how do you navigate?

[Birdseye]

further down the page there is a post about gps repeaters and a discrepancy of 3 degrees (no , not the group!). i was about to post a facetious comment concerning their apparent ability to helm to within this figure, when it occurred to me that i very rarely look at the compass anyway.

i do all my nav in true, and i do most of my passage making by comparing the gps figures for track made good with the bearing of the waypoint and adjusting the autohelm accordingly. ie track 310 waypoint 315, add 5 to autohelm. now i know that a purist would tell me that this practise is wrong, but it seems to work ok in real life.

so how do you navigate on passage in this modern electronic age? and do you keep a log or just a few crosses on a chart? i keep a log because dr is my fallback, never my prime nav method.

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[billmacfarlane]

I'm afraid I'd qualify as the world's laziest navigator. If for example I'm doing a cross channel trip , I put the rhumb line on the chart , work out roughly the tides and start the passage using my compass. Because it's difficult to see the compass sitting down behind the helm I use the Autohelm compass but I first look at its error compared to the steering compass. I put the GPS position on the chart once per hour and mark it in the log as well. Before I put it on the chart I compare it to the rhumb line and distance run on the log , and if it looks roughly OK I mark it on the chart. That's about it really but about half way across I'll check the tides and make any course adjustments to make sure I finish uptide. If I'm feeling really laid back I won't put the position on the chart too often but I'll still keep the log up to date because if the electrickeries goes up the creek so to speak I'll still have a reference point to start navigating the pre-electronic way - tidal diamonds and all that sort of stuff.

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[jimi]

Bill, virtually exactly what I do.

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[Birdseye]

bill - when you talk about working out the tides, do you mean doing the rya "course to steer" bit, or checking tidal gates and heights at arrival and departure? i do the latter, but dont worry about course to steer since the tidal info is duff away from the diamonds, and the track made good versus waypoint bearing allows for this anyway.

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[Neal]

Here\'s wot I do....

On a cross tide passage eg Le Havre to Weymouth, I'll spend ages, giving myself a headache, doing a tidal vector, hoping to be able to hold the same compass course all the way across. Never works out, but it makes me feel virtuous, and should help to minimise distance sailed. I use Reeve- Foukes for tidal steams.

I plot a gps position at least every hour on a paper chart, noting time and log reading. I then do a quick E.P. and look at the echo sounder as checks that nothing has gone massively wrong. I guess it would be best to plot the EP first, but I'm being honest here.

Like you I work in true.

I do kep a log: time, course, distance, wind speed (Beaufort as I don't have instruments) and direction, and barometric pressure if I'm worried. I also put any comments I feel appropriate. I write it up at least hourly.

As destination gets closer, I keep a watchful eye on the GPS's track and bearing to waypoint, and adjust as necessary.

GPS is wonderful, I wouldn't want to be without it now, but it defintely reduces the satisfaction I get from a good landfall by 'traditional' means.

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[tome]

Hi Birdseye

Interesting question. The post to which you refer indicated a 'bust' between GPS and repeater which is annoying rather than critical, and was simply a case of the GPS using mag whilst the repeater used true.

For local (Solent) sailing I hardly bother with formal navigation unless the viz is poor. Even then I know my courses and distances well enough. I do take the trouble to calibrate my log and check it from time to time, also my compass deviation against transits. For longer passages I write up the log every hour and mark the chart. I take a look at tidal charts if in unfamiliar waters, but rarely bother to plot vectors.

Like you I do all my nav in True and always round to 5 degrees for steering.

In years gone by I've had to navigate with much more care and could easily revert to traditional methods if I lose power or GPS. I don't use an electronic plotter but prefer a Yeoman as it gives me the ability to continue using DR if necessary. I'll use the Yeoman cross channel and particularly Channel Islands where I pay much more attention to nav.

Regards
Tom


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[billmacfarlane]

If I'm on a Channel crossing I'll reckon on an average speed , usually 6 knots , total the tides up for the entire passage and from that work out a course to steer before I set off.

