Chapter 3. Prevention of water ingress

1. Objective
2. References
3. Documentation and verification
4. Openings and closing appliances, general
5. Requirements for openings and closing appliances
6. Openings, classification
7. Definitions and requirements common to all types of appliances
8. Requirements for doorways
9. Requirements for hatchways
10. Requirement for Windows and Portlights
11. Requirements for openings that are kept open at sea
12. Hull ports
13. Air pipes
14. Through-hull fittings and associated systems

The objective of the rules in this chapter is to set requirements for safety against water ingress into the interior of the boat as a result unsuitably located and/or designed openings or through-hull fittings. 

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2. References

Reference is made to the following documents:

• ISO 12216 :2002 Windows, portlights, hatches, deadlights and doors
• ISO 12217-1:2002 Stability and buoyancy assessment and categorization
• ISO 11812 Watertight and quickdraining cockpits
• ISO 9093:2002 Seacocks and through-hull fittings
• International Load Line Convention 1966 with amendments

3. Documentation and verification  

To verify that the requirements presented in this chapter are met, the following documentation is required:

• Location of openings (for instance on general arrangement drawing)
• Drawings of purpose-built closing devices
• Manufacturer and type designation of prefabricated closing devices
• Layout of seacocks an through-hull fittings
• Testing protocol of watertight integrity of closing appliances.
• Declaration of conformity of prefabricated closing appliances

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4. Openings and closing appliances, general

4.1. Scope
When applying the rules in this chapter one must bear in mind that the different types of deck arrangements (see Chapter 2) vary with regard to the watertight integrity of the boat. Only the openings penetrating an area which requires watertight integrity, are subject to the requirements.

Note! An opening may be subject to additional requirements based on the freeboard and downflooding angle, as given in Chapter 4, and based on the special mission in Chapters 34-39.

If requirements for stability and freeboard are met assuming a compartment fills with water through a particular opening and progressive flooding from that compartment into other compartments cannot occur, requirements for that opening need not be complied with. This may be the case for example in closed boats (see definition in Chapter 2) where some compartments might not be watertight and therefore may fill with water without causing risk of sinking or capsizing, due to the high requirements on positive flotation

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5. Requirements for openings and closing appliances

5.1. Closing Appliances
An opening may be equipped with a closing appliance, which is a common term for opening covers as windows, doors and hatches.

5.2. Assessment
The requirements for openings and its possible closing appliances are based on:

• The Design Category
• The Classification of an opening and closing appliance
• The Connecting space
• The Size of an opening
• The Position of an opening and/or closing appliance
• The Closing State of a closing appliance

The classification of closing appliances is explained in 6. Definitions common to all types of appliances can be found in 7. The requirements for different types of appliances are given in table 2-5 and in 8-12 detailed requirements for different class closing appliances.

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6. Openings, classification

6.1. Types of openings
Some requirements are based on the type of an opening. According to their function, openings are classified as:

• Doorways. A more or less vertical opening fitted with a closing appliance (door) that enables people to move approximately upright between the spaces connected by the door.
• Hatchways. An opening fitted with a closing appliance (hatch) that provides access between the spaces connected by the hatchway. (A vertically fitted hatch is regarded as a door if it is big enough for a person to step through approximately upright).
• Windows and portlights. A window is a glazed appliance, the function of which is to lead light into the compartment to which it is fitted. A portlight is a small window, the area of which is at most 0,16 m². Windows and portlights may be opened under certain circumstances. Depending on its function, it is also possible that an opened window is a hatch
• Hull ports below freeboard deck. Opening with a closing appliance in the hull topside of an open or partially decked craft
• Openings, that cannot be shut weathertight. These openings have no closing appliances and/or cannot be shut weather or watertight without impeding the normal operation of the boat (for example, the engine air inlets and most ventilation openings).
• Small ventilation openings fitted with non-return valves that prevent water ingress in case of submersion. Air pipes from tanks or battery spaces are examples of such openings.
• Through-hull fittings. Openings penetrating the hull shell connected to systems inside the boat. A through-hull fitting may or may not be fitted with a closing appliance (seacock).

