Thi" paper not to be cited without prior rererence to the author. Tonnage Certificate Data aß Fishing Power Parameters

Transcription

1 , Thi" paper not to be cited without prior rererence to the author International Council for the Exploration of the Sea (Trr Jr:> Special Meeting on "I1easurement of Fishing Effort" Ref.: Gear and Behaviour Committee No. 16 Tonnage Certificate Data aß Fishing Power Parameters by F. de Beer, Naval Architect, Technical Fisheries Research Department, IJmuiden, the Netherlands..,'

2 - 2 - Introduction The international exchange of information about fishing vessels and the increasing scientific approach of fisheries in general, requires the use of a number of parameters. Especially in the field of main dimensions, coefficients, propulsion data (horse power, propeller, etc.) and other particulars of fishing vessels, there is a great variety. This variety is very often caused by different historical developments in different countries. The tonnage certificate is often used as an easy and official source for parameters. However, though this certificate is an official one and is based on International Conventions the value of its data for scientific purposes is questionable. June International regulations for tonnage measurement of Brief historical review Geneva, ships were issued through the league of nations to obtain a kind of uniform "parameter" (gross tonnage and net tonnage) to use for harbour dues, dock dues, lock dues, canal dues, etc. Oslo, June 1947 Oslo, Nay A convention was convocated due to differences in the regulations for tonnage measurement of ships and in the application of such regulations; called the "Convention for a Uniform System of Tonnage Jlfeasurement of Ships". (1) - Arevision of the regulations of the convention (1). The tonnage mark has been introduced. London, June An entirely new system of measuring the grass and net tonnage was set up; called the "International Convention on Tonnage Neasurement of Ships, 1969". NOT YET IN FORCE. (2) The regulations still in force (Convention 1947/1965) Tonnage certificate: a certificate, called "International Tonnage Certificate" in accordance with the Convention concluded in Oslo, June 1947, issued to every ship which has been measured and marked in accordance with this convention

3 - 3 - Tonnage: the tonnage of avessei eonsists of gross tonnage and net tonnage. In this paper only the grobe tonnage iß discussed as the net tonnage is not often used as a parameter. The grass tonnage of a veseel, expressed in eubie meters and register tons (of 2.83 m 3 ), is determined as the SUffi spaees: spaee below tonnage deek tweendeek spaee enelosed foreeastle bridge spaees break(s) poop trunks round houses exeess of hatehways of all the enelosed spaees above the upperdeek ineluded as part of the propelling maehinery spaee. However, not ineluded in the gross tonnage are: double bot tom spaees parts of tanks spaee of engine room base easings ceiling in holds eonerete floors in fish holds spaee of fish proeessing maehinery above tonnage deek ete. Moreover, all the included spaees are measured from top of frames, beams, floors, ete. (see fig. 1). This review shows that the grass tonnage must be regarded as a kind of "administrative parameter". Great differenees ean oeeur in the gross tonnage between to similar vessels regarding dimensions, displaeement, ete., caused for instanee by: the plaee of watertight bulkheads in superstructures differenees in type of eonstruetion applieation of exeluded spaees type of tonnage certifieate

4 - 4 - Botwcen sinilar fishing vessels, measured in accordance with the regulations of the convention of 1947 but before the revision of 1965, differences can occur of 10% to 15». The upperdeck (weatherdeck) of fishing vessels with more than one deck was generally regarded as the tonnage deck. The convention of 1965 (came in force in the Netherlands in April 1967) introduced thc tonnage mark. This resulted in three types of tonnage certificates, viz.: 1 2. type I type Ia type Ib a tonnage certificate for vessels with one deck (upperdeck = tonnage deck); no tonnage mark required. a tonnage certificate for vessels with more than one deck and having two grass tonnages... upperdeck tonnage deck (closed shelter deck ship) second deck tonnage deck (open shelter deck ship) A tonnage mark is required. a tonnage certificate for vessels with more than one deck. For this type the second deck is the tonnage deck (open shelter deck ship). A tonnage mark is required. The above mentioned system of gross tonnage measurements ean create.. great differences between similar fishing vessels. Example: construction plan, etc.): Main particulars~ length overall length p.p. moulded breadth depth upperdeck depth second deck mean draught two Dutch trawlers built to the same design (body plan, meters " 8.50 " 6.45!I 4.20 II " - 5 -