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[claymore]

Hmm
completely de-skilled it. Wife calls it sailing by numbers as I plot the waypoints into my laptop-based nav. software then just follow the red line from one to another.
I keep a log hourly if undertaking a new passage but on regular passages I just note the times at critical points along the way so that on future passages I can look back and work out how long it took me to get from A to B. I normally do this when I'm working out the time to arrive at a tidal gate.
If not using waypoints I have a ship predictor line on the software and I use that. Interestingly ParaHandy did a distance off calculation on a light using a rangefinder when we were out together two weeks ago. I was rather impressed with his accuracy and his figure more or less agreed with the distance circle I have in the software.
I know the day ought to come when the gps or the software takes a dive so I will occasionally do a manual EP or Fix just to keep myhand in, but in truth I don't do this as often as I used to. Then again, I don't think you are likely to completely forget how to navigate by traditional methods, just get a bit rusty!

<hr width=100% size=1>regards
Claymore
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[bob_tyler]

In days of yore, long before GPS, I had a steering compass, hand bearing compass and echo sounder No log or anything else besides charts.

To cross Channel, Langstone to Cherbourg or to Alderney, did just like you but, being in a twin keeled Caprice 18'6" loa, worked on 4 knots. Put on 4hp outboard if wind dropped too much to save re-plotting!

That was my total "passage planning". What would the MCA say today?

By the way, I was never more than about 1 mile out, always up-tide, on approach to Cherbourg.

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[Gunfleet]

I think, Claymore, once you have learnt it that's the end of the matter. If the gps breaks you will remember in quick time! 35 years on I can still do the proof of Pythagoras my maths teacher taught me. Why should I forget navigation vectors after ten years? By the way the way my day skipper course tutor taught navigation, vectors were treated entirely inappropriately... but that's another matter.

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[claymore]

Yes
I agree with you about the skills - I do a fair bit of hill walking with students and with my family so I do keep in practice in that respect - it's those natty little numbers like doubling the angle to find distance off that just make you think a bit when you haven't done them for a while
Nice thing aout sailing in Scotland is that the tide is either with or against you so it tends to make tidal vectors a bit academic really!

<hr width=100% size=1>regards
Claymore
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[ccscott49]

I do exactly the same as you! But I do know my position and plot it, I also sometimes when in sight of land take a couple of sights with the handbearing compass (remember those?) and plot it, just as a check. Along with radar bearings etc. Belt and braces jobbie.

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[wpsalm]

when near land I keep the chart in my hip pocket folded so as to show the nearest danger estimate my speed , keep track of the time put a little x down occasionally look at the compass now and again.. out of sight of land GPS ....by the way whats a tidal diamond , just kidding sort of ...saw an add in a British yachting mag not to long ago for a device about the size of a pocket calculater shows the state of the tide for all the little ports around the British Iles looks very handy can,t find the magazine and think I,d like to have one anybody familiar with it...

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[rex_seadog]

Pleased to see that most of you experts combine traditional and electronic techniques pretty much like myself. The important thing is to know when corners can be cut and when it has to be done properly. Would be a bit concerned at using a laptop on my Delta but, as you know Claymore, it's a bit different to a motorsailer. On our last cross channel to Guernsey last October in rather lively conditions we had water leaking through the vent over the galley and running (due to port tack) along the headlining straight into the electrical switch pannel for a dozen hours. Spent some time this last winter re-making the corroded connections. Have also re-sealed the vent!

More seriously, it concerns me at all this reliance that many (not including this exhalted company) place on electronics. It's not unheard of for the all-singing computer systems in my nice dry level office to go on the blink from time to time with the ensuing chaos that that causes. At least when my Imray chart gets wet I can wipe it with a tea towel.

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[claymore]

Dolphin Maritime do a psion dedicated software package.
They have a website if you want to have a look
http://www.dolphinmaritime.com
hope this helps



<hr width=100% size=1>regards
Claymore
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[claymore]

Interesting you should mention the leak in the Delta. My Delta used to grow an impossible to detect puddle under the forward bunks. I kept the water bottle in here but it wasn't from that. Never did fathom it. My GPS, echo sounder and radio were fastened to the bulkhead over to starboard above the 'chart table' where it seemed to stay dry - do you have this arrangement?
I loved the boat and we still bemoan the loss of its sailing qualities when we are sat in light winds and wondering whether to motor sail.