6.3. Opening Application Area
The following Application Areas are defined, see also Figure 1:

• Area A: Hull topsides below the weather deck on decked craft and up to level of the downflooding height requirement for open and partially decked craft
• Area B: Weather deck, including superstructures and deckhouses, up to the "second deck line", except forward facing surfaces belonging to Position C
• Area C: Approximately vertical surfaces on superstructures and deckhouses facing forward.
• Area D: Surfaces on superstructures and deckhouses above the "second deck line", except forward facing surfaces belonging to Position C

Figure 1. Opening Application Areas.

6.4. Closing state
According to their closing state when under way, openings can be classified as:

1. Always open. Openings without closing appliances, open at all times. Example: engine air inlets.

2. Occasionally open when at sea. Openings vital for the normal operation of the boat, which must be used at sea but which can be rapidly closed weathertight. Example: Wheelhouse doors

3. Always closed when at sea. Openings that are closed at all times when at sea. Example: Engine service hatches

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7. Definitions and requirements common to all types of appliances

7.1. Coaming or sill height.

7.1.1. The coaming height for a horizontal appliance or the sill height for a vertical appliance is the least vertical distance from the upper edge of the coaming or sill to the deck surface at or near the same location. In cases of ambiguity, the principle for sill height in ISO 11812 shall apply.

7.1.2. The coaming and sill height requirements given for application area B in Table 2 - Table 5 are valid for appliances located where the height of the deck adjacent to the appliance above the waterline in loaded displacement condition equals a minimum value, h_{LOCAL_MIN}. This minimum height shall be taken as:

h_{LOCAL_MIN} = k_DC × k_L × 0,7 × /(1000 × L_WL × B_WL)

Where k_DC = 1,0 for design category A

0,9 for design category B

0,75 for design category C

0,5 for design category D

 

The factor k_L is to be taken as 1.0 for locations from the stern to a longitudinal location 2/3 × LH from the stern. At the stem k_L shall be taken as 1.2; values between 2/3 × LH and the stem shall be obtained by linear interpolation

7.1.3. If the height of the deck above the waterline adjacent to the appliance is greater than h_{LOCAL_MIN}, but less than h_{SECOND_DECKLINE}, the required coaming or sill height requirement is reduced:

h_S = h_SB -  (h_SB-h_SD) × d_h/ h

whichever is greatest

Where:

h_S corrected sill or coaming height to be applied, mm

h_SB sill or coaming height according to Table 2 - Table 5 for application area B, mm

h_SD sill or coaming height according to Table 2 - Table 5 for application area D, mm.

d_h excess local deck height (exceeding hLOCAL_MIN), see Figure 2.

h excess local deck height according to table 1 above which the minimum sill and coaming heights requirement applies as in application area D. This height is also known as second deck line, see Figure 1 and 2.

Table 1. Excess local deck height, h, mm, above which the minimum sill and coaming heights requirement for application area D applies. Linear interpolation is to be used between L_H = 15 - 24 m

NOTE! No reduction is allowed in the forward quarter of the craft!

Kuva 2. Principle of sill and coaming height reduction.

7.2. Size limit
The area of an appliance is defined as the area in m² of the projection of the opening in the plane of the surface to which it is attached. Width of the shorter edge of an opening (b) is usually obvious but in a case of ambiguity an appliance is defined in ISO 12216.

7.3. Distance from deck edge
The distance from the deck edge is measured as the least horizontal distance from the opening to the local deck edge (without fenders or similar).

7.4. Degree of watertight integrity

The two degrees of watertight integrity referred to in the rules are:

Degree 1 = watertight

degree of tightness providing protection against the effects of continuous immersion in water

Degree 2 = weathertight

degree of tightness providing protection against the effects of temporary immersion in water. If in doubt, the watertight integrity test for "Degree 2" appliances in ISO 12216 shall be followed.

7.5. Locking devices
Locking devices shall be of substantial strength and designed to achieve the required degree of watertight integrity

7.6. Hinged appliances
Appliances that are allowed to be opened at sea shall remain attached to the surrounding structure when opened. If opened, closing appliances in Position A shall have hinges and shall open inwards. Hinges shall be of sufficient strength. If questionable, the hinges shall be assessed according to ISO 12216

7.7. Sliding appliances
In areas other than Area A, appliances may alternatively be arranged as a sliding appliance provided that all relevant requirements in Table 2 and Table 3 are met.

