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Joshua Slocum in Google Earth: Port Natal to Cape Town

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

Slocum sails from Port Natal [Durban] on 14Dec1897. The passage to Cape Town is about 800 miles. When the Spray is at her best it would take Slocum about one week to cover this distance; however, he expects the weather to be rough even though he has waited and waited for the southern summer to develop. His expectations are met:

On Christmas, 1897, I came to the pitch of the cape. On this day the Spray was trying to stand on her head, and she gave me every reason to believe that she would accomplish the feat before night. she began very early in the morning to pitch and toss about in a most unusual manner¹, and I have to record that, while I was at the end of the bowsprit reefing the jib, she ducked me under water three times for a Christmas box.

A large English steamer passing ran up the signal, “Wishing you a Merry Christmas.” I think the captain was a humorist; his own ship was throwing her propeller out of water.

Two days later the Spray is passing Cape Agulhas, the southernmost point of the African continent, 13 days from Port Natal and with 120 miles still to cover. The winds are more moderate now, but there is still one more gale to come. He shelters in Simons Bay [False Bay] until the wind slackens then he beats the Spray around the Cape of Good Hope, accurately named by early Portuguese navigators as the “Cape of Storms.”

Thirty-five nautical miles later, the Spray runs into calm water in the shelter of Table Mountain. Slocum is in reflective mood; despite sailing alone for so long he anchors in the bay, “clear of the bustle of commerce”, and takes a day to contemplate his achievement of negotiating both Cape Horn and the Cape of Good Hope single-handed.

The next day, he sails the Spray into dry dock where she remains for three months. Slocum does not record the date of his arrival at Cape Town; perhaps it was two or three days after passing Cape Agulhas, which would make it 29Dec or 30Dec1897.


The section of Joshua Slocum’s journey reported here opens Chapter XVIII of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. To simulate pitching and tossing “in a most unusual manner”, I combined animations on all three axes by specifying AnimatedPitch, AnimatedRoll, and AnimatedYaw in the TourMaker Input File for this section of the passage.

Copyright © Colin Hazlehurst, 2012

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Joshua Slocum in Google Earth: Mauritius to Port Natal

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

Fully provisioned and rested, Slocum sails from Port Louis, Mauritius on 26Oct1897. At first the winds are light and he draws away from the island slowly. By the next day he is passing the island of Réunion. The sea is too rough to consider landing, but a pilot comes out of Galets on the north-west corner of the island when Slocum hands over a Mauritius paper.

A course is set to Cape St. Mary, the southernmost point of the island of Madagascar. The trade winds are weakening now and by 30Oct1897 Slocum finds himself becalmed:

The sloop was now drawing near the limits of the trade-wind, and the strong breeze that had carried her with free sheets the many thousands of miles from Sandy Cape, Australia, fell lighter each day until October 30, when it was altogether calm, and a motionless sea held her in a hushed world. I furled the sails at evening, sat down on deck, and enjoyed the vast stillness of the night.

On the following day, a light breeze carries the Spray past Cape St. Mary. About one week later and for the rest of the voyage to Port Natal (Durban) strong gales batter the yacht and heavy thunderstorms were prevalent¹.

Here the Spray suffered as much as she did anywhere, except off Cape Horn. The thunder and lightning preceding this gale were very heavy.

It takes the Spray 18 days to cover the 800 miles between Madagascar and Durban, an average of 45 miles per day made good. This is less than half the distance per day that she is capable of. In reality, the course is not a straight line because the “succession of gales of wind…drove her about in many directions.” So, the Spray is sailing as fast as ever, but on some crazy zig-zag course dictated by the winds².

Slocum stays in Port Natal for four weeks; he meets all the members of both yacht clubs and sails on the crack yacht Florence; he meets Henry Morton Stanley, the Welsh-born naturalised American who is a renowned explorer of Africa; and he encounters a trio of men who believe that the world is flat. They visit Slocum actually expecting to find information that will support their hypothesis. He must disappoint them:

With the advice [to them] to call up some ghost of the dark ages for research, I went ashore, and left these three wise men poring over the Spray‘s track on a chart of the world, which, however, proved nothing to them, for it was on Mercator’s projection, and behold, it was “flat”.

The Spray sails from Port Natal on 14Dec1897 and is once more: “off on her alone,” as they say in Australia.


The section of Joshua Slocum’s journey reported here concludes Chapter XVII of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. Thunder and lightning or rather lightning followed by thunder was a fresh challenge to my animation skills. Again, I used models created in Google SketchUp to represent the effect of lightning; I added to this a couple of thunder tracks from the WavePad sound effect library. Normally I would try to enhance TourMaker by adding a directive that would generate the thunder and lightning automatically. This time I hand-coded it. Each lightning model flashes on and off twice (by setting visibility=1 then visibility=0 ) with each period of visibility lasting about 100ms. A few seconds later the thunder-clap audio is output.

