STACKS Awareness!!!^

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Mike Marshall
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STACKS Awareness!!!^

Post by Mike Marshall » Sun Apr 29, 2007 6:37 pm

OK folks,
Here is a little heads up or maybe a big heads up after a paddle around South Stack and into the bay yesterday.
Five of us set out, well equipped, from Dafarch and explored the coast to Penrhyn Mawr, moved into Abrahams bosom and paddled in the lee of the cliffs due to the Easterly (F4) up to South stack. Winds were a problem but swell was not. All this was done on the ebb but with a fairly small tidal range and lack of swell, the sea was very flat, except for wind derived chop and some minor wind/tidal effects.
The rear of South stack was stunning with oily water and climbers in abundance on the crags. The rock folds there, never cease to convey the power on this planet to me.
Looked at going through the channel inside of South stack, however, there was quite a flow through there, so decided to paddle the outside of the South Stack and forge into the bay from there. Quite hard to paddle around this due mainly to the rotoring wind down off the cliffs and obviously the tidal flow.
Gavin and I were alongside each other as we both noticed the HSS ferry inbound to Holyhead (approx. due North) and we both commented on the possibility of the wake potential from this vessel, based on some talk in previous posts here on the forum.
At this stage were we now firmly into the bay and really just battling the wind rotor. I suggested that we head for a cave ahead of us which can be seen on the GPS track below (Most Northerly point of the trip). All this time I was still mentally flagging up to watch seaward in respect of the possibility of a wake from the ferry.
As Gavin and most of the others reached the cave (and luckily didnt go into it), I glanced seawards to see a three set train of waves inbound with the leading wave face at least 6-8 feet high. These waves had a wavelength of about 2 boats length and were closely followed by a second set of the same height and frequency. I yelled at everyone "SWELL" and "Paddle straight out through them until I say different", which they duly did. You can clearly see this on the GPS track (NW track in a very straight line!). The waves were not breaking, however the suckback and resultant explosion onto the cliffs and into the cave completely engulfed the cave in foam and sent spray into the air about 30-40 feet. I then asked everyone to paddle South back around South Stack and regroup behind the island. Which everyone did without event. During this time the bay became complete chaos as wave refraction and clapotis was the order of the day and continued well after we had left the "impact" area.
Interestingly, from first "noticing" the HSS which was probably due North of the S.Stack lighthouse to the "impact" of the first wave in the bay was 9 minutes. Food for thought.
The regroup mustered everyone and we discussed the incident. we then headed out into the race South and paddled back to Penrhyn Mawr and into Dafarch after stopping for lunch in Porth Ruffyd.
A valuable lesson for everyone on the trip and I believe for anyone considering a trip around the stacks. You WILL have to factor in the effects of an inbound HSS if you are paddling in this area or anywhere where these vessels operate. There is no doubt that these were not weather generated swell and it was so obvious that they were linked to the ferry.
I propose to send a letter to the coastguard informing them of this. I also spoke to some guys from Plas Y Brenin, who recommended complaining to the ferry company as they have previously been warned about slowing down on the approach to the stacks, with reports of climbers there been nearly washed away from their belays.
If anyone can think of anyone else I should inform, then let me know.

Image

MikeM
Last edited by Mike Marshall on Sun Apr 29, 2007 8:13 pm, edited 1 time in total.

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Douglas Wilcox
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Post by Douglas Wilcox » Sun Apr 29, 2007 7:05 pm

Hi Mike,

That looks like a cracking day out. Your warning about high speed ferries is well taken. We have had similar experiences on both sides of the entrance to Loch Ryan.

We nearly got caught out by HSS Stena Explorer at the mouth of Loch Ryan because we went back to rock hopping after the wake passed. Unfortunately another set came at us, it was the ferry's other wash which had reflected off the cliffs on the far side of the loch.

If you are quite wealthy you might be interested in a sister ship which is up for sale. She is the Stena Discovery, top speed 40 knots, 20,000 tons, power 68 000 kw and fuel consumption 20,000 l/hr.

Douglas

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applejack
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Post by applejack » Sun Apr 29, 2007 8:57 pm

Phew....glad I was otherwise engaged ! I probably would have been the daft bugger who went into the cave.

