[Beowulf] Re: Ahoy shipmates

Gus Correa gus at ldeo.columbia.edu
Wed Oct 14 13:47:53 EDT 2009


Robert G. Brown wrote:
> On Tue, 13 Oct 2009, Prentice Bisbal wrote:
> 
>> I'm sure you would eventually still get some kind of buildup on the
>> walls, affecting the condictivity.
> 
> Yeah, the problem with barnacles is that you start getting significant
> encrustation in as little as a month of warm seawater exposure.  The
> little suckers are ubiquitous and attach themselves in hours, grow in
> weeks.  We dropped a lawn chair in the water by accident off of our dock
> last summer and hooked it and reeled it back in a month later, already
> partially covered with barnacles.

Yes, barnacles stick to hydrophone streamers,
which move at 5 knots or so.
Just as they do to the bodies of whales.
They cause a lot of trouble for seismic imaging
geophysical surveys, increasing the water drag on
streamers, reducing the signal to noise ratio on hydrophones,
etc.
Some pictures:

http://www.csiro.au/resources/Biofouling.html
http://cmst.curtin.edu.au/news/e&p/e&pbarni.jpg

http://www.glaucus.org.uk/Barnacles.htm
http://www.learner.org/jnorth/images/graphics/u-z/gwhale_Barnacles.wmv

Streamers need to be cleaned on a regular basis,
during the surveys.
There are devices to clean them up,
lubricants to reduce the barnacle capacity to stick, etc:
http://www.patentstorm.us/patents/7145833/description.html
http://www.freepatentsonline.com/y2006/0144286.html

OTOH, just to stay on the topic,
seismic survey vessels have
beefed up computer labs (or small data centers) on board,
for data acquisition and QC, data processing (seismic imaging), etc.
Not cooled by seawater, but not significantly
affected by corrosion either.

Gus Correa

> 
> There are paints and chemical compounds and so on that are "resistant",
> but dealing with them is still an ongoing battle of boat owners etc.
> 
>    rgb
> 
>>
>> -- 
>> Prentice
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> 
> Robert G. Brown                           http://www.phy.duke.edu/~rgb/
> Duke University Dept. of Physics, Box 90305
> Durham, N.C. 27708-0305
> Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
> 
> 
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