These pages have a motley collection of practical stuff for boats. It all comes from hands-on stuff on our boats that gets tested in the real cruising world and on those wet salty passages where you find out what works and what doesn't.
KISS keep it simple stupid
If you wander around the boatshow as I did this year, you could be forgiven for thinking that somewhere between the good old days and the glittering arrays on the stands at the boat show that we seem to be missing the point about going sailing and cruising. The basics have got mixed up with the toys that have a by-line like Ďessential for every cruising boatí or Ďdonít leave port without oneí. Its all for your convenience and you would be a fool not to have one on board.
There is a grand complication between the salesmanís patter about the integrated, PC or Mac compatible, talking to the instruments, gee-gaw that you must have and that simple old fashioned concept of capturing the wind in those white things and gliding over the sea to a destination.
In fact most of the equipment we need is low-tech and it needs to be reliable. We run all sorts of complicated gizmos in Skylax: a couple of chart-plotters, integrated instruments and autopilot, radar, lap-top navigation and routing software, all sorts of stuff. The nub of it all is whether you need to continually be repairing all this stuff or whether you keep cruising and repair or replace a piece of equipment when you can. I see all sorts of boats stuck in a harbours around the world waiting for a spare part or replacement gear. In fact most of what we need to keep these sailing dinosaurs going is simple basic stuff and a lot of what enhances cruising is low-tech or at best intermediate technology.
KISS. Below are some simple things that make your cruising more enjoyable and also some caveats on things we use.
This is a slightly modified version of an article from 2000 published in
In brief, we have an amazing system for position finding but nothing accurate enough to plot it on.
For the 1999-2000 Imray Mediterranean Almanac we decided to delete the astro ephemeris. For the previous two editions (spanning four years) I had been monitoring the reply cards on which one question was: Do you think the Almanac should include astro ephemeris? On the last count the Ďnoí vote was winning, although only just at around 60% NO to 40% YES. My guess is that of the Ďyesí group, only a fraction of them actually use the ephemeris and most of them want it there for the comfort factor as a back-up. Yet if you had taken the survey less than ten years ago I suspect you would have had somewhere around a 90% Ďyesí vote. No Almanac editor would have thought twice about including astro ephemeris. Today we find the majority of Almanacs do not include it.
The decline in the use of astro ephemeris to determine position can be attributed directly to the availability of GPS receivers and the chips and software which have made them easier to use. To some extent Loran-C and SATNAV helped to keep the sextant in itís box, but it was GPS that relegated many sextants to the most inaccessible locker on board and kept it there.
GPS was developed for the American military. The original acronym NAVSTAR more properly describes how it works. NAVSTAR is NAVigation System by Time and Ranging. GPS simply means Global Positioning System which tells us little. In fact the way GPS works is simple and familiar to anyone who has done some coastal navigation. If we know the position and distance of an object then our own position can be plotted on a line from that known object. Plot three known objects and distances and we have a relatively accurate position fix. In practice three satellites distances and positions are plotted because of the inaccuracy of receiver clocks and degrading effects from the signals passing through the ionosphere. The resulting cocked hat gives a consistent accuracy of ` 20 metres for 95% of the time. However the American military decided that this degree of accuracy should only be available to the military and so it degraded the signal to civilian users by Selective Availability (SA) to give an accuracy of ` 100 metres for 95% of the time. SA was removed on midnight May 1st 2000 so that civilian users now had an accuracy of `20 metres or so.
In 2002 WAAS (Wide Area Augmentation System) was introduced in the
All these systems rely on ground stations in known locations receiving satellite GPS positions, correcting them from the known position of the ground station, and then via relay stations sending the corrections back to the satellite and then down to a WAAS/EGNOS/MSAS enabled GPS receiver. Brilliant.
Modern GPS receivers are multi-channel and can receive at least twelve signals at any one time and decode them to determine a position. The speed at which a GPS receiver can do a cold start and produce a position is now around 30 seconds. The ease with which we retrieve data has been simplified by software that enables us to scroll through pages and pick out how we want to view the data. From the stream of position data we get speed over the ground, course heading in true and magnetic, distance off course from a waypoint, and a graphic display of our course. A GPS receiver can be interfaced to electronic charts or a chartplotter and we can plug in waypoints for a route and watch our boat sailing along on the chart like some arcade amusement game. In the early 90ís if someone had said you could buy an instrument for just over £100 that would do all this you would have politely changed the subject and declined to buy him another drink.