Getting lots of hairy stories about the Stacks.

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capsized8
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wake at Gogarth

Post by capsized8 » Sun Apr 29, 2007 10:07 pm

Hi Mike,

I,m afraid it is par for the course in Gogarth Bay, however it is also something of a lucky dip, sometimes there is and sometimes there isn't.

Just be very aware of the problem occuring, as for a letter, they already know about it. You can also find signs warning people of the danger, but not where you were :0)

pete

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steve-m
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Post by steve-m » Sun Apr 29, 2007 11:10 pm

Sounds horrible glad you managed to get out of the way in time. We paddled the stacks a couple of weeks ago and only saw conventional ferries on the move which did not seem to create anything like as much wash.
Do these high speed craft always create this much wave action? Looking at the on-line timetables, it looks like there are 6 highspeed crossings per day each way. So i guess you could predict approximately when these craft will be kicking things up around the stacks.
The caves between South and North stack are worth exploring but you sure would not want to get caught in them with that sort of hoo-haa going on.
Steve-M Shropshire

AllanJ
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Post by AllanJ » Mon Apr 30, 2007 8:44 am

Mike,

I think I would be worth contacting Stena directly as well as the CG, what you describe sounds like an excessive level of wash.


Regards

Allan

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soundoftheseagull
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Post by soundoftheseagull » Mon Apr 30, 2007 11:10 am

A testing day, thanks to Mike for being mother hen and guiding his faithful “chicks”

Slept well that night although some first class German lagers did play a part!

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A testing yet very rewarding day, great scenery and good company
Dave

Rockpool GT

Goldspoon
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Post by Goldspoon » Mon Apr 30, 2007 9:14 pm

Good informative post. I usually scoff a little at "ferry horror stories" but shall certainly be a little more careful now. Saw some good 4ft surf appear for a few mins in the med last year after not a ripple bigger than 1cm all day (was def a ferry wash)!

Did a solo paddle round the corner from you on Sun... Conwy estuary across to Puffin (1 3/4 hrs). A little windier than expected in the latter stages (I get a little twitchy solo lol).

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savegemountains
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Post by savegemountains » Mon Apr 30, 2007 9:39 pm

Julian - twitchy?? really?? I don't believe you.

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tpage
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Post by tpage » Tue May 01, 2007 1:06 pm

Mike, Are you sure the wake wasnt from the cargo-laden Dundarg on its way up to Oban? Tony

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applejack
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Post by applejack » Tue May 01, 2007 2:02 pm

Coincidentally...this has hit the climbing forum as well !

http://www.ukclimbing.com/forums/t.php?n=240116
UKC Forums - Gogarth Ferry swell

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Mike Marshall
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HSS Ferry

Post by Mike Marshall » Tue May 01, 2007 4:19 pm

John,
You need to post the link from here onto the Climbing forum.
But in my opinion it is only the HSS that caused this not the regular ferries.

MikeM

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steddyjames
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Post by steddyjames » Tue May 01, 2007 4:48 pm

applejack wrote:Coincidentally...this has hit the climbing forum as well !

http://www.ukclimbing.com/forums/t.php?n=240116
UKC Forums - Gogarth Ferry swell
I remember the climbing community having this discussion about the fast ferries when they were first introduced. Lots of warnings went out to climbers at the time.

Seems like a short memory syndrome. I'm sure I've still got some of the old climbing magazines with the warnings in somewhere but this has been round the houses before for climbers.

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steve-m
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Pondering sea states

Post by steve-m » Tue May 01, 2007 10:04 pm

I have been pondering the subject in this discussion and find myself wondering if the effect of these high speed craft is worse at times when the sea is otherwise quite calm. That is to say when the sea is busy with losts of swell and wave action, does this soak up the effect of these high speed craft?
Whereas when, as recently, we have had slight sea states, it may be the the effect of these craft is picked up to a greater extent?
Steve-M Shropshire

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Jim
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Post by Jim » Tue May 01, 2007 10:26 pm

The problem of wake from high speed ferries has been well known for sometime. My understanding is that speed limits have been set to stop these waves reaching Anglesey's tourist beaches (there were reports of these unexpected large waves landing on tourists and sweeping them away). I'm not entirely familiar with Anglesey but I think it was noted at the time that the stacks would not be protected by the speed limit because they are well away from tourist beaches (kayakers and climbers must be a minority the authorities don't mind 'losing').

