steam bending rubrail with scarf joints

Discussion in 'Boatbuilding' started by BRM, Mar 7, 2019.

  1. BRM
    Joined: Mar 2019
    Posts: 4
    Likes: 0, Points: 1
    Location: Haddam, CT

    BRM New Member

    I am planning to replace my rub rail on my Menger 17 catboat. I need about 18 feet of rail, so I will have to scarf together 3 pieces. My question is: Should I scarf and screw/glue before steaming or steam the 3 pieces and and connect the scarfs as I steam and bend the rub rail to the boat?
     
  2. NoEyeDeer
    Joined: Jun 2010
    Posts: 982
    Likes: 30, Points: 28, Legacy Rep: 300
    Location: Australia

    NoEyeDeer Senior Member

    Bend first. Scarf later.

    Doing it the other way is begging for trouble.
     
  3. BRM
    Joined: Mar 2019
    Posts: 4
    Likes: 0, Points: 1
    Location: Haddam, CT

    BRM New Member

    Makes sense. Thanks.
     
  4. NoEyeDeer
    Joined: Jun 2010
    Posts: 982
    Likes: 30, Points: 28, Legacy Rep: 300
    Location: Australia

    NoEyeDeer Senior Member

    I should have said that it's fine to cut and fit the actual scarf joints on the bench first. That makes a lot of sense. Just don't try to steam any scarf joint that is epoxied, because the heat of the steaming will break down the epoxy.

    So I'd a/ cut the scarfs and make sure they fit, then b/ steam bend the bits that need steam bending, then c/ leave them to dry out for a day or two, then d/ glue them up.

    ETA: Come to think of it, it will depend on where you place the scarf joint. If the boat is only 18 feet long you shouldn't need more than one scarf. That can be placed in the aft sections of the boat, in which case it probably would not need to be steamed.

    It's not necessary to steam an entire length if most of it will bend dry. You just stick the relevant part into the steambox and leave the rest hanging out. So, if you can get away with doing it like that, then you could glue the whole thing up in advance if you wanted to. It's arguably not worth it though, as joining it on the boat is probably easier if the scarf is in an area of gentle curvature.

    tl:dr; version is don't steam the actual scarf after it's glued, but otherwise just use whatever is easiest and makes the most sense.
     
    waikikin likes this.
  5. BRM
    Joined: Mar 2019
    Posts: 4
    Likes: 0, Points: 1
    Location: Haddam, CT

    BRM New Member

    Thanks for the clarification. Unless I find a source that will ship long lengths, I will need 3 scarfs because the length of the wood is 7 feet. I do appreciate your help. Thank you.
     
  6. DCockey
    Joined: Oct 2009
    Posts: 4,349
    Likes: 195, Points: 63, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    What kind of wood are you planning to steam bend? Kiln dried or air dried?
     
  7. BRM
    Joined: Mar 2019
    Posts: 4
    Likes: 0, Points: 1
    Location: Haddam, CT

    BRM New Member

    Iroko wood and kiln dried, which is all I can find.
     
  8. JamesG123
    Joined: Mar 2015
    Posts: 655
    Likes: 75, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    The sectional pieces can be useful if you ever bust or get one chewed up and you need to replace it.
     
  9. DCockey
    Joined: Oct 2009
    Posts: 4,349
    Likes: 195, Points: 63, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Do you have any experience steam bending kiln dried iroko? A quick internet search found reports of failure.
     
  10. gonzo
    Joined: Aug 2002
    Posts: 13,573
    Likes: 375, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If you are bending kiln dried wood, it will need to be soaked for a few days. It will make it much more pliant.
     
  11. waikikin
    Joined: Jan 2006
    Posts: 2,293
    Likes: 92, Points: 58, Legacy Rep: 871
    Location: Australia

    waikikin Senior Member

    Wow, just 7' lengths.. I'd be looking for a local alternative, maybe we're spoilt here but 20' in a durable hardwood is an easy get.
    Jeff.
     
  12. rwatson
    Joined: Aug 2007
    Posts: 5,839
    Likes: 276, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    ... or you could use a "scissor joint"to overcome the separation pressures, and "standard"Glue that won't come apart under heat.
    It's not like rub-rails have to keep out water.


    PlankJoinCompound.png
     

  13. NoEyeDeer
    Joined: Jun 2010
    Posts: 982
    Likes: 30, Points: 28, Legacy Rep: 300
    Location: Australia

    NoEyeDeer Senior Member

    Just as one example from a quick search: Welcome - Kellogg Hardwood Lumber http://www.kellogghardwoods.com/
    You could drive there and back in a few hours, or get something couriered over.
    They cater to boatbuilders. Best Boat Building Lumber For Wooden Mahogany Boats http://www.kellogghardwoods.com/boat-building-lumber/
    They'd probably have 20 foot lengths, I'd hazard a guess there are other yards around too.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.