Section 3 Hull Construction and Equipment

301. Application of Rules for the Classification of Steel Stern frames, rudders, steering gears, masts and equipment

Ships

are to be in accordance with the re-

quirements in the relevant Parts of Rules for the Classification of Steel Ships.

302. Stability

The requirements in these Rules are framed for FRP ships having appropriate stability in all con- ceivable conditions. The Society emphasized that special attentions are to be paid to the stability by the builders in design and construction and by masters while in service.

Rules for the Classification of FRP Ships 2014 3

Ch 1 General Ch 1

303. Passenger Ships 【See Guidance】

Hull construction, equipment, arrangement and scantlings of passenger ships are to be specially con- sidered with respect to the design features in addition to the requirements in these Rules. In this case, attention is to be paid to the compliance with the international conventions and the national regulations of the country in which the ship is registered.

304. Scantlings 【See Guidance】

1. The scantlings required in these Rules are specified for FRP ships moulded with fibreglass re- inforcements composed of chopped mats and roving cloths and moulded with FRP having the strength specified in the following, but excluding gelcoats :

(1) tensile strength

(2) modulus of tensile elasticity

(3) bending strength

(4) modulus of bending elasticity

: 98 NÕmmĪ

: 6.86×103 NÕmmĪ

: 150 NÕmmĪ

: 6.86×103 NÕmmĪ

2. For single skin construction the scantlings specified in these Rules may be modified by multiplying by the factors specified in the following (1) and (2) in case where moulded with an FRP having the strength higher than specified in the preceding 1. :

(1) For the thickness, a factor obtained from the following formula :

ÜÌJL

ᾼ Ņ Ρ̓ÜſſÆ

where,

ſſÆ : Bending strength of the FRP obtained from the material tests specified in Ch 3, 302.

(NÕmmĪ)

(2) For the section modulus (including section modulus of the transverse section of hull), a factor obtained from the following formula :

ĶK

Ě Ņ ÜD

where,

ſſD : Tensile strength of the FRP obtained from the material tests specified in Ch 3, 302.

(NÕmmĪ)

3. In case where the scantlings of laminates of sandwich construction are calculated, the modulus of bending elasticity of the inner or outer layer of FRP of laminates if sandwich construction may be as obtained from the FRP tests specified in Ch 3, 302.

4. In calculating the section modulus of structural members, the actual FRP laminates of 150 mm on either side of the web are to be included.

305. Hat-type Construction 【See Guidance】

1. The minimum thickness of webs and faces of girders, beams, frames, floors for the hollow hat-type or hat-type with cores for moulding are not to be less than obtained from the following formula :

Thickness of web: 0.034 ᾘLÅ (mm ) Thickness of face: 0.05 ᾎÅ (mm )

where,

ᾘL : Depth of web (mm ).

4 Rules for the Classification of FRP Ships 2014

ᾎ : Breadth of face (mm ).

Å : 1.0 However, where the section modules of the members exceeds the specified value, the value as obtained from the following formula may be taken as Å.

Ρ̓

ÜĚĈ

ÅŅ ÜĚA

where,

ĚĈ : Section modules specified for the member.

ĚA : Actual section modulus of the member.

2. The core for moulding may be reckoned in the strength at the discretion of the Society.

3. Other scantlings are to be in accordance with the requirements in the relevant chapters.

306. Sandwich Construction 【See Guidance】

1. The core of sandwich construction composing a panel is to be, as a rule, composed by one layer.

The thickness of core is not to be larger than 25 mm . However, the composition of core different from these is to be at the discretion of the Society.

2. Thickness of inner layers for the sandwich construction is not to be less than 0.8 times of outer layers

3. The cores may be reckoned in the strength at the discretion of the Society.

4. Other scantlings are to be in accordance with the requirements in the relevant Chapters.

307. Weight of Fibreglass Reinforcements and Thickness Laminates 【See Guidance】

1. The thickness of laminates per ply of chopped mats or roving cloths may be as obtained from the following formula :

EÄ

ᾼ Ņ ÜÌLƒ Ä

Ü

Ñ EÄ

ÌLLLƒ

Ň Ü Ä

E

ÌLLLƒ Nmm Ń

Ĉ Ä Ĉ

where,

EÄ : designed weight per unit area of chopped mats or roving cloths (gÕmĪ)

Ä : glass content of laminate (ratio in weight) (%)

ƒĈ : specific gravity of cured resin

Ā : specific gravity of chopped mats or roving cloths

2. The glass content (Ä) specified in the preceding 1. is preferable to be the value per ply for the actual laminates. However, it may be taken as the mean glass content of the whole laminates.

3. The specific gravity of the chopped mats or the roving cloths (Ā) specified in the preceding 1

may by taken as 2.5 in calculation of the thickness, if nothing specially intervenes.

4. The specific gravity of the cured resin (ƒĈ) specified in the preceding 1 may be taken as 1.2 in calculation of the thickness, unless any fillers are used in order to make the resin heavier.

5. Calculation of the thickness of laminates with fibreglass reinforcements other than the chopped mats and the roving cloths are to be in accordance with the discretion of the Society.