West Lothian, four-masted full-rigged ship

Shipbuilder
9th July 2014, 17:57
Just completed this drawing. British full-rigger West Lothian.
Completed 1882 by Charles Connell, Glasgow. 1,882 gross tons. 279 feet 5 inches long, 40 feet 5 inches beam.
Sunk by U93 on 18th April, 1917. All survived, as the U Boat commander allowed them to get away before sinking here with a single torpedo.
Bob

Pete D Pirate
9th July 2014, 22:44
Shipbuilder,
Nice drawing.
The progressive 'stagger'* of the masts is interesting, I've not noticed that on tall ships before.
Can you explain the reason for that for me?
*What is the term for the rake of masts?

Cheers,
Pete.

Shipbuilder
10th July 2014, 06:32
Hi Pete,
The correct name is, as you say, rake! I have no idea why they did it. It may just have been to make them look better, as ship design at that time usually involved making the ship look beautiful as well as functional (scrollwork, figureheads,etc). The angle of rake of the masts is usually noted on the plans for each individual mast.
There is very little interest in this type of ship these days, which I find rather sad. I doubt if the obsession with Napolenoic warships will ever die down in favour of these old iron and steel beauties of the late 1800s.
Bob

TOM ALEXANDER
10th July 2014, 07:15
Hi Pete,
The correct name is, as you say, rake! I have no idea why they did it. It may just have been to make them look better, as ship design at that time usually involved making the ship look beautiful as well as functional (scrollwork, figureheads,etc). The angle of rake of the masts is usually noted on the plans for each individual mast.
There is very little interest in this type of ship these days, which I find rather sad. I doubt if the obsession with Napolenoic warships will ever die down in favour of these old iron and steel beauties of the late 1800s.
Bob

I believe the reason for the rake in the masts is two fold. One is that the major wind pressure on the sails, and hence the rigging on each mast was usually from aft, and the weight of the mast leaning backwards would require less strain, and less robust rigging to support each mast. Hand in glove with that is that when a ship was running before the wind in heavy weather, as the bow ran into each sea there would be a considerable braking effect and the after rake on the masts would absorb the forward momentum of the rig and also take into account the head down trim of the vessel. At some point it is quite likely that the masts would be forward of the vertical when running in seas. You will also note that the rigging, especially the lower shrouds are also led aft for the same reason. This applies to all sailing vessels and is even apparent on modern racing boats.

Pete D Pirate
10th July 2014, 08:28
Thanks, Shipbuilder, thanks Tom.
I understand the purpose of rake on the masts but what drew my attention to the Lothian design was that each mast, fore to aft, has a progressively greater angle of rake.
I'd not noticed that on tall ships before.
Any thoughts?

Cheers,
Pete.

Shipbuilder
10th July 2014, 11:43
They are usually like that, but I can't imagine that a slight rake aft would add any great strength to something as strong as a steel mast backed with numerous steel shrouds and backstays. It might even weaken the structure when the wind was on the fore side of the sails when tacking or accidentally caught aback? Not all that many forestays!
Anyway, they certainly look better with a backward rake!
Bob

Pete D Pirate
10th July 2014, 17:18
Thanks again, Shipbuilder.
I'm not expressing myself terribly well.
The bit that caught my eye on the Lothian drawing is that the masts all have different angles of rake - going from fore to aft, ranging from, say, 1 degree of rake on the foremast, progressively increasing to, say, 3 degrees of rake on the mizzen.
Hope this makes my question a little clearer.

Cheers,
Pete.

Shipbuilder
10th July 2014, 17:46
Pete,
Yes, I knew what you meant exactly. I have no idea why though - that is how it was! It also seems standard for all ships of that era.
Bob

Pete D Pirate
10th July 2014, 21:18
Oh, OK - thanks. I'll take more notice in the future.

Cheers,
Pete.

TOM ALEXANDER
11th July 2014, 07:26
I think that the action of wind on rigging is a very complicated thing, and there are so many variables to consider that it is impossible to cover all eventualities with one design. The main thing to consider though is that square riggers were designed to mainly run before the wind, otherwise they would be barquentines. (Fore & Aft rigged like schooners.) Thus the wind approaching from aft would exert much more pressure on the mizzen than the main, or foremast which would be in an ever increasing wind shadow. Also please bear in mind that the masts, in effect, because the wind velocity increases the higher you go, act more as levers than a lineal force on the vessel. When square riggers are beating to weather, if you can find photos, you will note that the upper sails are trimmed differently than the lower, with a pronounced twist the higher you go. This is because the apparent wind direction ( a composite of actual wind speed and vessel speed) changes with altitude. Also when going to weather, the major force on the masts would be lateral, thus the forward shroud being abeam of the mast. There were normally sufficient fore and aft stays where those forces were transmitted from each mast component, lower, top, upper top, etc., right down through the bob stay to the vessels forefoot. I do note that the West Lothian doesn't appear to have a single bob stay, nor a dolphin striker, but rather several bowsprit stays to the hull, which would probably be sufficient given the bowsprit to be of stout steel construction.

Shipbuilder
11th July 2014, 18:03
Yes, that all makes sense. There is a very short stay between the steel bar that extends from bowsprit end to bow. I suppose that short stay at right angles to the bowspit is a token dolphin striker, but hardly worthy of the name. There were also the steel rods that you mention. The whole ship was very strong and as far as I know was never dismasted or damaged in 35 years of sailing.
Bob