(2) When the vessel is a twin screw and the space aft of the engines is open from side to side, the space should not be included in the engine room measurement for a greater height than 6 feet mean, and any space therein appropriated for stores or for any purposes other than the propelling machinery should be subtracted from the space to be included in the engine room. § 2.57 Engine room in small boats.

(a) When not bulkheaded off. In the case of a motorboat not having an engine room bulkheaded off from the rest of the hold, allow as engine space the space occupied by the engine and sufficient space on each side and end of itsay, about 2 feet-to permit the operator to handle it safely and efficiently; if sufficient space does not exist for such allowance then allow whatever space there is. Fuel tanks are not to be included in the said engine space.

(b) When bulkheaded off. If the engine room is bulkheaded off from the rest of the hold and is larger than is strictly required for safe and efficient handling of the engine, limit the engine space according to the said requirements and as indicated in paragraph (a) of this section.

(c) Engine on a bed. If the engine sits on a bed located on the vessel's bottom timbers, take depths when measuring the propelling machinery space from the under side of the deck, or line of same down to the top of the bottom frames or floor timbers as the case may be, or to the ceiling thereon when fitted.

(d) Boxed-in engine. (1) When the portion of the engine extending above a cockpit platform is boxed in such boxedin portion is considered to be all of the space available for the installation and operation of the engine above the line of said platform in that part of the vessel.

(2) In the case of a wholly boxed-in engine in the hold of a motorboat, the tonnage of the boxed-in space, plus the shaft, engine auxiliaries, etc., that may be outside the boxing is considered the propelling machinery space.

(3) The above restrictions may invalidate light and air exemption when the boxing does not extend above the line of the upper deck. However, when such boxing does extend above said deck line, the height of light and air exemption is

from the upper deck line to the under side of the top of the boxing.

§ 2.58 Deduction for propelling power.

In the case of a vessel propelled by steam or other power, a deduction shall be made for the propelling machinery space according to the percentage ratio between the actual tonnage of such space and the vessel's gross tonnage, calculated as follows:

For vessels propelled by screw in whole or in part:

13 percent or less: Deduct 82/13 times the tonnage of the actual propelling machinery space; or, in the case of a vessel the construction of which was commenced on or before June 4, 1956, if the owner so elects, deduct 14 times the tonnage of the actual propelling machinery space.

Above 13 percent, below 20 percent: Deduct 32 percent of the gross tonnage.

20 percent or more: Deduct 32 percent of the gross tonnage or 14 times the tonnage of the actual propelling machinery space, whichever the owner elects.

For vessels propelled by paddle-wheel in whole or in part:

20 percent or less: Deduct 37/20 times the tonnage of the actual propelling machinery space; or, in the case of a vessel the construction of which was commenced on or before June 4, 1956, if the owner so elects, deduct 11⁄2 times the tonnage of the actual propelling machinery space.

Above 20 percent, below 80 percent: Deduct 37 percent of the gross tonnage.

30 percent or more: Deduct 37 percent of the gross tonnage or 11⁄2 times the tonnage of the actual propelling machinery space, whichever the owner elects.

§ 2.59

Light and air spaces.

(a) Application for allowance. On a request in writing by the owner of a vessel to the collector of customs of the district in which the vessel is located, the tonnage of such portion of the space or spaces above the crown of the engine room and above the line of the upper deck as is framed in for the machinery, or for the admission of light and air, and not required to be included in the gross tonnage, shall for the purpose of ascertaining the tonnage of the space occupied by the propelling machinery, be added to the said machinery space; but it shall then be included in the gross tonnage. Such space or spaces must be reasonable in extent, safe, and sea

worthy and cannot be used for any purpose other than the machinery or for the admission of light and air to the propelling machinery space of the vessel.

(b) Reasonable in extent. In construing the words "reasonable in extent" the measurer should note that the length should not exceed the length of the propelling machinery space, and if any portion is plated over, the length of such part must be deducted from the full length and whatever the breadth of the casing may be, the breadth allowed must not exceed one-half the extreme inside midship breadth of the vessel.

(c) Purpose for including light and air spaces. The purpose of adding a part of the framed-in light and air spaces (above the crown of the boiler and engine room and above the upper deck) of a vessel to her machinery space below the upper deck is to entitle the vessel to a greater deduction for propelling power, and consequently obtain a smaller net tonnage than would otherwise result. To get this benefit, it does not always require the addition of the total of such light and air spaces. such cases only such portion need be added as hereinafter explained.

