Dover to Calais Single Handed

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alec

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I plan to make the crossing in July.

Having never made the crossing at so narrow a point , is it too much hassle dodging ships ?.

I can make about 5kts under power.

Many thanks for any suggestions or advice.

Regards,
 
Just one point which, surprisingly, quite a few people seem to misunderstand; when crossing TSS lanes you are required to HEAD at right angles to the lane even though that means your track will not be at right angles. Several people I have met seem to think that you are supposed to correct for the drift and (yikes!) set their autopilot on to 'nav' or 'track' mode resulting in ship's head pointing wherever it is needed to keep a TRACK at right angles. People do get pulled up for this.
 
From what I remember, the peculiar thing about this particular place is that you have three distinct streams of traffic: the big ships heading up and down the TSS, the streams of ferries that plough a regular route Dover-Calais, and a mass of small craft heading across the TSS in a rather less predictable manner. This can really mean you have to keep on your toes.

You can make life a lot easier for yourself by letting the tide carry you downtide of the ferry track (they follow one behind the other on a very predictable path). This eliminates one stream of traffic from your calculations. If you time it so the tide changes when you're half way across, you can use the tide then to sweep you back up towards Calais.

If you avoid the ferry route as described, then crossing the TSS here is probably easier than elsewhere since the ships are relatively concentrated in their tracks and are hopefully on their toes.
 
QUOTE:
"......when crossing TSS lanes you are required to HEAD at right angles to the lane even though that means your track will not be at right angles. ...."
UNQUOTE.

Are you quite sure?
As I know it you are supposed to take the shortest / quickest way across a TSS.
This can only mean a <u>track</u> at right angles to the lanes <u>regardless</u> of where the boat is pointing at.
 
Lemain.
is quite correct but we must not forget that it is required you should cross at a minimum of 5 knots (not compulsary) so that ships radar can determine your course.
Cross at right angles, keep above 5 knots alow the ships to see a definite course that they can adjust to way off your position..

Regards.

Peter.
 
with respect - speed either through the water or sog is not an issue ...... ships radars can plot anything they can get a radar return from ...... including buoys obviously.
altering course every few minutes will make a resolution of your course made good more difficult but arpa radars will allow for that as well. (a decent radar reflector is the secret)
/forums/images/graemlins/cool.gif
 
The quickest way across a shipping lane is with the bows pointing at 90 degrees to the lane. Trying to maintain a ground track at right angles to the lane by pointing the bows off to fight the tide will result in it taking longer to cross.
 
To take an example: East-West shipping lane 4 miles wide. Tide running at 3 knots East. Boat speed through the water is 4 knots.

If you point the bows due south ie. at 90 degrees to the shipping lane, the time taken to cross the lane is exactly 1 hour.

If you maintain a course over the ground at 90 degrees to the lane by pointing the bows WSW, then time taken to cross the lane is nearly two hours.
 
No it doesn't!

If there is a 3-knot East current / tide. after one hour the boat will be 3 NM east of the 90-degree 'direct route' and the boat will have pased through (track) 5 miles of water.

Boat 'speed through water' as shown on a log is affected, favourably or adversely, by the relationship between ship's heading and the current direction. Boat 'speed over the ground' as shown e.g. by the GPS is more useful for navigation purposes. The effect of the current on the boat's 'speed' is the inverse of the previous. Going <u>with</u> the current your SOG is increased but the STW is decreased. The opposite happens when you are going <u>against</u> the current stream.

That's why we draw vector diagrams.

It is quite possible that we mean to say similar things but it is difficult to describe in words what is easily made clear by a doodle on the back of a beer mat! /forums/images/graemlins/wink.gif

Fair Winds!
 
So here are the vectors to prove it. 1 arrow = water track, 2 = ground track, 3 = tide.

Vectors.jpg


4 mile lane at 4kts with a 3kt cross tide works well because it's a 3:4:5 triangle.

The first one shows what you should do. i.e. cross with heading at right angles. It takes exactly 1hr since you have to cover 4nm over the sea. The tide takes you another 3nm at right angles to your heading so your actual speed (SOG) is 5kts.

The second shows what would happen if you compensated for tide. You'd have to head up into it to maintain a course at right angles. Hence, you'd actually have to cover 5 sea miles which would take 1.25hr.

So there's the proof of why the colregs require you to cross with a heading at right angles.

You don't say if you have radar but if you don't then the easiest way to check if you're on a collision course with the big boys is to take a bearing with a hand bearing compass on possible threats. If the bearing remains constant over time, you're on a collision course.
 
[ QUOTE ]
Boat 'speed through water' as shown on a log is affected, favourably or adversely, by the relationship between ship's heading and the current direction.

[/ QUOTE ]
[ QUOTE ]
Going <u>with</u> the current your... STW is decreased. The opposite happens when you are going <u>against</u> the current stream.!

[/ QUOTE ]
Sorry, but this is very muddled = wrong. For a start, Speed Through the Water does not change depending on whether the current is with you or against you!!!