2. I realised that a better animation of a rolling yacht would result from oscillating the angle of roll about the current ‘Roll’ setting, rather than about the vertical. This would create the effect of the yacht being heeled over in the wind while  waves introduce an additional periodic rolling motion. I have amended TourMaker accordingly

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: Cooktown to Thursday Island

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Slocum sails from Cooktown on 06Jun1897 and by the evening of the 7th the Spray is at anchor near the Claremont Islands. Apart from in harbour at Port Denison and Cooktown, this is the only time Slocum anchors in the Barrier Reef Channel. By the next evening he wishes it isn’t. The Spray is sailing into the night at full speed ahead and passes the light-ship at the southern end of ‘m’ reef.¹ He expects there to be a beacon light at the north point; if there is one he doesn’t see it and the Spray strikes the reef. The next swell carrier her safely over but not before Slocum sees the ugly sharp coral rocks and realises just how lucky he is.

Keeping further out to sea now, heeding the advice to keep clear of the residents of Cape Grenville,  Slocum passes outside all of the islands including Home Island off the tip of the cape itself. He squares away westward in the direction of Sunday Island and shortens sail as he passes it; he doesn’t want to reach Bird Island before daylight — that island group is low-lying and surrounded by navigational hazards. On the morning of the 9th Bird Island is only 2.5 miles ahead, so he was lucky again that the current carrying him along was not stronger.

He spends the rest of the day sailing from Bird Island to Cape York, navigating Albany Pass, between mainland Australia and York Island, “as the sun drew low in the west over the hills of Australia.”

He anchors in a cove near the Tawara, an American built and skippered pear-fisher. Next day, he spends a pleasant few hours with the crew of Tawara and with the Jardine family from nearby Somerset. It turns out that Mrs. Jardine is cousin to Faamu-Sami, princess of Samoa and daughter of King Malietoa, who had visited the Spray at Apia.

From this cove, Slocum makes the short trip into the Torres Strait across to Thursday Island. He finds that celebrations are planned for Queen Victoria’s diamond jubilee on 22Jun1897, and doesn’t need much persuading to extend his visit here.


The section of Joshua Slocum’s journey reported here continues Chapter XV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. On the evening of 08Jun1897, the Spray struck a reef and luckily there was enough water for the next swell to carry her over it. Slocum identifies this as ‘M Reef’; however, a search of the web delivers no information about the location of this hazard. I didn’t want to use a random reef in the animation so I had to dig further until I found an online version of a chart compiled from mid-19th century surveys by the Great Britain Hydrographic Department. The chart is made available by the National Library of Australia.

British Hydrographic Department chart showing the reefs of the Barrier Reef Channel

By close examination of the chart, I was able to find the identification letters of the significant reefs that skirt the Barrier Reef Channel. I couldn’t find all of them but at least it was clear which is ‘m’ reef.

To help anybody else who is looking for reefs in the Barrier Reef Channel using their identification letter, I have plotted them in Google Earth and kept their labels visible throughout the animation.

2. This chapter of Slocum’s book is one in which a lot of ground is covered with relatively few words. I like the animation of the model Spray to coincide with the narrative so, at times, it is necessary to move the model to a new location without accompanying voice-over. This can seem like an awkward silence and to overcome it I use two techniques:

  • The background sound effect of water lapping against the hull; if nothing else this helps to distract sufferers of tinnitus from their condition, and it does seem to work.
  • Using the ‘Show’ directive of TourMaker, I pop up labels that identify significant landmarks like capes, islands, and bays.

3. I am using an unabridged version of Sailing Alone Around the World. There are a few places where I have chosen not to speak the words that Slocum wrote as they are offensive to the modern ear. This chapter includes one such passage in which he describes the appearance of the men and women who travelled over to Thursday Island for the jubilee celebrations.

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: Whitsunday Passage to Cooktown

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Captain Cook, taking Endeavour through Whitsunday Passage (named by him because 03Jun1770 was Whit Sunday), sailed through the night and arrived the following morning at: “a lofty promontory that I named Cape Gloucester”.

Joshua Slocum, a few days short of 127 years later, passes here on 26May1897. His charts show more accurately than Cook’s survey that the promontory is actually detached from the mainland and is now called Gloucester Island. The Spray hauls into the bay to the west of the island and anchors at Port Denison, close to the small town of Bowen.

Bowen at that time has a population of around 1,000; large enough to support a keen audience for Slocum’s story.

