Greenheart and Opepe wood.any opinions?

Discussion in 'Boat Design' started by sunnysideup, May 26, 2011.

  1. sunnysideup
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    sunnysideup Junior Member

    Does anyone have an opinion on Opepe wood as a keel timber with oak sawn and steam bent frames and european larch for the carvel planking?

    I'm close to embarking on a restoration project on a classic yawl.The boats principle dimensions are 46' lod,10.8' beam,draught 5.5'.
    I have a very good shipwright here in England to do the work.The boat is complete but needs major repairs to her bottom.
    We are looking at removing six or seven planks each side and reframing the lower parts. The keel timber is badly checked and will be replaced and the stern post will be renewed at the same time. A new rudder will be needed.

    These were some of the choices of wood for the restoration,but I've read about Greenheart being very durable and extremely strong with a high level of resistance to fungal attacks and certain marine borers.Would this be a better choice for the keel? Sawn and steam bent frames?

    I'd like to be able to rebuild her to cope with ocean sailing around the world.

    thanks :)
     
  2. JRMacGregor
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    JRMacGregor Junior Member

    Greenheart is as close to indestructible as you can get. It is also very heavy (sinks in water) so good for use low down in a boat. Greenheart is what they used to make harbour pilings etc. Not friendly to your tools or your health - you (or your shipwright) have to take care with avoiding to inhale the dust.

    Opepe is not in the same league, although often used nowadays in the UK as a substitute for oak. So not a terrible choice either.

    But if you have access to greenheart and can afford it - it would be the best choice.

    Larch planking works on both. Larch from the north is better than from the south.
     
  3. daiquiri
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    daiquiri Engineering and Design

    I recall reading somewhere that Greenheart wood should be used at higher moisture content than the usual 12-15%. Something around 20-25%, because at lower MC it becomes brittle. Do you perhaps have some info to share about it?
     
  4. sunnysideup
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    sunnysideup Junior Member

    Thankyou very much for both for your replies.If Greenheart is unavailable to me or too expensive then any other recommendations for other woods for the keel,sternpost,rudder....?
     
  5. JRMacGregor
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    JRMacGregor Junior Member

    If you can get good seasoned English oak it is excellent as a material for these heavy components. You can scarf your keel from two parts if you cannot buy it in one length.

    Scottish larch on English oak was a good spec. for working vessels. However, the steamed frames and narrow beam of your vessel makes me think it might be a bit more upmarket than a working boat (typically 14 feet beam for that length). English oak was also used for yachts.

    Elm and beech were sometimes used for the keel in fishing vessels if oak was unavailable - because available in large sizes, but these are not very durable - especially if there is any contact with fresh water.

    I would not rule out opepe as it is strong and rather durable - but I seem to recall hearing that it "moved" a lot - shrinking and swelling a lot depending on moisture content.

    Here are some figures for you (based on dried timber - will be heavier when timber wet).....

    Strength
    greenheart - 26,501 psi
    opepe - 17,670 psi
    teak - 14,300 psi
    elm - 12,080 psi

    Density (kg/m3)
    greenheart - 800
    opepe - 752
    teak - 576
    elm - 640

    Hardness (Janka)
    greenheart - 2593
    opepe - 1724
    teak - 1075
    elm - 769

    These show that greenheart is twice as strong as elm, but three times as hard. Any wood twice as hard as teak has to be respected. But for a keel or stem/stern where all fasteners will be bolts and have to be pre-drilled anyway that should not be too much of an issue.

    The surface of greenheart can splinter easily when dry - but in use as a keel it will be saturated. There are many old vessels in the UK with greenheart keels still sound - including the false keel on SS Great Britain.
     
  6. sunnysideup
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    sunnysideup Junior Member

    Great advice JRMacGregor,really helpful,thankyou.:)If i can find the Greenheart then I think its worth doing.The boat's had it's fair share of neglect so I'd like to try and put her back together as healthy as possible.
     

  7. rasorinc
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    rasorinc Senior Member

    Another wood to consider that might be more availably is Ironbark-known as Eucalyptus.
    I really like this wood and though they say it is heavy 62lbs. CF my samples are lighter. high rot protection, finishes clear beautifully. Very strong.
     
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