Entries closing at 2pm (14.00 hours) on Wednesday

Entries are open – here: https://myrtlevilleswimmers.niftyentries.com/RNLI-Swim and will close at 14.00 on Wednesday, June 19th, 2019.  There are NO entries on the night, no swaps, no transfers – insurance doesn’t allow it.

The forecast is looking good.  If you want to swim, enter on time.

If you have entered and want to save some time at registration, please download and complete the Waiver form for RNLI Myrtleville to Church Bay 2019 and bring it with you on the night.  All swimmers will have to have one completed.

It’s going to be a great night, so please enter now to be part of it.

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Tides and swimming in Myrtleville

Republishing this important article from 2014 on our local tides.  If you don’t have time to read it all, just skip to How might this impact my swim?  It’s important to know.

From Bernard Lynch & Ian Venner

This note is intended for those new and not so new to coastal swimming and simplifies some of the calculations and facts which you may well expect to see.  Much of it is specific to Myrtleville.

The tidal streams (coastal currents) are the most important part of the tides you need to understand as a swimmer.  Most OW swimmers average between 2-3km/hr.  Tidal streams near the shore in the harbour can run at between 0.5 to 1.0 km/hr – so they can make a very big difference to your swim.  The speed of the tidal stream varies during each High Water/ Low Water (HW/LW) tidal cycle, and also varies between spring (very high/very low) and neap (not very high/not very low) tides.  Spring tides occur a day after a full moon and recede over a period of one week to a neap.

The spring/neap maximum flow rate can vary from 0.5 to 1.5km/hr.  The flow rate within a 6 hour tide range will be three times as strong at its fastest (in the middle of the six hours) as in the first and last hour. This is explained by the Rule of Twelfths.

Rule of Twelfths

The level of water does not rise or fall at a constant rate throughout the 6 hour duration of a rising or falling tide.  The amount by which it will do so can be estimated mentally by means of the following rough guide:

  • 1st hour rise or fall = 1/12 of Range
  • 2nd hour rise or fall = 2/12 of Range
  • 3rd hour rise or fall = 3/12 of Range
  • 4th hour rise or fall = 3/12 of Range
  • 5th hour rise or fall = 2/12 of Range
  • 6th hour rise or fall = 1/12 of Range

This impacts tidal speed too – the fastest speed being in the middle of the period between HW and LW. In the table below, assuming a 12 foot rise and fall in the tidal height (typical for Cork Harbour) and a maximum tidal flow rate of 1.5km/hr, you can see the how fast the tide moves and rises/falls.

Time after HW Twelfths Change in Depth in that hour Avg tidal flowkm/h
+0.5hr 1/12 1’ 0.5
+1.5hrs 2/12 2’ 1
+2.5hrs 3/12 3’ 1.5
+3.5hrs 3/12 3’ 1.5
+4.5hrs 2/12 2’ 1
+5.5hrs 1/12 1’ 0.5

What else influences tides?

Other factors can influence tidal heights and flow rates. Low pressure will increase tidal height (think of it as less atmospheric pressure pushing down on the water).  Lots of recent rain will increase the strength of the ebb, especially out of Cork Harbour and Fountainstown too (it’s just more water trying to get out).

How might this impact my swim?

So what does all this mean for swimmers?  Be conscious of the time of HW – not because the beach might be more or less sandy, but because it should influence where/how you swim.  Swim against the prevailing tidal flow, so that if you get tired you will have the benefit of it on the way back.  For example, you might consider a swim from Myrtleville to Church Bay and back on the third hour of a falling tide (tide against you going to Church Bay and with you coming back).  You should not consider doing it on the third hour of a rising tide (tide with you going to Church Bay and against you coming back).

In reality, the tidal flows between Myrtleville Beach, the Dutchman and Bunny’s are fairly limited.  There is a little more effect to consider if going Myrtleville/Fountainstown and particularly at Bunny’s point where the push or pull can be significant on the 3rd and 4th hour. If needed, there are plenty of escape routes onto the rocks between Myrtleville and Fountainstown – weather dependent. Going to Church Bay, however, puts you into much stronger tidal flows and you really need to plan your timings. Generally you would not plan a swim past the Dutchman unless the tide was ebbing (going out) for the return leg. Equally, anything further afield needs careful planning with someone who knows the area and tides.

So what direction does the tide flow?

The diagram below broadly illustrates the direction of flow of the tides around the Myrtleville area.  Tides, especially close inshore, are subject to back-eddies and counter-currents, and there are a few of these to be found in the area shown.

To check tides, either purchase a tide table or click on this link.

You should always know the tide before you swim.  Swim Safe.

RNLI Swim participants – prepare

It’s just a week until the big event and the sea is colder than other years.  If you are swimming in the RNLI Myrtleville to Church Bay swim on June 20th, you need to be in the sea a few times in the next week.  The sea temperature next Thursday may be around 12C.  It’s not likely to be much more, although the forecast for next week is warming up.   

If you have not been swimming much, think about wearing a wetsuit on the night or get in every day until the swim!  Think of safety first and last.  Don’t take a chance.

While the Don’s away…

It’s lovely when people go on holidays and send us pics of The Hat joining them in idyllic locations.  Here’s one from Denis away off in the Rockies.  I think he may have found the hat there after it fell out of James Slowey’s bag when he cycled over them on his jaunt across America last year.  The pics give us something to remember them by.

However, it seems that Denis may have been active in making sure some of his disciples would remember him through a different means while he was away.  Always one to encourage his faithful followers to visit the camps of North Corkorea, news has reached us of his latest torture scheme for those foolish enough to place their trust in the one known as The Don.

An anonymous tipster known only as Paparazzi Magnet was in touch to advise that this notice had appeared at the Knocka freshwater camps last weekend:

All reservoir swimmers. Be careful on entry/exit to the water. We found these thumb tacks in the water this evening on the slip. We picked up as many as we could but there could be more.

Clearly The Dastardly Don was making sure nobody would be enjoying his absence down Knocka way.  He looked into spreading Weaver/Weever fish there, but found they didn’t take to the fresh water (who could blame them).

We believe the Condon plan was to claim that the phantom tack scatterer had run for the hills when Denis got back, as the spate of tacks will mysteriously stop once he comes home.  Just wait and see.  You couldn’t keep up with him. 

Watch your feet down in that place.  For those not under the Condon spell, stay where God intended – in Myrtleville.  In the sea.

New Swimmers evening – June 11th: 19:30 – Help wanted

June 11th, 7.30pm: Eilis Burns will be bringing a group of new open water swimmers to Myrtleville on Tuesday, June 11th at 19:30.

Any of the regular Myrtleville swimmers who can be around that evening to give any help would be appreciated. We need swimmers used to the sea to join the group for the swim and watch out for anyone who needs some support.  Also, any kayakers or SUPs available would be very welcome.

Please come down if you can. Remember what your own first swim was like and help out:-)

Some of the new swimmers in 2014 with Eilis and Mike Harris.

Some of the new swimmers in 2014 with Eilis and Mike Harris.