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special explications:

Pharaoh's Nile boats

navigation with daggerboars or dipping steer-oar


An explication specially for a comming Abora expedition


[ img - tomb24Ghizeh.jpg ]

Weering procedure explained

How to turn around = weer a boat using an aft-mounted "dipping steer-oar"
- as the Pharaohnic Nile-boats seems to have had

Rudder-steering will accumulate deviations from a course and need therefore a permanent and active helmsman

Guara-steering auto-correct a deviation as a windvane
- just in the same way as a "dipping steer-oar" can balance the leeway
- and that was perhaps what the Nile crafts of Pharaoh did
The principle of 'balanced leeway' has no need for a helmsman - only a watchman for change of course

[ img - farao-E.png ]
[ img - farao-SE.png ]
[ img - farao-SS.png ]
[ img - farao-SW.png ]
[ img - farao-W.png ]
Condition:
One central steer-oar as some pictures show !
- if there are two steer-oars, as other pictures indicate, then use principally the lee oar, because the lee will be kept pressed against the hull by the water - what brings a change of steeroar in the turn (just as a leeboard).
Two steeroars seems mainly for downwind sailing.

Process step1:
When sailing ahead with wind abeam, then dip deep down your aft mounted steer-oar, to move abaft the hold in water.
Then the wind will begin to work:
A sail powered boat will react as she have to: letting her wind center = sailcenter = center of winds effort = CE blow down leeward of this new hold - and the boat therefor will turn her behind up against the wind!
Technical explanation:
This dipping action move backwards the Center of Hydraulic Resistance = CLR = the water centre = the hold in water - and your boat have got a new hold in water more abaft to turn around. And that she does.

Process step2:
Now you move your sailcenter to the other side by brasing around your sail - and all the while you swing around the yard, the boat synchronous will turn. You will feel it as your brases are turning the boat and not the sail.
Technical explanation: Too under brasing, the wind - just as always - will blow the sail center downwind the water centre

Process step3:
Now you have turned (weered) your reed boat or pharaohnic wooden and you have to enter on your new course.
That you do by balancing the leeway of aft-end, as you controll yourself by lifting (or dipping) your steeroar - balancing it against the leeway of fore end, where the bow is caught by the instreaming water.

Finally:
After balancing your course, you can tie the shaft of the steearoar to the pool again, because the craft is self-correcting - just as a windvane.

Try it yourself with any dinghy!
Dipping deeper the steer oar
will move the water-centre CLR backwards

Steer Oar down = Lee Helm   -   versus   -   Steer Oar up = Weather Helm
Farao-CLR22.pngFarao-
CLR11.png

Note the difference for same turn-manoeuvre "stern against wind":
A "for and aft" rigged boat as gybe or jibe has to swing the boom across (uncontrolled against wind) over to the other side.
A square rigged sailer weer (brace) under full controll.
And this difference is the reason, why oceangoing "for and aft" sailers prefer to tack and the square sailers prefer to weer. In that way both have chosen the safer and less violent turn-manoeuvre for each types of crafts.

[ img - farao-EE.png ] [ img - farao-SE.png ] [ img - farao-SS.png ] [ img - farao-SW.png ] [ img - farao-WW.png ]
Dip your steer oar   -   Brace your sail   -   Lift up your oar again

And as I see it (without reed-raft experience) the WEER-manoeuvre is specially apted for reed-raft with her lonely square sail and relative high gravitation-centre en relation to Meta-centre, due to no ballast is placed in bottom of any hull, but furthermore all gargo is placed on a deck on the top of the two reed bunches.

reed-raft-cross.png
cross sections of classic reed-raft from Titicaca


Talking number and amount of Guaras/leeboards/daggerboards, please note, that the balsa raft Tangaroa 1965 was steered by three Guaras only - one in front and two aft - passing the dangerous Tuamotu Archipelago of French Polynesia by own means.

- and the following is a simple text-transfer from:  www.runasimi.net

An observation from Egyptian tombs and pyramids


Handling a Thor Heyerdahl theme, we inevitable - by the RA reed rafts - are brought in contact with the ship-lore of ancient Egypt.

Around Nile seafaring

The Nile river is and has allways been used for transport of goods along its length, and this natural and simple water transportation system grew a key element in the development of the ancient egyptian civilization, and was therefore too the base for development of water crafts - their boats.

