Pacemaker floor replacement

Discussion in 'Fiberglass and Composite Boat Building' started by kiwipirate, May 6, 2017.

  1. kiwipirate
    Joined: May 2017
    Posts: 10
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Hi all.
    My boat is a Western Australian made halfcabin pacemaker with a 130hp outboard.

    Looking for advice on foam that was inbetween stringers and how would i know if its structural?
    Foam was under floor from front of the bow to the transom and level to under the floor
    I would not like to replace the foam as the stuff i pulled out was saturated and weighed alot.

    I dident have any pics of the foam before I ripped it out.
    There were some small spots on the hull where some previous owner has tried to patch with who knows what, looks like plaster board mud and one spot had degraded and let water into the hull and was dripping water with the boat on the trailer.
     

    Attached Files:

  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    Yeah this is fairly common unfortunately, but is fixable. Your boat, judging from the pictures looks to have used 1x6's (20x140 mm) or taller stringers "tabbed" to the hull shell as the structural elements. You need to check these are still solid, as the moisture trapping foam tends, to cause these to rot out. The fabric tabbing will hide this, but inside the tabbing may be just gooey stuff that used to be wood. An ice pick or screwdriver will reveal the good or additional bad news. If they're good or mostly good you can scab or "sister" repair more lumber to the existing stuff, restoring the structural elements. At this point you can add more foam or not. The foam under the sole (what you're calling the floor) does help prevent flexing under foot, but a well bonded and fastened new sole (plywood) also tabbed to the hull shell can help a lot in this regard. I make this type of repair often and most of the time I don't put the foam back in, preferring to insure there's plenty of weep and drain holes in the stringers and partitions to let any accumulated water drain aft, so it can fall out of a transom drain or get pumped over the side, from an aft mounted well.

    To get started, grind and clean all surfaces where you'll need to bond and/or tab new material in. Bond and tab the new pieces in place, make provisions for weep holes, seal it all up (epoxy), then consider if you want the foam or not. A sealed chamber works just as well as flotation as a foam filled chamber. Technically, you're supposed to replace it, but no one is going to cut open your sole to check, so . . .

    The local big box store sells closed cell foam in sheet form, of various thicknesses, which can be placed in each compartment. These will not absorb moisture. Also foam "pool noodles" can do the same thing and are cheap and easy to find.
     
  3. kiwipirate
    Joined: May 2017
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Thanks for the info Par.
    Long time lurker when i started my project.
    Stringers mostly look in good health.
    Will have to definitely put drain holes in the stringer as water was just sitting in there.

    Par can i ask your opinion on removing the half cabin structure and converting the boat to centre console unit.
    I understand the cabin might have some sort of structural element?
     
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    This boat is a bit high sided for a center console, but it can be done. You'll have to build a casting deck forward, likely reinforce some side decks and of course the console. All not terribly difficult, though a lot more work than you might realize. If it was me, I'd remove the deck cap entirely and start from scratch, but you might be able to cobble something up with portions of the cap in place.
     
  5. kiwipirate
    Joined: May 2017
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Cheers Par.
    What are you referencing to when you talk about the deck cap?
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Your hull is made of two, possibly three main elements, the hull shell, a liner and a deck cap. The deck cap is the portion of the hull that lives directly on top of the hull shell and forms the decks, side decks, part or the deck/hull flange, the cabin and possibly part of the interior furniture as well.
     
  7. kiwipirate
    Joined: May 2017
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Alright.
    Further inspection of the stringers between the rear bulk head and stringers there is some timber rot.
    Im planning on replacing the stringers as i want it fixed correctly.
    Will replace them with the boat on the trailer and will make a frame to support the hull underneath to stop any warping.

    Do you consider marine plywood suitable as replacement material for the stringers?
    The timber thats in there looks like a single piece of hardwood with the grain running in one direction.
     

