Monday, 22 June 2015

The difference between feet and meters

We went over to Tangalooma on Moreton Island with Andrew and Robin Thiele for some snorkelling on the wrecks over there.

Good sailing weather with a forecast of 10 to 20 knots through the day and we had an average of about 12 knots on the beam most of the day meaning we sailed the whole way doing around 6 knots with all the sail up except for a single reef in the main (yep, I'm overly cautious).  Awesome stuff.

We got to the channel into Tangalooma around 12:00 pm and it was raining heavily so I hove to with the Yankee and reefed main in the East channel to wait it out.  We'd just settled when I noticed a rather large ship heading towards us so we had to hustle to get the boat sailing again.  We cleared it by a mile but the combination of turning off the AIS alarms (too many false alarms), really bad visibility and lack of local knowledge conspired to get the adrenaline going.  Not so awesome.

We anchored between the wrecks and the beach, had lunch and watched the world go by for a while.  As you can see below, we were very close to the wrecks and we were looking forward to swimming over in the morning.


One of the wrecks just off our starboard side at sunset

I noticed that when the tide changed, the current swung us right around pushing us to the south against the 5 to 10 knot southerly.  This meant that at the next change, we would have quite a strong current and the wind combining to push us to the north.  This sort of thing had happened in the Brisbane river and it caused our anchor to break free and re-set (which was pretty scary) so I decided to sleep in the cockpit overnight and monitor what happened when the tide changed again at 1:30 am.

So the alarm went off at 1:30am and I watched the boat swing around through bleary eyes.  The wind had strengthened to about 15 knots as well so the combined wind and tide fully tested our anchor.  Just as I was dozing off again, I noticed a large yacht moving slowly past in reverse between us and the wrecks!

I woke up quite quickly then and hopped onto the back porch to see what the hell was happening.  A big masthead sloop (50' or so) was slowly dragging it's anchor along the channel about 10 metres away from us and even closer to the wrecks.  I yelled out and shone a maglite into the port lights and eventually (it took a while..) saw some movement on the boat and the panic started.

They had some strife..  The anchor decided to hook up to something (probably one of the wrecks) and they couldn't get it free.  The boat was swinging sideways into the wrecks one minute and wildly out almost on the other side of Venture the next.  Bow thrusters blasting and big handfuls of engine trying to get control and break the anchor free.  They really needed to calm down and just maintain position (keep station) off the wrecks for a while to figure it out but they were way too busy and freaked to think of that.

In the end, the chap dashed back to the cockpit and returned with a hacksaw and cut the anchor chain next to the windlass.

They drifted away almost hitting some other boats and landing on the beach before taking off quite fast up other side of Venture and out towards Tangalooma resort.  We waved at them as they went past and someone yelled out thanks.

Terry took some video but it's impossible to make anything out in the dark except the fancy blue lights under the sugar scoop stern.

The following morning you could see that they'd gone up past the jetty at Tangalooma into the shallows to the south and anchored there.  It was low tide now and you could see the boat was resting on the ground as it was tilted over to starboard about 10 degrees.  Whoops..

A nice boat at peace after all the drama.
The skipper came past in his Jet Ski later which he carried on it's own davits (believe it or not) and tried to explain what happened but it was clear he was really embarrassed and just wanted to be somewhere else.

I think he made two mistakes.

The first and most basic is that he didn't properly set his anchor!  His explanation was that his first mate had called out the anchor rode length on the link counter in the cockpit at 60 when he was on the bow setting the anchor.  He assumed she was talking meters and told her to pull up rode to leave 40 out.  Unfortunately, she was working in feet.

They were in 7 meters of water at the time with a rising tide so with only 40ft out, the scope was around 2:1 and the anchor would be completely useless.  Even with the original 60ft of chain (3:1) any serious tug on it would break it free I'm sure. 

Secondly, he didn't set an anchor watch.  You can be as confident as you like in your anchor but to set it and forget it is a big mistake.  There are a heap of technical ways to warn you if your anchor breaks free or drags and there is the basic Mark-1 eyeball, checking regularly through the night.  Either would have prevented the drama.

Not to brag but on Venture, we had Terry's phone and the tablet both running anchor watch applications (geo-fences basically) and I was also worried about the tide change because we were so close to the wrecks so I made sure I was awake at the critical time.

Chances are that the boat would have kept dragging along the channel and the anchor would have set itself in the shallows to the north of the wrecks without mishap.  After all, it had already dragged past several boats and between Venture and the wrecks.  He would have woken up to find his boat about 3 miles north of where he anchored it with no obvious safe path through the anchored boats and the wrecks!  Can you imagine his surprise :-)

There really is a big difference between feet and meters!

We went snorkelling later but I'll let Terry tell you about that.

Location: Queensland, Australia
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