Artikel 81

(a) Length of the spaces below the top of the main space. (1) If, in carrying out the measurement of the propelling-machinery space, it is found that the length of such space exceeds what is necessary for the proper working of the main propelling-machinery and for the auxiliary machinery necessary for the main machinery, such length shall be restricted, subject to the provisions of paragraph (4).
(2) In the case of steamships, the following procedure shall be observed: (i) If the fire-grates are in a fore-and-aft direction, the length equal to that of the fire-grates increased by about 1 foot or 0.305 metres shall be allowed in front of the fire-grates for the stoking or working of the fires, but no additional length is required when the boilers are placed with the fire-grates athwartships.1) The same restriction would apply if the main boilers were situated wholly or partly above the upper deck.
(ii) In the case of ships propelled by reciprocating engines, the point to which the after boundary of the length of the machinery space is to be measured should be no further aft of the after cylinder, its valve-casing or other part of the main propelling-machinery than is necessary for safe working, but in no case without special instructions from the national central tonnage measurement authority should the actual point of measurement be more than 4 feet or 1.219 metres aft of such cylinder, etc., indicated above.
(i) If the fire-grates are in a fore-and-aft direction, the length equal to that of the fire-grates increased by about 1 foot or 0.305 metres shall be allowed in front of the fire-grates for the stoking or working of the fires, but no additional length is required when the boilers are placed with the fire-grates athwartships.1) The same restriction would apply if the main boilers were situated wholly or partly above the upper deck.
(ii) In the case of ships propelled by reciprocating engines, the point to which the after boundary of the length of the machinery space is to be measured should be no further aft of the after cylinder, its valve-casing or other part of the main propelling-machinery than is necessary for safe working, but in no case without special instructions from the national central tonnage measurement authority should the actual point of measurement be more than 4 feet or 1.219 metres aft of such cylinder, etc., indicated above.
(3) In the case of turbine ships, the restrictions laid down in paragraph (2) of section (a) of the present Article shall apply to the measurement of boiler spaces.
(4) The restrictions referred to in paragraphs (1), (2) and (3) of section (a) of the present Article shall only apply in cases where the cubic capacity of the propelling-machinery spaces upon which the propelling-power allowance is based is 20 % or more of the gross tonnage in the case of screw ships, or 30 % or more of the gross tonnage in the case of paddle ships, but whatever be the size of the machinery space these restrictions shall in no case be applied to fishing and hunting ships, tugs as defined in Article 75, ships constructed and intended exclusively for icebreaking, or yachts.
(5) If a departure from either of the above provisions as to length appears to be necessary owing to the high power of the engines or any peculiarity in the arrangement of the machinery, the national central tonnage measurement authority concerned, to which all necessary particulars and plans should be forwarded, will have to decide as to the length to be used for the purpose of calculating the cubic capacity.
(1) If, in carrying out the measurement of the propelling-machinery space, it is found that the length of such space exceeds what is necessary for the proper working of the main propelling-machinery and for the auxiliary machinery necessary for the main machinery, such length shall be restricted, subject to the provisions of paragraph (4).
(2) In the case of steamships, the following procedure shall be observed: (i) If the fire-grates are in a fore-and-aft direction, the length equal to that of the fire-grates increased by about 1 foot or 0.305 metres shall be allowed in front of the fire-grates for the stoking or working of the fires, but no additional length is required when the boilers are placed with the fire-grates athwartships.1) The same restriction would apply if the main boilers were situated wholly or partly above the upper deck.
(ii) In the case of ships propelled by reciprocating engines, the point to which the after boundary of the length of the machinery space is to be measured should be no further aft of the after cylinder, its valve-casing or other part of the main propelling-machinery than is necessary for safe working, but in no case without special instructions from the national central tonnage measurement authority should the actual point of measurement be more than 4 feet or 1.219 metres aft of such cylinder, etc., indicated above.