So is everything calm with fair winds and a few digital beeps as you make landfall. Iím afraid not. There are still sea monsters out there.
Problem No. 1 Knowing your position is not much use if you donít have accurate charts to plot it on.
With GPS we know what our position is to within 5-10 metres on the earthís surface. What we do not have are charts of the earthís surface which are accurate to this degree. Most of the charts we use were surveyed in the 19th century using celestial methods to determine latitude and longitude. Given the difficulties that many charts were surveyed under including bad weather conditions and hostile natives ashore, with just leadlines and sextants for equipment, the resulting charts are amazingly accurate. Many of them are beautifully detailed affairs and given the difficulties of standing in a small pinnace and taking sights to determine position, they are a tribute to the men who made them.
Section of a chart by Beaufort 1812. A work of art but not necessarily GPS accurate. This chart was still the stock chart until the 1980's.
That said, the charts could not possibly be consistently accurate compared to the repeatable accuracy of modern position finding equipment and so it is not surprising that in some areas there are errors of up to one nautical mile and more.
The British Hydrographic Office divides the problem of accuracy into three parts.
1 Modern surveys by the Royal Navy using DGPS have a standard of around plus or minus 13 metres accuracy and as such have an accuracy compatible to GPS accuracy Ė not surprising when the data is derived using DGPS. (Using SDGPS the accuracy is now probably around `5 metres.)
2 Paper and ARCS charts assembled from various datum sources have a relative accuracy dependant on how recent and how accurate the last surveys were and this is now shown on Admiralty charts with the source diagram of the surveys. Here the worst case scenario should be taken and in many cases this will include a portion of a 19th century survey. It is difficult to know what this relative inaccuracy is, but be warned that some relative inaccuracies of up to 3 miles exist between the charted position and the actual GPS position. While relative inaccuracies will be eliminated by future surveys in the developed countries, this is unlikely to be the case for less developed countries where hydrographic departments are under-funded and have relatively unsophisticated surveying equipment.
last problem is purely a cartographic one of scale. Small scale charts
will appear more accurate than large scale charts. Ergo, a small scale
chart has the appearance of accuracy although it cannot be used close
to land and dangers to navigation.
So depending on the source of the last survey there can be inaccuracies of up to 1 mile and in worst case scenarios probably a relative inaccuracy of up to 3 miles for some old surveys. The French hydrographic department will only guarantee itís charts to 1000 metres in the northern hemisphere and 2000 metres in the southern hemisphere according to a report by Bateaux magazine.
this means to craft navigating in these waters is that some circle of
error (COE) around the boat must be used when close to dangers to
navigation. Just what COE you use is difficult to sort out. In the Red
Sea I used a minimum COE of one mile, but extended it to 1Ĺ miles off
All of the above applies equally to electronic charts. Electronic charts are simply digitised versions of paper charts and so contain all the errors of paper charts. This explains why when you are close to land that the little boat on your plotter is happily toddling across a headland or a reef or whatever. Vectorised charts can be invisibly seamed together and this may give the appearance of a new chart, but seamless charts are purely the result of digital magic and not the result of new information.
Problem 2 Chart Datum
When you draw a chart you must determine where the lat and long lines go. In the early days of charting the surveyor would use a defined datum for his area or if one did not exist, he would define his own. This has resulted in there being hundreds of chart datums around the world. GPS requires that there be one datum system for the world and this has been agreed as WGS84 datum (though see above). This is the default setting on a GPS unit, but if you are plotting a position on a chart referenced to another datum then you will need to select that datum on the GPS. Most, but not all charts, will have the datum it is referenced to on the chart itself. Most GPS units will have around 100-150 of the most common datums in their memory and it is simply a matter of choosing the correct datum from a list on the menu so you can plot the GPS position directly onto the chart.
While I was in
Problem 4 Why am I such a Luddite?
Simple answer: I am not. There is no way I would not use GPS and in fact I carry three back-up receivers. As well there are two chartplotters running on board, one at the helm and one below in the chart table and on the lap-tops we have navigation software/routing software/weather/tides etc.
There would be few who would not agree that this one instrument is a revolution in position finding and like ziploc bags and velcro, you wonder how you ever managed without it. It is not just the position finding but the ancillary readouts like an instant magnetic heading and speed over the ground which provide much useful information at the touch of a button. Put in waypoints and you end up correcting your course when it is off by an ľ of a mile. I remember a time when if you arrived within a couple of miles of your destination you were well pleased.