5 - 5 - Tonnage certificate: vessel type of vessel year of built identification length type of certificate tonnage deck gross tonnage SCH 171 sterntrawlor m I upperdeck'?05.81 register tons SCH 6 sterntrawler m Ib second deck register tons Identification dimensions The main dimensions of avessei given in the tonnage certificate, called "Identification dimensions", are only set up for the determination of the tonnage. - overall length the distance between the extreme end of the stem and stern. - length - breadth - depth from the fore side of the uppermost end of the stern to the aft side of the upper end of the sternpost or, if there is no sternpost, to the point of intersection of the fore side of the rudderstock and the upperdeck. extreme outside (rubbing pieces not included). the depth is measured in the middle plane at half length, from tho underside of the upperdeck to the upperside of the double bottom platine or top of floors. The new regulations, Convention London, (not yet in force) Recognizing that the establishment of a universal system of tonnage measurement for ships should constitute an important contribution to maritime transport, a conference was held (London, May/June 1969), upon the invitation of IHCO, for the purpose of dra\ling up new international convention on tonnage measurement of ships. It was decided that the convention should come in force 24 months after the date on which not less than 25 governments or states, with a combined merchant fleet which constitute not less than 65% of the gros~ tonnage of the worlds shipping, have signed without reservation

6 - 6 - The new convention shall apply to new vessels* and to existing vessels' JE twelve years after the date on which the convention will come into force. Gross Tonnage: Con~ention, 1969 The grass tonnage of a vessel shall be determined by the following formula: The factor the "present" GT GT v,here GT K 1 V K 1 V gross tonnage (dimensionless) LOG 10 V = total volume (moulded) of all enclosed spaces of the vessel in cubic meters. For erections there are a number corrections (see fig. 2). K has been added to prevent great differences between 1 4t and "new" GT. Example: side trawler length p.p m gross t~e: breadth depth 6.40 m 3.10 m register tons gross tonna~ (ne'l-l): total volume of all enclosed spaces V 329 m 3 K GT K 1. V = ~ Dimensions The dimensions given in the new tonnage certificate, called main dimensions, are defined according to the Load Line Convention 1966 (3) - length the length shall be taken as 96% of the total length on a waterline at 85% of the least moulded depth measured from the top of the keel, or the length from the fore side of the stem to the axis of the rudderstock 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. *vessels with a length not less than 24 meters (79 feet) - 7 -

7 breadth - depth the breadth is the maximum broeadth of the ship, measured amidships to the moulded line of the frame in a ship with a metaloheil and to the outer surface of the hull in a ship with shell of any other material. the moulded depth is the vertical distance measured from the top of the keel to the underside of the upperdeck at side. (For v/ood and composite ships, ships having rounded gunwales and ships with stepped upperdeck, see regulations.) Conclusion 1. There is very little correlation between the gross tonnage (convention 1947/1965) of a fishing vessel as a parameter and other vessel parameters like length, h.p., holdcapacity, ete. (See table appendix I.) 2. Due to the introduction of the tonnage mark (1965), eomparison of gross tonnage of fishing vessels, espeeially sterntrawlers, will not be possible without taking into eonsidcration the type of measurement. (See table appendix 01.) 3. The convention 1947/1965 creates the possibility that the gross tonnage of fishing vessels with more than one deck ean be altered at any time, due to the three possibilities of measurement. (See table appendix I.) 4. The gross tonnage of a fishing vessel measured accorjing to the convention 1969 will deviate from the gross tonnage of the same fishing vessel measured according to the present convention. 5. If the convention 1969 will come into force, two types of grass tonnage measurement v/ill exist together for about twelve years after the date of its enforcement. 6. The gross tonnage of a fishing vessel according to the convention 1969 could be a reasonable Ilvo lume parameterli, if the volume of superstruetures (with the necessary corrections) should not be included. 7. The dimensions (calied: identification dimensions) given in the present tonnage certificates, are administrative dimensions, but are questionable as ship' s parameters with the exception of the Illength overall". Especially the "depth", depending on the height of the double bottom or floor, deck beams and camber, can create a lot of misunderstandings ('

