temptress
Well-known member
you can do that and get there but if you don't allow for the tide and currents beforehand you can add hours to a typical cross channel jaunt in the Uk or days to an ocean passage.
how do you sail your boat?
- Thread starter wotayottie
- Start date
you can do that and get there but if you don't allow for the tide and currents beforehand you can add hours to a typical cross channel jaunt in the Uk or days to an ocean passage.
westhinder
Well-known member
You are absolutely right, but I'm afraid reality has given way to steering the ship symbol straight across the screen to the destination or the next waypoint.
It is very disappointing that plotter software does not use all the tidal and currents information which is available in the system anyway. It does exist, however, the Seapro nav program gives you a course to steer that takes account of the current beforehand. It was a bitter disappointment when I switched to a boat with a plotter that the plotter did not do this. Nowadays I make an educated guess and roughly correct the bearing to waypoint for a course to steer. And to steer that course, the compass is still the basic instrument when there is no other convenient point of reference. Or I tell the autopilot the course to steer.
Bobc
Well-known member
I don't steer to the GPS. If for instance I'm doing a cross channel, I'll add up all my currents and get a net overall set, then plot my course to steer on the chart (simple vector triangle), then I'll simply set the autohelm to steer in that direction. I then just use my GPS to give me a fix every hour which I plot on the chart, and that's about it.
I often see people coming around the Needles and heading off at 170/180 in an ebb tide to follow the GPS ground track, and they usually arrive in Cherbourg a couple of hours after me because they've sailed big curves.
johnalison
Well-known member
The Navstar Decca in the last century could be programmed to take the tide vector and give a course to steer. Mind you, it cost over £400, the equivalent of a thousand or two today.
jordanbasset
Well-known member
The most use my compass gets is in working out where the sun will rise and set so I can adjust the shade and solar panels for optimal effectiveness
Moonbeam
Active member
Very very simple... We have a chartplotter in sight of the helm. On a passage, we have already plotted the route into the chart plotter (double checking against paper charts if unfamiliar waters). Our boat symbol on the chartplotter has a leading line/projected track line, whatever you want to call it, extending 5 nautical miles (you can adjust this) in front of our boat symbol on the screen, this shows where your boat is actually heading rather than where it is pointing.
You simply line that projection line up with the route you have plotted on the screen and hey presto, you are continually adjusting your course in real time to follow the shortest possible track across the ground accounting for tide, leeway etc. Even without a route to follow, when just boating about for fun, the leading line from your boat symbol always tells you where you are actually heading and allows you to make course to steer adjustments and anticipate best times to tack etc to work tides and avoid the rocks. Chartplotters are brilliant bits of kit.
We do keep an hourly paper log on passage and note down the boats magnetic compass heading as the course to steer (at that point in time), so if the electronics fail, we do have a fall back. But that has never happened.
We've been using this method for 10 years. About 5 years ago, I read what Tom Cuncliffe had to say about it in his complete yachtmaster book... "The projected track vector is the most important single navigational breakthrough since the chronometer... In the safe hands of a navigator who understands the variables, this is the most remarkable aid to security because it has, to all intents and purposes, already calculated set and drift, and applied them to your heading."
Whats not to like. Try it.
dancrane
Well-known member
That's undeniably convincing, like the sound reasoning behind latex prophylactics. Somehow, I'm not especially keen to start using a plotter, either.
Maybe I'll change my tune when I have a yacht - but the appeal of ownership is diminishing, at the prospect of navigation by microchip.
RobbieW
Well-known member
Fine with a constant current, its very useful - nearly as useful as using transits but theyre not always available
The scenario many above are describing is an 8-12 hour straight line trip where the current builds then diminishes and finally reverses every 6 hours. In that scenario following the track rather than allowing for its variation over time and setting a constant heading will delay your arrival
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doug748
Well-known member
The old Psion computer used to have a program that made a nifty job of this. Just put in your start and finish ports, plus time of departure and it dished out the Course to Steer. Alternatively it would give you the best departure time.
There must be an app somewhere?
RobbieW
Well-known member
The other way round surely ? You (& I) sail in big curves but utilise the tide, those following the track to thier destination end up punching the tide much of the time which is what slows them - combine that with some lee bowing and whats not to like. I often work out some vectors and check where I am when the tide turns adjusting heading as necessary
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capnsensible
Well-known member
Indeed, but Im afraid x box sailing is here to stay. In the same way that as soon as you step foot ashore the to the boozer, everyone whips their iphones out instead of talking to each other....
Now I am a big fan of the way small craft electronics have developed. From decca, gps, plotters, ais, radar, Ive learnt to use them all as they have arrived on the scene. It has made sailing safer and more accessible for a huge number of people.