By 31May1897, the Spray, has carried Slocum safely through 350 miles of the Great Barrier Reef. Without anchoring anywhere, Slocum sails past many of the other capes, bays, and islands named by Cook:

  • Cape Upstart
  • Cape Cleveland
  • Cleveland Bay
  • Cape Richards
  • Rockingham Bay
  • Cape Grafton
  • Fitzroy Island
  • Cape Tribulation (“for here all my troubles began”)

Cook also named the Endeavour River, for it was here that H.M.Bark Endeavour was beached for repairs after she had struck a reef just north of Cape Tribulation (the reef was named unsurprisingly Endeavour Reef).

Cooktown was certainly in existence before the gold rush of the 1870s, when the settlement grew rapidly as a supply port, because Slocum reports visiting on the steamship Soushay in 1866; he didn’t see much of it at that time because he was ill with a fever.

The “lecture tour” continues when a meeting is arranged in the Presbyterian church and Slocum delivers his “story of the sea.”


The section of Joshua Slocum’s journey reported here opens Chapter XV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: South Solitary Island to Whitsunday Passage

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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After exchanging signals at South Solitary Island, Slocum continues north and on 19May1897 sails past Point Danger, named by Captain Cook after his encounter with shoals and strong currents there.

On the 20th, the Spray rounds Sandy Cape, a significant point that marks the beginning of the Great Barrier Reef. The light on Sandy Cape is visible for 27 miles and his next way point is the Lady Elliot Island light. This is important to find because Slocum is heading into a dangerous region shoals and reefs and all the charts in the world are of little use if you don’t know where you are. Lady Elliot Island is about 45 miles from Sandy Cape but it seems to take an endless time to cover that distance. Slocum concludes he is pushing against a strong current.

The Spray had sailed for hours in suspense, evidently stemming a current. Almost mad with doubt, I grasped the helm to throw her head off shore, when blazing out of the sea was the light ahead. “Excalibur” cried “all hands,” and rejoiced, and sailed on.

So he finds the light on Lady Elliot Island¹ and passes into the serene, but still risky, waters inside the Great Barrier Reef and is protected from the worst of the Pacific Ocean’s waves. Progress is good and the Spray averages 4.6knots over the next four days:

On the 24th of May, the sloop, having made one hundred and ten miles a day from Danger Point, now entered Whitsunday Pass, and that night sailed through among the islands. When the sun rose next morning I looked back and regretted having gone by while it was dark, for the scenery far astern was varied and charming.


The section of Joshua Slocum’s journey reported here concludes Chapter XIV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. The  technical challenge in this part of the presentation was to simulate the light from the Lady Elliot Island lighthouse. I wanted to create a beam of white light that rotates about the location of the lighthouse; furthermore, I wanted it to have the same characteristic as the current light, which is described on charts as: Fl.W. 7.5s. This code means that the light is white and flashes every 7.5 seconds.

To achieve this I needed two things:

  • A model to animate.
  • A TourMaker directive to generate the animation.

I created the beam of light by drawing a cone in Google Sketchup and colouring it white. The cone was about a mile long, oriented along the green axis, which is north when the model is exported to Google Earth, and its apex was placed about 100 feet above the origin.

In the KML file for this leg of Slocum’s journey, I added the model as a Placemark, positioning it at the latitude and longitude of the Lady Elliot Island lighthouse (at the south end of the island). I set the visibility of the Placemark initially to zero (invisible), because I wanted to ‘turn on’ the light at the instant in the narrative that Slocum sees it.

To simulate a rotating beam I would need to animate the model by changing its orientation. By placing the origin of the model at the position of the lighthouse, a change in its orientation would have the desired effect of a light sweeping round.

I measured the angle subtended by the model and found that the edges of the cone were 15° apart. To achieve a smooth rotation, I would want each new orientation of the model to be no more than 15° away from the last one. I also knew that the beam should sweep through 360° in 7.5 seconds, in other words its angular velocity should be 360/7.5 degrees per second, which  comes out at 48° per second.

I used this information to determine how many orientation changes per second would be required to generate a smooth animation at the required rotation rate. Quite simply, if each animation step rotates the model by 15° and we need to rotate the model at 48° per second, then we need 48/15 animation steps per second (3.2), so the duration of each animation step should be 1/3.2 seconds (0.312s).

All of this is easy to code, taking only a few hours of development and testing. To control this behaviour, I added a ‘Rotate’ directive to TourMaker, and its parameters identify which model to animate, the duration of the animation, the angular velocity required, and the delay until the animation should start. This last parameter allowed me to switch on the beam as the narration reads:

Almost mad with doubt, I grasped the helm to throw her head off shore, when blazing out of the sea was the light ahead

The animation starts at the word ‘blazing’; the Placemark is made visible, the light sweeps around for 30 seconds and the Placemark is then made invisible.

