Passage plan, Portsmouth to Cherbourg

frlrubett said:
Just crack on south, autohelm set bang on the west entrance. Leave on the turn of the tide first six hours tide will pull you one way, next six hours it will push you the other way. Balances itself out usually, but in the last few hours when in sight on the entrance you might need to make a little adjustment. Easiest passage there is, pay attention at the shipping lanes but chill for the rest.
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I think they've been and come back (maybe a few times) since this thread is over 4 years old. I've jumped in just to clarify that your post contradicts itself. If you set the autohelm for a waypoint you'll keep on a track over the ground rather than go with the tide as you suggest.

Despite the curvy line in my crossing last year, there are less sea miles if you set a course to steer (heading) in the autopilot rather than a GOTO waypoint. In my case, worked up a CTS of 010 degrees from Alderney to the Fairway buoy and stuck that in the autohelm and just trimmed sails as we went along.

Even with a couple of hours to go to Fairway, the projected straight track line on the plotter screen was planted straight over St Cats and the IOW, it's only when the ebb really kicked in did the magic happen. See my scribbled workings, there is a 2.3kt then 4kt westerly flow only right at the end, the track history shows it grabbing us and pushing back across towards Fairway.

If I'd punched in a GOTO waypoint, the COG would have matched the line on the chart and we would have travelled a few more sea miles to achieve this, thus less efficient.

Since the general course had some east in it, I chose the passage time to make best use of all the flood since it would carry us generally in the right direction.

CTS plan.jpg

CTS result.jpg
 
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wonkywinch said:
I think they've been and come back (maybe a few times) since this thread is over 4 years old. I've jumped in just to clarify that your post contradicts itself. If you set the autohelm for a waypoint you'll keep on a track over the ground rather than go with the tide as you suggest.
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He didn't say to aim for a waypoint. He means set the Autohelm to a magnetic bearing and then recalculate the final leg in 12 hours or so when the opposing tides have roughly balanced each other out.
 
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Lovely to see these recovered posts- we diligently do our calculations having read in fear accounts of being set past the entrance towards the CapDH but in reality I guess it might turn on if passage is neaps or not as we notice little variance although that might be down to accuracy of predicting position at a given journey time. Anyway always interesting to see others calculation methods so thanks for sharing picture
 
Don’t worry everyone, it took three years but in 2014 he did make it to Cherbourg and the CI’s 😂 Here is the boat in the marina with our lunch in the sunshine.
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jhr said:
From Pompey, I'd go round the east of the Island irrespective of the wind, tbh.

From central/west Solent, the Needles route is more logical, because if you turn left at the Needles and head due south, you'll almost certainly fetch up in Cherbourg :). It becomes a less logical option if there's a strong ebb and the wind is S - SW F5 or more .....
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The Cotentin Penisular is a big target. Just ensure you arrive Uptide of which entrance you intend to use. The tide fair rips past there! Fighting it, even with our big donk, is hard!

Apart from that, it is a doddle.

When inside the most excellent Marina you will find it is first come first served. Get into a berth that suits. They will not tell you where to go and are not interested in radio comms. Smaller craft to starboard of the first set of pontoons. Very short fingers with loops in the end for mooring warps.

Have a great trip.

Always found the 'Commercial' Resturant/Bistro very reliable. Once you are settled, Cherborg can be a culinary delight.

Have a great trip.
 
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