Portland Tidal Streams - Getting confused

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MagicIsland

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Weather permitting planning a trip from Dartmouth to Weymouth next Mon 23rd, Reeds recommends arriving Plymouth HW-2 to HW ( 8:50am HW spring) but this would mean a 2am departure and we have limited night time sailing. The above also means you have a foul tide across Lyme Bay.
Our plan having studied the almanac is to Depart Dartmouth and be passing Mew stone at 6am, arriving Portland 1pm Plymouth HW+4 3nm south then passing east of the Shambles and having a slight foul tide up to Weymouth.

All the tidal streams will be with us around the south of Portland but having read so much about it (channel pilot talks of ships lost without trace) I'm now doubting everything I've done, is 3nm south of Portland enough to be able to pass Plymouth HW+4 ?
 
If you're going Weymouth its better to use the inshore passage (ie 50meters no and no further from the bill) check tidal stream at the bill of eta and you should be fine if close to slack (but don't attempt in the dark due to pots)
 
^What he says.

I've not looked at any streams, and at the end of the day it's your call, but if it is breezy don't underestimate the distance you need to head south by. I went round in a pretty solid 6 last year and left the recommended 6-7 miles clearance and it was still pretty exciting...
 
It's difficult going by Plymouth HW without any atlas etc to hand, but I imagine the tide will be going W strongly at Plymouth +4 ?

In any case 3 miles South of the Bill would put you in the middle of The Race, not a place to be unless it's really, really calm weather !

It's recommended to go at least 5 miles South of the Bill to skirt the Race.

If tempted to try the inshore passage be wary of lobster pot buoys, they litter the passage and are often pulled underwater by the current.

Also be very sure of the forecast if going for the Inshore Passage from the West, I did this once, good forecast and initial weather so committed myself North into the bay, then the weather turned very strong Westerly - against forecast - leaving me to bash through very unpleasant conditions at the Bill...

If the tides say 02:00 departure, then that's it, if inconvenient, tough ! It would be light soon enough and as soon as you're out of Dartmouth and on course you're in clear water.

Your alternative would be to set off in the afternoon, you could set off a bit early and punch tide to maximise daylight; Weymouth is well marked but beware the clutter of town lights in the background, keep an eye on compass headings compared to the chart to check you're on the right track.
 
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MagicIsland said:
Weather permitting planning a trip from Dartmouth to Weymouth next Mon 23rd,
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forecast is for winds with east or SE in 'em for then, although it looks as though they will be fairly light so you'll probably be motorsailing, also if you have the (spring) tide with you it will be against a lightish wind which will without doubt make any of the options interesting . . . . . . let us know how it went when you get there.
 
MagicIsland said:
Weather permitting planning a trip from Dartmouth to Weymouth next Mon 23rd, Reeds recommends arriving Plymouth HW-2 to HW ( 8:50am HW spring) but this would mean a 2am departure and we have limited night time sailing. The above also means you have a foul tide across Lyme Bay.
Our plan having studied the almanac is to Depart Dartmouth and be passing Mew stone at 6am, arriving Portland 1pm Plymouth HW+4 3nm south then passing east of the Shambles and having a slight foul tide up to Weymouth.

All the tidal streams will be with us around the south of Portland but having read so much about it (channel pilot talks of ships lost without trace) I'm now doubting everything I've done, is 3nm south of Portland enough to be able to pass Plymouth HW+4 ?
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I'm reading an old copy of Reeds (current edition is on the boat), but I think you may have missed a "+2" on the second line - i.e. Eastbound HW (Plymouth) -2 to HW +2. If so, then I have just got you an extra couple of hours in bed.

I wouldn't be tempted to leave it as late as HW +4. If it takes you longer to get there than your plan then you will have a foul tide round the Bill and you might just have to give up (as you say it is Springs). Also, heading an extra 3+ miles further south than necessary will add significantly to your passage time if heading to Weymouth.

A foul tide in Lyme Bay isn't really such a problem, as the tides are generally pretty weak there.
 
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It's going to be springs and probably light winds, so if you are going to go round the outside, I would leave Dartmouth with a couple of hours of foul tide still against you, so that when you get to Portland you have fair tide to take you past (you won't be able to punch against a foul spring tide past the bill).

Or as others have said, on the basis that it looks to be light winds, take the inshore passage, but you'll need to leave Dartmouth really early to get there in daylight.
 
At Portland Bill I prefer 50-100 yards or 6-7 miles - usually the former but only in daylight. After dark the 6-7 miles.
 
Personally I always go south of the Bill by 3 to 5 miles depending on conditions when heading east even when visiting Weymouth. I find, in common with Mark Fishwick, the extra time that this takes a fair exchange for the difficulty of timing for the inshore passage and the anxiety that this gives. If you go for this option, it's high water Dover that you need to be looking at which is 1420 on Monday and the BBC forecast is giving SE winds of about force 3. Difficult to say when you need to leave as you have given no information on your boat or speed that you use for passage planning, but I would plan to arrive 5 miles south of the Bill by about 1330 which will give you a fair tide most of the way.
 
richardbrennan said:
...If you go for this option, it's high water Dover that you need to be looking at which is 1420 on Monday ...
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Not exactly sure what you are suggesting he needs to be doing/have done by HW Dover, but at that time the tide at the Bill has already turned west - a strong foul tide close in to the headland, and even 3 miles offshore it will be 2-3kts in the wrong direction. Likewise on the northerly leg into Weymouth.
 
