The word haga means e.g. 'bay', an inwards bent part of the coast.

Sometimes the implication is not only bent but broken as shown here, in Pa5-40:

"The Polynesians mingle the time-indications based on the position of the sun with others which are derived from the life of men and nature. We are told that the Hawaiian day was divided into three general parts, 1, breaking the shadows, 2, the plain, full day, 3, the decline of the day... " (Nilsson)

Pa5-40 presumably is an allusion to daybreak ('breaking the shadows'), because a bent branch symbolizes 'change'. The 'curved' was according to the Pythagorean school a 'female' trait':

“Freeman describres the dualistic cosmology of the Pythagorean school (-5th century), embodied in a table of ten pairs of opposites.

On one side there was the limited, the odd, the one, the right, the male, the good, motion, light, square and straight. 

On the other side there was the unlimited, the even, the many, the left, the female, the bad, rest, darkness, oblong and curved.” (Needham 3)

From this it is clear that there is a high probability for 'curved' to also imply 'darkness' in the minds of the Easter Islanders. This is one reason (among othersl) to interpret 'breaking the shadows' as going from the female night to the male day.

GD36 must be understood not only as the object 'bent branch' but also - and primarily - as a symbol for the flexible 'female'. The bent branch is soft and pliant, otherwise it couldn't be bent at all - under stress it would break to pieces.

2. Sailing charts, rib charts, should be mentioned here as another application of bent branches to simulate changes. An example from the Marshall Islands (ref. D'Alleva) was made from 'wood, shells, and vegetable fibres':

"In order to traverse these great distances, the Lapita must have been skilled navigators and sailors, just like their descendants, the Polynesians. Navigational techniques still in use in Micronesia may provide insight into the ancient traditions of Lapita and Polynesian seafaring.

In traditional navigational schools on Puluwat in the Caroline Islands, students learn how to sail outrigger canoes. As Puluwat sailors conceptualize a voyage between two islands, it is the islands that move rather than the canoe: the starting point recedes as the destination approaches.

Puluwat map the skies by the constellations and the ocean by its distinguishing features; islands, reefs, swells, areas of rough water. Similarly, a Marshall Islands stick chart uses shells to indicate specific islands and patterns of sticks lashed together to illustrate currents and common wave formations in a form that is both supremely functional and aesthetically appealing." (D'Alleva)

In e.g. Pa5-31

the path taken by the 'canoe' of the sun from early dawn to dusk (at which a hand is waving 'good-bye') is illustrated lika a bough; at dawn the change is at its quickest and therefore we find a more curved orbit there.

Before we condemn the Polynesians for their ignorance when thinking that the canoe is standing still while the island in front is moving towards them, we should consider our own similar behaviour: We say that the sun and the stars move across the sky from east to west, when we instead ought to say that it is the earth that is turning.

Reality is too hard to face. Therefore we prefer to say that the sky is moving - not we (on earth). If we traveled by canoe we would therefore (presumably) say that the water is moving - not we (in the canoe).

The similarity between sky and ocean on one hand and an island and a canoe on the other hand once ago was firmly established. Ships have always been female like Mother Earth.

3. The primary meaning of GD36 is change.

In the morning when sun is eliminating darkness,  'breaking the shadows' (daybreak), an inverted GD36 is located above the sun in Aa1-20:

The sun has a haga over him like a parasol. But we should perhaps say umbrella, because umbra means shadow. Whether the haga glyph is inverted or not, the meaning here is darkness.

It is easy to misunderstand this sign as the sickle of the moon (especially as the moon is a symbol of the night), but comparison with the parallel text in Large St Petersburg tablet makes it clear that it probably is haga. Haga and the sickle of the moon convey similar ideas: darkness. In the rongorongo texts similarity in form means similarity in meaning.

Darkness is a power contrary to light. At spring equinox (or dawn) light is strong and winning over darkness, at autumn equinox (or dusk) the light is weaker than the darkness.

At the solstices the powers of light and darkness are equal in strength, but it is there that the most important changes occur, slowly at first and then accelerating. At noon (zenith) we find variants of GD36 illustrating this, e.g. at right in Aa1-26:

In the Hawaiian language the word moai means 'bending over, arching like a tree', and at some point in life ('zenith') people indeed start to bend over, a process which is difficult to see at the beginning but very clear later in life. Their backs are no longer straight and their heads are leaning forward, starting to hang down like ripe fruits.