The depth of the rabbet shall be sufficient to prevent disengagement of the plate under the pressure loads, taking into account the size of the appliance, the material of which it is made and the rigidity of the structure it is fixed on. In general, this depth shall be at least 12 mm. For the purpose of locking the appliance, the part of the appliance inside the rabbet may be considered a locking device

The appliance shall be fitted with stops at each end of its stroke to prevent disengagement of the sliding part from the frame

7.8. CE-marked closing appliances
All closing appliances, including those that are made by the boat manufacturer or on his behalf, shall comply with ISO 12216 and these rules where they supersede the standard. Prefabricated commercially available closing appliances may be used without additional requirements in areas permitted according to Table 2 and Table 3 provided they are CE-marked according to ISO 12216 for the design category and application area in question.

7.9. Special requirements for closing appliances in area A

The lower edge of any opening appliance in position A shall be placed at a minimum distance above the waterline in loaded displacement condition depending on the design category, see Table 2.

The smaller unsupported dimension of any appliance in Position A shall not exceed 300 mm.

All opening appliances in Position A shall open inwards.

No part of the plate or its framing shall extend outside the local vertical tangent to the hull, deck, rubbing strake, fixed fender, or of a built-in fairing that is an integral part of the hull.

If an appliance in Position A meets the requirements in Coaming or sill height 7.1.3, no further requirements are applied.

7.10. Protection of gaskets.
Where required (see tables 2-4), gaskets on appliances made of rubber or similar soft material shall be suitably protected against wear as shown in Figure 1

Figure 3. Protection of gaskets

7.11. Closing appliances on cargo decks
Closing appliances on decks designated for cargo must not be glazed. Protruding parts, like locking devices, shall be of substantial strength or protected to be able to withstand accidental impact from cargo handling.

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8. Requirements for doorways

A summary of the requirements for doorways is given in table 2.

8.1. Special requirements for doors
Half of the sill height given in Table 2 may consist of a semi-fixed part. This part shall be attached to or adjacent to the door and be readily available

When fitted with hinges, doors located on the side of a superstructure or deckhouse shall have the hinges on the forward edge of the door for craft in design category A and B. Hinged doors shall open outwards. Regardless of the maximum distance between locking devices given in Table 2, all doors shall be fitted with at least two closing devices in addition to the hinges. Doors shall be capable of being opened from both sides.

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9. Requirements for hatchways

A summary of the requirements for hatchways is given in table 2 and table 3.

9.1. Special requirements for hatches

9.1.1. Hatches that may be opened at sea shall be capable of being secured when open

9.1.2. Glazed hatches are not allowed in engine spaces. However, lighting shall be provided in the engine room, see chapter 21.

9.1.3. Hatches located below the loaded waterline are allowed only if all of the following requirements are fulfilled:

• all the relevant freeboard and stability requirements are met with assumption that the compartment is flooded through this open closing appliance
• no progressive flooding to other compartments can occur
• Such hatches shall be of at least the same strength as the surrounding hull shell
• The structure of the flooded spaces shall be designed to withstand the sea pressure that occurs in the position in question

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10. Requirement for Windows and Portlights

A summary of the requirements for windows and portlights is given in Tables 5a-d.

10.1. Special requirements for windows and portlights

10.1.1. Wheelhouse windows shall be non-coloured, see also chapter 30.

10.1.2. Windows are not allowed in engine spaces. However, lighting shall be provided in the engine room, see chapter 21.

10.1.3. The thickness of windows shall be taken according to table 5a-5d for rectangular windows of toughened glass. For other windows the standard ISO 12216 shall apply, with the exception that the design pressures shall be taken as follows

- Area A: 70 kPa

- Area B and C: 28 kPa

- Area D: 12 kPa

10.1.4. The required thickness of laminated glass shall be determined as follows:

- for 2 glass plies, the total thickness of the glass plies t1 and t2 shall be:

t₁ + t₂ ≥  1,2 t_req 

- for more than 2 glass plies, the total thickness of the glass plies t1, t2,...tn shall be:

t₁ + t₂ + t₃ + t_n  ≥  1,5 t_req

Where t_req is the thickness requirement for a solid window according to Table 5. In case of other window material the total thickness of window shall be compared to thickness requirements in 10.1.3

10.1.5. Windows shall be securely fastened, taking into account the risk of being pressed in. Usually metal frames are required. ISO 12216 shall apply for windows fastened with glue or other means.

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11. Requirements for openings that are kept open at sea

A summary of the requirements for openings that that are kept open at sea is presented in Table 4.

