Tides and full moon

learnerplates

Dudes,
Took a trip to Lahinch yesterday afternoon, high tide was not meant to be till 7.30, thought it'd be fine till at least 6.30 but the tide was nearly fully in at 5.30, what's the deal? is it because of the full moon, the tides are bigger?
Terrible waste of a sunny eve in the car.

cue

I am showing my ignorance here. What affect does the tide have on surf?

learnerplates

I'm no master myself, usually looks to me that when the tide is in the waves reduce in height, especially if there's zero sand left, also in my case I'm one of those beginner surfers who stays at shoulder height water so I don't go out all that far, if the tides in against the rocks I'd get broken.:eek:

Gone West

Would ya not just have spun down to silver strand? That works at all tides

learnerplates

you mean white strand near Doonbeg is it? I went down that direction after, well I think it was it, in at the Doonbeg golf course, it was the same deal there. If it's silverstrand in Galway then no.

SideshowBob

Well, Lahinch is known for having the tide breaking on the rocks fairly early relative to high tide time. If you're there and waves are already breaking on the rocks in front of O'Looneys, go down to the end of the prom, sometimes you can get down there easier and surf in front of the golf course. There isn't a predictable rip there though (except that it drags you towards the river) so you have to be careful that you're not being dragged around the place without knowing it. Sometimes the waves are decent. It does depend on how big the tide is though and how comfortable you feel about it.

To answer your question about surf and tides, wikipedia is your friend: http://en.wikipedia.org/wiki/Tide
A full moon will have a more direct pull on the sea so yeah, it can lead to higher tides and, in turn, can produce bigger waves. It also seems to me that a no moon phase also produces higher tides.

As well as that, the breaking of a wave depends on its energy, size, speed, wind and, perhaps most importantly, the depth of the water. As the water depth becomes shallower, the wave is forced up above the level of the surrounding sea. For the long shallow beaches that are common on the West of Ireland, this means that, on a clean day, you can see the wave coming for ages before it breaks. The wave breaks when it can no longer support its weight above the sea. At some beaches, the land falls off fairly quickly, so there's nothing to push the wave up and make it visible and the wave only breaks when it actually hits the shore. What happened yesterday in Lahnich is that as the tide comes in, it rises up above the level of the beach, up along the rocks. As there is now much more space underneath the wave, there is nothing to force it up until it actually hits the rocks. Hence the apparent "shortness" of the wave.

The tide plays yet another role in determining the size of a wave - usually a rising tide produces a bigger wave (the main body of water is trying to get in towards the shore and adds to the energy of the wave) and a falling tide produces smaller waves (the main body is trying to pull a way from the shore and detracts from the energy of the wave). There are some beaches where the opposite is true and some where the tide appears to have no effect on the size of the wave.

I'm not an expert on any of this so I'm open to correction on all of it! It's only what I've picked up from various websites and experience.

learnerplates

Cheers SideShowBob,
I'll have to remember the earlier high tide in future for lahinch. Thanks for the wiki too, a bit too much information for me, maybe over the bank-holiday I'll get to digest its...yeah.
Surf must be up this weekend, where's everyone going. I think Sligo maybe on the cards.

lightening

No expert here, but from what I can remember a full moons gravity will pull the sea up, pulling the water out causing a spring tide, this means the tide will ebb further than usual and flood more than usual. The opposite is a neap tide, hardly goes out or in.

Jak

More from diving knowledge,

Spring tides have higher highs and lower lows basically and occur at the start and end of the moon cycles - so both full (end) and new.

Neaps are in the two phases in between and are generally more moderate high and low tide levels or "lower highs and higher lows".

As for how these affect waves it is (as far as I understand) down the underwater topography and how different tidal depth and varied tidal flow affect wave formation. So really, it comes down to knowing your beach - I generally just try to be aware of the 'general' rule for a given beach and use that.

Maybe the whole rule of twelfths thing plays a part in terms of when the strongest flow in the tide is also - but I never think about it when surfing.