00z Jun 4—Anchored and moored waiting for less wind

Background: Notes here on our Google Earth tracking of Jacob Adoram         Index of Google Earth overlays.  Download the KLM file.

New KML online now with new charts and routes

We got word yesterday that the wind was relentless at 170 to 180T at 30 kts gusting to 35.  This was simply unmanageable so he looked for first opportunity to anchor and wait it out.  He found a place just on the west side of Flynn Reef, and we made a new chart insert to show this on the google earth. Please update the KML to see it.

As luck would have it, after his anchor caught (a 16# Danforth,  with 200 ft of line) and he played out the line, he noticed a mooring buoy right there so he is tied to it and his anchor...which is good news as the winds are still strong.

Below is a pic Jacob just sent.

Jun 4 03z.  Notice the prominent streaks on the waves.  That is a typical telltale sign of wind approaching 30 kts. 

It's hard to see in this pic, but he says he can see the green water ahead where the reef is located. ("Green water" and green reef on the chart is a coincidence of course. The latter simply means that at zero tide height the reef is exposed... depending on the waves.)

We also see here his two radar reflectors; the antenna on the top is maybe his AIS transceiver to monitor traffic and be monitored. The white instrument looks like a sonic anemometer. The boat is moored at the bow.

I thought his discovery of a mooring buoy was really unusual, but these are what the dive boats hang onto while diving the reef.  He is just off the reef to the west, both anchored and moored.

You will also notice on the Google Earth display a huge spread in the GPS fixes.  This is not normal!  This comes about because his GPS receiver antenna figuring the tracking positions is on Iridium Go box and that is below decks, in fact even worse, under a solar panel.  The GPS antenna can barely see the horizon, which limits the view to only a few intermittent satellites, maybe even in the same direction, and hence to poor fixes. In this case really poor fixes. If we had this GPS in hand, it would be warning us of this; the tracker code does not do that.

Users of the popular Iridium Go should be aware that the GPS antenna used for the tracking signals is in the stubby antenna connected to the box.  Even if you have a very nice external antenna that enhances the satellite connections this does not improve the GPS. There is no GPS receiver in that external antenna.

Below is our system, which is a sliding average over the past 3 hrs of PredictWind positions.

True position is the red and yellow dot. The red line is 4.5 nmi long, which shows a huge range in GPS positions, all artificial. A GPS with good antenna  would be well within a 100 meters or so. Dotted circles are the averages of past 3h reported positions from PredictWind tracker, shown below 

Blue dot is the true position. In this static collection of data points, it is not clear if the Starpath averaging is improving the display, but underway it is definitely better which can be seen by comparing our GE display with the PW display.

We will watch the weather to see when he might get underway again. ASCAT passes show strong will still, and models do not show relief this week.

See how we evaluate the forecasts at this note on crucial weather routing. Our conclusion is that the FV3 GFS model did the best for the longer term (~96h) forecasts. The Oceanic National Blend of Models was the best for short term (day or two).

We can see the tides in that region from within OpenCPN, where we have the AU charts installed. The tide data come with OpenCPN. We see below that the tide in this region has a range at the moment of about 2m or about 6.5 ft. That seems to imply that he might see the reef dry briefly if the waves don't interfere.

Tide stations near Flynn Reef, viewed in OpenCPN.

Below is a video discussion of these topics...

You can see the live Cairns report at: http://www.bom.gov.au/qld/forecasts/cairns-coast.shtml. Not looking good at the moment.

Weather Situation

A high pressure system [1039 hPa], moving slowly eastwards over the Great Australian Bight, will extend a firm ridge over northern Queensland waters for the next few days with fresh to strong southeasterly winds.

Forecast for Tuesday until midnight

Strong Wind Warning for Tuesday for Cairns Coast

Winds

South to southeasterly 20 to 25 knots, reaching up to 30 knots in the late morning and afternoon.

Seas

1 to 1.5 metres, increasing to 2 to 3 metres outside the reef.

Swell

Easterly 1 to 1.5 metres outside the reef, decreasing to around 1 metre later in the evening.

Weather

Partly cloudy.

Wednesday 5 June

Strong Wind Warning for Wednesday for Cairns Coast

Winds

Southeasterly 20 to 25 knots, reaching up to 30 knots inshore north of Cape Grafton in the afternoon.

Seas

1 to 1.5 metres, increasing to 1.5 to 2.5 metres outside the reef.

Swell

Easterly 1 to 1.5 metres outside the reef, tending southeasterly 1 to 1.5 metres during the morning.

Weather

Partly cloudy.

Thursday 6 June

Winds

Southeasterly 20 to 25 knots.

Seas

1 to 1.5 metres, increasing to 1.5 to 2.5 metres outside the reef.

Swell

East to southeasterly 1 to 1.5 metres outside the reef.

Weather

Cloudy. 70% chance of showers.