The Swellies - 53° 13' 12" N 04° 09' 54" W
Heading through the Menai Strait from the marina in Caernarfon involves navigating the infamous Swellies. The Swellies have a bit of a reputation. The tide runs in from both ends of the Strait but have different tide times and levels. This creates an atypical tidal stream with a slack tide that does not occur at high or low water. The tidal stream is also rather zippy - up to 8 kn on springs*!
Legend has it that Lord Nelson was the first to sail through the Strait and used the area as a training ground for his sailors. There is even a rather large statue of him jutting out from the Anglesea side of the Strait!
 |
| The Swellies - bridges, rocks, narrow channels, shallow water and huge tidal currents |
Navigating The Swellies requires going under two bridges and squeezing through narrow channels. Because of all the rocks and the strong tidal currents, it is recommended to go through at high water slack. This is when the current is changing so it is at its slowest. But be warned, if you are late, the current increases by a knot every ten minutes.
So we did our homework, figured out when High Water Slack would be, checked that there would be enough water under us and we had enough air clearance under the bridges. The Britannia Bridge is 27.4m and the Menai Suspension Bridge is 30.5m. We have an air draft of just under 21m with our aerial so we were all good.
 |
| The passage through The Swellies as provided by the Harbour Master. The air draft (vertical clearance) doesn't seem to be a problem. |
 |
| Navionics shows a similar story but ... what is that red line to the left of the bridge. Better zoom in ... |
 |
| Crikey! An overhead power line!?! |
Then we noticed the power line on the chart.....
Not mentioned on the Harbour Master diagram but on the zoomed-in charts, it was shown as 22m MHWS. But there was a little note on Navionics (our electronic chart) saying it was 21m MHWS. MHWS is Mean High Water Springs which means it is the average of the highest high tides during spring tides. As we were on springs and with our mast being just under 21m, it was waaaay too close.
And so we consulted the locals. The Royal Welsh Yacht Club WhatsApp group went into overdrive with everything from "you'll be right" to "I wouldn't"! Yikes. We then started getting into the details. Just how high was this particular tide? How close to high tide would we be passing under the power lines? How close, height-wise, could we be before it would arc? Where was the channel in relation to the lowest point in the power lines? Should we go at low tide (not recommended)? Should we go around the outside of Anglesey and avoid the Menai altogether (adding almost a day to the journey)?
We then had a chat to the Harbour Master who was extremely helpful and advised that the power lines did not drop below the bridge deck at the spot we were transiting and that we would be fine. What a relief! He sent us some drone footage and amended the hand-drawn passage chart to mention the power lines.
 |
| Drone footage from the Harbour Master clearly showing the power lines above the top of the arch of the Britannia Bridge. |
Confident now that we wouldn't electrocute ourselves, we left the marina in time to get to The Swellies at High Water Slack. As we approached the Britannia Bridge, it looked awfully low and we had a few nail-biting moments (thanks parallax!!) until we were safely under. Geoff Hilditch, on his lovely yacht Aslan, followed us through and took some amazing photos. Thanks Geoff!
 |
| Chinook heading towards the Britannia Bridge and the power lines! Still looks awfully close. |
 |
| Safely through The Swellies and heading towards the Menai Suspension Bridge. |
We wiggled our way through the Menai Strait and spent a rather bouncy night at anchor off Conwy. Next morning, under a beautiful blue sky and brisk but favourable winds, guess what we did?
We sailed across the Irish Sea - just for something different!
And please remember that Blogger posts your comment as anonymous if you don't have an account, so please sign off with your name so we know who you are!
Comments
Post a Comment