strip planking

Discussion in 'Wooden Boat Building and Restoration' started by shipwright, Dec 6, 2016.

  1. shipwright
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    shipwright Junior Member

    Hi troops. Am building a 6m tri. strip planking? how thin can you get with strips.
    was thinking 40mmx6mm,how to keep planks aligned.
    Shipwright:cool:
     
  2. upchurchmr
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    upchurchmr Senior Member

    Kayaks have been built with 1/8, 3/16, and it use to be typical to use 1/4 (6MM about).
    This is usually with WRC or some people use spruce. Both light weight and relatively weak woods, coated with 6oz glass/ epoxy on inside and outside.
    In a kayak the width is only 3/4" (~18MM).

    The only 1/8" I actually know was then coated with a graphite fiber weave on the inside.

    But Kayaks have almost no loading compared to a Tri.

    You might look for a thread by Corley who is re-building a 25' Kraken tri. He has mentioned that he might should have chosen strip planking instead of compound molding.

    Keeping the strips aligned is usually done by making an open mold with multiple stations - possibly 1' apart.
    Here is a build sequence for a kayak from a guy who knows what he is doing.
    http://etiennemuller.com/northstar/index.html there are some details that won't matter to you, but the building frame/ mold is easily understood.

    What Tri? That is about what I want but I can't find a daysailor for strip building.

    You really should use what the designer specified - unless you are the designer?
     
  3. PAR
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    PAR Yacht Designer/Builder

    Why are you deviating from the recommended scantlings in the plans for this Tri?
     
  4. shipwright
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    shipwright Junior Member

    Tri hull

    Upchurchmr: Thanks for reply, Design is similar to a searail, My design criteria is for a an open tri hull capable of carrying myself 2 grandkids and 2 of there friends and stores for the day all up around 200kg.Other need is to be able to keep up with Hobie 16-18, a lot of our sailing time in our waters wind can be around 20kn against a 3 knot tide, bay is not especially deep so have on average 4' swell with lumps on top . and sometimes and erea fairly short between so adequate buoyancy is paramount
    Other main reason is I am now 76 started sailing in 1953 present boat is a catamaran-HYDRA, a fairly good performer but it is getting harder to rig and sail.
    Have been a professional boatbuilder and ship designer with Gov. accreditation all my life. built many 18-16-14' skiffs as a younger guy eventually moving into commercial boats up to around 25m ,so for me at this stage designing and building a 6.3m hull is akin to making model boats.
    I have never been to proud to ask questions re my projects.
    As one of my old employers said to it takes the same amount of labour and material to build a dud as a good one.
    Re:strip planking have done a few smallest was a 6m inboard launch.
    I used airex foam in strips with a plastic bead was very fast construction time and hull was used to take a plug off.
    Anyway I will see if I can upload the body plan here
    Regards Shipwright:cool:
     
  5. shipwright
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    shipwright Junior Member

    Tri hull

    PAR: Thanks for question ,in short I am the designer, after 50 years of this I am not to proud to ask questions and there is always other methodology .
    New materials and practices are a part of our industry.
    Shipwright:cool:
     
  6. TeddyDiver
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    TeddyDiver Gollywobbler

    There's no lower limit except what comes from the working methods and layout schedules. Generally the workable width is two to four times the strip thickness but depends of the curvature of the hull so no limit in that direction either. For alignment I tend to use less stations and double sided "ribbets" between them. This works when the hull shape is quite constant.

    BR Teddy
     
  7. upchurchmr
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    upchurchmr Senior Member

    I don't understand "double sided ribbletts".

    Do you have a picture?
     
  8. rwatson
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    rwatson Senior Member

    "double sided ribbletts".
    Are just just bendy "vertical" strips temporarily screwed (not stapled, so that planks are pulled into alignment) to the "horizontal" planks.
    By keeping the planks aligned, the whole hull side is much more self supporting and self fairing, requiring fewer stations.

    A 6m (18ft) hull is not much bigger than the canadian canoe I built
    http://greencanoe.weebly.com/building---the-very-beginning.html, and that was 6mm strip.

    Its had some very rough treatment, and I think you would only need to use a little bit heavier fibre, and some internal framing at chain plates and crossbeam locations, to cope with the pressures on a trimaran, based on my observations.

    I would go further than the "standard" 200 gsm ( 6oz) cloth, and go up to around 280 gsm on the outside of the hulls. I find the heavier cloth wieghts easier to lay and wet out

    For me, the 6mm very clear WRC was thick enough to be self fairing, but not too stiff.

    Bear in mind that the strips are really only "core", and structurally, they are not nearly as critical as the glass on both sides.
     
  9. upchurchmr
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    upchurchmr Senior Member

    That link is not working for me.
    Wish I could see it because I'm being more block headed than usual.
    I don't understand what "planks are pulled into alignment" to the "horizontal planks".

    I thought the only planks would typically be "horizontal planks.
     
  10. rwatson
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    rwatson Senior Member

    Attached Files:

  11. upchurchmr
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    upchurchmr Senior Member

    Watson,

    Thanks, looks like it might be necessary for thick planks.
    Personally I wouldn't want to fix all the screw holes, but that is just talking from not having tried the technique.

    Basically it seems that you wouldn't need to do this with thinner planks (and narrower like a kayak).

    I'm assuming this is all temporary until the planks shown are set (glued?) to each other, so the vertical strips can be removed and the "filler" planks are fit and installed.
    This might not be a desirable technique for brite finished wood. Of course, it would work fine if you were cold molding a layer over the planks (at a 45 for example).

    Thanks for introducing the technique, I need a lot of help.:D
     
  12. TeddyDiver
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    TeddyDiver Gollywobbler

  13. shipwright
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    shipwright Junior Member

    6.3 Body Plan

    Hi Troops having problem attatching a PDF File a body plan. Can any one assist.
    Shipwright:cool:
     

  14. messabout
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    messabout Senior Member

    The photo from Teddy Divers reply showed a nicely curved brace. The brace can also be a much simpler straight post with wedges to push the planks to the moulds as needed.
     
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