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Re: [PSUBS-MAILIST] Postion Sensors for marine service

Cliff,
 
Since your directional controls are hydraulic, I'm not sure how this might be applied, but maybe the concept can be adapted.
 
I have a reversible electric motor driving a worm gear assembly all together in a sealed unit on top of the rudder shaft.  The rudder shaft extends downward out of the assembly through a seal.  The assembly is oil-filled.
 (this shows the hole for a horizontal shaft for the rear dive planes)
 
Originally I intended for the position sensor to be located within the sealed unit and read off the gear assembly.  However what I have decided to do is eliminate the position sensor altogether and instead use a position indicator in the cockpit that mimics the operation of the rudder motor by sharing a common electrical feed.  In other words, any time power is fed to the rudder motor to activate it, power is also fed to the position indicator in the cockpit to move the needle.  The needle is adjustable in case it gets out of sync with the rudder over time.  It might be possible to find an off-the-shelf position indicator for electric trim tabs or electric flaps for aircraft. 
 
Actually the rudder shaft carries the main propulsion motor.
 
Best regards,
Jim T.
 
 
In a message dated 9/4/2011 10:42:39 P.M. Central Daylight Time, ojaivalleybeefarm@dslextreme.com writes:
Hi Cliff,
               This company has some interesting equipment.
 
 
Brian

On Sun, Sep 4, 2011 at 6:41 AM, Cliff Redus <cliffordredus@sbcglobal.net> wrote:
Do you have any links to possible optical sensors rated for submergence in sea water?
 
 

From: "ojaivalleybeefarm @dslextreme.com" <ojaivalleybeefarm@dslextreme.com>

To: personal_submersibles@psubs.org
Sent: Sun, September 4, 2011 8:18:54 AM

Subject: Re: [PSUBS-MAILIST] Postion Sensors for marine service

Cliff,   What about some type of optical sensor?  Maybe utilizing leds
 
Just a thought.
 
Brian

On Sat, Sep 3, 2011 at 6:37 PM, Cliff Redus <cliffordredus@sbcglobal.net> wrote:
This looks like it could handle the pressure and the marine environment.  It is to big by a factor of four for my applications.  Also I need something that is rugged as the location where two of these sensors is on my jet pump and exposed to abuse.
 

I looked at the vendor web site for the pot and they seem to have only the one size for the rotary pot.

 

Thanks for the info.


 


From: Alan James <alanjames@xtra.co.nz> Sent: Sat, September 3, 2011 7:51:10 PM

Subject: Re: [PSUBS-MAILIST] Postion Sensors for marine service

Hi Cliff,
I made up a position sensor & had the electronics sorted for it to run a bar graph from a 12 volt supply.
It's on my projects page.
It's based on a rotary magnetic potentiometer that I've glued acrylic to & potted the wires.
In theory it should go thousands of meters. You need a rare earth magnet of sufficient strength to operate it.
Regards Alan
----- Original Message -----
Sent: Sunday, September 04, 2011 10:30 AM
Subject: Re: [PSUBS-MAILIST] Postion Sensors for marine service

I have my boat torn down and am in the process of adding some external position sensors for my control surfaces.  Specifically, I am looking for a small rotary potentiometer (or equivalent) that is rated for 400 fsw.  I found a sensor NRH280 from Penny+Giles http://www.pennyandgiles.com/Dual-Output-'No-Contact'-Rotary-Position-Sensor-pd-483,3,29,.php that looks promising.  The spec on this meets the IP69K standard which is designed to withstand high pressure wash-downs at high temperature.  IP69K testing involves subjecting the sensor to steam generated from 100 bar water pressure.   These sensors cost $157 and has a six week lead time.  Does anyone have any experience with this sensor or with the IP69K spec?  What I am trying to determine is will this sensor handle 200 psig external water pressure?  While the IP69K spec does not directly address external pressure, it is a fairly demanding test standard so any device that passes this standard should be able to handle some external pressure but the question is how much? The vendor has no data that they are willing to share on maximum external pressure their sensor can withstand.  If all else fails, I can buy one of the sensors and do a bench test to failure but this will take 13 weeks to get the parts assuming it takes six weeks to get the test unit , one week to test and six more weeks to get the remaining sensors assuming the unit passes the test.
 
Alternately , does anyone know of any off the shelf small rotary potentiometers that are designed for this service?  My goal is to mount one of these sensors on my yaw, roll and pitch control surfaces and then bring the electrical leads into the boat through an electrical penetrator.  Any thoughts.
 
Cliff