The reducing heeling moment when pressed is a safety
feature. I am not inclined to test any boat on the limit
unless it's mine and the consequences are not dire. However
any boat that spends a long time at sea has a high
probability that the limits of control will get tested.
I have not seen that Aerojunk rig but I did do
some calculations on a bi-directional square rig similar
to what is used on Maltese-Falcon:
It is a very promising design as it
dramatically simplifies shunting. The sail only needs to
be rotated about 10 degrees during a windward shunt. You
get some idea of that on this model where I was playing
with a canted bi-directional sail:
In the first few seconds you see how the boat
shunts just by swinging the sail a few degrees. There is
also a shunt about 25m from the shore but the gust caught
me out on the return leg and I was too slow to shunt and
ended up beached. We actually got this boat to fly with
just rudders in the water but never got a video of that.
We only had two controls, steering and sail rotation. We
needed to have some means of controlling the cant angle to
depower in gusts but never got that far.
It appears Paul McKay’s Aerojunk rig has
addressed some of the issues I identified as we got into
detail of the bi-directional square rigger - note the
three sheeting points. For a bi-directional square rig
each bottom corner of the panels would require sheets and
the trailing sheets would need to be released to depower.
One of the issues when the sail is not directly attached
to the mast is the high drag of the circular section..
The drag coefficient is often quoted at 0.5 but that is
at high Re#.. At low Re# the drag coefficient is around
1.2 and for a freestanding circular mast it forms the
majority of the drag on the rig. With square rig I found
it was beneficial to include a fairing panel for the mast
to lower the drag of the rig. The yards were curved to
achieve the camber and each fairing panel would be secured
to yards at each corner; in fact, the fairing panels may
have their own small yards that help form the shape and
also hold the main yards close to the mast.
This idea was explored as an alternative to
the schooner rig to simplify shunting compared with
swinging the Aerorig through almost 180 degrees on a
windward shunt. It does not improve the balance much.
The issue with going to schooner rig was the high cost
involved in making two new mast bearings and associated
hull stiffening plus the second mast. The schooner rig
should be the preferred option for a new build although I
have not sailed on a HP with that rig.
Rick
Rick:
The heeling aspect
was discussed in an earlier thread........My
single question with regard to this is how
relevant is it in real life sailing... when one is
not pushing the boat to it's limits as you might
in racing??? It's one of the ingenious aspects of
Rob's designs. A lot of details had to come
together in the HP that make it very very
different from other proas so that it would be a
stable safe ocean going platform that can complete
with other blue water boats and acquit itself
well, even excel. I'm beginning to understand
the value of the slenderness ratio.... I forget
the proper term.
It has seemed to me
since I "discovered" the HPs that one of the split
junk rigs would be a pretty ideal rig on an HP,
not requiring the extremely heavy boom and
pivoting mast. The aerojunk by Paul McKay that
flies a flat sail inside of a batten cage which
imposes camber on the sail by virtue of it's shape
and the lines connecting the sail to the cage...
which can be adjusted fairly easily to change
camber, is my favorite rig. It is rugged, and it
is simple, and eliminates things like a track and
cars, and expensive commercially made sails with
huge amounts of tension across the entire sail.
It would be particularly appropriate where two
masts are used.
The HP really falls
closer to a trimaran than a catamaran in terms of
payload and accommodations per foot LOA. Those
are my most heavily weighted criteria after
safety.