Talk:UKCLRN

DavidAcland 21:23, 25 March 2010 (UTC)

Original definition:

1) Under-keel clearance means the minimum clearance available between the deepest point on the vessel and the bottom in still water. It can be defined with fixed and variable values.

Reference:

Extracted from Marine Exchange of Southern California Chapter XIV [Document name not known: ? Vessel Operating Procedures ?]

First sentence replaced with definition from IHO Dictinary. Name ammended in line.

jens 05:07, 28 October 2010 (UTC) We have to extend the list of attributes to UKC based on ship's beam and to amend the current definitions accordingly. (Source: Port of Rotterdam UKC policy.)

jens 10:40, 28 October 2010 (UTC) consider following source
http://www.porttaranaki.co.nz/Port/DUKC_Booklet.pdf

raphael 00:07, 1 November 2010 (UTC): The Port Taranaki information booklet says that they will calculate a maximum draft and sailing window given ship characteristics and natural conditions, so for the model the effect may be that we should attach a "service access procedure" to either REGLTS and its brothers or to APPLIC.

jens 13:52, 1 November 2010 (UTC) Actually I'm a bit concerned about using SVAPRC here. Currently SVAPRC is exclusively used for Marine Service and the definition was carefully written to avoid mixing of service access to marine service and others stated in reg/res/...
I think we can put the information of the passage window into the three brothers which are already associated to APPLIC.

raphael 19:03, 1 November 2010 (UTC): It may be interesting to review how many procedures there are in nautical publications, and consider turning "procedure" into an information object (with an attribute categoryOfProcedure). The idea would be to specify "what the crew must or should do, and how", which question turns up quite often during passage planning.
Some examples of allowed values for the category are: 1: procedure for accessing marine service; 2: procedure for determining under-keel clearance; 3: procedure for requesting permission to transit a restricted area or permission to use a facility.
Just an idea at the moment, what do you think?

jens 06:47, 2 November 2010 (UTC) Interesting approach. Actually we hoped having captured all procedures by SVAPRC and by using reg/res...
To get access to certain facilities (and there can be a lot) mariners have usually to contact a marine service which will manage all necessities.
Defining procedures to calculate UKC looks tempting. Unfortunately the calculation of the UKC is either be done by the ship (according to many different parameters the ships crew has to be taken into account) or by authorities (based on theoretic models and experiences). Whereas the latter can be provided as a simple value in NPUB (I know it is bold calling our complex attribute UKCLRN simple :) )is the first case totally apart from our responsibility. That is simple good seamanship.
If the discussion turns up with a need for such categoryOfProcedure I will be interested to see the different values. I afraid we can't describe all. The value list will be either endless or incomplete.

raphael 04:57, 3 November 2010 (UTC): For Port Taranaki the procedure might be simply something like "Send vessel characteristics beam, draught, and hull profile to the port authority no earlier than 36 hours and no later than 8 hours before your ETA, and you will receive UKC and arrival window". In another port it might be "Obtain up-to-date information about local channel depths and sea state from the port authority and use them in calculating your own UKC using the guidelines provided by your operating company." Is the same as you were thinking? (The system would not be able to calculate UKC automatically, but the crew would be able to see at once the method they must use to calculate it for this port.)

jens 09:24, 3 November 2010 (UTC) Yes, actually we can put that information into reg section. We should think about a similar structure as used for Notice time if we intent to extend the UKCLRN to textual description too.

jens 13:34, 5 November 2010 (UTC) The extension to the definition in brackets bases on suggestion by Canadian Coast Guard. If it is ok for you pls remove the brackets. I feel fine with that.

jens 13:45, 5 November 2010 (UTC)to reflect the need of UCK based on ship's beam I added one line and created a new attribute UKCVBB and amended the acronym for draught based UKC to UKCVDB. If that goes ok I will rename the current UKCVAR. Pls reply here.

DavidAcland 17:03, 5 November 2010 (UTC) I do not think that the insertion of the bit in brackets is correct. It makes the definition ambiguous and I think something must be missing.
I am wondering if OPERAT is now suffficient. Do we now need to specify which of the 3 applies?
Did you think of changing UKCVAR to complex and making both UKCVBB and UKCVDB optional sub-attributes? In that case OPERAT would still work. I have changed the example at UKCVBB to Ben van Shepenzeel's (Rotterdam) example of 1.5% of beam.

raphael 01:45, 8 November 2010 (UTC): On OPERAT: The data capture guide should say that if a sub-attribute is present, it applies.

To handle the (hypothetical?) situation where UKC is a formula (more complex than plain "maximum" or "minimum" we can add an allowed value to OPERAT (3: formula) to indicate that UKC must be calculated by a formula (which might include UKCVDB, UKCVBB, UKCFIX). We could also add a fourth allowed value to OPERAT (4: procedurally determined) to indicate that it must be determined using a procedure to be carried out by the crew (e.g., the Port Taranaki situation). The formula or procedure can go into INFORM, TXTDSC, or another sub-attribute or two, say Formula (type: Text), and Procedure (type: Text).