8 The use of the "main dimensions" (to be given in the future tonnage certificates) as a ship's parameters is sensible. However, as these dimensions are defined according to those given in the Load Line Convention 1966, their definitions do not tako into account the special features of fishing vessels. The best solution will be to uso the definitions as tentatively agreed by IMCO (4). (See also appendix 11.) References (1) Convention for a Uniform System of Tonnage Measurement of Ships, Oslo 1947 (1965). (2) International Convention on Tonnage Measurement of Ships, London (3) Load Line Convention, (4) Unified Definition of Main Particulars and Other Properties of Fishing Vessels, PFV X/iv.P. 8, July 1970 (Sub-Committee on Safety of Fishing Vessels).

9 FIG.1 CONVENTION 1947 (1965),t ' i. FIG.2 CONVENTION /0 0 Benamlng TONNAGE MEASURE MENT ACCORDING to CONVENTIONS t--..., (1965) AND Formaat flsherles dl rectorate Schul Gecontroleerd A 4 technlcal research dept.t----~ _---l----_i Auteursrecht yoorbehouclen yolgens c1e wet Getekend i= Gezien Rangschikmerk

10 TAB L E Sterntrawlers.; APPENDIX I TOtlNAGE CER { I F I CATE' 0 ATA BOOYPLAN oata Gross tonnage Registration no. Year of buht h.p /19G5 Length o.a. L s B s Os l~p L ewl B type I type Ib m m m m m m m m.. UK 66 19G GO KW /4.25 SOl KW * KW * a --- lt KW n -- ft N KW ft 3.79 I I --- KW _ IJM ft ft UK UK I n , --- e KW i4.34 N SOl 24/SCH /4.34 SCH /4.24 SCH /4.24 GO SCH UK UK UK n } series series } series Iseries series l I Nremeasured: vessels with a nell tonnage eertifieate.

11 Appendix II Summary of the tentatively agreed unified definitions for dimensions and coefficients of fishing vessels. Standard waterline Standard waterline - The waterline which is parallel to the maximum load'displacement design waterline of avessei, but located at a draught of O~85 Iftaken at the midship section. It is recommendedthat the waterplane defined by this waterline be the horizontal co-ordinate fer the framework used in integrating hull areas and volumes. On vessels where the design waterline is not known, it is recommended that the co-ordinate system for'developing the vessels lines and integrating hull volumes and areas be established with the vertical co-ordinate parallel to the vertical plane ef the bulkheads and frames. Perpendiculars The forward end after perpendiculars shall be taken at the forward and after ends of the standard waterline (L), drawn perpendicularly to the standard waterline. Length Length overall (LOA) - The distance between lines at the extreme end of the bow and stern, perpendicular to the standard waterline. Standard waterline length (L) - The length on the standard Haterline as defined above measured from the inside of the stern shell plating to the inside of the stern plating cf a vessel with a metal shell or fr~m the rabbet aft line of the stern to the rabbet front lines of the stem of a vessel with a shell of any ether material. Breadth Breadth (B) - The maximum breadth of avessei on the standard waterline measured to the moulded line of the frame of a vessel with a metal shell or the outer surface of the hull of a vesael with a shell of any other material. Depth -

12 - 2 - Depth Depth CD) - The distance from the underside of the freeboard deck at the side to the top of the keel of a to the rabbet lower line of the keel of vessel with a avessei with metal shell, or a shell of any other material plus the minimum thickness of decking. The'distance is to be measured perpendicularly to the standard waterline. The term "D" gives the depth at any section. When used in tabular form the term "D" must be followed by a defining term, or sub-index, such as: D min - Depth minimum D - Depth amidships m D f - Depth at forward perpendicular Da - Depth at after perpendicular.