How to install floor in empty sailboat

Discussion in 'Sailboats' started by slow_boy, Sep 11, 2006.

  1. slow_boy
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    slow_boy Junior Member

    Pardon the newbie question.

    I purchased a 23ft Islander sailboat that has the insides stripped out of it, including the floor. I want to start this project by installing a floor. The only mounting point that I can see is the main stringer that runs from the front to the stern of the boat.

    What is the easiest way to install a floor in an empty sailboat? Do I need to build stringers, or can the plywood rest directly on the edges of the hull?



    Matt
     
  2. Figgy
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    Figgy Senior Member

    Totally gutted? Why was it stripped, fire? What year is it and do you have pictures? Do I have any more questions? Yes I do! but I'll wait :)
     
  3. Seafra
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    Seafra Sailing Nerd

    I would use stringers to avoid potential warping issues in the future. I'd also coat the wood in epoxy or varnish to avoid potential issues with condensate rotting the rood.
     
  4. slow_boy
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    slow_boy Junior Member

    Stringers?

    Thanks for the response!

    I don't know why the boat was gutted but there isn't much to it anyway. It is a 1974 Islander 23. It is a smaller boat with a retractable keel. I think the inside was fairly simple even when it had stuff in it. I just want to have a safe floor in there so I'm not stepping on the hull.

    I am thinking stringer are probably the way I have to go, although it sounds like that is a lot of work. I need to match the curve of the hull on the ends of the boards right? Then glass them in if I want them to last?

    I don't see any evidence of it ever having stringers glassed in. This is perplexing because I assume it had a floor at one point. Is there another way to do this?

    Matt
     
  5. Crag Cay
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    Crag Cay Senior Member

    I think it might help if you try to standardise the terminology here. There are people from around the world on here and it may be easier if we clear up what you want to do.

    Do you want to put in a large flat area to walk on in the cabin (called the cabin sole) ?

    If so this is best supported by some frames running across the boat known as 'floors'. Stringers run from front to back along the inner surface of the hull and don't really help you much with what you are planning.

    'Floors' of 3/4 WPB ply do have to be cut out to the shape of the hull (sort of D -shapes) and then glassed in place with their upper surfaces lined up to support the cabin sole.

    Any help?
     
  6. slow_boy
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    slow_boy Junior Member

    Floors?

    Yes, I do want to put in a large flat area to walk on in the cabin.

    Well, "floors" it is then. In that case there is only one "stringer" down the center of the boat. It seems to me that "floors" sound very difficult to build. Any suggestions on where to start?
     
  7. Crag Cay
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    Crag Cay Senior Member

    If you search on the web for 'tick stick' you will find some references on how to take off an internal shape.

    www.shortypen.com/essays/tickstik

    With only needing a simple shape like the floors you can probably work out a simplified system once you have grasped the basics. To start with, transfer the shape to some stiff carboard and check you have got the right shape. Then jig saw it out. You don't really need to bevel the outside edge to fit flush against the hull as the fibreglass bonding (tabbing) will transfer the loads. One floor every 30 inches will probably be enough.

    Just make sure the hull is clean (scrubbed and degreased and ground with 60 grit where you are going to glass. This tabbing will be a 'secondary bond' which needs a good 'key' to work. Ordinary polyester resin and chopped strand mat will be fine as the loads on these floors are low. (Epoxy and biax tape would be stronger if they were more critical joints you were making).

    PS the stringer along the centre line has a variety of names, including a keelson (or kelson). Welcome to the wonderful world of boats.
     
  8. Toot
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    Toot Senior Member

    Home Depot (DIY home supply store) sells a contour gauge.

    You know those silly things you can buy at toy stores that's comprised of a sheet of black plastic with hundreds of metal pins stuck in it, so you can press your hand/face/nose up against it and make a metal-pin copy?

    Well, the contour gauge is just like that, only it's a flat two-dimensional version. You simply press the pins up against the surface and they slide through a holder. There's just enough friction there to hold them in place and you've then got the contour that you're trying to copy.

    Same idea. Probably not really any easier or more difficult than Crag's method that he linked to.
     
  9. Cliff Pope
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    Cliff Pope Junior Member

    Cut one out in cardboard first and try it in position. Then make correction marks on the cardboard and use these when transfering the pattern to the real thing.
     
  10. slow_boy
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    slow_boy Junior Member

    Pictures

    Well, I have added some pictures and a couple of more ideas.

    The floor that I am starting with is actually a 20" wide space. I think it would be possible for me to lay two stringers of varying heights long ways and just fasten the sole plywood to this.

