We had to sail El upwind and uptide for 300m in a 50m wide channel a couple of weeks ago. I would not want to be doing it all day long, but it was not too hard. A couple of 10 year olds were doing the sheet and steering. Shunting in this situation was safe, as if they stuffed it up (happened while trying to avoid a power boat coming in) it was easier to correct than getting in irons on a tacker.
Shunting a schooner is not as hard as it appears. The fore sail is sheeted on first, which eliminates any tendency to luff up and the air off the front sail blows the aft sail almost all the way in. The last little bit is very lightly loaded as it is in the disturbed air of the fore sail, much like a jib and mainsail configuration. This works well to meet the requirement for more sail reaching than upwind, without requiring extras.
Just found and uploaded an old, poorly filmed (the camera was in a cut off plastic Coke bottle to make it waterproof) and even more poorly edited video of W, a 12m/40' cat I designed and built in NZ 20 odd years ago. It has a single rudder and a daggerboard mounted on the single beam. It tacked reasonably well (1min 40 secs), given that this was the first sail, the main was not cut for the very stiff mast and the jib was sheeted to the mast.
http://www.youtube.com/watch?v=o6Z97sslgm4.
On the end of it is a TV clip about the windmill cat, 30 years ago.
Dennis,
Looks good. When are you starting to build?
Couple of details:
1) rudders a long way back are hard to access to lift them. I find weed and reducing wetted surface for reaching/running are the cause more often than shallow water.
2) Outboard masts solve the dropping problem, but the drag will be huge. Will you have to remove the sail and boom each time you drop the mast?
3) What is the purpose of the platform? If the boat has enough sail area to be fast, you will be sitting on the ww hull most of the time, and on the lw one the rest of it. There is not much middle ground as, once you start moving, the apparent goes up very quickly. Clambering over the platform to balance the boat, and to reach the sails and rudders will be harder work than necessary.
4) Folding looks good, just make sure all the overlaps are big enough to support the righting moment and that it all locks into place, rather than relying on lines.
rob
On Fri, Jul 27, 2012 at 11:40 AM, Mike Crawford
<mcrawf@nuomo.com> wrote:
The one time I'd want to tack a Harry would be to short-tack up a
long inlet in light breezes with a schooner rig.
I've got about five miles to truly open water, and switching two
sails over on every shunt could get to be a bit of a hassle,
particularly because the inlet narrows to 1/2 km at points:
http://mapq.st/OyFukp
It's for this reason that we're upgrading our monohull to a
self-tacking jib. I actually do like to tack some of the time, the
way I also like to drive a standard transmission some of the time,
but there are days when it's nice to just steer without getting up
or putting down one's cold drink. The catamaran won't really handle
a self-tacker, so it remains old-school.
In any case, it would be neat to have the huge sail area and lower
COE of a schooner while tacking when the wind is right.
Very light breezes would demand a shunt, perhaps with the lw hull
to windward. Heavy winds would also demand a shunt. But in the
middle area, tacking could save some time.
That said, it's possible I'm making the wrong assumptions about
shunting.
- Mike
Rob Denney wrote:
I have never seen the need to tack a harry. Shunting is
just too easy and diagonal stability too low to do it in
any sort of breeze. A few years ago I designed and built
a cat (W) with the ballestron rig in one hull. It tacked
pretty easily, so no reason why a similar proa wouldn't.
Gybing is a different ball game. In narrow waterways,
gybing is handy when running dead square.
The key is not so much making a boat with low enough
windage etc to tack, but having both hulls the same length
to make it safe. There have been a few "harry cats"
drawn, but apart from W, none built, mostly because a proa
makes more sense.
rob
On Tue, Jul 17, 2012 at 11:12 PM,
bjarthur123
<bjarthur123@yahoo.com>
wrote:
so can the visionary's tack? i assume
elementary can since it has no cabin. ditto
for any traditional pacific proa like
russell brown's. one would just need to
arrange for the main sheet to accommodate a
load from the opposite side.
would be an interesting exercise to design a
full-sized harry that could point well
enough to tack. unarig i presume for
efficiency. fairings on the beams. i wonder
if the accommodations could be kept as
spacious.
do you think it would be more difficult to
tack from rig-to-lee to rig-to windward, or
vice versa, or both the same? i presume
gybing is not a problem.
ben