    Attached Files:

  8. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Don't use ply for stringer material, it is less suitable than a length of solid timber, but what would be a suitable choice of species depends on local suppliers. The foam was not likely added as a structural element, but for buoyancy purposes in case of a breach of the hull. Your boat appears to be very much a 60's product of the Hunt drawing board, it is very similar to the early Haines Hunter and Huntsman hull shapes, though I got confused looking at the internal pics where the transom "vee" appears steeper than further forward ! An optical illusion perhaps.
     
  9. kiwipirate
    Joined: May 2017
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    I have been undecided if i want to completely replace the stringers as only rotten part was at the rear of the middle stringer where it meets the bulkhead and part of the rear bulkhead where it meets the outside stringer.

    Is cutting out the rotten parts and replacing with a good joint and glass an accepted way of repair?
     
  10. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Hard to say what would need complete replacement, or might be otherwise repaired, without seeing it in the flesh, but you need to be careful not to rip out internal framings without supporting the hull properly first, as it likely will go out of shape to some extent at least. That requires a cradle being constructed, which is a job in itself. It is all a bit of a task, and not a particularly pleasant one, and in my humble opinion not something to get into unless you are sold on the hull's merits. Plenty of people still rate those old Hunt design boats, though. I am inclined to the view that old stringers and bulkheads that are in reasonable condition can be used a s a former and encapsulated with glass, and with mainly use of unidirectional rovings particularly, give adequate stiffness and strength that will persist even if the old timber continues to deteriorate. But you need a little nous with glassing to successful accomplish that, like radiusing any corners. Might sound like a bodgie methodology, but done properly, stripping it all out and starting afresh, is no small task. You might increase the weight a bit with my suggestion, but life is full of compromises. What is the transom like ?
     
  11. kiwipirate
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Not completely sure of the transom condition yet.
    Haven't had any issues to suspect transom is in any sort of trouble.
    Will get some pictures of her rear end when im back to where i store her.

    I think encapsulating the stringers will be a good option that suits me.
    I will remove the rotten parts and replace with new timber, seal the wood with epoxy.
    Scarf joint the area with epoxy mix as a jointing adhesive and then relay with glass.

    Shouldent amount to too much weight compared to all the crap that was pulled out. Filled up 8x garbage bags of foam and those bags had some weight to it.

    Still got the old girl up to 34 knots with 2 pob and a 100ltrs of fuel.
     
  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I would probably go "Cheap Charlie" and use polyester resin. You should get a reasonable bond to the old glass, if it is cleaned up well, a good idea is to use 3M Scotch-Brite strip and clean discs, which you can get to fit a power drill, it is a black abrasive-impregnated plastic mesh material about half an inch thick. Won't tear into it and cause damage. I'd use a lightweight CSM for the initial layer, then mainly unidirectional rovings laid along the length of the timber grain, interspersed with a light mat layer(s) in between, and in the final layer. Even if the timber goes to hell, you will still have a frame, but obviously it needs some substance to it, hence the weight comment. But I'm tipping it won't be too deleterious to that boat, which is likely a touch tippy.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    As to replacing the foam, I certainly like the idea of having that kind of insurance, a cheap option would be slabs of polystyrene cut to fit the voids reasonably snugly. The problem with it is mainly that fuel spills will destroy it. Painting it with acrylic house paint before installation, is probably a good idea. But you need to figure out the best places for it, and the volume required, otherwise it can be as much as a hazard than a help, especially concentrated along the centreline. The PU pouring foam is certainly notorious for breaking down and absorbing water eventually, especially in the lighter (and cheaper) product typically used. The more substantial foam that is less inclined to cause these problems, adds weight and cost, and being out of sight underfoot, it is not a popular choice.
     
  14. kiwipirate
    Joined: May 2017
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    Location: Perth, Western Australia

    kiwipirate Junior Member

    Why would you use polyester over epoxy?
    I havent checked what sort of price difference there is in Perth.
     

  15. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    To get sufficient strength and rigidity, independent of the existing timber, you will need a fair bit of material, sure epoxy is to be preferred, but the strength will come from the glass, and to wet out the amount of glass needed, will use quite a bit of resin. Epoxy isn't exactly "dear as poison", but isn't far off it ! Great stuff for many jobs, but cost limits its uses in boats like yours.
     
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