background image

4

4. Remove the plug of core material so the

 inside

 of the outer skin and the 

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

5. If you are skilled with fiberglass, saturate a layer of fiberglass cloth with 

a suitable resin and lay it inside the hole to seal and strengthen the 
core. Add layers until the hole is the correct diameter.
Alternatively, a hollow or solid cylinder of the correct diameter can be 
coated with wax and taped 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 marine 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 “Bedding” (see page 3).

Operation & Maintenance

How the Valve Works

THE VALVE IS NOT A WATERTIGHT SEAL!

 The multisensor 

incorporates a self-closing valve which minimizes the flow of water into the 
boat when the insert is removed. The curved flap valve is activated by both 
a spring and water pressure. Water pushes the flap valve upward to block 
the opening, so there is no gush of water into the boat. Always install the 
insert or the blanking plug secured with the cap nut and safety wire for a 
watertight seal.

Using the Blanking Plug

To protect the paddlewheel, use the blanking plug:
• When the boat will be kept in salt water for more than a week.
• When the boat will be removed from the water.
• When aquatic growth buildup on the paddlewheel is suspected due to 

inaccurate readings from the instrument.

1. The O-rings must be intact and well lubricated to make a watertight seal. 

On the blanking plug, inspect the O-rings (replace if necessary) and 
lubricate them with the silicone lubricant supplied or petroleum jelly 
(Vaseline

®

) (see Figure 5).

2. Remove the insert from the housing by removing the safety wire and 

unscrewing the cap nut (see Figure 3). This will jack up the insert. 
Remove the insert with a slow pulling motion. Replace it by sliding the 
blanking plug into the housing.

NOTE

: In the very unlikely event that the valve breaks, replace the 

housing the next time the boat is hauled.

3. With the blanking plug fully inserted, screw the cap nut several turns until 

the threads are engaged. Continue to tighten the cap nut completely. 

Hand tighten

 only. Do not over tighten.

NOTE

: The blanking plug must be fully inserted in the housing and the 

cap nut screwed on completely for a watertight seal.

4. Reattach the safety wire to prevent the blanking plug from backing out 

in the unlikely event that the cap nut fails or is screwed on incorrectly.

Winterizing

After the boat has been hauled for winter storage, remove the blanking 
plug to let the water drain away before reinserting it. This will prevent any 
water from freezing around the blanking plug and possibly cracking it.

Servicing the Insert

Aquatic growth can accumulate rapidly on the depth transducer’s face and 
impede or freeze the paddlewheel’s rotation reducing performance within 
weeks. Clean the insert with a Scotch-Brite® scour pad and mild 
household detergent, being careful to avoid scratching the depth 
transducer. If fouling is severe, remove the paddlewheel (see step #1 
below). Lightly wet sand it with fine grade wet/dry paper.

The water lubricated paddlewheel bearings have a life of up to 5 years on 
low-speed boats [less than 10kn (11MPH)] and 1 year on high-speed 
vessels. Paddlewheels can fracture and shafts can bend due to impact 
with water borne objects and mishandling in boat yards. O-rings must be 
free of abrasions and cuts to ensure a watertight seal. Order a 
replacement Paddlewheel Kit No. 33-540-01.

1. To remove the old paddlewheel shaft, grasp the end with small diagonal 

wire cutters and pull (see Figure 5).

2. Place the new paddlewheel in the cavity with the flat side of the blade 

facing the same direction as the arrow on the top of the insert.

3. Tap the new shaft into place until the end is flush with the outside wall 

of the insert.

4. Install the yellow O-ring near the top of the insert. Install a small O-ring 

near the paddlewheel.

5. Place the remaining two small O-rings near the bottom of the blanking 

plug.

Replacement Sensor & Parts

The information needed to order a replacement Airmar multisensor 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 one.

Lost, broken, or worn parts should be replaced immediately. If you have 
purchased a plastic housing and have a wood hull or desire greater 
strength, purchase an Airmar metal housing. 

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]

Blanking 

Plug

Hull Nut or 

Isolation Bushing

Paddlewheel, 

Shaft, O-rings

Housing, Hull Nut & Washer

33-538-01

04-004 (plastic)
02-530-02 (stainless)
04-186-1 (isolation)

33-398-04

Valve

:

33-510-01 (plastic, P617V)
33-588-01 (bronze, B617V)
33-617-01 (stainless, SS617V)

NO Valve

:

33-100 bronze low-profile, B17
33-224-01 bronze flush, B21
33-094-01 stainless low profile, SS577

Copyright © 2005 - 2014 Airmar Technology Corp. All rights reserved.

Figure 5. Replacing the paddlewheel and O-rings

arrow

flat side

of blade

shaft

blanking

insert

faces bow

yellow

O-ring

small

O-ring(s)

Copyright ¬© 2005 Airmar Technology Corp

BOW 

plug

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

 

www.airmar.com 

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