A navigation question

[EdWingfield]

When making a North Sea crossing of 200M+ should you a) make course adjustments to counter the effect of tidal streams? Or b) make no course adjustments for tide?

 

[Phoenix of Hamble]

calculate a CTS for the whole leg and steer it.... if you adjust for each tide, you'll sail further through the water, and take longer

 

[KenMcCulloch]

b) the tidal vectors will mostly cancel each other out over the 2 days or so it's likely to take. Keep uyp the plot though so you know where you are even if th GPS fails.

 

[alan17]

How long is your trip estimated to take?

Effectively I take note of the effects of current etc and reassess my course after 25% of the estimated trip time and again at 50% and 75%. Inevitably there are adjustments to make not just because of tides but separation schemes, other vessels. fishing nets and many other things.

 

[sarabande]

that would be true if the course were mainly across the tidal streams but, say, going from Hull to Oostend, there are going to be more critical tide components on the last section than the first.

I suggest that you have to take wind direction into account to optimise the lee bowing effect. Plus you may be forced to adopt a certain course by TSSs.

 

[Rosemarine]

Just a thought, but where are you going across the North Sea on a course of 200 magnetic?

It seems an odd direction to cross the North Sea!

 

[alant]

Work out likely time for trip, using departure time, nominate the tides in one direction as +, with the tides in other direction as -. Then add up all +, subtract all -, this gives the tide to use in your tidal vectors.

Use this for plotting CTS.

Or you could plot all the tidal vectors & use this for plotting CTS (should be similar to above).

Use total boat speed for all the hours of your trip in both methods.

This is in RYA YM booklet (English Channel crossing).

 

[Twister_Ken]

No degree sign, 200 nm I suspect

 

[EdWingfield]

Course will be 135deg for 260M or reciprocal. I would hope to maintain 5kn min

 

[dolphin]

it is all depent from the navigational area! the speed of the boat and the speed of the tide are very close or small differences between the both and this, will affect the main course dramatically ! i will never neglect the tide and will try to use the current as much as possible in my favour

 

[bbg]

Buy MaxSea (or another routing software) and let the computer figure it out?

 

[Refueler]

[ QUOTE ]
Just a thought, but where are you going across the North Sea on a course of 200 magnetic?

It seems an odd direction to cross the North Sea!

[/ QUOTE ]

Think he meant 200 nm /forums/images/graemlins/laugh.gif

 

[Mariner69]

I would plot the track I want to make over the ground. Identify any hazards in the vicinity and mark them on my chart. Assume my speed based on my normal progress through the water and allow for the tidal effects for the best course to steer to make the desired track but not for the whole voyage as there will be so many changes and the speed is low. I then plot my progress frequently and adjust as I go to maintain the desired track. ETA based on a realistic speed over the ground for the voyage. Upwind 50 percent of speed normally achieved.

 

[johnalison]

With a 200m crossing in about 36 hours you'll be subject to roughly six changes of tide. As has been said, they'll largely cancel out but ignoring necessary course changes on the way, it is good practise to do the tidal calculations anyway. In the shorter crossing I do from Essex-Den Helder I experience four tides and the offset for the tide is seldom more than a few miles, and I can't steer accurately enough for the odd degree of adjustment.

 

[matelot]

dont over navigate - easy to do when boredom sets in. personally I would aim the boat for the destination and only review when half way there.

Actually, to be frank, I would be tinkering with the autohelm and plotting position all the time because I cant stand doing nothing much. so do as I say not as I do.

time difference? who cares if you lose an hour or so in a 2 day trip? I always find on longer legs that I'm disappointed when they finish anyway

 

[Cruiser2B]

Tides don't always take reciprocal paths, particularly in basins. It depends on where you are going - something like this might be helpful: http://www.bsh.de/aktdat/modell/stroemungen/no/noe.htm

 

[planteater]

[ QUOTE ]
calculate a CTS for the whole leg and steer it.... if you adjust for each tide, you'll sail further through the water, and take longer

[/ QUOTE ]

As long as there are no hazards. If there are sands, rocks, TSS etc. then you need to know where you a likely to be on an hourly basis. Not just where you'll end up 40 hours later.

 

[Anonymous]

[ QUOTE ]
When making a North Sea crossing of 200M+ should you a) make course adjustments to counter the effect of tidal streams? Or b) make no course adjustments for tide?

[/ QUOTE ]

Or c) Follow the ferries /forums/images/graemlins/wink.gif

 

[Kawasaki]

Fascinating thread.
There is always one [--word removed--].
Lemain You win this time /forums/images/graemlins/laugh.gif

 

[EdWingfield]

Thank you Cruiser2b for that fascinating tide stream chart.

As for following the ferries, I have the waypoints of the Newcastle-Ijmuiden ferries. The skipper assures me he won't run me down in the middle of the night! /forums/images/graemlins/smile.gif