Re: Skuldelev 2

On Wed, 19 Apr 2006 21:52:40 +0100, "Vaughan Sanders"
<vjs@xxxxxxxxxxxxxxxxxxxxx> wrote:


"Vaughan Sanders" <vjs@xxxxxxxxxxxxxxxxxxxxx> wrote in message news:...

"Eric Stevens" <eric.stevens@xxxxxxxxx> wrote in message
news:3ija42lmppun7omkmnkjl5268l6auodt2j@xxxxxxxxxx
On Tue, 18 Apr 2006 18:45:19 +0100, "Vaughan Sanders"
<vjs@xxxxxxxxxxxxxxxxxxxxx> wrote:

snip


(A simplified version of Eagle tacking)
On the command "helm alee" rudder is applied while simultaneously hauling
the stern spanker boom amidships, the mainsail quickly starts to luff and
is doused, then as the foresail luffs it is backed and the mainsail hauled
on to the opposite tack while still blocked by the foresail. At this point
she is approx head to wind, as the backed foresail pulls her around the
mainsail is set on the opposite tack along with the spanker, then as she
falls off the order is given to let go and haul the foresail, at this
point because the foresail is backed the wind will assist with the haul if
the timing is correct.

Jamie


This from the Viking Ship Museum explains how the sail could be backed, they
btw seem to see no problem with these ships tacking.
http://www.vikingeskibsmuseet.dk/page.asp?sideid=616&zcs=402
"The Viking ships' square sail was, in size and shape, developed together
with the individual hull size and type of ship. The central crucial factor
is the elementary balance between hull, sail and rudder when sailing against
the wind, i.e. sailing close-hauled.

If the sail is too broad relative to the hull and the shape of the hull, the
ship seeks away from the wind - it has lee helm, and cannot tack against the
wind.

If the sail is too narrow, the ship turns into the wind without the rudder
being able to prevent this - it has weather helm. If this is not corrected,
the ship is dangerous to sail - in fact it is useless as a sailing vessel.

If the sail is too low, the ship will sail too slowly and it will first sail
properly when the wind is very strong.

If the sail, and with it the mast, is too high, the load is too great and it
is necessary to reef the sail too early.

Further to all this, it is vital that the individual types of ship are
ballasted and loaded correctly.

All these factors can be followed closely on Skuldelev 3, which not only has
traces of the mast preserved but also has tacking holes for securing the
sail forward at the rail, and sheet holes towards the stern to take the
sheet. The breadth of the sail can therefore be calculated precisely."

For the sail to back, sheeting lines need to be connected to both sides of
the boat or it would just fold up around the mast.

Interesting,

There is not a word either in your quote, the URL you cite or the
pages linked to the URL which say anything about the views or
experience or views of the Viking Ship Museum about the ability of
Skuldev2 to tack.

As for the discussion about lee and weather helm in relation to the
proportions of the sail, I am sure the Vikings knew about the need to
position the mast in the right place and how fine tuning could be
attended to by raking the masts back or forward.



Eric Stevens
.

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