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- Summary
What we know
What we NOT know
Material & Tools
Fate of Log Rafts
Guara steering
Hull Shape
Sails on Rafts
Modern Gear
+ Addenda
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Inca's sail powered Balsa Log Raft

Essence = Synopsis = Summary

The result of our Guara research

The Kon-tiki raid of Thor Heyerdahl 1947 gave inspiration to many other primitive boat expeditions on the oceans of which only a part succeeded - and the rest did not.
Heyerdahl re-discovered the Inca rafts steer-system as since the Spaniards' first surprising meeting with a raft, has been something of a mystery for the european newcomers - they didn't understand how it worked. Obviously it still is a mystery, because none of the rafts as sailed out in wake of Thor Heyerdahl have returned to their port of departure.
With the last two rafts lost on sea, the decision was made to produce a manual for raft skippers: How to handle and how to use Guaras - and that is what is done with this publication.  
If there are any relation between the existence of Guara-steering in Asia and that of South America, we don't know, but that may be a theme for a next "Heyerdahl investigation" of migration over the same huge ocean.  

'Balancing of the Sidesliding' is all what a raft sailor need to know
We found two Guara explications:
1): The 'Balanced Sidesliding', where a craft with wind abeam balanced the leeway of aft-end versus that of fore-end.
This simple explication was mostly developed for in-line Guaras placed along the central balsa-trunk, but showed up of great general value for the most sail powered boats.
2): The 'Weather-cock principle' is where we on the broad log-raft utilize the cracks between trunks all over the raft.
By plunging down Graras in that way, may give a more stable pointing in relation to wind gust and big waves. That is so, simply because with Guaras in cracks more to windward we could obtain larger horizontal distance from the 'pivot point' = CLR to the CE = 'Center of Winds Effort'. And this CE will as usual blow leeward of the hold in water of craft = the CLR.

The hull of every sail-powered vessel (inclusive a Guara raft) has to be designed with high lateral hydraulic resistance - and low forward ditto.

Around the sails
CE as Center of winds Effort is strictly bound to the canvas. We are sorry about only to have a superficial knowledge of kite-boarding, but at least kite + board seems to follow the general rules of interaction between sail and hull
(and we don't know anything around "Flettner-sails")
Whatever you have of rigging, the task of a sail is to divide the force of wind in a lateral and a forward directed force.
The lateral force from sail together with the wind on hull and rigging is up against the high lateral resistance of the underwater-hull, and the result is the leeway - as hopefully is low, exactly because the lateral resistance should be high.
That is the forward aimed force as push the vessel ahead, and the vessel will accelerate until the generated forward resistance of hull match the thrust from sail.
The relation between forward hydraulic resistance and hull speed is rather complex, and is normally defined empirically by hydraulic tank tests, as did the Kontiki2.
Of course the same hydraulic rules are valid too for the leeway movement - and with same complexity.

Summary of Guara steering:
Use your Guaras to place your CLR - your pivot point - where you want it,
and the wind will blow the Centre of Wind CE leeward of this Center of Water Resistance CLR
- and if your sail is adjusted for this pointing, you are sailing -


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If you are in doubt, how wind and sea work together their centres CE and CLR
- then ask a wind-surfer.

He has no rudder other than a fin (a Guara) aft -
moving around and balancing CE and CLR is what he use for surfing -
and the rules for his wind board are the same as for your sail vessel.

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The more SCIENTIFIC relation

Inca's sail powered Balsa Log Raft

The core of sailing by Wind

The pointing of ANY sail-powered vessel:

As an extension of those two named "Guara-theorems" we discovered the general relation between the two centres CE and CLR, and found that it is those two point of attack for the only two present natural elements as determine the pointing of any sail powered ship - and overall seen, we steer by influencing on position of this two centers by using rudder, Guaras, sail etc - - -

CE and CLR is a scientific way of looking at the steering of sail vessels, as we don't use everyday. We normally rely on and talk about the rudder position and balance of sails - and nothing more fundamental. But CE and CLR is used in mainly technical considerations by design of sail yachts.
By setting sail and plunge down some Guaras skipper adjust his CLR, and he can point the raft all the compass around - because the wind will blow CE leeward of CLR.