    Any reason why I shouldn't do this? Do I really need floors for a space this wide?


    Below is a picture looking at the place where I need to put the floor. The picture is taken from the bow end pointing towards the stern.



    I plan to have the floor(sole) sit about 2" below the keelson because...well, lower is better and I can.

    [​IMG]


    from the second photo you can see also that the hull is pretty flat here. I might be able to use a flat "floor".

    [​IMG]
     
  11. LP
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    LP Flying Boatman

  12. Crag Cay
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    Crag Cay Senior Member

    If the inside of the hull is that flat and level, I would give it a lick of paint and cut a couple of pieces of outdoor carpet to fit loosely.

    Job done.

    Or.... slightly more salty, get a piece of 'holly and teak deck' thin plywood and cut out a couple of pieces to fit, with the stripes running for and aft, and stick them down with epoxy.
     
    Last edited: Sep 14, 2006
  13. slow_boy
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    slow_boy Junior Member

    When I step on the bottom of the hull I can see it flexing. I don't think it's a good idea to leave it as is but that certainly would be easier!
     
  14. PAR
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    PAR Yacht Designer/Builder

    The floors, as previously described aren't what holds up the sole. Floors are structural members that hold onto frames and the keel, in wooden boat construction. In all boats, the elements that hold up the sole is the sole support structure, which usually consists of several pieces, both athwart and longitudinal stringers or cleats. These pieces may or may not rest on actual floor members, but most times in small 'glass boats, the sole support is a series of wooden stringers, sometimes ply, others solid lumber, which are "tabbed" into the hull shell.

    Laying out a new sole isn't as easy as you might expect. Where's level, for example? Do you want level or maybe drainage into the bilge or toward a scupper(s)? Maximum headroom will limit foot space and leave precious little bilge.

    Typically, the 'glass boats of that era used a stringer, tabbed into the hull shell, if a liner wasn't used (which wasn't on your boat). The stringer was usually lumber, maybe a 1"x2" for that size boat and several athwartship, plywood risers (with a nailer along the top edge) were tabbed to the hull bottom and sides, up to the stringer. The sole was glued and screwed to all of this then it too was tabbed to the hull sides, hopefully making a watertight sole (it never lasted) with a few access holes in key locations, like bilge pumps, wet sumps, chain lockers, etc.

    The easiest way to fix a stringer location to the hull sides is with a laser level set for a horizontal beam, mounted inside a well leveled hull. You can level the hull on the trailer with jacks, shims and letting air out of the tires. Use the LWL as the guide, but the boat needs to be dead nuts level or the sole layout will be off. This is also the best way to mock up a bulkhead location too, just a vertical beam is used, which will come in handy when you build cabinets and cabin furniture.

    With the stringer location set and marked, decide if you want some pitch, crown or other type of self drainage system employed in the sole. Water will find its way into all boats, particularly small ones, where it will eventually get below and soak your socks. Most boats have a cabin sole that permits drainage (ain't gravity cool) of this moisture to a low point where it can be pumped overboard.

    A simple sole structure could be a few athwart 1"x6" pieces of Douglas fur (or other reasonably rot resistant lumber) tabbed into the hull. The plywood sole can be glued and screwed to this (and the hull side stringers), providing a 6" deep bilge where the pump can live. You would be wise to have some aft slope to the sole, so when you parked her on the trailer she could drain through the transom drain. The athwartship pieces should have ample "weep" holes to permit water to migrate aft to the lowest point for pumping overboard or drain through the transom.

    Personally, I haven't seen one of these in many years, but I remember a sole piece that was sort of on the small side, resting on two small stringers, not far off the centerline of the boat. The sole outboard of this was the hull shell (covered in heavy roving) and sloped upward. From your pictures it appears to be the stock sole, though there isn't enough in the photo to tell for sure. The stock hull has some reverse curve in the bottom along the centerboard (stub keel area) which was covered. Do you have a photo with a view taken from the companionway hatch? This would help a lot.
     
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  15. slow_boy
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    slow_boy Junior Member

    Thank you for the detailed responses! Wow, there are a lot of terms and language I need to learn :)

    What does "tabbed" mean?

    I'm not really that concerned about whether the floor is level, I don't have a trailer for the boat, so that is not an option. I was originally planning to level it in the boat with a bubble level.

    I was planning to go very low, less than 1' off the hull on the edge, for the sole. Why is bilge space "precious"? Is it a bad idea if I have only 2" of bigle?

    I was hoping to make the sole removeable, and not glassed in, it would just set on top of the stringers/floors and fit in the tight space available.
     
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