(i) If the fire-grates are in a fore-and-aft direction, the length equal to that of the fire-grates increased by about 1 foot or 0.305 metres shall be allowed in front of the fire-grates for the stoking or working of the fires, but no additional length is required when the boilers are placed with the fire-grates athwartships.1) The same restriction would apply if the main boilers were situated wholly or partly above the upper deck.
(ii) In the case of ships propelled by reciprocating engines, the point to which the after boundary of the length of the machinery space is to be measured should be no further aft of the after cylinder, its valve-casing or other part of the main propelling-machinery than is necessary for safe working, but in no case without special instructions from the national central tonnage measurement authority should the actual point of measurement be more than 4 feet or 1.219 metres aft of such cylinder, etc., indicated above.
(3) In the case of turbine ships, the restrictions laid down in paragraph (2) of section (a) of the present Article shall apply to the measurement of boiler spaces.
(4) The restrictions referred to in paragraphs (1), (2) and (3) of section (a) of the present Article shall only apply in cases where the cubic capacity of the propelling-machinery spaces upon which the propelling-power allowance is based is 20 % or more of the gross tonnage in the case of screw ships, or 30 % or more of the gross tonnage in the case of paddle ships, but whatever be the size of the machinery space these restrictions shall in no case be applied to fishing and hunting ships, tugs as defined in Article 75, ships constructed and intended exclusively for icebreaking, or yachts.
(5) If a departure from either of the above provisions as to length appears to be necessary owing to the high power of the engines or any peculiarity in the arrangement of the machinery, the national central tonnage measurement authority concerned, to which all necessary particulars and plans should be forwarded, will have to decide as to the length to be used for the purpose of calculating the cubic capacity.
(b) Shaft trunks in screw ships, escape trunks. (1) Thrust-block space. When the thrust-block is not situated within an ordinary thrust-block recess and when, according to the present Article, a limitation has to be applied to the length of the main machinery space, the thrust-block being situated within the main space outside the restricted part, the height of such thrust-block space to be allowed for shall in no case exceed what is considered necessary for the purpose of overhauling (see Figure 111).
(2) When there is no built tunnel: (i) In the case of single-screw ships, the space allowed as a tunnel shall be of ordinary dimensions suitable for the ship; if the after machinery bulkhead is recessed, the height of the space allowed for shall not exceed, above the shaft, what is necessary for working and overhauling (see Figures 111 and 112).
(ii) In the case of ships with two or more screws, the same provisions shall, in general, apply, but when there exists a large space or recess open from side to side immediately aft of the main space, the space included in the propelling-machinery space shall not be larger than would have been necessary in the case of ordinary-sized shaft-tunnels for each shaft line (see Figure 113).
(i) In the case of single-screw ships, the space allowed as a tunnel shall be of ordinary dimensions suitable for the ship; if the after machinery bulkhead is recessed, the height of the space allowed for shall not exceed, above the shaft, what is necessary for working and overhauling (see Figures 111 and 112).
(ii) In the case of ships with two or more screws, the same provisions shall, in general, apply, but when there exists a large space or recess open from side to side immediately aft of the main space, the space included in the propelling-machinery space shall not be larger than would have been necessary in the case of ordinary-sized shaft-tunnels for each shaft line (see Figure 113).
(3) In ships with two or more screws and built shaft-tunnels, the recessed part immediately forward of the stern tubes shall not be larger than is reasonable for the purpose of overhauling of shafting, due account being taken of the general construction of that part of the ship (see Figure 114).
(4) Escape trunks shall be regarded as part of the propelling-machinery space, provided that they are not larger than is necessary for the purpose of access to and escape from the tunnel. All doubtful cases shall be submitted, together with the necessary particulars, to the national central tonnage measurement authority concerned, for their decision.
(1) Thrust-block space. When the thrust-block is not situated within an ordinary thrust-block recess and when, according to the present Article, a limitation has to be applied to the length of the main machinery space, the thrust-block being situated within the main space outside the restricted part, the height of such thrust-block space to be allowed for shall in no case exceed what is considered necessary for the purpose of overhauling (see Figure 111).