But. Plotting DR and EP, looking at tide tables and charts or even looking out the flippin window seems to have been overtaken by electrons to the detriment of the prudent sailor. My view is that all the above are tools to assist me in voyaging, not making me a slave to an icon on a screen.
ctva
Well-known member
As mentioned, you are talking about the passage planning part. Once you have a course to steer, pop it in the autohelm and watch your course vary it XTE within your safety limits to get to your destination efficiently and safely.
Anyway, here on the west coast, the tide is usually either with or against you and only affects the amount of drinking time at your destination...
BelleSerene
Active member
You are right that constantly tweaking heading to keep your projected course on your destination will follow the shortest possible ground track.
Why you would want to do that, though, is anybody's guess. Sailors want to follow the shortest possible WATER track, which gives the shortest passage time.
On a short passage (within one tide) over a short distance (where tidal flows are pretty much the same), the two are fairly similar. Venture further afield - let alone a simple Channel crossing - and they are not. Maintaining COG by constantly tweaking your heading to compensate for the shifting tidal drift will take you to France in a straight line over the sea bed. But for much of the time you'll be offsetting your course to fight an East-going tide, increasing your water distance and so your sailing time, and for much of the rest of it you'll be doing the same to fight a West-going tide, also increasing your water distance. All the time you're doing that, you are increasing your sailing time compared with calculating in advance the net tidal drift of the whole passage, offsetting for that, and staying on a constant heading for the whole passage.
Your quotation is from where Cunliffe is explaining kit and how to use it. When he says that the projected-track vector has 'already calculated set and drift', that's true and it's the point - but it's only calculated the set and drift that it has been feeling over the most recent snippet of time - it has no idea of the set and drift coming as you cross a changing sea bed over changing states of tide. If you don't compensate for that yourself, you're in for a longer sail.
I know that later in that excellent book, Cunliffe explains (as does any other Yachtmaster text) how to handle a passage with changing tide, so perhaps you should read on.
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dancrane
Well-known member
Doug, I always read your input with the respect you've earned in my view...but even as someone who keeps a big smartphone at his side 24/7, I find your comment amazing!
Isn't there any enjoyment here, of going aboard, setting sail and intelligently approximating the influences of tide, leeway, etc...and then (having done the best according to one's mental powers) sailing for a little longer to make up for factors you couldn't wholly predict in advance? Is that actually less fulfilling than pushing buttons and steering by electronic guidance? Or are we talking about voyages so extended and tedious or terrifying, that the crew's single, urgent priority is simply to end the passage without delay?
capnsensible
Well-known member
GHA
Well-known member
Having the choice is nice, having a car parked out the front doesn't mean you are not allowed to enjoy a nice walk to the shops
RupertW
Well-known member
We use the compass as a reference point and when checking what angle we are tacking through but steer using autohelm by landmarks or iPad checks on the chart table every now and again.
As we haven't used DR for years I've never checked its complete accuracy.
I can't say we are going down the basic boat model as we like the domestic electrics from dehumidifier to ice maker but haven't felt the need for a proper charplotter, let alone a cat cockpit visible one.
As we haven't used DR for years I've never checked its complete accuracy.
I can't say we are going down the basic boat model as we like the domestic electrics from dehumidifier to ice maker but haven't felt the need for a proper charplotter, let alone a cat cockpit visible one.
Bobc
Well-known member
Yes, quite. What I meant is people constantly altering their course to stay "on track", which is effectively sailing curves (if you get me drift).
doug748
Well-known member
Aw go on.
It's amazing that anything is read in this place - but Respect is summat else ;-)
The program I mentioned was very handy for racing long, cross tide, legs with a flexible start time. You could rapidly see which was the worst and best departure time in terms of distance through the water. What's more, when you were becalmed within sight of the start line after 12 hours, you could entertain yourself by plotting a new course to steer and playing games of Pipemania on the Psion.
Rest assured that in ordinary mode, I pull the sails up, point the boat in the general direction of travel and watch the little boat on the screen.
DJE
Well-known member
There wasn't much point having the compass on the boat until I adjusted it. ?
I find it indespensible on Channel crossings aiming to lay off the set for the whole passage and keep the same heading all the way across. It feels great when it works!
But we also use it a lot for inshore pilotage. It lets us split the work between navigator and helmsman. A big screen at the wheel means that one person has to do it all. With Sue steering I can work on the paper chart or the plotter telling her something like, "steer 240 after the beacon and the next buoy should be on the bow." This lets her concentrate on traffic, echo sounder, or just enjoy the view. It also preserves her night vision in darkness.
I find it indespensible on Channel crossings aiming to lay off the set for the whole passage and keep the same heading all the way across. It feels great when it works!
But we also use it a lot for inshore pilotage. It lets us split the work between navigator and helmsman. A big screen at the wheel means that one person has to do it all. With Sue steering I can work on the paper chart or the plotter telling her something like, "steer 240 after the beacon and the next buoy should be on the bow." This lets her concentrate on traffic, echo sounder, or just enjoy the view. It also preserves her night vision in darkness.