Safety standards for inflatable boats
including RHIBs.
The
U S Coast Guard defines an inflatable as any boat that depends
primarily on inflation for it's buoyancy. There are basically two
types of inflatables, those that have only fabric or rubberized
material divided into compartments that can be inflated with air, and
those that have a small rigid hull that is surrounded by inflated
cylinders. The latter are usually referred to as RHIBs, Rigid Hull
inflatable Boats.
ABYC
defines Inflatable Boats as:
"A boat that achieves all or part of its intended
structure shape and buoyancy through the medium of inflation."
and a RHIB as:
"Rigid Inflatable Boat  RIB. also know as a Rigid Hull
Inflatable Boat, (RHIB): An inflatable boat with a portion of its hull
constructed as a rigid unit and another portion that achieves all or part
of its intended structure shape and buoyancy through the medium of
inflation."
The U. S. Coast Guard does not directly regulate
construction of recreational inflatable boats. They are required to have a
Hull
Identification Number (HIN). Other than that there are no US Coast
Guard standards for Horsepower, Capacity, or Flotation. There are
standards for all of these published by the
American Boat and Yacht
Council (ABYC), the
International Standards Organization (ISO) and
Canada (see below). All inflatable boat manufacturers follow one of
these standards and they are all nearly identical. The
ABYC Standard is H28
However, should the boat have an inboard gasoline
engine, then the boats must comply with the U S Coast Guard
fuel
systems,
electrical systems and
ventilation systems
standards. The engine may have to have a flame arrestor.
Several manufacturers of inflatables have boats with inboard gas engines,
similar to those used in Personal Watercraft (PWC). Use of PWC
engines may require a
Grant Of Exemption from the US Coast Guard. Also some manufacturers
have had difficulty complying with the fuel systems standard. there is a
portion which says that fuel cannot be spilled into the boat.
Inflatables that have a permanently installed fuel tank have problems with
this. There have been some unique solutions such as catch basins
that have a drain that goes overboard. If you are installing
an inboard engine in an inflatable boat consult with the US Coast Guard
Office of Boating Safety first to find out what requirements they have for
you.
If you look at an inflatable boat, most will have a
capacity label listing maximum weight capacity, persons capacity and
horsepower if rated for an outboard engine. The below image is a European
capacity label for an inflatable boat. It is in both metric and english
units.
You can put a
capacity label on an inflatable. However, it cannot say
US Coast Guard at the top of
the label. If you are installing navigation lights or an inboard gasoline
engine then it must have a
Certification Label. Otherwise do not put the certification statement
on the capacity label.
The Canadian Rules for Inflatables are in
TP1332 Section 4.6 and are as follows:
4.6 Recommended Maximum Safety Limits for Inflatable and Rigid Hull
Inflatable
Vessels
4.6.1 Calculation Criteria (Intact Condition)
4.6.1.1 The criteria for developing the recommended maximum safe limits to
be marked on a capacity label for an inflatable or rigid hull inflatable
vessel is based on the buoyancy provided by the inflated tubes, and in
addition, where applicable, the volume of the hull below the cockpit sole.
4.6.2 Recommended Maximum Gross Load Calculation
4.6.2.1 The recommended maximum gross load in kilograms marked on a
capacity label for an inflatable or rigid hull inflatable vessel is
determined in relation to the total volume of inflatable tubes (V) and the
weight of the vessel as follows:
GL = (Vt × b × 0.75) − Wv
Where:
GL = recommended maximum gross load in kilograms
Vt = the total volume of the inflated tubes in cubic metres, and where
present, the volume of the rigid or inflated hull below the cockpit sole
b = constant buoyancy factor = 1000 kg/m3
Wv = the weight of the vessel in kilograms, including deck, railings,
console, seats, and any other permanent structures and fittings. For
outboard powered vessels, the outboard engine and related equipment weight
from
Table 42 is excluded. For vessels fitted with permanent fuel tanks
the fuel weight must be included.
4.6.2.2 The following load reduction dependent on design features is
applied to the recommended maximum gross load, calculated in accordance
with 4.6.2.1.
4.6.2.3 The load reduction based on the minimum number of chambers in the
collar is as follows:
(a) 1 air chamber = 50% load reduction;
(b) 2 air chambers = 33% load reduction;
(c) 3 air chambers = 25% load reduction;
(d) 4 air chambers = No load reduction.
4.6.3 Recommended Maximum Number of Persons Calculation
4.6.3.1 The recommended maximum number of persons marked on a capacity
label for an inflatable or rigid hull inflatable vessel is determined in
relation to maximum gross load and engine weight in kilograms as follows:
(a) For inboard or sterndrive powered vessels:
Number of Persons = GL/75
(b) For outboard powered vessels:
Number of Persons = (GLWe)/75
Where:
GL = recommended maximum gross load in kilograms
We = engine and related equipment total weight in kilograms, as determined
from
Table 42
75 = assumed weight of one adult person in kilograms
4.6.3.2 The maximum number of persons shall be rounded off to the nearest
whole number. If the fraction is less than 0.5, round down to the next
whole integer and if the fraction is equal to or greater than 0.5, round
up to the next higher whole integer.
4.6.4 The Recommended Maximum Power Calculation
4.6.4.1 The recommended maximum power for outboard powered inflatable
vessels is determined by:
(a) The formula given in 4.6.4.2 for vessels of all sizes; or
(b) The test given in 4.6.4.3 for vessels fitted with a motor of more than
15 kW.
4.6.4.2 The recommended maximum power for outboard powered inflatable
vessels is determined in relation to total vessel length, its beam, the
total internal volume of the inflatable tubes and a design factor, as
follows:
Maximum Power kW = (Lh × V × fx) = B
Where:
Lh = vessel length of the vessel in metres as per Figure 01
V = total internal volume of the inflatable tubes in cubic metres
B = beam of the vessel in metres
fx = a constant factor determined by transom type as follows:
(i) Factor (f1) for stern tube type = 2.5
(ii) Factor (f2) for stern transom type, vessel length not exceeding 3.0 m
= 6.5
(iii) Factor (f3) for stern transom type, vessel length greater than 3.0 m
but not exceeding 5.0m = 7.5
(iv) Factor (f4) for stern transom type, vessel length greater than 5.0 m
= 9.0
4.6.4.2.1 For vessels of more than 3 metres in length that are fitted with
a remote steering, the factors f3 and f4 may be multiplied by 1.25 when
the steering position is located more than 25% of the length (L/4)forward
of the transom.
4.6.4.3 The maximum recommended power may be determined by the Manoeuvring
Test Procedure specified in the standard ISO 11592 Small craft less than 8
m length of hull – Determination of maximum propulsion power rating or the
Avoidance Line Test specified in section 26.8.3.2 of the ABYC standard
H26 Powering of Boats.
4.6.4.3.1 For vessels not fitted with a remote steering, the maximum
recommended power determined by the test specified in 4.6.4.3 shall not
exceed the value determined by the following formula:
Maximum Power (kW) = 10× Lh × B − 33
Where:
Lh = vessel length of the vessel in metres as per Figure 01
B = beam of the vessel in metres
4.6.4.4 When the calculated power is not more than 10 kW (15 hp) the power
may be rounded up to the next increment of 1.5 kW (2 hp). When the
calculated power is more than 10 kW (15 hp), the power may be rounded up
to the next increment 3.75 kW (5 hp)
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