High Resolution Echo Sounders
and Acoustic Systems for Precision Seafloor  Exploration
office (401) 921-5170
fax (401) 921-5159

In-Hull Mount Installation Instructions
Survey Echosounder Transducers

IMPORTANT: Please read the instructions completely before proceeding with the installation.
NOTE: Use these only as a guide. It is the responsibility of the end user to select the correct installation type for your vessel and transducer type.

Certain cleaners, gasoline, paint, sealants and other products may contain strong solvents, such as acetone, which can attack many plastics dramatically reducing their strength. Clean surface of transducer with a mild detergent only.

    Mounting location | Installation  |  Antifouling Paint | Maintenance and Repair
Mounting location    <back>

The transducer must be fully immersed in water and not subjected to air bubbles flowing across the radiating face.

Acoustic Noise

Acoustic noise is always present and these sound waves can interfere with the operation of the transducer. While background noise cannot be controlled, carefully selecting the transducer mounting location can minimize the effect of vessel generated noise. The lower the noise level, the higher the echo-sounder gain setting that can be used.

· Background noise sources:

  • Waves and air bubbles
  • Fish and mammals
  • Rain and hail
  • Other vessels and shore

· Vessel generated noise sources;

  • Propeller(s)
  • Propeller shaft vibration
  • Aerated and turbulent water flowing across the hull
  • Machinery such as: engine, generator. gears and pumps
  • Interference from other echo-sounders

On Displacement Hulls:

Carefully study the shape of the hull to determine the best transducer mounting location where;

  • The transducer is away from the propeller and other sources of vessel generated noise.
  • The water is smoothest with a minimum of turbulence and bubbles.


1. Locate the transducer about 1/3 aft LWL. Generally, this provides the best compromise between obtaining aeration-free water away from the bow and minimizing propeller noise.

lwl.gif (5290 bytes)
Figure 1    <click to enlarge>

177f2.gif (8671 bytes)
Figure 2        <click to enlarge>


2. Water near the keel can be quite aerated. Mounting it away from the keel can minimize interference with the transducer. Also, the deeper the transducer protrudes into the water, the less aeration.

3. Mount the transducer on the side of the hull where the propeller is moving downward. The upward motion of the propeller generates pressure waves and pushes bubbles up against the hull. By mounting on the downward side, the hull shades the transducer from this effect. Caution: Do not mount the sensor in an area of turbulence or bubbles:
  • Near water intake or discharge openings.
  • Behind strakes, fittings or hull irregularities.
  • Near the keel
  • Behind eroding paint (an indication of turbulence)
Installation      <back>  
In-Hull Mount (Fiberglass hull only)

Inside mounting can be used on fiberglass hulls to minimize drag when the top speed of the boat is more than 25 kn (29 MPH). Although this placement results in a sound loss of 50% or more, these powerful transducers more than compensate. Also, inside mounting creates less turbulence so the transducer's performance can improve above 20 kn (23 MPH).

Locate the transducer where the hull is solid fiberglass resin to maximize sound transmission. Do not locate over balsa wood core material. Consult the hull manufacturer if you are unsure of the core material or the best location. Never bond large resin housings directly to the hull; always use a liquid-filled box.

1 - Position the transducer at the selected location and test it with the echo-sounder before proceeding. There are two test methods.

a. Lay the transducer against the hull and flood the area to cover the acoustic window.

b. Grind the interior test surface smooth and wet it generously Put the transducer in a plastic bag and fill it with water. Place the bag containing the transducer on the test surface.

2. Construct a water box with a removable lid using the hull as the bottom. Design the box so that the lid is parallel to the waterline (see Figure 4).

3. At the selected location grind the inside hull surface smooth and fiberglass the box in place.

4. Mark the location of the two threaded rod holes (used to mount the transducer) on the lid (see Figure 3). Locate the cable exit hole about half way between the threaded rod. Locate a fill hole between the transducer and the wall of the box. Drill two 10mm (13/32") diameter holes for the threaded rods and the remaining two holes.

5. Following the manufacturer's directions apply a 3mm (1/8") thick layer of marine sealant to the perimeter of the transducer that makes contact with the lid.

6. Attach the transducer to the underside of the removable lid. Thread the cable through the center hole. Apply marine sealant to each threaded rod end. Secure each rod with a nut. The rods should extend a minimum of 3 threads beyond the nut. Slide a stainless steel washer and rubber washer onto each rod. Push the threaded rods through the transducer and lid. Apply marine sealant to the rod near the lid. Secure the assembly in place with a stainless steel washer and nut. Tighten the nuts with a torque wrench using a force not exceeding 4 N-m (3 ft-lb) (see Figure 5).

7. Apply marine sealant to the space around the cable and the lip of the box. Fasten the lid to the box ensuring there is a watertight seal,

8. Fill the box with distilled water, or in cold climates use polypropylene glycol or mineral oil. Plug the fill hole.

9.Wire the transducer to the Echosounder per diagram:  Bathy-500MF or   Bathy-1500.

Threaded Rod Spacing
Figure 3 <click to enlarge>

177f10a.gif (14908 bytes)
Figure 4 <click to enlarge>

Threaded Rod Mounting Hole Spacing
Figure 5 <click to enlarge>

Checking for Leaks:

Warning: Never install a transducer and leave the boat in the water unchecked for several days.

When the boat is placed in the water, immediately check around the bolts that fasten the transducer to the hull and the stuffing tube for leaks. Note that very small leaks may not be readily observed. It is best not to leave the boat in the water unattended for more than 3 hours before checking it again. If there is a small leak, there may be considerable bilge water accumulation after 24 hours (probably not enough to cause water damage). If a leak is observed, repeat the bedding and installation procedures immediately.

Antifouling Paint:      <back>

Surfaces exposed to salt water must be coated with antifouling paint.

Use water-based antifouling paint only. Never use ketone-based paints as it can attack many plastics damaging the transducer. Apply antifouling paint every six months, or at the beginning of each boating season.

Maintenance and Repair     <back>

Aquatic growth can accumulate rapidly on the transducer's surface reducing its performance in weeks. Clean the surface with a soft cloth and mild household detergent. If necessary, use a stiff brush or putty knife to remove the growth taking care to avoid making scratches. if fouling is severe , wet sand with #220 or finer grade wet/dry sandpaper.

Inspect the cable periodically for kinks, abrasions and cuts. Repair any damage using an approved waterproofing cable repair system. Inspect connections for indications of corrosion.

Save or Print the Text version here install2.rtf