So I am not a Luddite. I love my GPS(Ďs). But I am conscious that the appearance of accuracy can lull us (myself included) into a sense of well-being that can put us in danger. They really do mean it when that message flashes up on the screen to the effect that GPS is an aid to navigation and should not replace all other means of navigation.
you carry a spare GPS (or two) its a good idea to have a 12V DC plug so
you can run it off the ships batteries. On the way across the Atlantic
in 2005 our chartplotter (new) failed and Lu modified an old yoghurt
pot so the back-up GPS could sit outside and get a signal because the
integral aerial didn't receive down below. It also made it easy for the
person on watch to keep an eye on things.
When you carry a spare GPS (or two) its a good idea to have a 12V DC plug so you can run it off the ships batteries. On the way across the Atlantic in 2005 our chartplotter (new) failed and Lu modified an old yoghurt pot so the back-up GPS could sit outside and get a signal because the integral aerial didn't receive down below. It also made it easy for the person on watch to keep an eye on things.
(My thanks to G Shimmin at the Geodesy department of the British Hydrographic Office for his help with this article.)
Chart plotters are a useful aid to navigation and previously we had a small Garmin 276 down at the chart table. For this trip I got a Garmin 3006 and a plastic nacelle from ebay so it could be mounted on the binnacle bar. The bar needed to be modified, as did the nacelle (it was for another unit), but overall it looks OK and importantly gives the helmsman something to look at. It was tempting to link it up with everything else, but Iíve had too many electronics go down in the past, even those mounted down below and in several cases only just out of the box. Itís fine for the manufacturer to say he will replace it within warranty, but thatís little help mid-Atlantic and all your waypoints have just disappeared. So Iím going for lots of standalone units without having the instruments, radar, other chart plotter, etc. all interfaced to one another.
A friend on another boat has been without his radar for months. It is piped to the chart plotter display but somehow his software for it has been corrupted . Now thatís fine if you are in the UK near a dealer, but just try to get it fixed in southern Italy or Greece. Heís taking the unit back with him. As for us, just makes me happy to have a standalone unit that is visible from the cockpit (itís mounted on the bulkhead where the chart table is) and not interfaced to everything else. The wetware we were all born with is pretty good at bringing together disparate bits of information and we all need to be aware of that warning that comes up before you are allowed into a display unit: This is an aid to navigation blah blah. And so it is. We need to combine all the information we have, from the plotter, depth sounder, the Mk I eyeball, the chart, the pilots, radar, and cautiously use it to make landfall or approach any of those hard bits above or below water. Iíve just plotted a position of an alleged uncharted rock. Well itís about 30 metres away from a charted rock and you are just plain foolish to believe your electronic chart or plotter is that accurate.
Have a look at the plot below.
From the Skylax blog 30-04-08
you need to keep an eye on any nearby shipping and if it looks a bit
iffy then give them a call on VHF to establish their CPA. This always
led to conversations like Ďmotor vessel in approximate position
da-de-da this is sailing yacht Skylax in position da-da-da on a true
course of daa, overí. Sometimes we would get an answer and sometimes
not. So when I was back in the
We had it fitted in no time and connected up to the GPS below despite the primitive little instruction manual that comes with it. Like most NASA stuff it has itís limitations, but for the price it is a grand little receiver and does what says on the box.
On the trip from Sint Maarten down here to
It also has the benefit of drawing very little power compared to the radar that we would normally turn on to establish distance and course relative to us. It has a few little niggles. Lu finds it hard to get used to a N-up read-out compared to head-up. It occasionally gets a bit flustered and loses the GPS signal, though re-booting the GPS plotter usually sorts that out. And it has no on and off switch so Lu installed a little push-pull switch so it can be turned off independently Ė the breaker feeds other instruments as well.
So for £200 I give it full marks and it suits my KISS philosophy keeping all instrument systems separate rather than linked. We could have bought an AIS engine that came up on the Garmin plotter in the cockpit, but that would mean a hardware or software failure there would shut down not just the plotter but the AIS as well. I also installed a separate VHF aerial on the pushpit instead of a splitter to the masthead VHF aerial. This gives us a spare aerial for the VHF should anything happen to the masthead unit and despite not being very high, we have had signals from ship up to 16 miles away, though more commonly it is half this distance.
