CHAPTER 2. GENERAL ARRANGEMENTS

1. Objective
2. References
3. Summary of general arrangement-oriented topics

The objective of the rules in this chapter is to define the types of general arrangements with respect to:

• Decking and weathertight protection
• Prevention of downflooding

In addition, to make the rules more "user friendly", an overview of general arrangement-related topics is given, for which more detailed requirements can be found later in the rules. This should help designers and others using the rules to identify issues that often have a large impact on the design of the craft

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2. References

Reference is made to the following documents:

• ISO 12217-1:2002 Stability and buoyancy assessment and categorization
• ISO 11812 Watertight and quickdraining cockpits
• ISO 12216 :2002 Windows, portlights, hatches, deadlights and doors

2.1. Types of general arrangements
The rule requirements are in many cases given with regard to the general arrangement of the craft. The decking arrangement with regard to weather tightness and water drainage is frequently referred to. It is assumed that the craft will fit one of the concepts below, which follows the same principles as in the international standard ISO 12217.

2.2. Fully decked craft
A craft in which the horizontal projection of the sheerline area comprises any combination of:

• watertight deck and superstructure; and/or
• quick-draining recesses complying with Chapter 5, and/or;
• watertight recesses complying with Chapter 5 with a combined volume of less than
  L_H × B_H × F_M /40
• all closing appliances complying with Chapter 3

The combined surface comprising the parts listed above is defined as the Weather Deck.

The strength of the parts comprising the decking or covering (the weather deck) shall meet the requirements of Chapter 10, 14 or 18, the quick-draining and watertight recesses shall fulfil the requirements in Chapter 5 and the closing appliances those in Chapter 3.

The plan area of recesses permitted for boats of design category A or B is restricted by the requirements of Chapter 5.

 

Strong and weather tight deck and superstructures Quick-draining recesses Sufficient reserve buoyancy Adequate freeboard at bow Strong and tight windows Door weather tight and fitted with sill Deck arrangement facilitates fast draining of oncoming water

Figure 1. Features of a fully decked craft.

2.3. Partially decked craft
A boat in which at least two-thirds of the horizontal projection of the sheerline area consists of decking, cabins, or other rigid covers that are watertight and designed to shed water overboard, in which area all that is within L_H/3 from the bow and also the area 100 mm inboard from the periphery of the boat (excluding the transom) are included. All openings and their closing appliances shall comply with Chapter 3. In addition, the strength of the parts comprising the decking or covering shall meet the requirements of Chapter 10, 14 or 18, depending on the structural material used. Possible quick draining recesses (quick draining to be specified or chapter referred) shall qualify for the requirements in Chapter 5, their openings and closing appliances shall meet the requirements in Chapter 3.

 In addition, the loaded displacement mass of partially decked craft shall not exceed

(12∙ L_H∙ B_H)^1,5 kg.

At least 2/3 of the horizontal projection of the deck shall be covered. This area includes 1/3 of the length in the bow and 100 mm along all edges. The rest of the boat may be open. Partially decked craft is qualified at most for design category C (shore). Craft doesn’t expose dangerously to over washing waves. In-splashing water is managed with bilge pumps. Hull sides up to the lowest point of downflooding include in the reserve buoyancy. Additional requirements for doors and hatches are required only if they are a part of the 2/3 deck.

Figure 2. Features of a partially decked boat.

2.4. Open craft
Open craft does not comply with either the definition of a fully decked or a partially decked craft. It is assumed that the reserve buoyancy in an open craft consists of the watertight continuous hull sides. If the craft is fitted with a deck and/or recesses that are mainly above the waterline in light craft condition and may retain water, and, therefore, will have an adverse effect on the stability, the craft has to be treated in one of the following ways:

• Freeboard and stability requirements are to be fulfilled when 25% of the volume of the recesses above the waterline is flooded with water; or
• The deck arrangement has to be re-designed to drain water from the recesses above waterline quickly down into the bilges from which the water is pumped overboard.

The loaded displacement mass of an open craft shall not exceed (12∙ L_H∙ B_H)^1,5 kg.(excluding the water in the recesses).

2.5 Open Craft with Flotation Tanks

Open craft can be equipped with flotation tanks. In this case some requirements are lower or are not valid for a craft.

2.6. Closed Craft
In a closed craft the main part of the buoyancy consist of completely watertight compartments. These compartments shall fulfil the requirements for flotation elements and -materials, and they shall be capable of supporting the craft with an additional load of 133% of the maximum load. Other than closed compartments are to be assumed to fill with water. Compartments, which are capable of being shut weathertight, may be assumed to contribute to the intact stability. The width of recesses shall not exceed 70% of the hull beam and the water retention height from the waterline at the stern shall not exceed 30% of the hull beam.

A typical closed craft is a Rigid Inflatable Boat (RIB) in which the watertight compartments usually consist of inflatable fabric thread polymer coated chambers whereas the rigid hull is made of reinforced plastic, aluminium or a similar material. In a RIB at least 80% of the volume consists of overpressurized air chambers. Flotation material and arrangement shall fulfil requirements according to ISO 15372 and rigid hull structure shall meet the requirements in chapters 10, 14 or 18. If the craft is to be of craft type Fast Rescue Boat the additional requirements in Chapter 35 shall also be met

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3. Summary of general arrangement-oriented topics

As many requirements affect the general arrangement of the craft, a summary of general arrangement-oriented topics with references to the appropriate rule chapter is presented below in Table 4.

Table 4. General arrangement-oriented topics with references.
 

Aihe	Luku
Personal safety
- Working deck	27
- Means of protection	27
- Door and companionways	27
- Emergency routes and escape	27
Accomodation
- Toilets	26
- Width of corridors	26, 36
- Seats	36
- Standing height	36
Arrangement of steering position and navigational equipment
- Visibility from helmsman's position	30
- Arrangement of controls	30
- Navigation lights	30
Accessibility and maintenance
- Anchoring, mooring and towing	32
- Fuel system	32
- Cooling system	32
- Seacocks	32
- Bilge system	32
- Steering gear	32
- Hydraulic systems	32
- Electrical system	32
Fire protection
- Boat layout and design, structural fire safety	28
- Engine and fuel spaces	28
- Structural fire safety	28
- Fixed fire-fighting equipment	28
Cargo handling
- Loading and cargo distribution	34

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