Allowing for tides etc on medium length trips?

The easy, or lazy man\'s, way, of crossing the Channel or North Sea

For the first 12 and a half hours, ignore the tide completely.

Unless your boat is a good deal faster than mine, which has twice managed to get from Ostende to Harwich in that time, but never in less, you won't have arrived at the end of 12 1/2 hours, but you will be on the direct line to where you want to go, (unless the wind has played silly beggars and headed you).

Now establish where you are, and how far you still have to go, and guess how much longer you are going to be.

Lay off a course allowing for tide for the remaining part of your passage, and steer it.

NB. Do lay off this course the right way. I once sighted the Shipwash, 12 hours out of Ijmuiden, patted myself on the back and laid off a course for Harwich.

Next thing we saw was Sizewell Power Station; crew decidedly un-amused! /forums/images/graemlins/wink.gif
 
Re: The easy, or lazy man\'s, way, of crossing the Channel or North Sea

Glad I'm not the only one! /forums/images/graemlins/smile.gif
 
if going to Channel Islands work backwards using times of Start of Southbound Aldernay Race.Alternative go to Cherbourg Steer 175 from Needles or 185 from Nab.It usually works!!..But please do the sums yourself.
 
...Or of course take soemone with you who has already done it a few times ;-)

Or sale in company with another boat of similar type/speed
 
[ QUOTE ]
If the wind is blowing direct from target, then learning the principle of lee-bowing saves hours of passage time!

[/ QUOTE ]
What's this lee-bowing? Sounds great!
 
It's an effect that is at its strongest when the wind and tide are at about 90 degrees to one another - a typical scenario when crossing the Channel to France with a southerly wind and east/west tidal flow. It is based on the fact that the movement of the tide creates its own apparent wind, which has the end effect that on one tack you will be able to point several degrees higher than the other. If you start of on the favourable tack and follow it for, say, 6 hours until the tide turns, it speeds up passage times enormously. The favourable tack is always the one where you present your lee bow to the direction the tide is coming from, hence the name.

Think about it like this: if you were sitting in the Channel in an absolute flat calm, but in a 4 knot tidal stream from the west, you would actually feel 4 knots of wind from the east, because that is the speed that the tide is carrying you throught the air.

Now, say there is a wind from the south and a tide from the west. The actual apparent wind that you feel on the boat seems to be coming, not from south, but from slightly EAST of south. You can take advantage of this fact by starting to head towards France on the port tack. When the tide turns, the wind will seem to come from slightly WEST of south (assuming the true wind direction hasn't changed), and it is time to tack onto starboard tack. In this way you will be able to point much higher all the way to France than if you had done the opposite! /forums/images/graemlins/smile.gif
 
Also...

About Harwich - IJmuiden, there is a VTS roundabout bang in the middle which wouldn't be very nice to go through. The really satisfying bit (which worked perfectly the last time I went that way, it was REALLY satisfying) is to set off such a time so that the tide boosts you North up the coast so that you hit a waypoint just north of the roundabout, then let the tide carry you back down to IJmuiden. In other words, taking advantage of the S-curve that the tides give you over the ground to avoid an obstacle while all the time pointing the bows more or less in the same direction /forums/images/graemlins/smile.gif

There are one or two tides in between, but the idea is to get two tides carrying you the right way and one the wrong, so the net effect is to cross the VTS at the right point with little effort.

This was one case where I found an intermediate waypoint (edge of the VTS) was really useful.
 
french side tides are stronger. Plan your arrival (assuming you can leave your moorings at anystate of tide If not Move earlier to suitable departure point or expect to delay your arrival for the suitable land fall)
Take a bearing (grid) and assumed speed? which will give you ETA and adjust your departure time according to the needs of your destination port.
Assuming Yacht, speed 5 knots (use engine if necessary to keep to plan) Work out tidal vectors for the duration of the trip , say 12 hrs andplot the vectors from the start point. Draw your line from the final vector position and you have a new bearing. Work out the variation (GRID TO MAG ADD) and you will have your new bearing to follow (Compass)

Ensure you plot to up tide of destination.

I hope this helps?

regards.

peter.
 
That's a pleasure, Simon

Simon /forums/images/graemlins/wink.gif
 
I should just mention that I have not actually been accross the channel yet....... so bear this in mind! However I have been around this part of the world for a couple of years, or so /forums/images/graemlins/grin.gif

I would suggest that you work out a passage plan on paper, around crossing the Shipping lanes and heading down the Alderney Race, so as to do these with the most favourable conditions, with everything else being a secondary consideration.

In practice this may mean you stopping off in Cherbourg or Alderney, even if you did not originally intend to - just that whilst you don't of course want to be heading down the Alderney Race when it is going the wrong way, IMHO you may just as well time your arrival so that you get it's maximum benefit - if you miss your intended / hoped for "window" (because other parts of your passage did not go to plan) this means you just stay the night somewhere.

Obvioulsy their is no reason why you can't do the trip in one go, but as you do seem to be at least wary of the trip it may make sense to break it up anyway, lot easier to re-plan when tied up or sitting in a pub ashore than being tired and bouncing around, in any event I always beleive that when learning something new it is best not to start off pushing yourself tp the limit (IMHO even if you were capable of doing it in one go and the weather gods permitted.....why not break it up anyway?)

On a practical point I would make sure you get a Tidal stream Atlas for the Channel Islands! Fairly fast currents are NOT intrinsically dangerous and can be a big help - as long as you know what time they are turning and in which direction they are going and plan around them / with them. I would also say do not get "greedy", just accept that you will end up punching some tide, no one likes having a couple of knots knocked off their speed, but overall it should more than balance itself out - getting it wrong should only be matter of adding time to your trip and should be treated as learning curve - you will no doubt make the time up on the return trip /forums/images/graemlins/cool.gif

Despite what has already been said you do not need training for a trip down to here - experiance comes into play when you are "taking shortcuts" or getting into some (many!) of the smaller bays. But no reason why someone new to the area can't try the smaller bays etc, just that I would suggest that after a trip accross the channel and down the Alderney race it makes more sense to head for somewhere easy to tie up, and then go and explore somewhere more "tricky" the next day - I would however make sure your engine was reliable, 3 /4 knots of current at the wrong time.........and no wind......... can "ruin" your day. /forums/images/graemlins/laugh.gif

Have a good trip.
 
Thanks all, great advice and I'm used to the occassional alternative opinions on the forum.

Snowleopard picked up on my situation very well. We have done RYA courses (whole family is Day Skipper Tidal) and I've done the Channel Islands trip myself last year as navigator, on a HR42. I did it "by the book" with GPS to make sure I was where I thought I should be, but I thought there must be sensible & practical ideas that you only gain through experience, not through books & courses - hence posting the question.

NB for those clearly worried about our safety (nice to know!) our first family X-channel trip will be either in company or with experienced skipper onboard.
 
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