On whether UKCVAR should be complex or not: Either way works.

jens 09:43, 8 November 2010 (UTC) removed the CCG suggestion, the UKC is not related to a water depth. It is clear that the change of the water depth changes the distance between the sea bottom and the hull and should be taken into consideration. Anyhow, that has nothing to do with the UKC we mean.

jens 10:44, 8 November 2010 (UTC) Raphael, your idea simplifies the model if I understand that correctly. We would have
UKCLRN and the attributes UKCFIX, OPERAT (with the new values) and TXTDSC. I guess we should keep UKCFIX simply because it is quite often used in NP. The UKC based on beam or length would be given as instruction how to calculate and that can be covered under TXTDSC similar to extended procedures. Accepting that I hope to have modeled also the Harbour Masters requests on UKC.

jens 17:43, 8 November 2010 (UTC) special thanks go to David for correcting the English spelling and grammar at the post above :)

DavidAcland 18:24, 8 November 2010 (UTC) Always happy to oblige.
I think we were wrong to think that the UKC that applies in a port is the largest of either a fixed allowance or a variable allowance. I do not think that that comparison is made. I think you apply one rule or the other. Just as we now know that at Rotterdam for tankers they apply a fixed allowance up to 20 m beam and thereafter apply a variable beam based allowance. I have now radically simplified the model along these lines and as discussed with Jens this morning. At the moment in my mind OPERAT is not in play. If we bring it back in based on Raphael's post this morning we probably only need the (3: formula) and (4: procedurally determined) but I am not convinced that that is our business. As I only came across this rarely while editting SDs, I think it may be that it properly lies in the conversation between Masters and Pilots and may not be in NPs at all. So the hunt is now on for real situations where this is covered in NPs and that will be on my list for tomorrow. It would be useful to see the examples you mentioned at 10:44 this morning, Jens.

jens 11:05, 9 November 2010 (UTC)

IJmuiden: DW-Route IJ-Geul: UKC depends on ship's draught, height of the tide, water depth and wave period

Rotterdam:
for vessels up to 17.4 m draught
bound for ... 10% of draught, in the harbour basins ... 0.5 m, alongside 0.3 m
for vessels over 17.4 m draught
inboud at least 1 m
for vessels over 22 m draught
inboud at least 1.5 m
in the harbour basins 1 m
vessels departing at least 10% of ship's draught
vessels departing from Maasgeul and Eurogeul at least 15% of ship's draught

Liepāja: Underkeel clearance at least 15% of ship's draught
Stockholm E: Underkeel clearance at least 0.5 m
Friedrichskoog: Underkeel clearance at least 0.2 m
Elbhafen Bützfleth: according to current water level at least 1 m
Eemshaven: Underkeel clearance at least 10% of ship's draught
Delfzjil, Harbour entry and Zeehavenkanal: Underkeel clearance at least 10% of ship's draught
Scalloway, harbour entry and harbour fairway: Underkeel clearance at least 0.5 m
Symbister: Underkeel clearance at least 0.5 m
Sullom Voe appraoch: Underkeel clearance at least 2 m; along berth 1 to 4 at least 1 m
Plymouth, eastern Channel: Underkeel clearance at least 2 m

That's what a search of some of our SD results. I only have putted some details in line. all other information is been given verbatim (ok, it was translated from GE to EN).

raphael 03:33, 23 November 2010 (UTC): Offline email discussion with Eivind today brought up the point that the Canadian concern, as we understand it, was this: The definition of under-keel clearance should not even appear to hint that vessels could use the physical sea-bottom depth instead of the advertised depth when calculating under-keel clearance. The official depth is the greatest safe depth the official body can support.

We may want to review and tighten the definition in the light of this concern. (I agree that the inserted phrase made the definition ambiguous, but haven't yet been able to think of a suitable replacement.)

jens 06:03, 23 November 2010 (UTC) @Raphael's post 23 Nov: The Canadian concern was well understood. Anyhow, the UKC is simply the minimum difference between the deepest part of the vessel and the highest part of the sea bottom. It makes no difference if the water depth is advertised or real or whatever. Only the difference is important.
SNPWG is only to forward a value specified by the responsible authority to the mariner's attention. It is not our responsibility to specify the value or the calculation method(s).

@ David's post 8 Nov: I remember having read something like that: "... the UKC is 10% of the ship's draught but at least 1.5 m ..." I don't have the example recorded in our publications yet. I believe it was somewhere at the European W coast or Mediterranean. I think OPERAT is ok.

DavidAcland 15:26, 2 December 2010 (UTC) OK. So we have four basic rules:
1) Apply a fixed allowance (0.2m, 1m, 2m etc)
2) Apply a % of draught (10%, 15%)
3) Although not quoted in Jens' examples, apply a percentage of beam (Ben van Scerpenzeel's emails October)
4) Apply a combination (10 % draught but at least 1.5m).

These are applied to 5 circumstances:
6) All situations
7) Inbound only
8) Outbound only
9) At the berth
10) Vesssels using specific channels

At risk of making this further complicated, we now need another attribute to capture 6 to 10 above. And Cases 9 and 10 would need a string sub-attribute as well to capture the name of the berth or Channel. In Jens' examples above this would be "Berths 1-4" for Sullum Voe and "Maasgeul and Eurogeul" for Rotterdam outbound.
We need an attribute to capture the ships' draught bands in which the rules apply:
11) Shallow draught, or perhaps draught band 1, (0-17.4m)
12) Medium draught, or perhaps draught band 2, 17.4 - 22m
13) Deep draught, or perhaps draught band 3, over 22m
And we need an attribute similar to daught band to capture beam bands,
14) Small beam
15) Medium beam
16) Large beam

raphael 03:39, 3 December 2010 (UTC): We can use attributes of APPLIC to describe situation, draft, and beam, defining new attributes for verbal descriptions like "small beam", "medium beam", large beam" if we must.

Alternatively, I am beginning to think we should make under-keel clearance (to be precise, "Requirements for Under-keel Clearance") a new information type and bind attributes for vessel measurements situation, etc., to it.