Talk:UKCVAR

jens 12:09, 6 October 2009 (UTC)

That might fix the problem of UKC stated sometimes. The problem remains is if authorities declare. "... an UKC of 10% of the ship's draught but at least 2.5 metres". That sounds serious to code.

However, ideas please!

raphael 15:19, 7 October 2009 (UTC): In that case ("at least") use both UKCFIX and UKCVAR? That leaves, theoretically, "... an UKC of 10% of the ship's draught or 2.5 metres whichever is less".

If we want a complete solution one way is to make it a complex attribute like this:

Attribute: UKC...
Sub-attributes:
UKCFIX
UKCVAR
OPERAT: 1 (whichever is more) or 2 (whichever is less)

where OPERAT is an operation applied to the other sub-attributes.

Just an idea. (And now that I have put it down, it (OPERAT) could be extended to define expressions to other combinations of attributes in other circumstances...)

jens 05:53, 8 October 2009 (UTC)

Your proposal makes sense. But S100 v 0.0.4 which is the current draft now state on page 17 1-4.3 "In S-100 operations are not used". However, further down operations seems to be possible, or my English goes the German way ;) ... and more down it is prohibited again page 74 3-5.2.9

raphael 23:31, 8 October 2009 (UTC): Function (FUNCTN) is a better word than operation but FUNCTN is an existing attribute in S-57. Anyway, the proposal is consistent with S-100 because it is not an operation in the UML sense. It would not have to be represented by an operation in UML. It is just another attribute of type Enumeration that can take one of a set of values from a CodeList {1, 2}.

jens 13:12, 24 October 2009 (UTC) Thanks for your explanation. I understood your idea now and have developed the complex attribute using OPERAT.

raphael 07:11, 15 January 2010 (UTC): There are different terms in use for this concept: "under keel clearance", "under keel allowance", "under keel clearance allowance", with slightly different definitions:

U.S. Code of Federal Regulations, July 1, 2009 (33CFR 148.5):
Gross under keel clearance means the distance between the keel of a tanker and the ocean bottom when the tanker is moored or anchored in calm water free of wind, current, or tide conditions that would cause the tanker to move.
Net under keel clearance means the distance between the keel of a tanker and the ocean bottom when the tanker is underway, anchored, or moored, and subject to actual wind, waves, current, and tide motion.

Report for the Australian Maritime Safety Authority (www.amsa.gov.au) ("Assistance with the Implementation of an Under Keel Clearance System For Torres Strait") defines UKC as "the distance between the keel of a vessel and the sea floor". The report also says that Gross UKC is the sum of allowances (in the figure currently on the UKCVAR main page).

Regulations for Los Angeles/Long Beach: "Under-keel clearance means the minimum clearance available between the deepest point on the vessel and the bottom in still water."

The IHO Hydrographic Dictionary (IHO S-32, 5th ed., 1994) has the following definitions:
Under keel clearance: "The distance between the lowest point of the ship's hull, normally some point on the keel, and the sea bottom."
Under keel allowance: "The estimated minimum underkeel clearance in a given channel accounting for the ship's squat, movement due to swell, tide height etc.

Given all the above, I suggest using one of the two terms (underkeel clearance/underkeel allowance) from the Hydrographic Dictionary, adapted for the use of percentage of draught. For example:
Name: Under keel clearance, variable:
Definition: "The distance between the lowest point of the ship's hull (normally some point on the keel) and the sea bottom, defined as a percentage of the ships draught."

Remarks: I suggest changing "No remarks" to:
"UKC is calculated from the vessel's draft and various allowances. The figure below shows an example of the calculation of Gross UKC."

Example: Delete the word "metres" (percentages don't have dimensions).

UKC calculations are specific to the vessel. Calculation of UKC is supposed to be done by the master from data provided by the owner/operator. Should the figure on the UKCVAR main be retained? Also, will SNPWG need to obtain reproduction rights for it?