logo Arnamentia's Web Diary
Date: 17 Jul 2012 22:40:47
Title: Tuesday 17th July - Approaching the Dangerous Archipelago

15:15.84S 144:30.68W

Tuesday 17th July –  Approaching the Dangerous Archipelago

One thing we had to achieve before departure from the anchorage in Hakatea Bay was the much delayed cleaning of the topsides and waterline which were still looking a disgrace after the crossing from the Galapagos to the Marquesas.  But this is not easily achieved in a rolly anchorage.  However, after much prevarication we got on with it on the morning of Saturday 14th.  Many such tasks of boat maintenance are worse in anticipation than execution.  Not so this particular one this time.  It was ‘orrible.  However we got the worst of the fouling off even though getting under the counter at the stern proved impossible in the swell.  A crash helmet might have been useful for that purpose.

So, when to leave for the Tuomotos?  We had about 540NM to go to our chosen first atoll, Keuehi.  That meant that we’d have to plan our arrival date as Wednesday 18th.  That being the case, we needed to be off the entrance to the atoll at 1045 local time (GMT-10) to catch the short period of reputed slack water following low tide.  Why so important?  Give us a mo and all will be revealed.  We also needed to leave the Hakatea Bay anchorage in daylight.  If we left at dawn on Sunday 15th we’d have to average a little over 7 knots to make it in the 76 hours or so available.  Chances of that given that for much of the voyage we’d be dealing with a 25 knot (F6) ESE breeze and we’d be heading SSW?  A near certainty.  Consequences of unlikely failure?  Heave to for 24 hours + and await the next opportunity.  If we left at sunset on Saturday 14th we’d have around 88 hours to do the journey and would need to cut our speed to around 6 knots on average.  Chances of achieving that – even triple-reefed with a handkerchief sized rolled up jib but big enough to punch through the swell?  Negligible unless we towed a drogue or a couple of buckets.  Consequences of almost inevitable failure?  Heave to for a night close to destination but far enough away to be out of danger.  On balance we chose the latter.

Why is the timing so important here?  Well, the Tuomotos have long been known as the Dangerous Archipelago for good and sufficient reasons.  They are very low-lying coral atolls and the tallest things visible are the tops of palm trees whose bases are within a few feet of sea level.  So, typically, the first indications of them can be seen only from a distance of no more than 8 miles in good visibility.   Then there is the charting.  This all well pre-dates GPS – often by several centuries.  Which means that GPS position and chart information may differ by several miles – usually a longitude problem; the same issue that plagued the Admiralty for many years until Harrison devised a clock that kept accurate time at sea.  Typically the islets surrounding the lagoons within the atolls are clustered on the northern and western sides whilst the southern sides are made up of coral reefs which are awash and very difficult to spot at any distance.  Meanwhile the sounds of the wind and the sea mask the sounds of the breakers on the coral.  There are narrow passes into the lagoons in those atolls that are navigable.  At its peak, the rate at which water exits those passes is often enough to create dangerous standing waves at the entrance (enough to overwhelm a yacht) and anyway you’d need a very powerful engine to counter that flow.  Whilst you are doing all that just bear in mind that you have coral heads all over the place that need to be identified and steered around.  So, all of that suggests pretty strongly that you arrange your entry time with some care – slack water and good daylight.  There is often and in many cases an outflow, no matter what the state of the tide, caused by the prevailing easterly sector winds pushing water across the windward reefs of the atoll into the lagoon.  But, the rate of that outflow varies markedly with the tide.  If you want to be in any sort of control on exit you need to pay attention to your planned time of departure as least as much as your planned time of entry.

We departed Hakatea Bay at 1645 on Saturday 14th and headed out into the 25 knot ESE wind.  Not surprisingly the situation at the entrance to the bay was pretty bumpy but Mr Perkins did his thing, albeit a bit slowly at a couple of knots over the ground, in getting us clear enough to hoist sail.  We banged in two reefs immediately and shortly thereafter put in the third reef and an absurd 9 rolls in the yankee once we’d established that we were making well over 8 knots.  We know we’re going to be too early but let’s be reasonable.  The next 48 hours can best be described as wet, lumpy and too fast (still over 7 knots) as we barrelled our way SSW beam reaching in a 3+ metre swell abeam from the east superimposed on the top of which were the waves associated with a ESE F6.  Regrettably, even less sail would have meant even more rolling.  Ho, hum.  Last night the wind abated somewhat to a more manageable 20 knots and the swell began to decrease – although naturally that takes several hours to take effect.  At 0800 this morning, with only about 80NM to go and 26 hours to do it in it was obvious we’d have to heave to in due course.  We tried rolling the yankee away completely to slow us down further but the rolling was horrible.  So, here we are; triple reefed with about a dozen furls in the yankee which make it look like a very unattractive duvet cover – possibly artistic but you’d have to ask an expert like Tracey Emin.  Speed is now a little under 6 knots and we’ll have to heave to some time this afternoon until a bit before dawn if we are to drift about well clear of all dangers.

For some reason the baby stay decided to break at its foot around midnight last night.  It’s a minor problem – I think.  I very much doubt that we’ll see the mast fall over for lack of it and we can probably get it fixed when we get to Tahiti.

On a final note, we put our watches back a further half hour at 0800 this morning to conform to Tuomotos time.  Apart from anything else we want to keep the calculation of times of slack water as simple as possible and the tidal information for the Tuomotos is based on GMT-10 hours.  So, it’s approaching midday now as far as we are concerned and it’s approaching 2300 in the UK.  Sleep well!


Diary Entries