(2) When there is no built tunnel: (i) In the case of single-screw ships, the space allowed as a tunnel shall be of ordinary dimensions suitable for the ship; if the after machinery bulkhead is recessed, the height of the space allowed for shall not exceed, above the shaft, what is necessary for working and overhauling (see Figures 111 and 112).
(ii) In the case of ships with two or more screws, the same provisions shall, in general, apply, but when there exists a large space or recess open from side to side immediately aft of the main space, the space included in the propelling-machinery space shall not be larger than would have been necessary in the case of ordinary-sized shaft-tunnels for each shaft line (see Figure 113).
(i) In the case of single-screw ships, the space allowed as a tunnel shall be of ordinary dimensions suitable for the ship; if the after machinery bulkhead is recessed, the height of the space allowed for shall not exceed, above the shaft, what is necessary for working and overhauling (see Figures 111 and 112).
(ii) In the case of ships with two or more screws, the same provisions shall, in general, apply, but when there exists a large space or recess open from side to side immediately aft of the main space, the space included in the propelling-machinery space shall not be larger than would have been necessary in the case of ordinary-sized shaft-tunnels for each shaft line (see Figure 113).
(3) In ships with two or more screws and built shaft-tunnels, the recessed part immediately forward of the stern tubes shall not be larger than is reasonable for the purpose of overhauling of shafting, due account being taken of the general construction of that part of the ship (see Figure 114).
(4) Escape trunks shall be regarded as part of the propelling-machinery space, provided that they are not larger than is necessary for the purpose of access to and escape from the tunnel.
(c) Spaces between the top of the main space and the upper deck. In general, the only restrictions to be applied are those indicated under(a).
(d) Spaces on or above the upper deck. For the purpose of determining whether these spaces are “reasonable in extent”, it should be noted that: (1) In the case of spaces situated outside the boundaries of the propelling-machinery space or the casings above same, and fitted with machinery which in accordance with the provisions of Articles 78 and 79 may be regarded as part of the propelling-machinery, such spaces are not to be larger than is necessary for the proper working of the said machinery.
(2) In the case of spaces serving for the admission of light and air to the propelling-machinery space: (i) Their total length should not exceed the length of the machinery space underneath (see Figure 115), and if any portion is plated over, the length of the plated part should be deducted from the full length in the tier affected (see Figure 116).
(ii) The breadth to be allowed should not exceed half of the extreme tonnage breadth, the restriction as to the breadth shall, however, not apply to the portion of a break or a raised quarter-deck referred to in Article 76 (see Figures 100 and 101).
(i) Their total length should not exceed the length of the machinery space underneath (see Figure 115), and if any portion is plated over, the length of the plated part should be deducted from the full length in the tier affected (see Figure 116).
(ii) The breadth to be allowed should not exceed half of the extreme tonnage breadth, the restriction as to the breadth shall, however, not apply to the portion of a break or a raised quarter-deck referred to in Article 76 (see Figures 100 and 101).
(1) In the case of spaces situated outside the boundaries of the propelling-machinery space or the casings above same, and fitted with machinery which in accordance with the provisions of Articles 78 and 79 may be regarded as part of the propelling-machinery, such spaces are not to be larger than is necessary for the proper working of the said machinery.
(2) In the case of spaces serving for the admission of light and air to the propelling-machinery space: (i) Their total length should not exceed the length of the machinery space underneath (see Figure 115), and if any portion is plated over, the length of the plated part should be deducted from the full length in the tier affected (see Figure 116).
(ii) The breadth to be allowed should not exceed half of the extreme tonnage breadth, the restriction as to the breadth shall, however, not apply to the portion of a break or a raised quarter-deck referred to in Article 76 (see Figures 100 and 101).
(i) Their total length should not exceed the length of the machinery space underneath (see Figure 115), and if any portion is plated over, the length of the plated part should be deducted from the full length in the tier affected (see Figure 116).
(ii) The breadth to be allowed should not exceed half of the extreme tonnage breadth, the restriction as to the breadth shall, however, not apply to the portion of a break or a raised quarter-deck referred to in Article 76 (see Figures 100 and 101).