The post is 2450m from P Tower. Probably, at least 3000m will need to be swum. At 2m/100m this would take an hour. The tidal stream is stronger offshore, and one would be swimming across it. The image of the flood at Wadgate Ledge, on a not especially strong tide, gives an impression of the speed. To reach the post would require accurate navigation else one would never reach it, or overshoot.
Preferably the swim should be done when the sea is calm and the tide at its weakest. This would imply a neap tide. On neap tides the slack before ebbing occurs in the morning or evening at about 90 minutes (needs checking at P Tower) before HW. The swim should start a little before this on the very last of the flood. This leaves the problem of sighting.
Swimming directly from the shore sighting on the pole has two problems.
If the swim could be done around slack water then the tide could be ignored.
- It will be hard or impossible to see it unless the sea is very flat until fairly close.
- By constantly sighting on the pole, the tide will cause the swimmer to follow a curving track which could be significantly longer than is ncessary. The stronger the tide, the more pronounced this will be.
To avoid risk of ending up in the shipping lane then this should be swum on the ebb. To stay up tide the start should be made from south of P Tower and a course taken through the water which, when combined with the tide, brings you out in sight of the pole but still up tide.
The shortest distance is from P Tower at 2450m, but the tide will have an effect. To allow for this the distance the swimmer is carried by the tide is calculated and the start is from that distance south of P Tower. Then swim, not to the pole (probably invisible anyway) but a on a predetermined heading which allows for the tide.
That leave the problem of how to follow a particular heading. The easy option is to use a GPS device to stay on track.