Bardsey Sound slack

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Bardsey Sound slack

Post by GEOFF S »

Bardsey Sound slack water.
a) Is there such a thing ?
b) when is it / are they ?

There seems to be quite a variety of opinions on this - I've seen various suggestions in eg Terry Storey's book, Pwllheli S.C., Welsh Sea Kayaking.

Anybody got any info to throw into the mix ?


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Re: Bardsey Sound slack

Post by seawolf856 »

Hi Geoff, I am not a regular visitor to the Bardsey Sound but I have extensive experience of paddling and navigating the North Wales coastline and I have had the 'pleasure' of paddling across this notorious stretch of water, so in the absence of any other replies so far I'll give you my take on it.
I don't know your level of competence or experience so forgive me if I'm talking to an expert but I assume you are asking the question so that you can plan a crossing by kayak when the flow will cause you the least amount of difficulty, which is a sensible thing to do and I completely understand why you would plan to do that. However, if your skill level means you would only want to paddle across Bardsey Sound at slack water, I would re-evaluate your ambition.

To answer your original question, the short answer is yes, there is of course a time when the flow through the sound has to stop and change direction as the tide changes from flood to ebb and vice-versa, BUT this period of "slack water" is most certainly not a fixed condition for the whole of the crossing and it doesn't last for any more than a fleeting moment at any point in the sound. Most kayakers paddle across the sound after launching from Aberdaron and the shelter of Aberdaron Bay, but once past the point of Pen Y Cil the crossing to Bardsey Island is approx 3km so even if you can paddle VERY fast you are never going to have slack water all the way across.
I assume you know the basics of Spring and Neap tides and that the slower flow will be on a Neap. You have mentioned the Welsh Sea Kayaking guide (fifty great sea kayaking voyages) and that is the guide I would recommend that you study VERY carefully before setting off for Bardsey Island. Journey timing is critical and although more advanced paddlers often do the crossing both ways on one tide, the less experienced (and those who want to explore the island) tend to wait on the island between tides, so it can become a long day out.

I hope some of this helps. The paddle to Bardsey Island is definitely worth the planning and patience waiting for good conditions but the Sound can be very dangerous if you are not aware of the potential conditions or choose to ignore the warnings.

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Re: Bardsey Sound slack

Post by GEOFF S »

Thanks for replying seawolf856,
My inquiry was mainly with a passage through the sound in mind ie Porth Oer to Aberdaron.
I have done this paddle before using using the info in the Wales SK guide and the paddle went well, although it definitely wasn't the expected
slack at the S end of the sound, with a lively tide race pouring out of the bay past Pen y Cil. I had one of those internal debates - do I go now because it's going
to get worse, or am I ahead of schedule and it's shortly going to calm down. In the end I opted to go for it.
The next day I walked the route and observed a large group of paddlers doing the same route at the same tide time, presumably using the same info.
They arrived at Pen Y Cil to find the same conditions which clearly came as a surprise to them too
I watched from the cliffs as they presumably had the same conversation that I had the previous day then they turned round and paddled back to Port Oer.

As I mentioned there are several times for Slack quoted in Snowdonia White Water, Sea and Surf , the Welsh SK guide and on a number of sailing and diving websites.
I guess this all just proves that it's a complex area, possibly without a simple answer.

Any other inputs welcome...

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Re: Bardsey Sound slack

Post by Jim »

I started on that trip once but we had to turn back due to sea sickness.

Can't remember anything about the tidal planning but assume that there is an underwater ledge or ridge extending out to the island which will cause the tide to pile up on one side and continue to run after it changes. Something often overlooked is that actual height of tide can vary by about +/- a foot (300mm) either side of the published value depending on the atmospheric pressure on the day. The impact of this in an area where there is a delay to the tide due to an underwater obstruction can mean the direction changes earlier or later than predicted.
On top of that water can be moved by wind as well as moon, and the wind direction when the wind is strong can have an effect too.
To throw in more confusion, the times for the change of tide stream are usually based on 'local knowledge', and opinions between local experts can very for many reasons - a fisherman working the sound in all seasons might give a different timing to a yachtsman who generally transits in fine weather. A kayaker hugging the coast might find conditions different that a ship in the middle of the sound.

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Re: Bardsey Sound slack

Post by richb250 »

I've only made the crossing to Bardsey once and the navigation on the return leg was not an unqualified success. It seems that information on the tidal flows here is not in good agreement, or at least that there are some complications.

In Ralph Morris' 'Cruising Anglesey and Adjoining Waters' it is stated that the time of slack water is 2:15 after local HW and LW, or ~50 minutes before HW/LW Dover. The Pesda Press guidebook times loosely agree with this (they equate to ~ Dover +5:00/-1:00).

However, the Admiralty Pilot gives the times of slack water as +3:50/-2:10 Holyhead, which is about Dover +3:00/-3:00. The same data is given in Reed's Small Craft Almanac. These sources give Dover +5:00/-1:00 as the slack times of the offshore stream, running south of Bardsey. (oddly, the full-scale Reeds Almanac gives a different and somewhat confusing diagram, but does describe a 'young flood' flowing west inshore from 2 hours before the main flow changes).

A close inspection of the tidal stream diagrams in Ralph Morris's pilot suggests eddy streams inshore, hinting that the entire sound may not change direction at the same time - and that there may indeed be a strong stream at Pen y Cil at the supposed times of slack water.

Interestingly, a friend of mine who I was planning a paddle across the sound with shared the following note with me:
Last year, I was determined to get to the truth of the tidal streams, and I was lucky-enough to be able to sit on the top of Mynydd Enlli on a glorious summer's day at the critical time watching a yacht becalmed off the E shore of the island - ie just drifting with the tide. This allowed me to verify what I'd thought re the timing of the start of the flood (which dictates the departure time from the island, obviously) based on my previous experiences and to confirm that Reeds has the correct info (and that the GB is misleading).

I'm not entirely sure what to conclude from all this, without local knowledge, but I suspect that:
  • The inshore stream turns at a time rather different to that given in the guidebook at ~Holyhead +3:50/-2:10
  • This 'inshore stream' may extend across some proportion of the sound
I hope that helps. I'd be interested to hear if anyone has better information, as I'd like to put something more credible on the website: ... &over=NONE.

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Re: Bardsey Sound slack

Post by Mr Ed »

Some great posts here already.

Just to add- there's some great information here: ... dsey-sound

Adding to the replies- There's so much going on tidally here, when the back eddies get going with the momentum through the tidal cycle at what should be slack water you can have a full on tiderace on your hands. Notably at Pen Y Cil and the area I outline below.

One area that doesn't receive any attention in the guidebook but should come with a big warning is the point at the immediate South of the Island if you're planning on doing a circumnavigation. Marked on my chart as 'Maen Du'. This has similar features to Pen Y Cil in the fact that when we passed through recently at nominally slack water, slack water equalled around 3-4 kts of tidal movement... If you look at the charts too there's numerous shallow shoals around the island nicely funnelling the eddies at certain places. Incredible place- Nice Whirlpool at Maen Bugail too.

If you're heading out to the island far better instead of heading straight for Pen Y Cil is to paddle to the Gwylan islands first and allow the tide to assist getting you there on the last of the flood.

Any of the above back eddies interacting with any residual swell or wind against will make conditions 'interesting' to say the least. One of the most serious bits of water i've ever paddled in. Usual advice re at your own risk, capabilities etc apply.

Hope some of that helps.

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