From the Skylax blog 12-04-09
Laptops on board
to make sense and for a while I used a laptop for navigation, backed up
of course by paper charts. In the bad old days once you had paid your
money for the software you were given a key that sat on the hard drive.
was kept secure on the chart table with Velcro and this was fine except
when things got really bumpy and the hard drive protested at all the
thumping the boat was taking. This can still be a problem and a lot of
modern laptops will flash up a warning about vibration affecting the
hard drive. A few laptops have cushioned hard drives that can cope with
a boat thumping along in a sea.
In the end laptop navigation was not for me. Kiwitech was bought by Raymarine and I kept up through several versions of the software now called Raytech. There are a lot of functions on Raytech software and this is part of the problem for me. When I was tired and went below to check things I would need to first find my glasses and then attempt to get the cursor over the button or menu I needed. This can be difficult and in the end I found it easier to use a mouse than the touchpad found on most laptops. Software that has the facility to be configured with a few big buttons, the ones you will likely use when at sea, makes it a lot easier and you can always revert to a lot of smaller buttons and more functions when in harbour planning the trip.
I have to confess that I stopped using a laptop and navigation software when at sea and have become a convert to the chartplotter. Its got less buttons, itís tougher, and its waterproof. We have one at the helm and a small Garmin 276 down at the chart table.
Garmin 3006 at the helm
I still use the laptop and navigation software for some planning, though really I like to get those old fashioned paper charts out and have a good look at where I am going on them. I also use Visual Passage Planner (http://www.digwave.com ) quite a lot for planning longer passages. We do have one computer we use at sea and that is an older tablet PC (with a cushioned hard drive) that is used with a steam-powered Pactor modem and the SSB to download weather GRIB files and to email our position at sea. Itís quite a compact unit that sits on a shelf next to the chart table and has a touch screen and a rubberised keyboard. I doubt it would be fast enough to run todayís processor and RAM hungry software, but you could conceivably run simple navigation software.
Tablet PC on shelf at the chart table - it's steam-powered but runs plenty fast enough for the Pactor modem and other simple functions like tides. Bought on Ebay for £180.
A friend of mine, Jack Marsh in Turkey, showed me this little trick to increase a wi-fi signal. Just take a collander, any old metal collander, and tape a wi-fi receiver dongle in it as shown. Fire up the computer and then put the collander 'dish' out of a hatch and angle it at the aerial broadcasting the signal. In some cases the signal will be bouncing off solid objects like the walls of a building so the angle may not be directly pointed at the aerial. Its cheap and its worth buying a dongle to put in the 'dish' even if your laptop has an aerial (as most of them do) enclosed somewhere around the screen. Thanks Jack.
Update on Wifi
From the Skylax blog 03-01-09
Almost as important as a secure berth or anchorage these days is access to wifi. An increasing number of places broadcast wifi over a marina and an anchorage and although we are not talking the sort of speeds you get from broadband at home, there is usually enough to get email and browse slowly. To some extent it is a matter of picking a time when there are not a lot of other people trying to use the wifi signal Ė that can be early in the morning, at lunchtime or around dinner time, itís a matter of experimenting in the location you are in.
In a marina or especially at anchor one of the problems is to get a good signal and for this you need an external aerial you can poke outside.
The first external aerial I used was simply a USB dongle taped into a colander (thanks for the idea Jack) that acted as a dish to amplify the signal. It works so so.
The second one I got is a Hawking dish aerial that we nick-named Ďmini-Jodrell Bankí. You can get two types. One plugs into the wifi card via a coaxial cable. Most laptops donít have this option. The second plugs into a USB port. You simply install the software and the rest is pretty seamless. What you will need is a USB male/female extension cable so you can park the dish up out of a hatch or somewhere on deck so it has an easier time picking a signal. Jodrell worked just fine but it has a couple of drawbacks.
The first is that it needs to be aimed approximately towards the transmitting aerial. When you are swinging around at anchor this means that signal strength goes up and down and sometimes disappears. The second drawback is that it is not waterproof and the little PCB inside doesnít like to get wet Ė not even moist. Does this sound like the voice of experience? Oh yes, one little tropical shower and Jodrell was dead though he still valiantly tried to light up the LEDís on the front. No amount of drying him off and spraying the insides worked. Jodrell is a dead parrot.