See Wooslehunter's diagrams as to why it is faster crossing the shipping lanes with a HEADING, not COG at 90 degrees to the lanes.
 
Quote:

"Sorry, but this is very muddled = wrong. For a start, Speed Through the Water does not change depending on whether the current is with you or against you!!!"

Unquote.

Sorry but I don't see what is muddled.
If you anchor in that same 3kt stream you would be at a standstill in relation to the ground and you would be going nowhere; yet your speed/log would still indicate that you are going 'nowhere' at 3 knots!

I think that muddling comes in when one speaks of 'boat speed' and it is not clear whether one means 'speed through the water including the effects of current' or 'speed relative to the ground'.
If you motor East with your current, your speed over the ground will be 'X <u>plus</u> 3knots'. If you motor due West at the same engine setting your SOG will be 'X <u>minus</u> 3knots'.
The validity or otherwise of Woozlehunter's vector diagrams and their interpretation depends on precisely what was meant by your "Boat speed through the water is 4 knots."

Perhaps it would be more clear if we were to assume that the current is going either South or North. Would anyone care to say that the speed over the ground would be the same in both cases - given the same heading and similar motor settings?!? /forums/images/graemlins/shocked.gif
 
[ QUOTE ]
Boat 'speed through water' as shown on a log is affected, favourably or adversely, by the relationship between ship's heading and the current direction.

[/ QUOTE ]To help you see that this cannot possibly be true, consider how we measure 'Speed Through Water'. Either we trail an impeller behind the boat (old way) or we have a little paddle wheel that protrudes through the hull (newer way). Can you describe any physical mechanism which could result in tide or current affecting the paddle wheel or the impeller?
 
Sorry Wally, I have to agree with the others... you are wrong on this one..... Simon specifically talked about boat speed through the water..... its basic vector mathematics....

Once the anchor is weighed your SOW is totally unaffected by current... its your SOG that current affects..... its not relevant to assume a Nth/Sth tide, as that isn't what happens in the Dover straight.... its East or West, and if you head south, the 'latitude or southerly' distance travelled is entirely a function of SOW... you may end up East or West of your starting longtitude, and this would affect your SOG, but not your SOW.....

So it is definitely quicker to point your bow at right angles to the TSS, and not to generate a ground track that is at right angles....

Besides it intuitively makes sense.... if you are having to stem tide on your course, then you are slower....
 
Having recently done the trip the other way - Calais to Dover - rest assured that the crossing is not as daunting as often outlined. Yes you need to keep a good lookout and yes you should plan to cross parallel to the cross channel ferry route. Keep a good distance from the cross channel ferry routes, as they do not appear to cross the TSS at right angles, but take a more direct route from Dover to Calais. Hence, the ferries will tend to cross your track, if you are following the rules.

All of this is no problem if you pick a day with good visibility.

Waypoint
 
Quote:
Can you describe any physical mechanism which could result in tide or current affecting the paddle wheel or the impeller?
Unquote

I don't wish to argue but wasn't this the situation that I described when I wrote:

"If you anchor in that same 3kt stream you would be at a standstill in relation to the ground and you would be going nowhere; yet your speed/log would still indicate that you are going 'nowhere' at 3 knots!"?

I don't think that <u>that</u> is wrong!

Fair Winds!
 
Yes, Neil, it <u>is</u> basic vector mathematics!

What happens in the Dover Channel is beside the point. It is the princples that count.

If you wish, change the South/North options that I mentioned and substitute for them 'With the current' and 'Against the current'.

Given the same engine settings the vector diagrams would be two straight lines of a manifestly different length.

This is why I maintain that saying 'boat speed through the water' does not mean much and can be misleading unless it is qualified. 'Speed over the ground', on the other hand, is absolute (for the purposes of this situation, anyway) and can only mean one thing.

Let us not forget that the purpose of navigation is to get from A to B, both of which are points that are fixed in space. The important factor is our velocity relative to each one of them and not the velocity relative to the supporting fluid - which is what 'speed through the water', by definition, implies!

I suspect that at this stage I ought to invoke 'Language Barrier'; I am, after all, trying to communicate in a foreign language!

Fair Winds!
 
Wally... but that is the whole point..... in the Dover TSS you do NOT go with the current or against the current.... you cross the current at pretty much right angles with it either pushing you to starboard or to port..... so it doesn't affect your crossing time, merely the distance travelled and hence SOG..... and in crossing a TSS, point B is definitely not a fixed point in space... point A is fixed, as is your heading, but your COG will define point B, and not vice versa.... to define point B beforehand and then back calculate course to steer is a fundamental misunderstanding of a TSS... where the rules very clearly require a course to steer at right angles to TSS, not a CMG at right angles....

So, here are 2 statements... you tell me if you disagree:

1] SOW is only a function of engine revs or sail plan/set up.... and is not affected by tide

2] SOG is a function of SOW and tide, both direction and strength..
 
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