Bulwark height

Discussion in 'Boat Design' started by SeaJay, Feb 23, 2010.

  1. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    Project: 46' motorsailer (based on modern canoe body, composite hull), under construction.

    I want to add bulwarks in lieu of an aluminum toe rail and would appreciate some input on design considerations before I commit to a particular profile. Ideally, I'd like my stantions to be mounted in the top so a certain minimum width is necessary. I don't want them too high where freeing ports and stablity issues become a major factor, but I do want them to provide both a real and visual sense of security. The character of the boat is not "traditional", but maybe more along the lines of Dashews FBS...design follows function. I think my question relates to the æsthetics as much as to the practical issues of this design element.

    I know it is difficult to make suggestions without actually seeing the actual boat, but at present it is just a bare hull and my autocad abilities are such that you wouldn't gain much from my drawings. Anyway, I'd be interested in what other designers have used and why.

    Best Regards,

  2. gonzo
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    gonzo Senior Member

    One option is to install the stanchions and secure the bulkwarks to them on the outside. Kind of a plank bolted to them.
  3. alan white
    Joined: Mar 2007
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    alan white Senior Member

    The stanchions can be stainless or bronze weldments--- a deck mounting plate, a strong vertical pipe also serving as a lifeline stanchion socket, and a plate to bolt a board to. 12" height could be done on that size boat. The bulwark could be an 8" plank of maybe 1" thickness. A 3" wide laminated capping piece would be attractive and functional, if a bit more complicated.
    Making the lifelines easily removable out of sockets would be nice in port or for inshore sailing for ease of docking and aesthetics.
  4. mark775

    mark775 Guest

    For boats that are supposed to spend a large part of their lives leaning, it has struck me that sailboats, in general have the limpest, just under average human tipping point railing conceived - an ambulance-chaser's dream. I applaud your decision to raise the bulworks a bit - your railing will be stiffer and the through-deck penetrations eliminated. The curvature of the boat (in the horizontal dimension) and the width of this shelf can make it stiffer than much glass. Best to do it when the hull is layed up. IMO, a slight camber is worth the trouble and adds a touch of interest (you will have to make the stanchion bases to match the curvature - no store-bought cast bases.
    Above are two examples of what I believe you are after. The left is my preference, with a metalic-looking paint job contrasting hull color. Wood is easier in the short run and adds warmth.
  5. SeaJay
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    SeaJay Senior Member


    Thanks for the input and suggestions. It gives me conviction that I'm moving in the right direction. Mark, your sketches have suggested an approach I hadn't given a lot of consideration...I like the idea.

    Regards to all,

  6. dreamer
    Joined: Nov 2004
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    dreamer Soñadora

    that's pretty cool, Mark. I like this idea Is that a C-channel?
  7. JohnTT
    Joined: Feb 2009
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    Location: Atlantic

    JohnTT Junior Member

    I think you're on the right track. The "U" shape will add incredible strength to the hull/deck joint. I'd consider a bulwark that is about 4" high and 3-4" wide. This is wide enough that you can easily get tools inside the bulwark during layup and for hardware installation.

    I would lean away from topping it with wood so that you are never tempted to make it bright. All of those stanchions and other stuff will have to be removed for each varnishing to get a tight varnish seal. Lifting varnish will haunt you!

    I would also not take the stanchion through but just bolt on top. This will avoid any concern about crevice corrosion on the tube. A 30" stanchion raised by the 4" of the bulwark will be an excellent height.

    The key to lifeline strength are the end attachments. Most stainless guys weld on little bitty wire loops and don't adequately brace the pulpit and pushpit. A study by the Naval Academy found that this is where lifelines systems fail.

    You'll need a freeing port or two but these don't need to be huge. A couple of 1 1/2" round tubes through the bulwark per side will work. Also end the bulwark a foot or so before the transom. You might also put a deck mounted drain at the low point and lead it to a through hull at the waterline. This will avoid the constant dirty stripe down the topsides from rain run-off.

    Finally, consider putting your mooring cleats right on top of the bulwark so as not have to worry about chafe from chocks. With composite construction, that bulwark can be made far stronger than the deck.


  8. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member


    Great stuff, thanks! Don't worry about wood on top...I'm maintance-phobic. A friend of mine makes store fixtures / cabinets, and is fond of saying, "if it's wood, it's no good". (now all of you wood-a-philes out there don't get in a huff, it's just a joke). Your dimensions are just about what I think will do the trick. I've been thinking about mounting the cleats as you've suggested but couldn't figure out the attachement until this "C" channel idea surfaced.


    Sea Jay
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