So whatís next? A couple of other boats used an outdoor omni-direction rod aerial. With an extension you can hoist this up on a flag halyard and get better signal strength. You can even further weatherproof it by sticking it in an old plastic water bottle with a bit of silicone around the neck and hang it up that way.
Iíve tracked down a omni-direction outdoor job for a tad over £60 and given the Hawking was around £40 that seems OK. The picture below is from the internet site which majors on bad English but hopefully has a good techy background.
Wifi locations Greece to NZ
Gibraltar: Fairly expensive system in
Lanzarote (Puerto Calero): Good system in the marina and reasonably priced.
St Maarten (Lagoon Marina): Reasonable signal and not too expensive.
French Polynesia: Iaoranet provides wifi in Nuka Hiva, Rangiroa, Tahiti, Huahine, Raiatea, Tahaa and
NZ: Wifi in Opua Marina. Wifi in
New Caledonia: Wifi in Noumea but difficult to organise (has to be authorised through a local phone number). Wifi in the MacDonalds near the harbour so ingest some awful food or coffee and connect.
Vanuatu: Wifi in Vila. Internet cafes in Luganville.
Australia: Wifi in Cairns Marlin Marina. Wifi in Cullen Bay Marina, Bayview and Tipperary.
Indonesia: Some internet cafes in larger towns.
Singapore: Wifi in Raffles Marina and RSYC.
Some basic paper reminders
We make up our own logbooks using the pages reproduced below. Then it's off to the local print shop to get the pages photocopied with the overleaf page on the back so pages are back-to-back, then print off your own cover and get them laminated and then the whole affair is spiral bound. OK so they don't last as well as a properly bound book, but generally they will last a season.
We keep a 3 hour log on board which is filled in on change of watch when on passage. Apart from it being a legal requirement, it can be useful if for any reason all the instruments go down (and they do) so you will at least know where you are from the last log entry. And it makes for interesting reading at a later date - food seems to figure prominently in the comments section.
Put the boats name and registration number and any other pertinent details at the top of the page. Use an Excel or other spreadsheet to make up an A4 page or use the tables feature on a word processor.
Date Time Lat Long Wind Sea Barom mb Course reqd. COG (Track) Dist NM Speed knots SOG
Don't forget to leave a margin on the right hand side of the left hand page and vice versa for the ring binding.
Don't forget to leave a margin on the right hand side of the left hand page and vice versa for the ring binding.
If something bad should happen, (libations to all the gods that it never does) I have a check card on the bulkhead at the chart table so if I get jittery from the adrenaline pumping through me because something bad has happened (libations to all gods ancient and modern and any others i don't know about) then I can look at the card and at least phonetically spell the name of the boat and then run through the correct procedure. It also has a checklist of the order and type of things to grab should we need to abandon (I promise wonderful libations to all gods the next time I open the finest bottle of wine) ship. I just print it off the computer and then get it laminated at the local stationery shop. The layout I use is below.
Sierra Kilo Yankee
Call sign MGAY Mike Golf Alfa Yankee
Mayday Mayday Mayday
Skylax Skylax Skylax
Give position (GPS and/or bearing and distance off fixed point or major port)
Brief description of problem: Urgent assistance reqd./POB/over
Pan Pan Pan and then as above
Launch Liferaft and tie to yacht
Food and additional water
Documents/ fishing lines/ torch/ anything useful/ more water
One of the cheapest and best bits of navigation equipment you can buy is a pair of polarised sun-glasses. By this I mean polarised sun-glasses and not any other sort however much they promise in terms of glare reduction, UV protection and style. Polarised plastic is known as a dichromic material and the important thing about it is that it transmits light only in one plane, typically the vertical plane. By cutting out the horizontal plane polarised materials effectively remove one plane of the reflected light on the surface of the sea and this allows us to see transmitted light bouncing off shallow areas such reefs and sandy bottoms. These are all the light blue, green and turquoise colours that identify underwater obstacles.
The value of polarised sunglasses in detecting just where a reef is and where the sandy patch is to drop anchor should not be underestimated. Normal sunglasses just will not do. You can check if your sunglasses are polarised plastic by getting hold of a pair you know are polarised and rotating the lenses of the two through 180ļ. At some point the two lenses together will not transmit light and will effectively go black.
And of course polarised sunglasses help cut down UV radiation which is damaging to your eyes.
Non polarised Polarised