The "Starved Cow" effect, how do you prevent it?

Discussion in 'Boatbuilding' started by MarkOHara, Aug 23, 2023.

  1. MarkOHara
    Joined: Oct 2021
    Posts: 51
    Likes: 10, Points: 8
    Location: Bataan Philippines

    MarkOHara Junior Member

    When it comes to steel boats one thing I cannot stand the sight of is the "Starved Cow" effect where you can see all of the ribs through the skin. This gets worse as the boat ages and unfortunately it makes a lot of now historical boats look unsightly and on their last legs.

    I always thought it was just the hull getting pounded from rough seas but a yacht finisher told me it has to do a lot with weather too and the expansion and contraction of the plate. He just finished a ex- Royal Navy (1968) to Yacht conversion recently and the fairing compound was 50mm (2") thick in some places. He reckons it will have to be done again in another 10 years.

    Boat builder Charlie Ward tried to avoid it by using heavier plate and the addition of longitudinal stringers when building S/B Juno (launched 2000). So far it looks like his efforts have been successful.

    Below the "starved cow" effect
    [​IMG]


    Compared to S/B Bruno
    upload_2023-8-23_12-13-40.jpeg
     
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,933
    Likes: 1,304, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Heavier plate and closer frames is about it. Note that wave slap is ~2000 to 4500 psf. But I wouldn't expect much without significant expenditure of time, weight, and money; the photo below shows the USS IOWA bow plating...that's 3/8" STS...75 ksi yield strength.

    [​IMG]
     
    rwatson and MarkOHara like this.
  3. wet feet
    Joined: Nov 2004
    Posts: 1,627
    Likes: 541, Points: 113, Legacy Rep: 124
    Location: East Anglia,England

    wet feet Senior Member

    A small correction about Juno,the boat was completed by Charlie Ward but the hull construction was by George Prior Engineering as they had the steel working ability.Which has been amply illustrated above.
     
    MarkOHara likes this.
  4. MarkOHara
    Joined: Oct 2021
    Posts: 51
    Likes: 10, Points: 8
    Location: Bataan Philippines

    MarkOHara Junior Member

    Thanks for that! Are George Prior Engineering still in operation? I see a history for them on Google but nothing up to date.
     
  5. Tiny Turnip
    Joined: Mar 2008
    Posts: 871
    Likes: 283, Points: 63, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Personally, I really like the hungry horse' effect, particularly on naval vessels and working ships. It's an aesthetic that is an honest result of the material and construction, like the planking lines on a timber vessel.
     
  6. MarkOHara
    Joined: Oct 2021
    Posts: 51
    Likes: 10, Points: 8
    Location: Bataan Philippines

    MarkOHara Junior Member

    Perhaps your "hungry horse" is a far better adage for the condition. When a horse gets that hungry and long in the tooth you just put it out to pasture. I appreciate your opinion but I'm not a fan. I'm a boat builder to trade myself, but I specialize in wood and composites and I find the older wooden barges far more pleasing on the eye.
     
    waikikin likes this.
  7. Ad Hoc
    Joined: Oct 2008
    Posts: 7,949
    Likes: 1,818, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Frame spacing, long.t spacing, plate thickness, and of course the welding sequence all play a major part.
    Too much heat on thin plate that is widely spaced between stiffeners, ...is not a combo.
     
    DogCavalry and MarkOHara like this.
  8. baeckmo
    Joined: Jun 2009
    Posts: 1,739
    Likes: 751, Points: 113, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Add curvature between long:s.
     
    DogCavalry and Ad Hoc like this.
  9. Ad Hoc
    Joined: Oct 2008
    Posts: 7,949
    Likes: 1,818, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    That too :D
     

  10. waikikin
    Joined: Jan 2006
    Posts: 2,439
    Likes: 179, Points: 73, Legacy Rep: 871
    Location: Australia

    waikikin Senior Member

    Agree with the "Hungry Horse" analogy,... alliteration is always awesome:)

    Jeff.
     
    DogCavalry likes this.
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.