Section 4 Floors

401. Arrangement and Scantlings

1. Where transverse framing is adopted in the bottom construction, floors are to be fitted at every frame and the scantlings of floors are not to be less than obtained from the following formula. In no case, however, is the thickness of floor plates to be less than 4 mm. Depth of floor plates at the centre line of ship:

ĴĪǾJᾎ Nmm Ń

where,

ᾎ : Horizontal distance between the outer surfaces of the side shell laminates measured on the upper surface of the floor (m ).

Thickness of floor plates: 0.4 Ã (mm )

2. Beyond 0.5 Ã amidships, the thickness of floor plates may be gradually reduced toward the ends and it may be 0.9 times the value specified in the preceding 1 at the end parts, However, the floors in the strengthened bottom forward are to be in accordance with the requirements in 702.

3. Floors under main engines and thrust blocks are to be of sufficient depth and to be of specially substantial construction. The thickness is not to be less than that of webs of centre girders obtained from the formula in 201.

402. Section Modulus of Floors

1. The thickness of face plate provided on the upper edges of floors is not to be less than the thick- ness of web of floor at the place.

2. The section modulus of floors is not to be less than obtained from the following formula:

Ě Ņ ÌJǾĨĊÁ ᾎĪ NcmĮŃ

where,

Ċ : Spacing of floors (m ).

ᾎ : As specified in 401.

3. The section modulus of floors under the main engine seatings is not to be less than 1.5 times the value specified in the preceding 2.

403. Floor Plates Forming Part of Bulkheads

Floor plates forming part of bulkheads are to be in accordance with the requirements for watertight bulkheads in Ch 12 and those for deep tanks in Ch 13 in addition to those in this chapter.