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What I am saying is that if he goes for the 3 or 5 mile option south of the Bill, it's the Channel tides that will be relevant. The tide will be east going until HW Dover -1 and pretty slack for an hour after that.
 
richardbrennan said:
What I am saying is that if he goes for the 3 or 5 mile option south of the Bill, it's the Channel tides that will be relevant. The tide will be east going until HW Dover -1 and pretty slack for an hour after that.
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... but not when heading north up the east side of Portland. By HW Dover there is a decidedly strong southbound stream off the east of the peninsula. Even an hour earlier would still result in slow progress being made.
 
You need to remember that pilot books advising the best times for the bill make assumptions as to where you are coming from to get a low water slack or high water slack. It is a choice to have a fair tide to the Bill or a fair tide after which the pilots often seem to gloss over.
 
Angele said:
... but not when heading north up the east side of Portland. By HW Dover there is a decidedly strong southbound stream off the east of the peninsula. Even an hour earlier would still result in slow progress being made.
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Just how far south should I aim for, the boat is relatively new to us so were trying to avoid Night time passages until were comfortable with every thing, we not in a rush to get there as will enjoy the sail so slow progress up the east side is fine as long as were avoiding the worst of the race.
Looking at Navionics and Admiralty charts the race seems to extend no more then 2kn of shore, what I can find is how far the effect extends, we aim to average 6kn in a Southerly 105 sailing or motor sailing so if we pass at 1pm ish then a 3 hour sail to Weymouth against the south stream will give us more boat time . Will 5nm miss the race effect ?
 
LadyInBed said:
See http://montymariner.co.uk/tide-stream-charts-2/ for Tide stream
Don't use Plymouth or Portland tides, use Dover as tide starts West half an hour before HWD and East at HWD plus 5.
See http://montymariner.co.uk/wp-content/uploads/2013/03/Dover-9-13.png - Sept
See http://montymariner.co.uk/wp-content/uploads/2013/03/Dover-10-13.png - Oct
NOTE: All times GMT

So be at Bill 0500 BST or 1917 BST
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Thanks, on the tidal streams you attached we would be passing HW+3 (Dover HW 2:15pm) so Dover HW -1 to HW-2, there is no race on the charts for this time and we look to then have a 1-2 knot foul stream up the east side, does this seem a long but reasonable plan ?
 
MagicIsland said:
Just how far south should I aim for, the boat is relatively new to us so were trying to avoid Night time passages until were comfortable with every thing, we not in a rush to get there as will enjoy the sail so slow progress up the east side is fine as long as were avoiding the worst of the race.
Looking at Navionics and Admiralty charts the race seems to extend no more then 2kn of shore, what I can find is how far the effect extends, we aim to average 6kn in a Southerly 105 sailing or motor sailing so if we pass at 1pm ish then a 3 hour sail to Weymouth against the south stream will give us more boat time . Will 5nm miss the race effect ?
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TBH I am in the same camp as Fergus and IanC. I would go the inshore route in reasonably settled weather (which is the only weather I have had going round the Bill to/from Weymouth and the inshore route has been without incident). So, I don't have firsthand experience of how far the race extends offshore depending on conditions and state of tide - only what Reeds says "... race normally extends 2M S of the Bill, but further S in bad weather ....." Goes on to say it can be avoided by going 3-5 M offshore.

Given that the wind is forecast to be from the East on Monday/Tuesday, so you'll be beating all the way, and, according to your calcs, the tides don't exactly suit your plans on Monday, could you choose another day - either a couple of days earlier (and go for the tidal gate in the evening) or a couple of days later (when times should facilitate sailing in daylight)?
 
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ahabdonal said:
You need to remember that pilot books advising the best times for the bill make assumptions as to where you are coming from to get a low water slack or high water slack. It is a choice to have a fair tide to the Bill or a fair tide after which the pilots often seem to gloss over.
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You have hit the nail on the head, it seem the passage before or after is forgotten somewhat, as we are not in a rush and not experienced in night sailing I think we will go the long way round at approx Dover HW-2 and give the shambles a miss. When we look at the Channel Tidal streams HW Dover -1 shows east going where as the same time on the Portland streams shows it set west but this maybe 5+miles south.
 
MagicIsland said:
You have hit the nail on the head, it seem the passage before or after is forgotten somewhat, as we are not in a rush and not experienced in night sailing I think we will go the long way round at approx Dover HW-2 and give the shambles a miss. When we look at the Channel Tidal streams HW Dover -1 shows east going where as the same time on the Portland streams shows it set west but this maybe 5+miles south.
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At HW Dover -1, the most noticeable tidal effect is the relatively strong southward set off the east of Portland. It will be that you will have to fight against as you head north. The only way to avoid this is to overshoot (i.e. go 2 or 3 more miles east before you turn north).

Have you done the inshore route? In reasonable conditions it really is very benign.
 
Last time I came East in light weather, I just took a straight line from Start Point to the Shambles, which kept me far enough out to miss the worst of the bumpy stuff, then turned left just before the Shambles to head up into Weymouth (we only went that way because we were initially planning to keep going to Studland). This is fine in fair weather and the tide in your favour, but beware that the tide at springs will push about 6-7kts, so you won't get anywhere fast trying to push against it.

Nipping around the inside is easy in daylight and light winds, and it's definitely the better option.
 
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