And talking dynamic CE and CLR
The rule is simple:
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The wind will blow CE leeward of CLR
- and if your sail is adjusted for the now pointed course, you are sailing

That means, that where a ruddersystem normally need a helmsman as continously control and correct the course, a Guara-system doesn't have this need.
It is a great self-steering system, where the raft herself act as a wind vane, making very stable autocorrection in relation to the wind.
The crew could be ocupied by other - as go fishing for their next meal.

One thing is pointing, but that is the forward headway as together with the lateral leeway define the true course over the ocean.

Sailing ahead, the bow is pressed into the sea, and in that way side-sliding of fore-end is restricted. More forward speed = more restriction.
Sailing speedy ahead a skipper therefore can use more foresail - and a raft skipper, as normally has no foresail, he now need less front-Guaras and can therefore lift those upwards, as they only brake the headway.

When sailing with wind abeam the skippers on sail crafts often are talking 'weather helm', even if that is their aft-end as slide sideways with wind - or more scientific we could say:
Sailing-on, the water press onto lee bow is influencing on the position of CLR, as move ahead, but fortunately it is followed by the CE as too move ahead, due to the sails are sheeted out and perhaps too heeled. Playing together so, the sailing will only need minor adjustments of Guaras - or angeling of rudder.

A trimmed vessel is neutral in her steering, when sailing with wind abeam - even a rudder-steered vessel. If not trimmed, the vessel need to activate her ster-system.
Any trim on any sail-powered vessel (on rudder-steered crafts as well as rudder-less sailers) is fundamentally done by adjustments on CE or CLR - or both.
Logically it must be so, because wind and water are the only natural elements, as yield forces on a sailing vessel - and they attack of course in their own centers.

Speaking figurative:
The wind will always blow its center of attack down to lee of the crafts hold in water. Thus in that way the actual CE and CLR together will define the pointing of the vessel!
We could say that your boat is stretched out (or suspended) between its CLR and its CE, as thus define the pointing - and heeled (those who can heel), even more evident!

A "laundry line" between blow of wind and resistance of water  to make you remember  CE and CLR as the attack points for wind and sea
- and that is those two "attack points" as define the pointing of your craft
You steer your craft by a rudder, as push on the streaming water
- or you steer her by a dipping oar or Guara, as balance the leeway of aft end against that of for
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blowing of wind

close reach[ img - suspend-dinghy.png ]
broad reach
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beam reach
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resistance of water
- but whatever you use to steer, you manipulate the position of CE and CLR
- as said:
that is the position of those two centres as define the pointing of your sail powered vessel
ALL sail powered boats are suspended /stretched-out between wind and sea - just as these examples shown here

After ended edition came the Patín Catalán
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sailing wind abeam
The 'Patín a Vela' = 'Patín Catalán' is a class of boat, as is shaped as a double hull dinghy. It is interesting, because she is born without rudder nor Guara. The Patín Catalán is steered by moving CLR = relocating the weight of crew (1 man) and adjusting CE by sheeting in or out.
With an open deck as banks all around the mast the sailor can place his weight where he want - and the boat will react.
Note right photo: The sailor have moved his weight (CLR) to extreme aft, and the wind is just now blowing the CE to lee of that - and the patín is turning.

The laws of nature for this patín (patín in Spanish means skate in English) are the same as for any sail powered vessel.

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turning around a way-point

Rudderless sailing, wind surfing and kite boarding together with the Patín Catalán, are all the active sport verification of the thesis:

The wind will blow its center of effort down to lee of center of hydraulic resistance

- and pointing of the "vessel" is defined by those two centres -

kly site - Lima, November 2019 - Fifth edition of this page #0