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: Waterloo Bay, St. Kilda and Launceston

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Joshua Slocum shelters for three days in Waterloo Bay on Wilson’s Promontory in the company of a few whaling boats. Then, in more moderate weather, he sails to Melbourne and picks up a tow at the entrance to Port Phillip Bay. On Christmas Day, 1896, the Spray is anchored in the Yarra River (which he calls the Yarrow), but Slocum soon moves to St. Kilda.

He catches a shark and puts it on display, along with the 26 cubs born by Caesarean section. He charges sixpence per visitor, having set up this enterprise to cover the cost of port charges incurred here. Apart from at Pernambuco (Recife) in Brazil, where he has some history with the regime, these are the only other fees he has to pay on the whole voyage.

News comes in of unusually large amounts of Antarctic ice drifting northwards, bringing with it much stormy weather. Slocum’s plans change again. Rather than head west to battle around Cape Leeuwin he opts to spend time in Tasmania while the season’s change enough to make an easy passage through the Torres Strait; in other words, he intends to sail up the east coast of Australia inside the Great Barrier Reef, where, reaching warmer waters, he would sail round Cape York and into the Indian Ocean.

He sails from St. Kilda on 24Jan1897 and in strong and favourable winds it’s only a two-hour trip across to Tasmania. He reaches the mouth of the Tamar River and follows its meanderings up to Launceston which is about 30 miles inland. The Spray is grounded, on account of arriving at the top of an exceptionally high tide and she eventually has to be dug out:

The Spray was berthed on the beach at a small jetty at Launceston while the tide driven in by the gale that brought her up the river was unusually high; and she lay there hard and fast, with not enough water around her at any time after to wet one’s feet till she was ready to sail; then, to float her, the ground was dug from under her keel.

In this snug place I left her in the charge of three children, while I made journeys among the hills and rested my bones for the coming voyage, on the moss-covered rocks at the gorge hard by, and among the ferns I found wherever I went.


The section of Joshua Slocum’s journey reported here concludes Chapter XIII of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

To ‘sail’ the 3D model of the Spray up the Tamar to Launceston is not something I would have attempted without the use of the TourMaker tool. The model has to follow the meandering of the river and to be scaled appropriately, and this would have been very laborious to create using hand-written <gx:tour> directives.

Using TourMaker, I was able to create a series of Placemarks, positioned along the course of the river, and generate the tour automatically. Now, of course, I will need to get the Spray down the river again, but using the same Placemarks in reverse order, this should be quite straightforward.

Copyright © Colin Hazlehurst, 2012

You might also enjoy Cook’s first voyage round the world at: http://www.hazelhurst.net/Cook

Joshua Slocum in Google Earth: Buenos Aires to the Straits of Magellan

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum.

On 26Jan1896, Slocum sails from Buenos Aires and soon runs into a gale which changes the appearance of the River Plate from silver disk to brown mud. It takes 2 days to reach the mouth of the river against a head wind, then Slocum plots a course between Point Indio on the Argentine shore and English Bank on the Uruguayan side of the channel.

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He keeps about 50 miles offshore in order to avoid the tide races around the capes. The disadvantage of this approach is that the Spray is exposed to heavier seas. One particularly mountainous wave completely submerges the yawl, but Slocum hears it coming and manages to drop all sails and climb to relative safety in the rigging.

The mountain of water submerged my vessel. She shook in every timber and reeled under the weight of the sea, but rose quickly out of it, and rode grandly over the rollers that followed. It may have been a minute that from my hold in the rigging I could see no part of the Spray‘s hull.

After his life has finished flashing before his eyes, Slocum’s first thought, in paraphrase, is: “I’m going to need a bigger boat.” Even so, he is encouraged to think that the Spray will survive the tempestuous seas around Cape Horn.

The giant wave rolls on by and the following days are more serene with light winds and a smooth sea. In these conditions Slocum often sees mirages that affect the apparent size of everything: an albatross looking like a ship and fur-seals looking like great whales.

The kaleidoscope then changed, and on the following day I sailed in a world peopled by dwarfs.

Technical note: Using my TourMaker tool, it was fun to animate the submergence of the Spray. I wanted to dip the hull 3 metres below the surface; however, the scale of the model at that point of the animation is X7500. That meant setting the altitude of the model to -22500 metres below sea level to get the desired effect i.e. right down into the Earth’s crust!  I later adjusted this to -22000.

Copyright © Colin Hazlehurst, 2012

If you haven’t seen it yet, do please take a look at the presentation of Slocum’s voyage at: http://www.hazelhurst.net/Slocum. It use the Google Earth plug-in which works in most modern browsers.

You may also enjoy Cook’s first voyage round the world at: http://www.hazelhurst.net/Cook

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