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Offbeat Charters from SuperYachtWorld

This is another great Google Map from Louise Busby..and in her own words “An increasing number of superyacht owners and charter operators are relocating their vessels to far-flung corners of the globe to entice the growing band of charter guests tired of cruising round the same old watering holes. We’ve searched the planet for the pick of these yachts and the experiences they offer, from sun bathing with iguanas in the Galapagos to snorkelling with elephants off those gems of the Indian Ocean. “….Great job Louise !

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..although sailors and power boaters dont always get along:-) – I have to take my hat off to Louise who is web editor of the Broom Users Club and who has also the author of Inland Waterways of the Netherlands.


How many decimal places do you need?

180px-2spheres intersectingWhen I do a passage plan, especially one which involves one of even two changes of tide, I would count myself lucky to plan to within 1 or 2 nautical miles – relying on adjusting the plan as the passage develops and then pilotage when nearing the destination.

The Wikipedia entry (from which this great graphic was borrowed!) tells us that after the US DOD imposed selective availability program was turned off, the largest error in GPS is usually the unpredictable delay through the ionosphere.

The phase difference error in the normal GPS amounts to between 2 and 3 meters (6 to 10 ft) of ambiguity. Carrier-Phase Enhancement (CPGPS) working to within 1% of perfect transition reduces this error to 3 centimeters (1 inch) of ambiguity.

By eliminating this source of error, CPGPS coupled with DGPS normally realizes between 20 and 30 centimeters (8 to 12 inches) of absolute accuracy.

On a boat with your GPS pitching and yawing to something greater than this then it stands to reason that the software in your GPS is having to try very hard to maintain a reasonably consistent position fix. I presume that the internal arithmetic in the GPS is being conducted with lets say 16 floating point accuracy – but the display of long and lat that it shows you is probably 3 dec places.

So is the GPS Long and Lat to 3 decimal places good enough?

Well, as my corespondent indicated to me below (see comments), because that is equivalent to 111 metres (122 yards or 364 feet)

Each degree at the equator represents 111,319.9 metres or approximately 111 km (= 68.97 miles or 121,391 yards or 364,173 feet ) see the Wikipedia refrence here.

The thickness of your pencil on an ocean passage planning chart could be the same as 1 decimal place (11.1 km) , depending on the scale of the map of course! So, 1 good decimal place is enough for ocean passage planning – but I guess if I was giving my position to the Coastguard I would use as many decimal places as I could lay my hands on!


ActiveCaptain Mobile for Palm OS – Win Mobile coming soon.

ActiveCaptain Mobile for Palm OS was released this month (March 2008). ACMIt is a boating-specific application for Palm devices (typically Treo’s and Centro’s). It provides a chart plotter capable of handling thousands of charts at the same time as well as integrates to all of the point-of-interest data from the ActiveCaptain web site.

They provide all US NOAA charts for free with free 6 month updates.

ActiveCaptain has just signed contracts with UKHO for international charts. Because of royalties, they have to charge a small fee to pay for government royalties (but not for updates!). For example, they will be releasing a folio of every chart for the UK for $19.95 US this Summer.

These charts will also integrate with the ActiveCaptain web site which has international support today – they have quite a few markers for UK and NL among other countries.

With ActiveCaptain, you can add your own data. So your “local knowledge” of a nice anchorage, the fuel prices at a particular marina, or your personal feelings (review) of a certain facility can be shared by everyone.

The ActiveCaptain web site is completely free and free from advertising. It requires registration to cut down on spam entries and robots.

ActiveCaptain Mobile for Palm OS costs $49.95US. A Windows Mobile version has been announced and is in alpha testing with a dozen users right now. They expect the WM version to be completed in the next couple of months. An Apple iPhone version is being designed and evaluated currently based on the recently released SDK.

I really like their little book application too its a nice way to display information, FAQ’s and manuals.

I would encourage all European sailors to add their handy tips and local knowledge to the ActiveCaptain website – that way the info is shared for all of us to benefit from – especially up to date tips on a recent visit that you may have had.



handsetsmallMobiletide is a Java program designed to run on your phone without need to connect to the phone network (GSM) or the internet (GPRS) – just as well !

It has a database of worldwide locations and can display a tidal curve for any location without you having to reference tide tables or do any standard port calculations.

The makers list a broad range of mobile phones that are supported, but basically any phone that runs a Symbian or Windows Mobile should suffice since they will then support internet connections and also Java software.

Mobiletide is synchronised to the moon’s daily cycle of 24hrs 50mins and 28 seconds. On average across a Lunar day (month) this is how much the tide moves on by each day. Working to an average tidal progression means that Mobiletide will remain accurate over a longer period of time, so in 5 days, 5 months or 5 years mobiletide will still be showing the correct tide. It does mean that throughout a month Mobiletide will fluctuate in and out slightly, however it will remain within 0-30mins for the majority of the time.

There are other influences on sea levels that affect exact tide times and these should be taken into account e.g. Strong on / off shore winds; Changing volume of river flows; Atmospheric pressure

Due to the variable nature of tides mobiletide is only intended as a guide to tide times. If you do have internet connection however, then the makers claim that Mobiletide has direct links to the most respected swell, wind and weather WAP sites around the world, providing the whole detailed picture.


Passage Planning

Following my previous post on Passage Planning I received a number of requests for copies of the passage planning documents that I use. So I thought I would post them here to make it easy to just download them. Just click on the icons below.

Excel Icon1. EXCEL doc – a template and guide to the passage planning process. Inside this workbook there are the following worksheets:

a. Passage Planning Process (for complete novices)
b. Yacht Data Sheet – its becoming a real chore in Europe to carry all these documents and information with your all the time.
c. Departure Checklist – a bit like a flight check list before you “take off”
d. Passage Planning Template – for when the electronics all fail (and the backup) and you forget the vital information that seemed so easy and obvious before you set off!

Word Icon2. WORD doc – a copy of a typical set of weather and tide information that I would take with me . The URL’s take you to the UK sites that I use, but you can easily swap these for your own locale. I just copy and paste (right click on images and copy and paste) into the WORD tables and re-size so they fit on A4. Then I print them and put them in a Nyrex clear plastic wallet and binder.

The documents are all editable – so feel free to amend and doctor to your own taste. If you do distribute to friends and club members and so on, I would only ask that the footer is maintained that gives the URL of my blog site.

I would welcome feedback – I am sure you all have other good ideas….