So basically there are 2 possibilities, either as I suspect the limits do not extend far enough, or the ferries are simply ignoring the limits (it's easily done when you are running late).

Steve-m your theory is not entirely off the wall, but not quite there. When waves interact you do indeed get interference patterns and some waves will cancel each other out, the thing is that some other waves will also combine to become bigger... What you observe in waves at sea is already a complicate set of interference patterns, and in the bigger picture smaller waves ride on bigger waves and all sorts of other complicated stuff. Why do surf waves come in regular sets? Because waves of different sizes travel at different speeds and the much longer period waves are at times boosting and at other times shrinking the shorter period waves that we can actually see.

But yes, on calm days the wake is very obvious, although on wavy days when it is hidden more you should statisitically end up with some even bigger waves.

Jim

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active4seasons
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Post by active4seasons » Wed May 02, 2007 6:39 pm

I seem to remember the HSS starting service about ten years ago whilst I was at uni in Bangor and at first it was causing bigger waves but they were more localised. They were then told to slow down further out (coming down of the foils) and this resulted in smaller swell (like you describe) but it travels further around the coast. They also posted signs on the land stating something like 'take care as there will be a distrubed surface after the arrival of the HSS'! To call this a slight understatement is rediculous!
At the time we all made a bit of a joke about it but it is common knowledge not to go cave exploring when you know the HSS is due to land. As you say the climbing world have known about it as they were regularly being washed off the rocks.
The coast line in question is the West facing one, normally the South coast gets away with it if I remember correctly?
Glad to hear you were all okay.
Ollie
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Chris Bolton
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AIS

Post by Chris Bolton » Wed May 02, 2007 10:19 pm

If there's any doubt about which ship it was, have a look at the Liverpool AIS history. You can set time and date (click "Set Map" after changing the time) and see which ships were where. Very interesting site!

Mike, what time was the incident?

Chris

Edit - not all the ships are shown at every time point

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Mike Marshall
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HSS

Post by Mike Marshall » Wed May 02, 2007 10:44 pm

Chris,
12.43 we clocked it due North of the South Stack lighthouse.
12.52 the wave struck
9 minutes

MikeM

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Jim
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Post by Jim » Wed May 02, 2007 11:05 pm

active4seasons wrote:(coming down of the foils)
HSS is not a hydrofoil. There are lots of different types of high speed ferries, they all throw up a big wake at speed, HSS is I think the worst of the bunch.

Jim

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Post by Chris Bolton » Thu May 03, 2007 6:46 am

From Mike's timing, looking at the AIS plots for 12:40 and 12:50, it was the Explorer, at about 35kts. Not the Stena boat, which passed at about 11:10 at 18kts.

Chris

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Pelagic
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Post by Pelagic » Fri May 04, 2007 5:33 pm

Did it look like this Mike?
HSS. STENAEXPLORER

Image

Just had a refit at Harland and Wollf apparently, came back into service February, capable of 40 knots, scary eh?
Holyhead to DunLogaire route I believe.

Phil

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Mike Marshall
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Guilty Boat

Post by Mike Marshall » Sat May 05, 2007 10:39 am

That is without doubt, the culprit.

MikeM

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Re: Guilty Boat

Post by Quest 129 » Wed May 09, 2007 5:57 pm

Well done to eagle eye Mike. Boat wash is an interesting topic and I would agree that it appears more pronounced on calm water than when the sea is bumpy and soaks it up.It always appears that very fast moving craft are going to produce a large wake when in fact these small tug like vessels that hardly seem to be going above 4 or 5 knots throw off a large wash,obviously due to the amount of keel under the water.
In my early days of kayaking I dreaded boat wash and notice that when out with novices they appear to look uncomfortable with them.
My worst was when paddling down loch fyne south of Inverary a naval frigate was doing speed trials on the other side of the loch from us a fair distance away. I noticed its very high corrugated close wash in time and took it head on. If I had taken it on broadside I would definitely have been a swimmer.

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