caused by the failure of the coating on there.
     
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  6. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    We did a refurb of an old Luders 47 yawl years ago which had laid decks and the novice owner wanted to save the deck and try as we did he could not be swayed. The boat had rather light scantlings and the deck beams were sided 1 1/4" and the decks had been refastened at least once before which had split many of the beams, the teak was very dry and brittle, there was decay around many of the screw holes so we ended up with rather large bungs, we spent thousands on bronze screw, had to rout out miles of seams to recreate somewhere for the polysulphide all to end up with a substandard job imho which could never stay watertight, not a part of the job im proud of but he was warned. After a number of years we coated it with some insanely expensive German made 2 part wonder goo which as far as I know has been holding up well and he still has his pretty deck so.... What we should have done is ripped it all up, rebuilt the frame and laid a new deck with new teak but the boat had an amazing history and he didn't even want that.
    Obviously if your deck ends up being reasonably sound a repair will be the cheapest but be sure you have a sound deck frame under the planking. If you do go with a new plywood deck you will end up saving quite a bit of weigh up high which is nice. I have also replicated the beaded look with plywood but rather than buying of the shelf stuff we bead our own on bs1088 okoume ply, its a bit of work of course but I really prefer to us proper marine ply. We use an old sears craftsman molding head on the table saw and it works well but pricey for the client.
    I actually have a deck job to do next summer which is pretty much the same as you have except it is yellow pine on a 39ft double ended motorsailer built in Finland in 1970. It has never been sheathed though and this boat does not have 1 square inch of rot anywhere, but the decks are worn down so many of the seams are gone, it may just get the German clear goo. Again, novice owner who likes the wood deck look.

    Steve.
     
  7. whitepointer23

    whitepointer23 Previous Member

    Once I have whole deck exposed I will takes photos of the whole thing with the rotten areas marked and see what you blokes think is the best option and that will be what I go with. It has to 100 % water tight. I hate leaks. At the moment the deck is leaking everywhere . Even lockers under the bunks were wet.
     
  8. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Oregon is Probably your most reliable choice there.I'd only laminate if you cant get the size- bowsprit should be no prob. Just been researching some for a classic yacht topmast, one of the sources was in Vic- Simply Oregon or similar. No idea on pricing yet as the season is still on.

    Jeff.
     
  9. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    Tall order for a laid deck, I used to look after the J Craig with around 2.5 km of seam- if we didn't have a couple of leaks we just weren't trying hard enough........:D

    Jeff.
     
  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Agreed, a tall order for a laid deck, they just have way too many potential leak points to stay tight.

    Also agreed, it's ***** to pull everything, to lay down plywood, though you do get a real good lock at the beams when you do.

    Refasten and sand the deck, if it's mostly sound, then Xynole the crap out of it.
     
  11. whitepointer23

    whitepointer23 Previous Member

    How much epoxy does a square meter of xynol drink par. I have not seen it before. The actual plank deck area of my boat is quite small. The side decks are 2 ft wide and the bow is only about 6 ft long the rest is ply cabin tops so material wise I won't need a lot which ever way I go. On a different topic. The main mast is one piece stepped off the keel with about 7 ft to where it goes through the cabin top. If I back off the stays a bit I should be able to completely disconnect the forestay to change the bowsprit shouldn't I. I can temporarily attach the forestay to a deck fitting.
     
  12. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    I think xynol is something like Dynel that we get here- a synthetic fabric, I'd guess about 600 grams per meter squared- first layers to a porus substrate take extra, subsequent layer will take a bit less, international & norglass should have info..
    It's usual to run a couple of halyards forward when dropping the forestay out, if there's no where left to hook them to with the planned work just drill a beam for some threaded rod & ring nuts- you can link/ the lower one to a stringer or whatever below, you should be able to just back off the rigging screw & pull the pin.
    Jeff
     
  13. whitepointer23

    whitepointer23 Previous Member

    Thanks again jeff. I know about dynel but haven't actually used it. The reason I asked about the mast is its a lot bigger than what I have had before. The bowrail is pretty solid I might get away with attaching the halyard there. With the mast buried so deep it should not go anywhere should it. The masts are aluminium.
     
  14. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    It really isn't that much of a ***** ripping the whole deck up on a boat that size, its really more of a perception than actual problem and the benefits are huge. I would have that deck off in a day with a circular saw, sawzall, jigsaw, hammer and pry bars. The key is to resist removing the screws initially and just cut across on each side of each deck beam. That gets rid of most of it in a hurry, then split the bits on top of the beams with a hammer and chisel and they are gone the remove the screws with a vice grips. The nice part is you then have access to the whole deck frame for any repairs and painting before putting down the new ply and you will end up with a lighter deck.
    Whatever method you choose, to do a proper job you are going to be removing all the deck hardware, bowsprit and toerail and anything else where the sheathing should be going under rather than around and all these items need rebedding anyway.
    Of course if the existing deck turns out to be reasonably sound one of the shortcut methods will work fine if done right. You will find after removing all the hardware that the deck will have been sanded and worn away over the years so the deck will need considerable fairing before you will be able to glue plywood down. If you skip the plywood and just sheath right over the planking with dynel or xynole (not something I would recommend) you would need multiple layers, I don't know how many, and even if the fabric could handle the movement of the planking you would need a high elongation epoxy to have any chance of success. Another method that was used on carvel hulls, supposedly with success by Alan Vaitse in the US was to build up a fiberglass sheathing strong enough in its own right to overcome the inherent movement of the planking.
    On the bowsprit issue I agree that oregon pine which is I believe is what we call Douglas Fir in the US would still be a good choice, either solid or laminated.

    Steve.
     

  15. whitepointer23

    whitepointer23 Previous Member

    Thanks steve. If the deck turns out bad enough complete replacement with ply will be the way to go. What we call oregon is Douglas fir.
     
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