Which wood?

Discussion in 'Materials' started by Pippin, Feb 18, 2014.

  1. Pippin
    Joined: Dec 2013
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    Pippin Junior Member

    Hey All,

    I am planning to build the Glen L fisherman, a fiberglass encapsulated plywood 13 foot runabout. I have to choose an Australian timber for the frames, stem, keel and battens. Anagote is my local supplier and stocks the following -

    Spotted gum
    White beech
    Huon pine
    Queensland maple
    Fijian Kauri pine
    Hoop pine

    I would like to keep the boat lite so will be limited to 5-600kg/m3 density. Does anyone have any suggestions or experience using these timbers? Which parts of the boat should I look at using a stronger timber?

    Cheers
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Spotted Gum is pretty heavy, but exceptionally strong. If you stick to the dimensions in the plan, that will escalate the weight. You'd have to think Huon pine would be good, but doesn't it cost an arm and a leg ?
     
  3. PAR
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    PAR Yacht Designer/Builder

    Select species substitutes with similar densities as the species the plan calls for. Don't be tempted to add a little here and there, thinking you'll make it stronger. This is a common novice mistake and you'll usually just make it weaker and heavier with this approach.
     
  4. Steve W
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    Steve W Senior Member

    Fijian kauri would be a good choice for all the components of a little runabout. What does Glen L specify?
     
  5. Pippin
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    Pippin Junior Member

    Glen L specifies oak, mahogany or spruce. I am leening forwards huon pine or queensland maple but price is a consideration too. I think I need to get down to it and compare weights and relative strength to the specified timbers. I might also contact my supplier for suggestions. Thanks for the feedback guys.

    Cheers
     
  6. PAR
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    PAR Yacht Designer/Builder

  7. Pippin
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    Pippin Junior Member

    Thanks PAR, I'm down to Queensland Maple, White Beech & Fijian Kauri. All of similar density and strength. Just wondering how important durability will be as the hull will be encapsulated? Kauri is slightly stronger but less durable than Q/M.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Durability will rise greatly with encapsulation, permitting less desirable species to be considered. You have a number of nice hardwoods down there, which can easily replace the oak and mahogany sped'd in the plans. Finding a repetitively light softwood will be the big trouble.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    The Hoop Pine he mentioned is light and readily available, but I wouldn't fancy it as the best for durability, it is quite susceptible to dry rot.
     
  10. Steve W
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    Steve W Senior Member

    Ok, that range of species pretty much says you can choose anything from a strength or weight standpoint. I wouldn't be too concerned with rot resistance since you are epoxy encapsulating everything, I would still choose kauri just because ive used it before and it is nice to work with, moderate in weight, holds fasteners well etc. I would be interested in what you have to pay for the various timbers you listed.

    Steve.
     
  11. rwatson
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    rwatson Senior Member

    Traditionally, WA Kauri is quite heavy, but brittle. I cant remember ever seeing Fijian Kauri.

    Spotted gum can vary a lot in weight - you can actually pick three planks from a pile, and the weight will vary hugely depending on what part of the trunk it was cut from.

    I have picked over piles to get the lightest, clearest planks for boatbuilding.

    The very best framing timber is celery top - way better than Huon Pine, and quite a bit cheaper.

    Huon Pine wont take epoxy all that well, as it has a lot of natural oils that make it last so long - and it is really too soft for framing.

    It really is a toss up between Queensland maple, Fijian Kauri, Spotted Gum, and Celery Top Pine.

    For a 13 foot runabout - it may be as simple as heading into your local hardware shop, and seeing if they stock 'tasmanian oak' building studs.

    If you can pick over a pile, and get some lightweight, fairly clear studs to saw up - they would be the most cost efficient, and will take epoxy well, as well as being very long lasting timber.
     
  12. waikikin
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    waikikin Senior Member

    Hi Pippin,
    go the Queensland maple, it will glue the best, some spotted would be nice for the rubbing strip/sponson & to use as a cap for a skeg if the boat has one, the White beech is a nice timber to work(though a bit wiffy) you could use it for stem & rub rails also but bruises easier but the bonus is it's a non staining timber-dont bleed grey/black when coatings injured. If your not set on Aus timbers our Northern neighbors have some nice ones, some PNG rose wood for frames would be nice if clear finished, also Kwila(Bunnings Merbeu) could make some nice stringers.
    Anagote is a great supplier with a terrific range & machining available, can be a little exxy but you get service- we don't worry about that cos once we cut it & fit it the material cost is minor.
    Sounds like a nice project, all the best from Jeff.
     
  13. Steve W
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    Steve W Senior Member

    Ive used quite a bit of Fijian Kauri but not in the last 35 years so I don't know what the quality is like now. Its not as good as NZ kauri but pretty nice.

    Steve.
     
  14. redreuben
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    redreuben redreuben

    WA is Karri not Kauri and it virtually dissolves in fresh water so no.

    I'd be looking for Australian red cedar from the paddock tree re-millers and second hand market. Otherwise just use Meranti.
     

  15. rwatson
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    rwatson Senior Member


    No, you have that wrong.

    Karri and Kauri - both from WA, are different types of wood.

    WA Kauri
    "Various species of kauri give diverse resins such as kauri copal, Manilla copal and Dammar gum. The timber is generally straight-grained and of fine quality with an exceptional strength-to-weight ratio and rot resistance, making it ideal for yacht hull construction."
    http://en.wikipedia.org/wiki/Agathis

    "Eucalyptus diversicolor



    http://en.wikipedia.org/wiki/Eucalyptus_diversicolor
    "Not to be confused with kauri.

    Karri
    Climbing a famous karri tree - the Gloucester Tree
    Scientific classification
    Kingdom: Plantae
    (unranked): Angiosperms
    (unranked): Eudicots
    (unranked): Rosids
    Order: Myrtales
    Family: Myrtaceae
    Genus: Eucalyptus
    Species: E. diversicolor
    Binomial name
    Eucalyptus diversicolor
    F.Muell.

    Eucalyptus diversicolor, commonly known as the karri, is a eucalypt native to the wetter regions of southwestern Western Australia."
     
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