continental shelf question

[garbarrage]

I live in ireland and a friend told me a while ago that ireland doesnt get "real" world class waves because our continental shelf is about 100 miles off the coast. that when waves hit it they slow down losing power all the way to the beach. I know we have nothing that compares to teahopu but i've taken a few beatings by biggish waves over here and they feel pretty powerful to me. anyone able to clarify this?

[CHarvey]

Your buddy is full of it. I have seen footage of Ireland going off. You guys get just as good of waves as anywhere else. There was a big artical about it in surfer magazine. The waves were awsome, huge too.
Tell your buddy to read up on his info before he flaps his jaws.
The Malloy brothers don't spend all that time in Ireland because they like surfing ankle biters.

[PapaW]

Its true. he fact the the UK and Ireland are fronted by the cont.shelf does affect the swells that are produced in the Atlantic.
This is most noticable in the SW of England and Wales (there is had to travel over 200+ miles of cont. shelf...)

However...
For Ireland West coast and Northern Ireland it is nowhere near as noticeable.

tbh there isn;'t much in it really. it all depends on the break as to how much of the swells power is transferred into heaver waves..


so tell your mate to go out and hit some of the slabs and reefs around the island and then let him tell you they arn't 'real' he's a fool.

[CHarvey]

One of the big reasons I want to go to Ireland is to surf. Can't wait to get out there next year...hopefully.

[drowningbitbybit]

Absolutely true.

But as PapaW says, it'll be less noticeable on the west coast of Ireland than in the UK.

Go and surf somewhere with very little continental shelf and you'll be stunned at the power of the waves. If its a proper groundswell, even the small stuff packs a hell of a punch compared to UK waves.

[Hang11]

I've surfed Ireland, and it had enough grunt to kick my arse on a few occasions. Sweet waves, with plenty of power.

But, the contintal shelf does make a big difference. Hossegor has a big trench running out from the river, and that's why it has more grunt as there is less to take the power out of the swells.

And in NZ, near where I live, in Kaikoura, the continetal shelf drops off about 1km offshore to about 2km deep, hence lots of whales and stuff feeding on the upwelling of plankton etc. The difference is very noticeable. 4 foot waves at Meatworks are so grunty compared to 4 foot waves 200 km's down the coast where there is more shelf. It's a significant difference.

But having a longer shelf out from the coast doesn't mean the waves will be rubbish.

[Surfing-Innovation]

No - not real waves at all, are they!!

[drowningbitbybit]

No - not real waves at all, are they!!

yeah, but imagine if there hadn't been a continental shelf in the way

[Otter]

I would think that a shelf wouldn't disseminate the power, but rather force it up into a larger more powerful wave as it nears the coast. But I'm no oceanographer, so I'm probably the wrong person to ask.

[garbarrage]

very real.. no doubt about it! where's the picture taken Mullaghmore or Aileen's? (Aileen's get that big?) so would I be right in thinking then that it only really makes a significant difference to smaller waves?
Oh and CHarvey... if you do make it over here drop a line before you come... happy to show you around. have a couple of friends from san diego livin here aswell.

[PapaW]

very real.. no doubt about it! where's the picture taken Mullaghmore or Aileen's? (Aileen's get that big?) so would I be right in thinking then that it only really makes a significant difference to smaller waves?
Oh and CHarvey... if you do make it over here drop a line before you come... happy to show you around. have a couple of friends from san diego livin here aswell.

Lahinch area

[drowningbitbybit]

I would think that a shelf wouldn't disseminate the power, but rather force it up into a larger more powerful wave as it nears the coast. But I'm no oceanographer, so I'm probably the wrong person to ask.

It doesnt act like a reef - the wave energy is lost because its travelling through shallower water (this is how I understand it anyway). A 'pulse' of energy, of which the wave on top is only a part, can travel freely through a deep body of water. But if the water is relatively shallow (compared to the middle of the ocean that is, I dont mean 6ft deep) the energy is lost in drag along the seabed and also disseminated in various directions as the contours change beneath the wave.

And so the longer it travels over the continental shelf, the weaker the wave gets.

[Hang11]

It's refraction and diffraction of the energy that travels through the water - shallow water = more interference with the energy, deeper water = full power, hence places like hawaii, which have no continental shelf having grunty surf, nothing in the way of the energy until it smacks into a reef.

[Otter]

I would think that a shelf wouldn't disseminate the power, but rather force it up into a larger more powerful wave as it nears the coast. But I'm no oceanographer, so I'm probably the wrong person to ask.

It doesnt act like a reef - the wave energy is lost because its travelling through shallower water (this is how I understand it anyway). A 'pulse' of energy, of which the wave on top is only a part, can travel freely through a deep body of water. But if the water is relatively shallow (compared to the middle of the ocean that is, I dont mean 6ft deep) the energy is lost in drag along the seabed and also disseminated in various directions as the contours change beneath the wave.

And so the longer it travels over the continental shelf, the weaker the wave gets.

Thanks Brah. Going to have to do a bit of research on my own coastline and see what I can learn. Any good references you can think of where a guy could get a quick lesson? Never thought about researching the effects of a continental shelf on wave formation. I was thinking it might be like a reef, but I can see that the energy probably wouldn't be as concentrated after traveling over the shelf as it would be when hitting a reef. Haha, guess that would depend on the effect of the shelf on the wave before it hit the reef!

[garbarrage]

there's a book called surf science available... really good. they mentioned the continental shelf thing but only touched on it. for most other things its really detailed with seperate sections for the technical science parts and equations so you can ignore them if you want. available on play.com prob on amazon also. got it mainly for the forecasting section. well worth a look, especially ifyou have a long way to travel for your surf.

[Otter]

Thanks garbarrage!

[CHarvey]

I'll definetly let you know when I am on my way garbarrage. Probably won't make it till next year though unfortunetly.