R2Sonic 2026 - 3.2 Sonar Head Installation Guidelines; 3.2.1 Introduction; 3.2.2 Over-the-Side mount; 3.2.3 Moon Pool Mount

Page 46 of 254
Version
6.3
Rev
r012
Date
05-11-2022
Part No. 96000001
3.2 Sonar Head Installation Guidelines
3.2.1 Introduction
The proper installation of the Sonic MBES sonar head is critical to the quality of data that will be
realised from the system. No matter the type of installation (hull mount, moon pool, or over-the-
side pole), the head must be in an area of laminar flow over the array. Any vibration or movement
of the sonar head, independent of vessel motion, will reduce swath coverage and noise in the data.
To this end, the head must be installed on as sturdy a mounting arrangement as possible; fore and
aft guys are NOT recommended as a means to obtain this stability.
The initial investigation of where to mount the sonar head should take into account any engines,
pumps, or other mechanical equipment that may not be operating at the time but may cause
vibration or noise when operating under normal survey conditions.
The structural stability of any decks, bulkheads, or superstructure, which will be employed when
mounting the sonar head, must be taken into account and strengthened if necessary.
3.2.2 Over-the-Side mount
The over-the-side mount is typically employed for shallow water survey vessels or temporary survey
requirements. The over-the-side mount consists of a frame structure that is attached to the vessel’s
hull or superstructure. A pole will be attached to the frame, normally through the use of swivel
flanges, flanges, or other means by which the head can be swung up when not in use and deployed
when needed. A similar mounting arrangement is the bow – mount, which is a specialised form of
an over-the-side mount.
To ensure the pole's stability, it should have a securing arrangement as close to the waterline as
possible. As stated above, the use of guy wires is strongly discouraged.
When the pole is in the ‘up’ position, it should be secured so that there is no or little movement that
would strain the flanges or mount. The head should be washed with fresh water as soon as possible
and inspected for any damage or marine growth. If the head is to remain in the ‘up’ position, a
covering should be put over the head to protect it from the sun.
3.2.3 Moon Pool Mount
Deploying the sonar head through a moon pool is usually a more stable mounting arrangement than
an over-the-side pole. A moon pool is an area within a vessel that is open to the water. The sonar
head is usually mounted so that it can be deployed and recovered through the moon pool. The pole
or structure that the sonar head is mounted on is normally shorter and sturdier than an over-the-
side mount; this can allow for higher survey speeds.
3.2.4 Hull Mount
The hull mount is the sturdiest of all possible ways to mount a sonar head. With a hull mount, the
sonar head is physically attached to the vessel’s hull. With this way of securing the sonar head,
there is no possibility of movement outside that of the vessel's movement.