• iainmacneil

Week 17 - Not for the Faint Hearted!


Ummmm.....should we really be looking up at those waves.......?!


7 days after passing the dateline, we have crossed through 30° of longitude. Crossing two time zones in that period on the open ocean in our little vessel seems quite an achievement. (yes folks - its maths time again! 15 degrees of latitude is one hour..... so 360 degrees....or a big circly thing like a globe, which takes 24 hours to go round.....must mean that each hour is 15 degrees!......... because 24x15 = 360 so each 15 degrees MUST be an hour! Easy!!....Ed )

This is the pace we are now achieving on a weekly basis as we head almost due westwards. We will cross another 30° (were you concentrating? thats 2 Hours......Ed) of longitude this week because we left Hobart at longitude 147°E on Fri 25/03 (Day 114) and will round our 4th Cape, Cape Leeuwin in Longitude 115°E on Fri 01/04. At that point our time zone onboard will be UTC +8Hrs. It feels like we are really getting closer to home. This will be our 2nd of the 3 'Great Capes'


Taking in to account last week's distance, this weeks and next weeks as we enter the Indian Ocean, in that 3 week period we will have crossed through 90° of longitude, which is a quarter of the circumference of the planet (at our mean latitude). (OK folks - I have left you a pure Macneilism here.....if your mind is not yet blown, mine is.....Ed)


The Tasman Sea Fri 25/03 (Day 114) saw us complete our crossing of the Tasman Sea, affectionately known as the Ditch by both Australians and New Zealanders. It is regarded by many sailors as being one of the most dangerous stretches of water in the world.


Unlike many other bodies of water, wind and wave conditions on the Tasman Sea are rough for most of the year as the currents of the Southern Ocean collide with those of the Pacific. Low Pressure systems frequently rush through (below the 40°S latitude) at all times of the year.

It has a reputation as a 'challenging' stretch of water and for followers in the Northern Hemisphere, I’d describe it as the Southern Hemisphere's equivalent of the Bay of Biscay (and then some!).

Our five day crossing of the Tasman Sea presented sleeping problems for all with the pounding and pitching and sleep was generally in snatched blocks of 40 minutes for the middle two days. While it was incredibly tiring, there were no complaints from the crew.

It can be harder to sleep onboard when pitching and pounding and in such conditions, Iain wedges the two pillows either side of him to arrest his body movement as he grabs sleep in ~40 minute chunks. (He's lost weight!....Ed)



Wed 23rd March (Day 112) - Big Waves in The Tasman Sea


The height of the waves in the Tasman Sea varies with the passage of each pressure system, and waves and swell heights can quickly and frequently reach heights of 5m (15ft) or more.


The tallest wave recorded in the Tasman Sea was 42.5m, or 120ft,by a rescue helicopter during the 1998 Sydney to Hobart Yacht race. This was the year that 6 people lost their lives, 5 boats sank, 7 boats were abandoned, 60 boats retired and 55 sailors had to be rescued from their yachts by ships and helicopters. The rescue operation involved 35 military and civilian aircraft and 27 Royal Australian Naval vessels and it remains, to this day, Australia's largest ever peacetime rescue operation

The Tasman Sea is challenging due to the merging of the currents of the Pacific Ocean and the Southern Oceans, each of which have varying temperatures. Where the waters meet waves and swell will occur and when you add tropical cyclones and storm depressions to the mix, it is easy to understand that it can be extremely rough and unpredictable.


As if this wasn’t enough, cold fronts rushing up from the ‘Roaring Forties’ and smash in to the warmer Australian currents, which can lead to seriously high and steep waves as well as frequent storms.


This all serves to make the middle of the Tasman Sea a recognised global hotspot for freak or rogue waves with its strong tides and ridge along the sea floor. In 2015 a team of International researchers investigating ‘sub-surface’ waves said "The waves that happen deep in the ocean can be really large: 100 metres or more".

Interesting boat fact

In his research on wave heights, Iain came across this observation about boating and the Tasman “Most boats without modifications will capsize if breaking waves reach a height of 30% of the boat length”. (Hold that thought....Ed)

Two Irregular Waves

The terms ‘freak wave’ and ‘rogue wave’ makes all mariner think of the waters off South Africa.......... and we still have that area to negotiate! However, without doubt mariners can be a superstitious bunch and Iain noticed a new superstition onboard. It went along the lines of “…I hope you don’t have a copy of ‘The Perfect Storm’ onboard…” . Maybe that film itself has resulted in the overuse of the phrase rogue or freak wave.

Anyway.....

At 01:55 and 20:05 Hrs on Wed 23/03, as we were in the mid-point of the Tasman Sea, our rolling motion was stopped in its tracks by an 'irregular' wave of such force that on, both occasions, they woke everyone onboard and left quite a mess of the Galley, Bridge and our poor bike....


It would be best to describe both of these encounters as an irregular wave as they were not consistent with the wave pattern or height at the time and when they impacted we knew all about it!


As both of these waves occurred in darkness they are harder to estimate. However, our wave analyser had been recording waves of 7 metres over a large period of that day, which suggests that they were likely over 10 metres in height. (You still holding that thought?....Ed)

I am carefully using the term irregular wave, because that is what they were....neither was a colossus towering over us, which would take on the status of rogue or freak wave. (I think!)


It was like leaving a large event at a stadium such as a football match or concert, where there are thousands of people going in one general direction, but you are proceeding against that flow of people (so you are bumping and dodging along), when suddenly another group comes at you from a different direction to the rest (say 30-45°) striking you with a significant force and knocking you off balance.


