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Chris
Doran of Newcastle, NSW asks:
I
would like to know, firstly, with the paravanes, how much
strain is there on the mast, or is most of the strain taken
on the front shrouds? Secondly, how deep do the fish swim,
and is the height above water - at the attachment of the base
of the outrigger to the vessel - critical to the performance
of the system? I am considering installing outriggers to our
vessel, however the mast is stayed from our cabin roof, hence
my question.
Jim
Leishman responds:
Chris,
the loads on the stabilizing gear are significant however
they're not as much as you might think. The rig of a typical
sailboat will put the spar under greater compression and the
shrouds under greater tension that the Paravane rig will.
One important difference between the sailboat rig and the
Paravane rig is that the Parvane loads are cyclical and we
have had problems over the years with chainplates working
loose. We use strong backs which are under tension then compression.
There
is a method to calculate the loads and it can be found in
Voyaging Under Power - all editions. I would suggest that
you consult someone with some engineering knowledge before
retrofitting a system to your boat.
We
run the fish at 15 feet below the waterline when the boat
is not running. Underway they stream aft and run shallower.

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