High Resolution Echo Sounders
and Acoustic Systems for Precision Seafloor  Exploration
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Tank Mount Installation Instructions

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.

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,
or turbulent water 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)

Threaded Rod Placement Dimensions

Threaded Hole Location
Figure 3        <click to enlarge>

Installation      <back>  
Preparing the Installation Site

Using a Threaded Stem Stuffing Tube

1. Position the Airmar fairing at the selected location being sure that the blunt end points forward toward the bow. (The example housing is symmetrical.) The distance between the two threaded rod holes equals 305mm (12.0") (see Figure 3).

The stuffing tube is located about half way between the threaded rods. Inspect the hull interior to ensure that there is clearance for the stuffing tube and that no cables, ribs or struts will interfere. Mark the site for the threaded rods and stuffing tube.

Warning: Always wear safety goggles and a dust mask.

2. From inside the hull, drill a 3mm (1/8") diameter pilot hole for the stuffing tube. However, if there is a hull irregularity near the selected mounting location, drill from the outside. If the pilot hole is drilled in the wrong location, drill a second hole in a better location. In a fiberglass hull apply masking tape on the outside of the hull over the incorrect hole and fill it with epoxy. For wooden hulls fill the incorrect hole with marine sealant; in metal weld the hole closed.

3. At the pilot hole, drill a 28mm (1-1/8") diameter hole from the outside perpendicular to the hull surface for the stuffing tube. Remove all burrs and clean the area around the hole, inside and outside, to ensure that the marine sealant will adhere properly. A backing block may be required under the flanged nut to ensure that it can be tightened against a flat surface.

4. Drill two l0mm (1 3/32") diameter holes through the hull and backing block for the threaded rods. Care must be taken to ensure that the two rods are parallel to the keel to reduce drag.

5. Install the stuffing tube first. Remove the nuts, washers and bushing from the stuffing tube. Select a marine grade sealant and follow the directions for its use. Apply a 3mm (1/8") thick layer of marine sealant to the stuffing tube from the flange that makes contact with the outside of the hull to where the flanged nut will be tightened inside the hull. This will seal the hull and hold the nut securely in place (see Figure 4).

6. Push the stem of the stuffing tube through the hull and fasten the flanged nut inside. On a fiberglass or metal hull, tighten this nut securely. On an aluminum hull use the spacers to isolate the stuffing tube from the hull, being sure to apply marine sealant to the spacers as well. If the hull is wood and has been out of the water for a prolonged period, it is suggested that the flanged nut be hand tightened only. Wood will swell after the boat is in the water and exert considerable pressure on the stuffing tube hardware. After the hull has expanded, tighten the nut securely.

7. Route the cable to the echo-sounder being careful not to tear the cable jacket when passing it through the bulkhead and other parts of the boat. To reduce electrical interference separate the transducer cable from other electrical wiring and the engine. Coil any excess cable and secure it in place with zip-ties to prevent damage.

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

Stuffing Tube Assembly
          Figure 4    <click to enlarge>

Tank Mount

Some transducers can be tank mounted. If this is your style transducer, it is recommended that the clamp bar be shortened and re-drilled to accommodate two bolts. They will secure the transducer to threaded stand-offs that are welded to the floor of the tank (see Figure 5).

In Resin Housing

1. Apply marine sealant to one end of each threaded rod. 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 (see Figure 6).

2. Insert the transducer into the housing and place the clamp bar on top. Slide the threaded rods up through the housing and clamp bar. 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).

3. Slide the fairing onto the threaded rods and against the surface of the transducer assembly. Following the manufacturers directions apply a 3mm (1/8") thick layer of marine sealant to the surface of the fairing that will make contact with the hull and the two threaded rods that will pass through the hull.

Caution: Never pull, carry or hold the transducer by its cable as this may sever internal connections.

4. Thread the transducer cable through the stuffing tube to the inside of the hull. Allow a service loop in the cavity of the fairing so there is no tension applied to the cable.

5. Place the entire assembly against the hull, pushing the rods through the hull. With a person stationed inside the vessel apply marine sealant to the two threaded rods where the backing block and nut will seat. Position the backing blocks on the rods and secure them with a stainless steel washer and nut (see Figure 6). Tighten the nuts with a torque wrench using a force not exceeding 7 N-m (5 ft-lb). Remove excess sealant from the hull.

Note: if a wood fairing is used, hand tighten the nuts only Allow the fairing to swell and then tighten to 4 N-m (3 ft-lb).

6. Plug the mounting holes to minimize turbulence on the surface of the transducer using the white, foam, plug material. Cut the foam to length so that, when installed, each plug is recessed 5mm (3/16") below the surface of the housing. Push these foam plugs into the holes and use marine sealant to fill the holes even with the transducer's surface. Remove excess sealant to ensure smooth water flow over the transducer (see Figure 6).

7. Seal the cable by sliding the washer, rubber compression bushing, washer, and the compression nut along the transducer cable to the stuffing tube (see Figure 4). Make sure the rubber bushing fits securely into the machined lip of the tube. Tighten the compression nut. Remove all excess sealant inside the hull.

8. Route the cable to the echo-sounder being careful not to tear the cable jacket when passing it through the bulkhead and other parts of the boat. To reduce electrical interference, keep the transducer cable separated from other electrical wiring and the engine. Coil any excess cable and secure it in place with zip-ties to prevent damage.


Tank Mount
Tank Mount
Figure 5 <click to enlarge>

Resin housing
Resin Housing
Figure 6 <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.

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