At the time, in both instances we had been rolling +/- 20° and as we rolled through the mid-point we hit the irregular wave (or it us), bringing us to an immediate stop. The 20.05 wave almost threw Dan clean out of his bunk!


Let's hear from the watchkeepers.........

01.55 Mikey "In the 7 months onboard, including the rounding of Cape Horn with winds gusting 60 knots, I have never experienced anything remotely like that wave"


20.05 Carlos "I had to grip hard on to the wheelhouse chair as the surprise hit triggered a series of engine room alarms. The impact moved/lifted the non-skid boxes and cleared books from their stowage and anything not nailed down in the bridge seating area. There was no spray, just a wall of water and the impact of it not only stopped our rolling, it pushed us 20-30° off course as it passed. My first action after checking everyone was ok was to switch on all the deck lights to check everything was still on the foredeck and aft deck. All good (Thanks Wes!), but the exercise bike was tangled in the railings!"


Friday 25/03 (Day 114) - Hobart


Hobart is very picturesque and seems to encapsulate the best of New England, Vancouver and British Columbia. However, it's unmistakably an Australian town with a leafy village green and characteristic 19th century buildings.

The 20 mile inlet that Hobart is situated in is guarded by the Iron Pot Lighthouse at the entrance.


Iron Pot Lighthouse is the oldest lighthouse in Tasmania (2nd oldest in Australia). Located on Iron Pot island in the Derwent Estuary in the approaches to Hobart, the square tower was built in 1832 and was initially manned by convicts living in tents. At one point a beautiful house just to the north of the lighthouse (left in the photos) housed the keepers and their families, now long gone!


The inlet seems to offer every opportunity for watersports and recreation activities and fishing.

Dan is pictured here with 8 x 2.5kg crayfish, which were without a doubt the best crayfish or lobster meat that Iain or Luke had ever tasted (From 2 ex lobster fishermen, thats quite a compliment!)


On arrival a team of three from the Australian Border Force met us to clear us through immigration and check our certificates etc. They were a great team and very interested in our exploits and commented that it was the first motorboat they had seen cross the Pacific. All three doubted they would see another achieve the feat in their careers!


Once immigration was completed, a team from the Australian Department of Agriculture boarded to complete their biosecurity checks, where they checked for:

- Asian Gypsy Moth Checking all masts, inlets, vents and crevices which are known places where this moth type settles on ships for a ride across an ocean

- Sanitation All checked to prove they are functioning

- Food/Stores Yet again the 1st class job on the vacuum packing of stores and particularly the flour bread mix (James Easton), got us top marks (we just have to use it Mikey/Dan). Although some of our tinned fish had to wait for a phone call to confirm it wasn’t a bio risk.

- De-Rat Certificate We were thoroughly checked to confirm that Luke or Paul didn’t have any pet rodents in the engine room. Again top marks for engine room cleanliness.

- Ballast Water Management As we don’t carry any sea water as ballast, we managed to dodge about 6 pages of checklists (phew!).

- Bio-fouling We ensured before we set off from Lanzarote that Astra was lifted out of the water and had her hull cleaned and a fresh coat of anti-fouling applied immediately before we sailed. We had all the relevant certificates for the ant-fouling coating, specifically at the time for New Zealand who are very particular about this. However, this also falls under the remit of Australian BioSecurity and we were very proudly able to present all our anti-fouling certificates and a full up to date Biofouling Logbook with a complete record from the date of purchase.

Hobart saw us lift 27,000 litres of diesel and a shout out goes to the great team from Bennetts fuel supply who were very patient with us as we filled our many tanks.

We also had our crew member (of abscess fame from last week) visit the local Doctor, who was able to confirm that the wound had healed and that it was a good job. The exercise bike beckons… (guessing its out of the railings......Ed!)

Sat 26 March (Day 115)

01:30 hrs we rounded SE Cape at the southern end of Tasmania, which again presented us with confused seas at the confluence of the Tasman Sea and the Great Australian Bight. The weather we experienced midweek crossing the Tasman Sea would have meant fairly treacherous conditions at SE Cape and we would have had sought shelter in Hobart if our timing been different.

We rounded the SE Cape at 3 miles off with very light wind conditions (5-8 knots), although the swell on the beam at 4 – 4.5 metres in height meant we needed the stabilisers for comfort and two steering motors to counter the yawing effect of the eddies and currents.


Running Repairs and Maintenance

Since we left Lanzarote on 01 Dec 2021, we have been dogged by overloads caused by our shaft generator spiking power loads, but we couldn’t identify the culprit. As we rounded SE Cape and entered the Tasman Sea, with the cooler air and sea temperatures, we had the air conditioning off for over a week and during that time we experienced no overloads, which indicated that the fitting of a soft start mechanism (a Soft Starter is a device that starts motors with reduced power supplied at start-up. Reducing the power, reduces potentially damaging electrical and mechanical shocks on the electrical system) to the air conditioning unit would reduce this peak load. As if to prove the point, immediately on starting the air conditioning we had an electrical overload.


For the other repairs this week we must provide thanks to the good work of Denise (Purchasing Officer) at Andrew Weir Shipmanagement and to Luke and Paul for hauling holdalls of spares out to locations all over the world as they join. We received, in February, among many other spares, heavy duty Teflon end cap spares for our reverse osmosis fresh water maker, which was good timing as one of those large Teflon caps cracked this week! This membrane chamber operated under 40-45 Bar/Kg of pressure and we would have had no fresh water making capacity without this repair.



ETAs

Cape Leeuwin: Friday 01/04 PM

Fremantle: Sat 02/04 PM

Mauritius: Sat 16/04 or Sun 17/04.


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