Re: Speed sensor rubber cap


 

And sometimes when the rubber cap comes off, you get more than the rubber cap.
image.png


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar

On Wed, Oct 6, 2021 at 3:45 AM Stefan Jeukendrup <sjeukendrup@...> wrote:

Hi Mohammed,


Yes, I had the same problem you have 2 times: replaced the sensor on the hull with the boat in the water 3 years ago and the sensor on the keel this year during haulout.

 The heart of these sensors is a thin piezo ceramic plate with 2 electrodes which is glued on one side to the rubber cap and the other side is epoxied together with the cable in the housing. See the enclosed sketch.

A possible reason that re-glueing the cap ( or filling the hole with silicone) does not work is that the actual sensor, a piezo crystal with very high impedance, should not be in contact with seawater which conducts electricity


This sensor fails too often and this might why:

The rubber cap is a little smaller than the hole so it can move a little and seawater can get to the side of the sensor.  Over time this dislodges the glue between rubber cap and crystal

I followed the advice of another member of this forum: when mounting a new sensor fill the space around the rubber cap with neoprene to make sure the water stays out and the rubber cap cannot move anymore.


Hope this is helpfull,


Stefan Jeukendrup

sv Malaka Queen

SM2k #348 @ Newry, Northern Ireland


Op 06-10-2021 om 08:32 schreef Mohammad Shirloo:

Hi  Stephan;

 

We were on a tight schedule to get to our winter berth. I did re-install the cap under water to protect the sensor. We were getting erratic speed readings afterwards. We will be hauling out next year and will address it then. Did you have an issue with your speed sensor?

 

Thanks

 

Happy Sailing;

 

 

Mohammad and Aty

B&B Kokomo

Amel 54 #099

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Stefan Jeukendrup via groups.io
Sent: Sunday, September 26, 2021 10:12 AM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Speed sensor rubber cap

 

Hi Mohammed,

 

The function of the cap is to protect the underlying high impedance crystal on which it is glued. That keeps the water and dirt out. 

 

If your Sonicspeed still works first check AGC and resistance, see the manual in the "files" section.

 

If still ok I would not try to put the cap back. Instead you could try to fill the hole where the cap was with underwater silicone. The "art" is to make good continuous accoustic contact with the exposed crystal.

 

Hope this helps you,

 

Stefan Jeukendrup

sv Malaka Queen 

SM2k #348 @ Northern Ireland

 

 

Op 26 sep. 2021 07:41 schreef Mohammad Shirloo <mshirloo@...>:

Does anyone know the function of the rubber cap? Is this for prevention of damage or growth on the main sensor, or does it have some other functional role?

 

Respectfully;

 

 

Mohammad and Aty

B&B Kokomo

Amel 54 #099

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of CW Bill Rouse via groups.io
Sent: Sunday, September 26, 2021 12:33 AM
To: main@AmelYachtOwners.groups.io Notification <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Speed sensor rubber cap

 

I had exactly the same issue. My sonic speed stopped working. I dove and found that I had one big barnacle on the rubber cap  When I pulled on the barnacle the cap came off.

 

Amel told me to reattach it with silicone sealant on the edges. 

 

I didn't haulout to do that and waited for about 6 months for a scheduled haul out. I replaced the cap, but Sonic Speed never worked. 

 

Good luck!

Best,

CW Bill Rouse 
Amel Owners Yacht School
+1 832-380-4970 | brouse@...
720 Winnie, Galveston Island, Texas 77550 
www.AmelOwnersYachtSchool.com 
Yacht School Calendar: www.preparetocastoff.blogspot.com/p/calendar.html


   

 

On Sat, Sep 25, 2021, 3:48 PM Mohammad Shirloo <mshirloo@...> wrote:

Our speed sensor was a bit erratic after a 3 week stay in Venice. I dove in it today to clean the rubber caps with my diving gloves. The rubber cap came off of the forward sensor and I was able to catch it before it went to the bottom. 


I need to put the cap on while in water, until we haul out next year. It appears to be just a pressure fit as I could not see any sealant. The sealant may have just worn off in the past 12 years. Any advice on how to fit it back in under water, would be appreciated.

i have added pictures of the part to be reinstalled.

thank you.

 

Join main@AmelYachtOwners.groups.io to automatically receive all group messages.