<hr width=100% size=1>regards
Claymore
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[rex_seadog]

On my Delta the forward under-bunk area is divided into two with the water tank (a simple 20 litre plastic bottle) in the port side. No leaks there. However, on the starboard side we have similar frustrating (not wanting to use stronger Scottish language on this forum) leaks which I am fairly convinced resulted from the Blakes seacocks, especially when sailing hard. This last winter I removed them with a view to replacing (I had previously reground in situ with little apparent success) but then discovered that to turn them off completely required rather more than a 90 degree turn - about 105 degrees! So I was never really turning them off. I think I was getting some leakage from the valve itself but much of my problem was that water was backing up the loo, overflowing and then finding its way back through into the starboard bow locker, when the boat was well heeled, via the hole cut in the bulhead for the pipes. That's not to forget all the water that used to find its way into every other locker on the starboard side - and then on the port side after changing tack! As I say, I think that was the problem but I will know more after doing some heavy sailing - so far this year I haven't got in any sailing since launching in March. Damn work - I need a job like yours or preferably retirement.

The instruments and VHF are indeed over the chart table on the starboard side. At least the old ones are - I've fitted an Echopilot Duo display in the cockpit but still retain the old Seafarer depth and Walker trailing log instruments down below. No luxury like a fitted GPS - I am using a Garmin hand-held GP45 (I think - 8 satellite anyway) which I plug into the 12v system and can use inside or out as required.

Apologies for boring non Delta owners with this reply - should have sent a PM.

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[billmacfarlane]

I did umpteen Channel crossings in pre Decca days and I actually preferred night crossings. You could always get a good fix on the French lights assuming reasonable vis.

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[qsiv]

I have to say that I still DO prefer night crossings. It's the defensive navigation thing - if it all goes pear shaped, I can see the ships more easily, they might see me, and the landfalls are easier.

Got caught out last year off Brest though. Crossing fom the Raz to Four at about 22:00, something ahead of me had me completely fooled - I still dont know quite what lights it was showing - seemed like a combination of minesweeping and purse seiner shooting nets. I actually believe it was a Frech trawler with an inebriated tea boy on watch - lights went on on and off at random, and the course owed more to Damien Hirst than Henry the Navigator. Even transferring lat lon off the radar onto a paper chart I couldnt establish whate they were doing - so I tacked and passed over a mile astern of him, rather than risk a close up encounter. The Chenal du Four with a full spring tide and force 5 (20 knots over the ground) was a cinch after that!

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[Peppermint]

It depends where you are

and which technique suits.

On an open water passage say Needles/Cherbourg I'd use course to steer, arrived at from tidal vector and mag. adjustments, rounded up to nearest 5 deg. I'd keep it honest with back bearings to start with and do EP's or fix's from GPS onto chart and log each hour. Maybe check with the sounder if a feature presents itself. If not using GPS I'm looking to arrive at an up tide position not the harbour entrance.

Pilotage waters require a plan of features transits and contours and the chart is more to familiarise myself with these and to develop a sketch plan for use on deck.

What many skippers seem to get confused is which technique suits which circumstance. i.e They'll be busy at the chart table doing tidal vectors during a passage from Lymington to Yarmouth. Or plot a GPS position in Southampton Water or down the Little Russel. There is often a tendency to believe something worked out rather than something you see. i.e the ebb starts at 15:00hrs eventhough a glance at a buoy shows it's done no such thing.

I sailed with one old boy who's tactic for the Chebourg trip was get passed the Needles and go South then he'd collect the position at the other end using lighthouses or RDF. If you asked him when was the best time to set off he'd say "Now". Too much tide against in the Needles Channel? He'd just use more rev's in the N.Channel. Besides his yacht, a 30ft Macwester, he'd got a fishing vessel and he reckoned that from Selsey to Penzance he knew where he was anyway.

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