11.1. Allowed positions for openings that are kept open at sea
In general, the number of openings that are kept open at sea shall be kept to a minimum. On boats in design categories A and B, such openings must not be fitted below the freeboard deck (in position A). In category A, no vital openings for operation of the craft shall be located forward of a position 25% of the waterline length abaft the fore perpendicular. This requirement does not apply to air pipes complying with air pipes described in 13.

11.2. Prevention of water ingress
The design of openings that are kept open at sea and are in exposed positions (positions B and C) shall be such that water ingress is reasonably prevented. This is considered fulfilled if the opening is fitted with a labyrinth according to Figure 4 or a similar arrangement.

Ventilation openings are preferably to be facing aft or athwartships.

Openings on craft of design categories A and B that are necessary for the operation of the vessel at sea are to be arranged with a coaming above the level of the deck on which they are located. The height of this coaming is to be as given in Table 4. On craft of design categories C and D it may be acceptable to have engine air intakes in the topsides of the hull as long as the openings are fitted with a water trap system..

Figure 4. Principle of labyrinth for openings.

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12. Hull ports

Ports in the hull shell are normally only allowed on open and partially decked crafts. If fitted on decked crafts, they shall comply with the requirements for underwater hatches according to 7.1.3

12.1. Freeboard to lower edge of hull ports
The freeboard to the lower edge of hull ports shall be at least 200 mm

12.2. Strength
The strength of the hull port shall be at least the same as the surrounding hull shell. When the sea load is carried partly or entirely by the hinges and locking devices, they shall be designed accordingly

12.3. Watertight integrity
The hull port shall be at least of watertight integrity degree 2. Gaskets shall be suitably protected according to Figure 3.

12.4 Hinges and locking devices
The hinges shall normally be no more than 300 mm apart. The locking device shall be able to lock the port firmly to achieve the required tightness. There shall be two separate locking arrangements, one of which is independent of hydraulic pressure and/or electricity supply

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13. Air pipes

Air pipes leading into the weathertight hull shall have a height as given in Table 6. The pipes shall be of strong construction, protected from damage and preferably braced at their upper ends.

Table 6. Requirements for air pipes

¹⁾ Minimum height between L_H 15 m -  24 m is obtained by linear interpolation

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14. Through-hull fittings and associated systems

14.1 Hull penetrations located below a level 100 mm above the waterline in fully loaded condition shall always be fitted with sea cocks at the hull penetration

14.2 Hull penetrations located between 100 mm above Lwl and up to 350 mm above the waterline in fully loaded condition shall be fitted with seacocks if the associated inboard system is completely located below a level 350 mm above the waterline at fully loaded condition and the system has an open end inboards. If the system is closed, a seacock is not required. A non-return valve is regarded as "closed" in this respect. Sea cocks are not required if the system is partially installed above the 350 mm-level ("gooseneck).

14.3 Hull penetrations located above a level 350 mm above the waterline in fully loaded condition are not required to be fitted with sea cocks. The requirements for through-hull fittings with associated inboard systems are shown in  figure 5.

Figure 5. Requirements for through-hull fittings with associated inboard systems.

14.4. Requirements for through-hull fittings with associated inboard systems
The through-hull fittings and seacocks shall meet the requirements of ISO 9093 or equivalent standard for marine use. In FRP hulls, fittings made of bronze or AISI 316 are allowed in all positions. Brass fittings are acceptable if the alloy contains at least 80% of copper. Plastic through-hull fittings and sea cocks according to ISO 9093-2 may be used outside the engine compartment in crafts L_H up to 15m. In aluminium or steel hulls, fittings made of copper alloys are not allowed.

14.5. Accessibility of seacocks
All seacocks shall be easily accessible. Seacocks in craft of design categorie A and B shall be accessible without impairing the weathertightness.

14.6. Inboard systems connected to through-hull fittings
Hoses connected to through-hull fittings shall be of the reinforced type and shall be capable of withstanding the pressure occurring in the system in question. Additional requirements for hoses used in bilge-pumping lines are given in Chapter 6

14.7 Combinations of materials shall be such as to avoid galvanic corrosion.

14.8. Hose connections
Hose connections for through-hull fittings and seacocks shall have double AISI 316 hose clamps where the outer diameter of the stud exceeds 25 mm. Note! additional requirements regarding hoses are given in Chapter 5.

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