As mentioned in our last news, we had been studying weather in order to find a suitable northerly wind which would be favourable for Impi to head SE - I seriously wanted to visit South Fakarava to do some diving with the sharks.
Since we had returned to the Tuamotu Archipelago from the Society Islands - Raiatea - the wind made it impossible for us to arrive at Fakarava in the first instance which of course would have been ideal given the dominance of the SE trade winds at this time of year … a means to have the wind from behind whilst cruising through all the atolls to the NW of that location.
Anyway, this was not meant to be … you will recall our passage from Raiatea back to the Tuamotu Archipelago, and the shift in wind conditions with no wind at all sometimes, and this made it necessary to change our destination to the NW atoll of Tikehau. Any movement SE of Tikehau now had to be very carefully chosen to avoid being in winds from directly ahead and of course this meant that any wind from the north now became desirable. It is also a given, that the later one moves into the season, the more entrenched and dominant the SE winds become, so it was important to take any opportunity that presented itself to us to get south.
We were anchored yet again off the little hotel in Kia Ora Village where we downloaded, studied and plotted the weather forecasts and waited patiently for that window. During this time we also did some fantastic snorkelling and especially off a little motu called ‘Motu Nuhi Nuhi’ at 14*58S 147*38W.
In the photo above, one can see Motu Nuhi Nuhi and behind it the entrance to the pass ... 'Passe de Tiputa'
This little motu lies within one of the two passes accessible for yacht transit into the atoll … the pass known as ‘Passe de Tiputa’.
This photo is nothing special, but does show the entrance to the pass on a calm day ...
Talking about these two passes … both are located on the north eastern part of the atoll and Impi ventured through both of these. The more popular pass is the pass slightly to the SE of Passe Avatoru … this pass called ‘Passe de Tiputa’ … also the favourite pass for diving and snorkelling.
I have mentioned before, that Passe Avatoru is a very picturesque pass … it truly presents a beautiful and quaint vibe as one passes the little village of Avatoru, however, the area marked out to be an anchorage at roughly 14*56S 147*42W, is anything BUT an anchorage. At certain times when water is rushing in or out of the atoll (depending on tide), this anchorage becomes a rage and can be pretty dangerous.
By the way, this ‘rushing in and rushing out’ of water is of importance when diving or snorkelling in passes due to the ‘extreme water currents’, but also, for having conditions with best visibility.
A good way to remember this is as follows:
Check tide tables for the locations within the atoll in the proximity you will dive or snorkel at. When this is at low tide … think of the fact that the water at this point has dropped … and as a result the water in the ocean now moves from high to low (like the osmosis effect) through narrow passes and as a result rushes in through the pass to this location = INFLOWING CURRENT!
When it is high tide at this position, the opposite is also true i.e. the water at this location is at a higher level (Pacific ocean is at a lower level) and as a result water rushes into the ocean from the atoll through narrow passes = OUTFLOWING CURRENT.
The period between these two is referred to as ‘Slack’ (little current) although technically exact slack water is affected by delays in time whilst momentum build up is being reversed, and this differs from atoll to atoll. Other factors that can influence this is the angle of the pass to the wind that is occurring on that particular day (i.e. wind direction and strength) … also … some atolls have submerged reefs (usually on the south side), and since wind dominates from the SE there is a constant inflow on these atolls over the reef which means that in the passes here, there is a CONSTANT OUTFLOW … beware of these!
We also take into consideration the ‘Rule of Twelfths’ … something I consider is worth understanding. I would encourage sailors and divers to get a grip on this if visiting the Tuamotus ...
In summary, the Rule of Twelfths states the amount of water flow for every hour between tides …
So…
Low Tide = slack water (technically)
1 st hr = 1/12 of the volume that will flow between slack waters
2nd hr = 2/12 of the volume
3 rd hr = 3/12
4 th hr = 3/12
5 th hr = 2/12
6 th hr = 1/12
High Tide = slack water (technically)
It therefore goes to common sense that the most water movement by volume is in the 3rd and 4th hour = not a time to be messing about in the middle of a pass.
Of course there are always ‘exceptions to the rule’ and it is important to familiarise oneself with this when visiting different atolls … we would usually consult local people or even take a ‘first dive’ with the local dive centre if there is one and glean information from them for dives to come.
It is best to dive when the sun light is good (if possible at 11:00am) and about 1 - 2 hours after slack on an INFLOW current for good visibility … mostly because the fresh water from the ocean pushes into the atoll but of course on a building current, so one has to be cautious in observing conditions.
Snorkelling is better closer to slack since it requires being at the surface where one cannot slow oneself down by holding onto objects like rocks or dead coral heads and so on. Timing is crucial and it is extremely important to watch out for OUTFLOWING current since one does not want to be swept to sea or get caught up in the ‘rip’ where it would be difficult for someone in a dinghy to spot you, let alone the difficulty of retrieving you in these conditions. In some places, diving can be extremely dangerous on an outflowing current since where the shallows meet the deep a downdraft can be produced which will have the end result of feeding you to some very deep swimming fish!
Anyway, here I am being side tracked as usual, but this information can be of assistance when snorkelling this little motu. If you are planning to dive or snorkel in the pass on the east of this motu, then keep the above notes in mind … and … to a lesser extent but still of consequence, even if snorkelling north of this atoll the effects can be felt.
If you are snorkelling on the west side of this motu, then seriously there is no need to be in the know except for 'timing better visibility' … the area is safe and a real pleasure to be in the water at!
So here we were … on this occasion taking things easy and in relaxed style … decided to do the more mediocre, lazy stuff and snorkel off the west side of this motu.
Here the authority has placed a number of dinghy mooring balls for ones convenience and tying up to these costs … nada, nothing and free of charge … typical of French territory sailing … they believe in keeping our space in the ocean … free!
Dropping into the water was terrific … the corals in certain places are dead but prolific with fish life … and in most places there is live coral and very beautiful fish.
I must say that both Ana and I agreed that this is one of our ’top rated' places to snorkel and definitely worth doing if visiting the atoll of Rangiroa.
Our next letter will see Impi heading south to the very beautiful atoll of FAKARAVA ... after a few days stop over in ANSE AMYOT on the atoll of TAOU ... see you there!
No comments:
Post a Comment