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Copyright © 2003 - 2011 Airmar Technology Corp. All rights reserved. 

Checking for Leaks

When the boat is placed in the water, 

immediately

 check around 

the transducer for leaks. Note that very small leaks may not be 
readily observed. Do not leave the boat in the water 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. If a leak 
is observed, repeat “Bedding” and “Installing” 

immediately

 (see 

page 3). 

Installation in a Cored Fiberglass Hull

The core (wood or foam) must be cut and sealed carefully. The 
core must be protected from water seepage, and the hull must be 
reinforced to prevent it from crushing under the hull nut, allowing 
the transducer to become loose.

CAUTION

: Completely seal the hull to prevent water seepage into 

the core.

1. Drill a 3mm or 1/8" pilot hole perpendicular to the waterline from 

inside the hull (see Figure 6). If there is a rib, strut, or other hull 
irregularity near the selected mounting location, drill from the 
outside. (If the hole is drilled in the wrong location, drill a second 
hole in a better location. Apply masking tape to the outside of the 
hull over the incorrect hole and fill it with epoxy.)

2. Using the appropriate size drill bit, cut a hole from outside the 

hull through the 

outer

 skin only. 

Be sure to hold the drill plumb, 

so the hole will be perpendicular to the water surface.

3. The optimal interior hole diameter is affected by the hull’s 

thickness and deadrise angle. It must be large enough in 
diameter to allow the core to be completely sealed.
Using the appropriate size drill bit for the hull interior, cut through 
the

 

inner

 skin and most of the core from inside the hull keeping 

the drill perpendicular to the hull. The core material can be very 
soft. Apply only light pressure to the drill bit after cutting through 
the 

inner

 skin to avoid accidentally cutting the 

outer

 skin.

4. Remove the plug of core material so the 

inside

 of the outer skin 

and the inner core of the hull is fully exposed. Sand and clean 
the inner skin, core, and the outer skin around the hole. 

5. Coat a hollow or solid cylinder of the correct diameter with wax 

and tape it in place. Fill the gap between the cylinder and hull 
with casting epoxy. After the epoxy has set, remove the cylinder.

6. Sand and clean the area around the hole, inside and outside, to 

ensure that the sealant will adhere properly to the hull. If there is 
any petroleum residue inside the hull, remove it with either mild 
household detergent or a weak solvent (alcohol) before sanding.

7. Proceed with “Cutting the Standard Fairing” on page 2.

Anti-fouling Paint

Surfaces exposed to salt water must be coated with anti-fouling 
paint. Use 

water-based

 anti-fouling paint only. Never use ketone-

based paint since ketones can attack many plastics possibly 
damaging the transducer. Reapply anti-fouling paint every 6 
months or at the beginning of each boating season.

Maintenance, Parts & Replacement

Cleaning

Aquatic growth can accumulate rapidly on the transducer’s 
surface reducing its performance within weeks. Clean the surface 
with a Scotch-Brite® scour pad and mild household detergent 
taking care to avoid making scratches. If the fouling is severe, 
lightly wet sand with fine grade wet/dry paper.

Replacement Parts

The information needed to order a replacement transducer is 
printed on the cable tag. Do not remove this tag. When ordering, 
specify the part number, date, and frequency in kHz. For 
convenient reference, record this information on the top of page 1.

Lost, broken, or worn parts should be replaced immediately.

Model

Hull Nut

Fairing Type

Fairing Part #

B45

02-031-3

Standard

33-351-01

High-Performance

33-509-01

B258, B271W

02-222-03

Standard

33-226-01

High-Performance

33-523-01

B260

02-036-2

High  Performance

33-391-01

B265LH/LM

02-036-2

High  Performance

33-391-01

SS258

02-539-01

Standard

33-226-01

High-Performance

33-523-01

SS260

02-036-03

High-Performance

33-391-01

SS270W

02-036-03

High-Performance

33-391-01

SS505

02-111-01

High-Performance

33-355-01

Obtain parts from your instrument manufacturer or marine dealer. 

Gemeco

Tel: 803-693-0777

(USA)

Fax: 803-693-0477
email: [email protected]

Airmar EMEA

Tel:  +33.(0)2.23.52.06.48

(Europe, Middle East, Africa) Fax: +33.(0)2.23.52.06.49

email: [email protected]

hull’s outer skin to

hull

outer skin

solid or hollow

cylinder

pour in

casting

epoxy

core

inner skin

Figure 6. Preparing a cored fiberglass hull

dimension equal to

the thickness of the

ensure adequate

clearance

Copyright © 2005 Airmar Technology Corp.

AIRMAR

®

TECHNOLOGY CORPORATION

35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA 

www.airmar.com 

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