page prepared on March 27, 2002

As a part of the OVAL 2002 project I am working to develop a device that will monitor and report underwater currents in an attempt to better understand the underwater environment in which the Orcas and other marine life are living and interacting. The V-meter is currently a collaborative effort of Hillary Swanson, Win Jewett, and myself.

The basic design includes a propeller turning a motor which produces a voltage which varies in a predictable way with the speed of the propeller. This voltage is sent from the motor to the monitor in the Beach Box where it is converted to meters per second.

Because this device has to live in salt water all the time, we had a few water proofing challenges to overcome. Anything that turns is rather difficult to seal effectively, especially when it will be submerged up to 20 feet in the Haro Strait. Our final design has no electrical parts that interact physicaly with "wet" pieces. On the shaft of the motor two small, powerful magnets are mounted side by side. These are just a few micrometers away from the cap of the waterproof casing. On the other side of that cap, in the water, are two identical magnets with identical mounting attached to the shaft turned by the propeller. As the propeller turns, the magnets are strong enough to cause the motor to turn as well. This is our current theory at any rate.

Update April 11, 2002

Last week the V-meter project was cancelled by an executive council due to the fact that many of the pieces we needed had not yet been machined and we were unable to locate a machine shop we could use on San Juan Island. Hillary, Win, and I had also gotten involved in a few other projects and were keeping ourselves busy.

I rebuilt the pre-amp for one of the hydrophones we pulled up. The casing on the cable had some how cracked and water had gotten in and shorted out the circuit. After constructing the circuit using an insturmentation amplifier chip AD25... I learned a whole lot about waterproofing and mixing epoxy. The pre-amp was encased in a thick layer of epoxy and then covered in a few layers of Scotch Kote and self-amalgamating rubber tape. A final layer of electrical tape is applied before the hydrophone is attached to a stand and deployed.

Here we are, mending cables.

Val and some of the kelp that has taken advantage
of our hydrophone cables.

Here we are removing bad cables from the cable protectors and un-tangling them. All the while battling the waves and the chill.	Removing cable protectors involves taking apart two halves of castiron shells by undoing two screws. Here Hillary and Mike demonstrate good technique.	No field course is complete without an oyster bake. This was my first and I actually enjoyed it! Thanks Doug and Cari!
At the Friday Harbor Labs, we got a chance to pet sea urchins, starfish and other biological samples.	Hillary and I about to head out on our first joit kayak adventure.	Here we go, niether one of us quite sure how to steer or launch the kayak.
With a little help we get in the water and get going. A little wet, but very happy.	Watching Harbour Seals with Peter Ross, PCB specialist at IOS in Sidney, Vancouver	Serious egg hunting also took up a fair amount of my time.

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