In

(d) Rule for computing addible light and air space. Below is given a simple rule for finding the amount of light and air space or spaces required to be added to the gross tonnage and also to the propelling machinery space of a mechanically propelled vessel to entitle her to 32 percent of her gross tonnage for propelling-power deduction when granted by the collector upon request of her owner or owners:

Find 13.1 percent of the gross tonnage inclusive of excess hatchways. Find the difference between this percent and the tonnage of the propelling machinery space below the upper deck to the hull. Increase this difference by 15 percent of itself, which gives approximately the amount of light and air space or spaces to be added to the gross tonnage defined above, and also to the propelling machinery space below said upper deck. The gross register tonnage in such a case is the gross tonnage as defined above, plus light and air addition, less one-half of 1 percent of said light and air addition, which one-half percent is additional allowance for excess hatchways due to addition of light and air to gross tonnage.

§ 2.60

763. 14 763.14

Verification of calculations, diagram of areas, and certification of results.

(a) Calculations to be verified and diagram of areas made. Calculations must be verified at least twice and a diagram of half breadths for areas made. (See Figures 52 and 53 (§ 2.65).)

(b) Certification of results. The deductions having been made from the gross tonnage and the remainder or net tonnage having been properly marked on the main beam, the surveyor or measuring officer will certify the result to the collector on Form 1322.

§ 2.60a Marking net tonnage and official number on vessel.

(a) The official number of a vessel, preceded by the abbreviation "NO.", and the net tonnage, preceded by the word "NET", shall be marked in a conspicuous place on her main beam at the expense of the owner or master, in Arabic numerals of the block type at least three inches in height, when the size of the main beam will permit. If the main beam is of wood, it shall be carved or branded in figures not less than threeeighths of an inch in depth. If the main

beam is of iron or other metal, the official number and net tonnage shall be outlined by punch marks and painted over with oil paint in a light color on a dark background or a dark color on a light background.

(b) The beam at the forward end of the largest hatch on the weather deck which is generally located forward of amidships shall be considered the main beam for the purposes of these regulations. In the case of a vessel which does not have a hatch on the weather deck, any structural member which is integral to the hull may be considered the main beam.

(c) The official number awarded to a vessel shall pertain only to that vessel. If a vessel, having once received an official number, is rebuilt or redocumented, the number originally awarded shall be retained.

§ 2.61 Appendix to certificate of registry.

(a) When a vessel of the United States carries passengers to a foreign port or ports the collector of customs will issue to each such vessel admeasured in his district a "Special Appendix to Certificate of Registry of American Passenger Vessels" (Form 1265-A), showing the tonnage of passenger spaces on a deck not a deck to the hull and exempted from inclusion in tonnage by the regulations in this part.

(b) The same requirement applies to vessels operating from his district not previously furnished such an appendix.

(c) At the end of each quarter, the collector must report to this Bureau the official number and name of every vessel in his district to which such appendix has been issued during that period. §2.62 Measurement of Government vessels.

When the tonnage of Government colliers, transports, supply ships, repair ships, etc., is requested this tonnage shall be ascertained in accordance with the rules in this part, but the following requirements will be waived: The marking of the vessel's name and home port, official number (none required), and net tonnage; the requirements as to size and conditions of crew space, and the certifications of deducted spaces on the beam over the doorway. The plate over the door designating its use is sufficient for such certifications.

§ 2.63 Foreign vessels.

A mode of measurement for the tonnage of vessels substantially similar to that of the United States having been adopted by Belgium, Cambodia, Central African Republic, Denmark, Federal Republic of Germany, Finland, France, Gabon Republic, Great Britain, Greece, Iceland, Israel, Italy, Japan, Liberia, Malagasy Republic, the Netherlands, Norway, Panama, Polish People's Republic, Portugal, Republic of Senegal, Spain, Sweden, Union of Soviet Socialist Republics, Venezuela, and Yugoslavia, and the like courtesy having been extended to vessels of the United States, it is directed that merchant vessels of these countries, the registers of which indicate their gross and net tonnages under their present laws, shall be taken in ports of the United States to be of the tonnages so expressed in their documents. Vessels of foreign countries other than the aforesaid are to be measured according to the laws of the United States.

(R.S. 4154; 46 U.S.C. 81)

§ 2.64 Adjustment and correction of

tonnage.

(a) If there has been a change of structure or use of space that affects tonnage, or, if the owner or his agent claims that either the admeasurement procedure or the officially assigned tonnages are in error, an application for adjustment of tonnage shall be made as provided in § 2.8. The application shall be accompanied by appropriate drawings as outlined in § 2.9 and by a precise statement of the alterations, changes in use of spaces, or assignments of error.

(b) The collector shall not readmeasure unaltered spaces or spaces for which no error is claimed, but shall use the figures shown on the latest record of tonnage admeasurement (Customs Form 1410 or 1410-A), unless there is an obvious error therein. If the vessel was previously admeasured at a port other than the port at which application for adjustment of tonnage is made, the record of tonnage admeasurement or a copy thereof shall be forwarded to the collector at the latter port upon his request.

(c) The collector shall determine the proper tonnage of the vessel. If the tonnage is found to be different from that shown in the vessel's outstanding document, he shall prepare a new record of admeasurement.