[PSUBS-MAILIST] building sonar transducer

[Alan via Personal_Submersibles]

Ludwig,
depth transducers in boats can shoot through up to 1/2" of fibreglass when
mounted inside the hull. They can't shoot through metal or an air gap.
   You could encapsulate the transducer in the required thickness of fibreglass
for the depth you are intending. I presume you could use the resin without
the glass fibres. I believe their is less shrinkage with epoxy as apposed to
polyester resin. Hopefully the shrinkage won't damage the transducer.
Make sure there are no air bubbles in the resin or air gap under the transmitting
face of the transducer. I would silicone over the wires going in to the resin
& over the resin itself where the wires enter; as resin doesn't always seal on
the wiring, and the compression of the wire casing can pull away from the resin.
You could build a fibreglass enclosure as an alternative to encapsulating.
Another alternative would be a metal housing with a fibreglass disk mounted
in it like a view port. You would mount the transducer on the disk with epoxy.
I haven't tried this myself but through hull mounts are a common practice.
Cheers Alan



Sent from my iPad

> On 6/03/2017, at 5:16 AM, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hello all,
> 
> I'm looking at building a sonar transducer to measure bottom depth for a small ROV project and would like to ask how I should go about pressure-proof/waterproof the system.  
> 
> I'm looking at building it with a Arduino Uno Rev 3 microcontroller and a Ultrasonic sensor module.
> 
> -Ludwig Johanning
> 
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