The square sail

Less than perfect attention to my history lessons and the same at Jorvik Museum meant that my concept of Viking ships was Leif Erikson, skulls, horns and boats which were pointy at both ends, plus they had colourful square sails.

It’s only been in the past few weeks that I’ve done my homework and have been most surprised – these were not primitives in the designing and building field, there was much thought behind the boats. Of course that evolved over time.

I’ve always wondered why the sail was square and not trapezoidal, the latter being the more pleasing look and the one used on tall ships. However, they persisted with the long yards – I’m thinking it’s so that the leading edge [luff] is shorter and therefore better able to be made tight. Looking at today’s replicas, they apply various lines to that leading edge.

Also a shorter sail foot means lower aspect – not by much, admittedly. Plus heading downwind, a very long foot has to be kept out to sea on both sides. With my Bruce foils out there, that would be possible but the idea was not to overpressurise those crossbeams by attaching anything lifting to them, so I see I am forced back to the square, which is easier to replace anyway at a moment’s notice.  Three or four spares can be kept folded down below.

It really is a simple sail and the more one thinks it through, the less fiddly and messy the rig actually seems. I mean – one sail only. I always thought these boats could not go upwind but a glance at the clip at the top shows that that is not so.

The two key questions are – can the boat tack [go through the eye of the wind] and can she point [go upwind]?  Look at that clip again and decide whether she can point.

As to whether she can tack, hmmm – my answer, based on what I’ve seen is – not well.  In fact, she might be better wearing:

Neither boat is designed for close inshore work but the Viking boat will do better because the foot of the sail is loose, unlike the tall ship’s and therefore it forms a natural Bernoulli curve, albeit with shallow camber, with the maximum depth about 35% back, as it should be, with the assistance of lines to the leading edge and foot.

The boat’s not intended to tack back and forth, as in a racing situation – she’s better heading for the Fastnet or Ireland or France.

Given that she is flatbottomed and light, she could tear into the tack when it’s time to go about – it’s the technique I used for the cats, always tear into the tack and “sail” her around.

If the manoeuvre fails due to a sudden wave or whatever, then just let her slide sternwards, reverse the rudder and haul the rig to the other side at the right time.

On the grounds that this is not insurmountable, how about sail area? Having just short of 500 sq ft on one mast does put a lot of stress on that mast, plus it is taller, wider and heavier, more difficult to drop via the tabernacle in a storm with a crew of three.

So drop it before the storm.

I looked at the variants and came to two separate rigs, one stored in a cradle on the port side and one stored in a cradle on the starboard. One is 480 sq ft and reefs to 420, 360 and 300, before it comes down and the N2 rig is 240 sq ft, reefing to 180 and 120, After that, it comes down and the storm jib is set before the mast.  Lastly, the mast comes down and the stormjib triangular cradle goes up.

Each reef of the main, of course, shortens the luff and that’s desirable, is very low aspect now and therefore inefficient upwind, also desirable, less heeling moment, also desirable.

The obvious criticism is that it’s a very long yard but if you observe in the clips, the yard is only aloft in light winds.  In heavier, it’s half or even quarter mast.

Plus one more thing – a short boom does not telegraph its swing, it can suddenly back up and hit you at any moment, it swings right and left behind the mast like a bronco let loose.

The Viking yard is heavy, moves less, is balanced either side of the mast, is thick in the middle, lighter at the ends.  When it swings, it’s a major event in which it telegraphs its motion before it does it.

The Vikings did think this through.

Criticism of the video:

There were too many landlubbers on board, old codgers too.  One nearly lost his arm, another was walking about with no concept of roll, the foot had a block with no line just swinging  in the air at head height, there were so many things  which annoyed.

But the boat and sail were nice overall.

https://www.why.is/svar.php?id=4730

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3 comments for “The square sail

  1. The Blocked Dwarf
    November 9, 2018 at 13:09

    That boaty mcviking boaty thing seems -to my lay eyes- to be going along at a fair pace (remember the only comparison i have is of Cross Channel ferries-if God had meant for me to enjoy ‘life on the ocean wave’ he would have made me a fenlander and issued me webbed feet when I was born- he didn’t, I don’t.)

    Question JH, what sort of speeds could those things sail at? It takes a modern ferry between 4-8 hours to cross from East Anglia to Hoek, depending on type of ferry.

    • The Blocked Dwarf
      November 9, 2018 at 13:17

      Apologies, just seen the linky at the very bottom of the page.

  2. November 9, 2018 at 13:30

    They claim around 16 knots downwind, with favourable breezes, about 6 knots upwind, which is about what you want in reasonable comfort. You’d want to be able to do about 250 nm in a day when voyaging.

    Just saw this:

    https://youtu.be/kb2HDL-tMq0

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