There is little chance you could train a Porty (or any other dog) to
untangle a truly fouled line. However, there was one case where we
hired a diver before we tried ourselves, and the line was only
slightly wrapped - we could have nudged it off our saildrive with a
boathook. Rather than use our dog, we have purchased (as yet untried)
this implement of destruction:
http://www.captnhooksolutions.com/

A Porty makes a great boat dog. The first thing you need to know is
that they are very high energy; don't consider getting a puppy unless
you can give it several hours of exercise a day. Ours gets a one hour
walk most mornings, plus an hour in the puppy play group. When we're
traveling, she'll get at least an hour most days running on the beach
or some other exercise.

Molly took to boat life even easier than house life - she immediately
figured out that the trampoline on the bow of our catamaran is the
perfect place to do her business. She's never had an accident on
board, the house hasn't been quite so lucky. Molly has no trouble in
the dinghy or kayak; in fact she insists on joining us for every trip
and gets rather upset when she isn't included. She has to be tied up
if the pumpout or harbormaster boat comes alongside or she'll jump ship.

On one short but very rough trip across Vineyard Sound (a two knot
current against 25 knot wind can turn the Sound into a Mix-Master)
Molly sat in the cockpit munching her kibble and chasing down bits
when they went flying.

Although Molly has no fear of the water she doesn't like to swim. At
first we thought it was just because she was a puppy and she would
grow out of it (and she may yet) but we've met lots of others that
don't hesitate to swim or even dive 5 feet with only a bit of
coaching. Other than that she's very intelligent and responds to
training quite well. Porty's are known as "courier dogs" because they
will not just retrieve, they will deliver packages to other boats.
This skill usually takes several years of training, and is often the
highlite of the Porty Association Water Trials.

http://www.sv-loki.com/Molly_Doodle/molly_doodle.html

wrote:
I wonder if the Portuguese Water dog can be trained and used to untangle
lobbers pots rope and fishing net wrapped around your propeller?

Background: From Wikipedia encyclopaedia: Originating back to the 1500s in
Portugal these dogs were used to send messages between boats, to retrieve
fish and articles from the water, and to guard the fishing boats. (They
often received a portion of the catch after a job well done, too!) They
helped to bring in nets and to save fishermen when they fell in the water.

May be some of the cruisers already have a Portuguese Water dog and want to
share their experience with that breed of dog for cruising.