1. MUZZLE TYPE
It is stated whether the muzzle of the speargun
is open-type, closed-type or variable-type
(i.e. with option for open- or closed-type).
2. BARREL TYPE AND DIMENSIONS
The material (e.g. aluminum, carbon or wood),
cross-section (e.g. circular or shaped) and
dimensions (diameter in mm, length in cm) of
the barrel of the speargun are stated.
3. SPEAR TYPE AND DIMENSIONS
The type, diameter (in mm) and length (in cm)
of the spear of the speargun are stated.
4. RUBBER-BAND TYPE, NUMBER
AND DIMENSIONS
The type, diameter (in mm) and length
(in cm) of the rubber-band(s) of the speargun
are stated.
5. COMPATIBLE HEIGHT OF
SPEAR'S INTERLACED END
The compatibility of a spear with the trigger
mechanism of the handle of a speargun depends
on the height and tolerances of its interlaced end.
Caution is needed because an incompatible spear
can be launched suddenly without pressing the
trigger thus putting human lives in danger.
The appropriate height and tolerances (in mm)
of the interlaced end of a spear, in order for it to
be compatible with the trigger mechanism of the
speargun, are stated.
6. SPEARGUN BUOYANCY
It is stated whether the speargun, without the
spear, has positive or negative buoyancy.
7. TRIGGER SENSITIVITY
Trigger sensitivity is defined as the level of
difficulty with which the trigger of a speargun can
be pressed.
Pressing a sensitive trigger requires a small force
thus contributing to the accuracy of the shot.
Trigger sensitivity is given in the form of a
diagram showing the force necessary to press the
trigger in relation to the total force applied by the
rubber-bands on the spear.
In the example of the adjacent diagram it can be
seen that when rubber-bands of a total force of
800N are used, trigger 1 needs 14N in order to be
pressed while trigger 2 needs only 9N.
Therefore, trigger 2 is more sensitive than trigger 1.
The range of values (ð.÷. ±10%) deriving from
tests on a sufficient number of samples is also
reported (level of confidence: 99%).
8. TRIGGER MECHANISM'S
ENDURANCE LIMIT
The endurance limit of a trigger mechanism
determines the maximum rubber-band force that
can be safely used on the speargun.
If this limit is exceeded then there is danger of
failure of the trigger mechanism or the handle with
unpredictable consequences.
The endurance limit of the trigger mechanism is
given in Newton (N) units.
9. SHOT PRECISION
The precision of a speargun reflects its ability
to send the spear at the same spot in repeated
shots.
According to Demka Standards, the precision of
a speargun is described by the dispersion of
five (5) shots at a target positioned at a given
distance from the tip of the spear.
10. SHOT VELOCITY
The time (from the moment the trigger is pressed)
necessary for the spear to cover various
distances defines a speargun’s shot velocity.
The greater the shot velocity of a speargun is,
the more chances the spear has to reach the fish
before it moves out from its course.
The shot-velocity of a speargun is depicted on the
displacement-time diagram. The “higher” the curve
is, the faster the shot of the speargun.
In the example of the adjacent diagram, the spear
of speargun 1 covers 3 meters in120 millisecond.
In the same period of time, the spear of speargun
2 covers less than 2.5 meters.
Therefore, speargun 1 gives faster shots at this
distance.
The range of values (ð.÷. ±10%) deriving from
tests on a sufficient number of samples is also
reported (level of confidence: 95%).
11. SPEARGUNS' RANGE
The ability of the spear to penetrate targets
located at various distances from it, defines the
range of the speargun.
The range of a speargun is depicted on the
energy-displacement diagram, which shows the
kinetic energy of the spear (in Joule) at each point
on its course.
The greater the kinetic energy of a spear is at a
given distance, the greater the chances to
penetrate a fish located there. In the example of
the adjacent diagram, the energy of the spear of
speargun 1 is 40 J at approximately 3 meters.
The spear of speargun 2 has the same energy at
less than 2 meters. Therefore, speargun 1 can
penetrate the same fish at a greater distance than
speargun 2. In other words, it has a greater range.
The range of values (ð.÷. ±10%) deriving from
tests on a sufficient number of samples is also
reported (level of confidence: 95%).
