...Load line convention 1966..

Discussion in 'Boat Design' started by fradrigo, Mar 19, 2008.

  1. fradrigo
    Joined: Oct 2002
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: CROATIA

    fradrigo Junior Member

    ...I'm back to freeboard marks, load line, draught marks etc...:confused:

    Does anybody know how to determine freeboard deck when we have rockered keel ? 1966 convention defines procedure just for even and raked keel ?

    Is there any pertinent standard for draught scales / marks for yachts ? MCA LY2 says nothing about size of lettering and it's projections on sloped aft/fore surfaces...

    Thanks
     
  2. aixam
    Joined: Mar 2008
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sweden

    aixam Junior Member

    Rockered keel are not conuted other then a tich hull.
    So its no afect to it.
     
  3. fradrigo
    Joined: Oct 2002
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: CROATIA

    fradrigo Junior Member

    could you clarify a little what is the 'tich hull' ?

    How could you determine ' least moulded depth' for the hull of , say, SY Adele ( Hoek design ) type ? Maybe it would be logical to start with a tangent to freeboard deck and rockered bottom which are parallel to DWL ?

    I've got several more vague examples but couldn't find solution in original convention and in several interpretations...
     
  4. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 188, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    Good question the rockered keel one, fradrigo. I have found nothing specific on this particular subject either. I think the right approach is the one you suggest, about using tangents parallel to DWL, interpreting in a wide sense the regulation 3(1) for raked keels:

    "(1) Length. The length (L) shall be taken as 96 per cent of the total length on a waterline at 85 per cent of the least moulded depth measured from the top of the keel, or as the length from the foreside of the stem to the axis of the rudder stock on that waterline, if that be greater. In ships designed with a rake of keel the waterline on which this length is measured shall be parallel to the designed waterline."

    In 1993 (LL55) it was interpreted:
    "For a ship with a rake of keel, least moulded depth, Dmld, is found by drawing a line parallel to the keel line of the vessel (including skeg) tangent to the moulded sheer line of the freeboard deck...... The least moulded depth is the vertical distance measured from the top of the keel to the top of the freeboard deck beam at side at the point of tangency....."


    An useful link (you probably already know it):
    http://www.iacs.org.uk/document/public/Publications/Unified_interpretations/PDF/UI_LL_pdf166.pdf

    Cheers.
     
  5. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 188, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    About the draught marks, I'd say the general rules apply, this is, marks should be located at each 20 cm (vertical projection), lower end of each mark indicating the particular draught. Marks height (vertical projection again) should be 10 cm.

    Cheers.
     
  6. fradrigo
    Joined: Oct 2002
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: CROATIA

    fradrigo Junior Member

    ...appreciate your comment, thanks :)

    I have motor yacht example which combines rockered bottom and appended skeg with even base line ( or even 'keel' line to be in accordance with convention ). You can see really rough sketch attached :) Least moulded depth could then be determined by drawing the tangent to freeboard deck parallel to keel ( skeg ) which in my case happen to be horizontal. I'd take ' moulded ' base line of the skeg as a reference for depth calculation but for draught marks I'd go from the deapest point of the skeg as a base...do you agree ?

    I've found nice set of numerals in Norsk Standard NS6300. It has little more character in the appearance and could be appropriate for yacht draught marks.
     
  7. fradrigo
    Joined: Oct 2002
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: CROATIA

    fradrigo Junior Member

    :confused: .doc is blocked, maybe .pdf will go trough :)
     

    Attached Files:


  8. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 188, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    I'd take the base line as the tangent to the rocked keel line, parallel to the intended DWL, and the least moulded depth as the distance between such base line and the tangent to the freeboard deck at the side, again parallel to DWL.

    Asuming the skeg has no significative volume, hydros should be referrred to the mentioned base line, but marks to the lower points of the keel or skeg at the perpendiculars, or the points where the skeg and keel projections cut them, which pose an interesting question at the forward perpendicular: what is the keel projection to be considered?

    Interesting case.

    Cheers.
     
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.