"Wilbur Hubbard" wrote in message
...

In a real blow, real sailors use safety harnesses and jacklines. A
single jackline down the center of a yacht is safer than two jacklines
down the side decks of a yacht. It would not be very difficult to get
flipped over the low lifelines and be drug though the water by your
safety line on the side decks. Walking in the center of the boat keeps
you on the boat.

Wilbur Hubbard

The question was guard rails not jacklines.
But for jacklines the safety factor is determined by the length of the line
you use to tether yourself to the jackline.
Here there is a problem because a short safety line is better for getting
forward but once you are there it may impose limits on the work you need to
do. For this reason the best solution is to have both a short and a longer
safety line on your lifevest.

Depending on the design of the boat and whether you have a large dodger in
the way or not the problem with a single central jackline is how you can
clip onto it before you leave the safety of the cockpit.

But guard rails are a necessary safety factor for any offshore yacht. Do you
think you just stroll forward in a force 8 blow? Of course you do not- you
can be reduced to almost crawling from one handhold to another and you are
better off clipping onto a jackline on the weather side deck with a short
line before you leave the cockpit than trying to reach round the dodger to
clip onto a central jackline with what has necessarily got to be a longer
safety line.
I favour a jackline on each side going forward as far as the mast and then a
single central one going right to the bow. No problem changing from one to
the other if you have two safety lines as I mentioned above..