Simrad EQ60 - Manual (Page 192)

Simrad EQ60
180
857-164342 / Rev.C
Transducer blister
Other transducers are designed for installation into the hull or in
a blister. In general, a blister installation is the recommended
method. It brings the transducer below the boundary layer. A
blister is illustrated below.
Figure 21 Transducer blister
Air outlet
Round off corners
Drainage holes
Stiffening rib
Transducer
Cable service loop
3°
Water flow
(CD1998)
Stuffing tube
Streamlined blister
Mi
n.
400
The best performance is obtained with a blister height of 40 cm
or more. A streamlined shape and rounded edges reduce the
flow noise. A vertical leading edge or front will guide the
aerated water to the sides of the blister. The orientation of the
blister should follow the water flow. On a conventional hull
shape, without a bulb, the front of the blister should have a few
degrees toe-in towards the bow.
→ See figure 22.
The blister is placed on one of the sides of the hull, and the
distance from the keel is a trade off between a close distance
giving a turbulent flow of water in a narrow passage, and a large
distance bringing the transducer higher up and also more
affected by vessel roll. Normally a distance of approximately 1
m is a good compromise.
→ See figure 23.
The interior of the blister must be filled with sea water. Use
drainage holes in the bottom and an air outlet on the top. The
water pressure behind the transducer will then compensate for
the outside pressure during vessel movements in rough sea.