As a natural navigation channel and river road along all Egypt, the Nile was favoured by wind and stream. The waterway is known for its special conditions: row and drift downwards with the current against North - and using the steady North or North-Eastern trade wind to thrust the boats upstream against South. And this phenomenon probably in some way has been determinant conditions for the creation of their early sail culture on Nile and Red Sea.
[ img - EgyptTombOarBoat.jpg ]
Egyptian tomb oarboat from 1450 BC.
[ img - TombOfMenna.jpg ]
painting from tomb of Menna
[ img - SenneferTombShip.jpg ]
from tomb of Senenfer

drawings published by Victoria and Albert Museum, London 1906 - Ancient and Modern Ships, by Sir George C. V. Holmes
[ img - battleship of Ramses III.png ]
battleship of Ramses III
[ img - boat-from-fourth-dynasty.png ]
Egyptian boat from fourth dynasty
[ img - V+A.museum.png ]
Egyptian ship on Red Sea, about 1250 B.C.
Looking at ancient egyptian paintings of Nile boats - 3-6000 years old - from pyramids and tombs, several of the depicted boats show a central aft mounted steeroar. The steeroars are rather long shafted and reach over the head of helmsman.
The shaft are sustained and sometimes tied to a post aft - as to take some sideforces?
It seems as it has a rope as a sort of downhaul near top-end of shaft.
We have seen no tiller - and to handle a so big steeroar without tiller seems for us impossible.
Sometimes we see two sidemounted steer-oars on each side - and sometimes only one central placed.
Other pictures show three or perhaps more steer oars - and that "nobody" will do, if the oars have to be twisted.

Considerations
These observations does that we are NOT convinced, that their steerors were twisted.
That brings in the idea, that the egyptians sailing by sail used to tilt and not turn their steeroar, when they needed to adjust their course.
'Ballanced side-sliding' we explained earlier, and just in same way the egyptians could have done navigating their boats.
The balanced sidegliding could have been a useful technology too for the old Nile sailing. If equipped with two sidemounted steeroars, probably only the lee oar was employed, and just of same reason as Dirch demonstrated earlier with his dipping steeroar pressed to boat by the water.

When a drawing show three steer oars, these probably was set down in acordance with need 1,2 or 3 - but in the depicted case, a man with braces in hand indicate us, that this boat is under a turn (weer), and that justify a maximum water resistance CLR plunged down aft.

That bring in the understanding, that the pharaohnic steeroar really was a dipping steeroar, as was fixed in the stern and with the shaft sustained, pressed by the waterpress on the oar blade against the wind side of a short pool placed aft.
'Balanced leeway' we call it, talking steer principles

reiterated rule valid for ALL sail crafts - and therefore too for Pharaohnic boats
The wind-center CE will always blow dovn to lee of water-center CLR
and that is what define the pointing of a vessel

Consequence
If it really is a dipping oar, that tell us, that such Pharaohnic boats didn't tack - they weered.
They weered by dipping the steeroar deeper, and this action forced the aft-end upwind, and they could swing the sail around with the boat. In the moment of turnning sail over, they guide the shaft of steeroar up and over to the other side of the pool. And so they were sailing on the other bow!

Only technical condition for 'balanced leeway': to sail by sail. What they did only rowing is not clear - but rowing has not the same need for a rudder, as long at the rowers are within direct voice contact with the commanding officer.

Copy from a relief recording Queen Hatshepsut's expedition to the Land of Punt.
[ img - punt1-ship.jpg ]
retouched details from same
[ img - punt3-ship.jpg ] [ img - punt2-ship.jpg ]

Pharaohnic Nile conclusion
Just as Dirch used his dipping oar at preceding photo - the egyptians could have done likewise.
The balanced sidegliding could have been a useful technology too for the old Nile sailing.


I have no idea if the model-boat for the reed rafts of Thor Heyerdahl was of same kind, but his reed raft is told to come from the Upper Nile of Sudan. Furthermore the system of double steeroar looks like the oldtimers - but the steer oars are at RA II mounted with tillers as we can't see on the old paintings. Neverthemind - who knows - Heyerdahl too discovered his Guarasteering after his Kon-tiki raid.
Thor Heyerdahl sailed mainly his reed rafts downwind, when crossing the oceans, and with two steeroars aft, then he at least had moved backwards the CLR - and furthermore because the RA2-photo show the mast relatively ahead, then he cleverly too stabilized his sailing moving the windcenter CE ahead.

Thor Heyerdahl - RA II
[ img - Schilfboot_Ra_II.jpg ]

Perhaps by using the Pharaohnic principle with a short pool to sustain the shaft of his long steer-oar, Thor Heyerdahl navigating Kon-tiki in 1947 could have used less forces by dipping the same oar than to angel it, as he did. But he didn't know that, because he had still not learned about the function of his Guaras.

[ img - ThorHeyerdahl+styreaare.jpg ]


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Lima - May 2018