Re: Sailing to windward: Was Draw -plate


"David Starr" <dstarrboston@xxxxxxxxxxxx> wrote in message
news:hdudnTRRapyVsVXZnZ2dnUVZ_t2dnZ2d@xxxxxxxxxxxxxxx
Eric Stevens wrote:
On 25 Jul 2006 15:20:20 -0700, jacklinthicum@xxxxxxxxxxxxx wrote:

Eric Stevens wrote:
On Tue, 25 Jul 2006 13:09:31 +0100, "Vaughan Sanders"
<vjs@xxxxxxxxxxxxxxxxxxxxx> wrote:


So why do you think the Mediterranean adopted the square rig over the
Arab
lateen?
Maybe because ships of the Mediterranean had been using square sails
for millennia before the lateen was invented? By the way, according to
George F. Hourani in his 'Arab Seafaring', the lateen was most
probably invented in the eastern Mediterranean and later found its way
into the Red Sea where it became the conventional rig.

According to
The Carrack / Carvel was the sum total of all European knowledge, but
those
of Columbus and Drake adopted the Norse square rig (not Roman btw)
over the
Arab lateen which is a very efficient sail.
They used a square rig but not the Norse version. See
http://viking.sjolander.com:5150/wiki/index.php/The_good_boat_Nutshell
for the diamond lattice grid of ropes which restrained the Norse
sails.


The Norse perfected the art of rigging these sails so they could sail
to
windward, and this technology had reached the Med by the 14th century.
That's an interesting claim but I know no basis for it.
A large lateen is almost impossible to tack and gybing is not much
better.
http://en.wikipedia.org/wiki/Caravel
Square sails don't like tacking either.



Eric Stevens
If I have my facts straight lateen sails require the entire boom to be
lifted with the sail to change to tack

The actual method of tacking would be a long and arduous process. It
would entail hauling down the sail with the spar and physically move
the entire apparatus to the opposite side of the mast. It is probable
that this was done in the destined port in anticipation of the return
journey.

Apparently it was not unknown for lateen sails to be tacked so that
they lay against the mast.

Apart from that, http://nabataea.net/sailing.html has some interesting
comments.



Eric Stevens

"The Ship" (Bjorn Lindstrom) has a drawing of tacking a lateen rig. The
*** is loosed, letting the sail luff freely. The takes any strain off
the rig. The lateen yard is then heaved straight up-and-down. Then the
short lower end of the yard is worked around the mast so that it is to
leeward on the new tack. Compared to a modern Marconi rig, this is a lot
of work. Compared tacking a single square sail, it's harder, but not by
as much.
Your nabataea reference places undue stress on the sail form, implying
that the lateen rig is a technological advance with superior pointing
ability over the square rig. In actual fact, either rig will go to
windward once the sail is trimmed in to set fore-and-aft. Viking square
sails could be set fore and aft, and the crew of a modern replica Viking
ship told me that they could point up 50-55 degrees, not quite as good as
a top flight modern Marconi rig (45 degrees), but respectable. I spent
several summers sailing on an old wood ketch which could not point much
higher than the Vikings could.
The Vikings carried a beitass pole. When going to windward one end of
this pole was stepped into a chock on the deck, and the other end was
lashed to the windward corner of the sail. The pole, properly lashed in
place, kept the windward edge of the sail pulled taut and kept it from
luffing. A modern spinnaker pole works about the same way. From
"beitass" we get the modern phrase "beating to windward". Needless to
say, tacking required unrigging the beitass pole and then rerigging it on
the new tack.
Later 18th and 19th century square riggers had trouble bracing their
yards around fore and aft. The yards would hit the shrouds (standing
rigging) before they reached the fore-and-aft position. Viking masts were
short and stout and did not need shrouds, so bracing the single yard
around fore-and-aft was no problem, making the longship more weatherly
than later square rigs.
At sea, with the wind astern, the square rig is superior to the fore and
aft rig because gybing is not a problem. Running down wind with a fore
and aft rig, the sail is winged far out on one side. A small windshift
will catch the sail on the wrong side and flip it violently onto the other
tack. An accidental gybe is a serious matter, it can break heads and
spars.

David Starr


I think the beitass was a "stretching spar", it was not connected to the
deck, it went into a block on the main spar and the leading edge foot was
connected to it.
This allowed the leading edge to be pulled taunt, much the same as battens
in a modern sail, there would be no need to remove it to tack. There is no
reason why two could not have been used during a tack, the new leading edge
beitass being tensioned as the other was removed, and after the transition
of the main spar.

Speed of the transition is the key, I've no doubt a lateen could be sailed
"back-winded" or even "clew first", which would get you out of trouble in
the Med but not in the Atlantic.

A line from a 12th century poem and a block from Skuldelev 1 is about all we
know of the Viking beitass.
"ut berum as at beita" ... we bear out the spar to sail close-hauled.

Jamie

..


.

Loading