jfe-582

JQS-2170 [O] Form 4 (2/2) Priority [ ] A: Carry out immediately [ x ] B: Carry out at periodical inspection [ ] C: Carry out upon clients request [ ] D: Information and news 1Subject

Check, replace and reject the 200kHz old type transducer for echo sounder. 2Objective Equipment

UT-200ND** transducers for 200kHz echo sounder JFE-582. 2.1 Over 14m deep draft vessels within one year after launch. 2.2 Stocked UT-200ND** transducers in our branches. ** means cable length 20, 30, 40 or 50.

We have released A version improved transducers UT-200ND**A from April 13, 2007. So, old type UT-200ND** transducers are objective.

3Outlines and provision

[Outlines] About only 200kHz old type UT-200ND** echo sounder transducers equipped with over

14m draft vessels, the transducer might bend by high water pressure for about one year. When the bubbles float under the vessels hull on berthing, the air would stay on the bend transducer. Then the bottom echo might fade out about half an hour or more. To check the bending, please see attached Check sheet for transducer bending.

[Provision]

a) Check and replace: On the berth, visit the deep draft (over 14m) vessels and use attached check sheet Check sheet for UT200ND echo sounder transducer bending to decide the bending is occur or not.

b) Scrap the old stocked transducers: Please scrap the stocked old type UT-200ND** 200kHz echo sounder transducers. On scrapping, please comply with the local law. Please order the standby new type UT-200ND**A transducers by z code sales order. Please count and take a picture of the reject transducers to report our marine

electronics quality assurance department. 4Attached document

Check sheet for UT200ND echo sounder transducer bending. (Total three pages.)

NA09AL0302A attached sheet Check sheet for transducer bending 1/3

Check sheet for 200kHz echo sounder transducer (UT200ND**) bending Outlines:

If the echo sounder transducer surface is bended, the bubbles would tend to stay the surface of transducer. The bubbles would block the ultrasonic to fade out the bottom echo and digital depth value. If sounding is good on vessel running but no sounding after anchoring, we should conclude that transducer surface is bended. Please do three steps checking to conclude the bending.

1. hear evidence from the officer 2. check past recorded paper chart on the vessel running and berthing 3. check depth sounding on the berth

1. hear evidence from the officer

1.2

Did the echo sounder lost the depth between 2m and

200m bottom.

Normal condition. No

Yes a) Sometimes Digital depth value

disappears.

b) On approaching and berthing, digital depth value disappear for few minutes

c) After anchoring, digital depth value disappear for dozens minutes.

d) On berth, digital depth value disappears always.

Hear the detail condition of disappearing.

Normal condition. Tugboat bubbles might flow under the hull temporary

Bending might occur. Go to 2 If paper chart is recorded, copy or take photos.

Bending or too shallow depth might occur. Go to 2

e) On running, digital depth value disappear. But after anchoring, digital depth value appear.

Bubbles from own bow might flow under the hull.

1.1

Can you hear evidence of echo sounder from the

officer?

Yes Go to 2. check past recorded paper chat.

No

*1

*2

*1

*1: We think a),b) is normal condition. If the paper chart was recorded, please go to next page check flow. *2: If this trouble was occurred on the first sea trial, transducer mounting position would wrong. If this trouble was occurred suddenly, the front of transducer might be uneven to made bubbles.


2. Check flow by using past recorded paper chart on the vessel running and berthing

Yes

No

Normal condition No bending

Yes

No

a) If bottom echo was recorded intermittently and vary by vessel speed or loadage, the bubbles made by the vessels bow might flow the transducer surface. We recommend to moving the transducer position on next dry dock.

b) If bottom echo was not

recorded at all time, other trouble; transducer broken or cable snapped off; might occur.

a) Intermittently bottom lost by tugboat bubbles is normal.

b) More than ten minutes continuous bottom lost, bending might occur. Detail check is next page.

2.2

On running, was bottom echo always recorded?

2.3

On berthing, was bottom echo always

recorded?

2.1

Does past recorded paper chart exist?

No

Go to 3. check depth sounding on the berth.

Photo 1 example of 2.2 a) bubbles effect on bottom echo photo 2 example of 2.3 a) Intermittently bottom lost by tugboat bubbles is normal

Unsteady bottom recording

One minute Time mark 30sec 30sec

Lost the bottom echo for about 80sec.

[draft setting: 10m]

Thin bubbles might display between zero line and bottom.

Dense bubbles block bottom echo.


photo 3 example of tag boat bubbles photo 4 example of paper recording Upper: JFE-585(50kHz) bow Lower: JFE-582(200kHz) stern

bubbles

(If 200kHz and 50kHz transducer is set to the same position, higher frequency 200kHz echo sounder is tougher than 50kHzs about bubbles interference)

Bow side seems slight bubbles interference. Stern side seems strong bubbles interference. The bottom echo recovers from the bubbles interference after few minutes. This is normal condition.

3. check depth sounding on the berth 3.1 check the depth by chart and hear

the vessels draft. Depth from transducer = depth -draft

Yes

No

Normal condition No bending

Yes

No

No bending but bottom echo might be rather weak. Check the echo sounder body, cable, connection and transducer.

Bending should occur. Check again after one hour. Still no bottom echo on the paper, conclude that transducer is bended.

3.3

Is digital depth display correct?

3.4

When set the gain to maximum, does the bottom

echo record on paper?

3.2

Is depth from transducer 2m or more? If the depth from transducer is less than 2m,

the digital depth display might disappear the depth value. Ask the officer to keep the recorded paper on next arrival, and check again.

No

Yes

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