Building better banks

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Building better banks

Postby johnnn » Wed Sep 17, 2008 2:36 am

I have been living in Tokyo for the last year or so, and going for a surf has been a very frustrating experience during this time. It takes at least two hours to get to the coast from where I live, and when I get there the conditions are usually pretty lame. On the rare occassions when there is some swell, the banks can't handle anything over about waist high. Well, actually, there are no real banks to speak of.

... which got me thinking - is it possible to build a better beach break?

I've looked at info about artificial reefs around the world, and it seems that most of them are trying to create a "perfect wave". (And why not, I reckon, if you've got the budget to do it.) Most artificial reefs seem to have been built (or to be in the process of being built) in relatively deep water, with a deep channel at both ends (left and right) to reduce the chance of the wave closing out, so that the wave is "makeable".

However, I don't really care if a wave is makeable. I mean it's nice, but right now I would settle for anything that didn't close out straight away. Even just five or ten metres of wave face to play with before the wave closes out would be fine.

RIght now there are no banks where I go to surf. Or, to put it another way, there is just one big, straight, long bank, without any channels in it, so that when a wave hits it, the wave just closes out all at once all down the line. Sometimes, the swell will hit the bank at a good angle and run for a little bit, but the bank is basically way too straight.

So, my idea is to build a kind of a "ramp" in the slightly deeper water about five or ten metres out behind the bank. The ramp would be roughly in the shape of a triangle, but I'm guessing any shape would do. The ramp would be just high enough (off the sea bottom) that the top of the ramp would be roughly a metre below the surface at mid tide.

If everything goes according to plan, the swell should hit the ramp first, creating a distinct peak and also causing the swell line to refract ever so slightly.

Right now the waves have no real peak at all, so even just having a peak should make a big difference. But I'm hoping the refraction effect will also cause the refracted swell to hit the existing banks at a better angle. And if there were two ramps rather than one, then the combined refraction effect might pull the swell line between the two ramps apart, into two sections (which might even be makeable if everything works out).

I haven't done a full survey of the shape of the bottom, but I have been watching how the waves break, as well as regularly checking the forecasts on MSW. Typically, the swell coming in is about a metre plus or minus a little bit. The banks can more or less hold this on the right tide. About once or twice a week, the swell pushes up to about 1.5m, which would be a fun size if only the banks could hold it. And then once or twice a month (at certain times of year) the swell can get up to 2m or more. Fortunately there are a few reefs that start to light up when this happens. Unfortunately, these spots get really crowded, so it would be great if we could build a few more places that could handle this kind of swell.

The longboarders seem more or less happy with the baby-sized waves, and I wouldn't want to make things worse for them. So, the ramps would have to be deep enough to let the 1m swell more or less pass over the top (maybe just peaking it up a little at low tide).

I'm mainly interested in improving the quality of the break on mid-sized swell (around 1.5 m). For this to work, the top of the ramp will need to come to within 1.5 m of the surface, at least most of the time. (The ramp might night have much effect on big high tides.) Because the ramp will be surrounded by deep water, I expect that the drop will be reasonably easy, but if the ramp is too far back from the bank, then the wave will "die" (lose power) before it reaches the bank and speeds up again. So the trick will be find the right distance between the ramp and the bank so that the wave jacks up at the ramp, slows down for just long enough to set up some kind of turn, and then speeds up again when it hits the bank, before eventually closing out.

First bunch of questions: Is it possible to calculate this distance? Or a range of distances that might work? What kind of measurements would I need to make in order to do the calculations? Or would it be a matter of trial and error? Roughly how wide would the ramp have to be to make a difference?

For larger swell, my idea was to build a two ramps close the bank, maybe about 50 to 80 metres apart, and then build a third ramp further out, half way between the two inside ramps. With luck and planning, the outside ramp would create the first peak, and also refract the incoming swell lines onto the inside ramps. The wave would be "sectiony", with a peaky take-off, a slower second section, followed by (maybe) a little barrel or bowl section before racing on to the bank to close out. But I imagine that building a ramp in deeper water would be a lot more work, so I'm not really considering it for starters.

Second bunch of qustions: Same as the first bunch of questions, except I would also need to know how far apart to space the two inside ramps.

Obviously building these ramps would be a lot of work, and I will need to do some rough calculations about the scale of things before I start. The basic idea is to use bags filled with sand. But I also thought it might be possible to let nature help out as well. Here's how...

The bay faces due south, and for much of the year the dominant swell is SE or NE, although most of the better (=bigger) swells come from the SW or due S. Anyway, most of the time there is an E component to the swell, so the cross-shore drift runs from east to west.

So my idea is to only build half a ramp, in the shape of a semi-circular wall. (Maybe about two thirds of a circle actually.) The open side of the circle would face ENE, so that the inside of the circle would fill up with sand flowing in with the dominant east-to-west drift. The wall of sand bags on the southern and western sides of the ramp would protect the structure from the larger S and SW swells, protecting it from being wiped out completely. (Some of the sand inside may get washed out, but this would be replaced sooner or later.) Hopefully, this approach would dramatically reduce the amount of work required to build the ramp.

Third question: How practical is this idea? What kind of shape would the wall have to be?

Finally, I am a little bit worried about the possible side effects of this kind of project. I'm not really worried about messing up other breaks further along, because they are all pretty useless. But I am concerned about the possible effects of erosion and rip currents. Hopefully this kind of setup would actually reduce erosion, but it's also possible that it might focus the wave energy on certain points on the shore, causing erosion to concentrate in those places. And safety might be an issue if it creates rip currents where there weren't any before. Obviously I won't be able to do this single-handed, and I will need to address any concerns that people might have. Any advice on these issues would be very much appreciated.

(I will post diagrams if any of this is not clear.)
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Re: Building better banks

Postby hughesy » Wed Sep 17, 2008 4:26 pm

I think you'll find that someone somewhere will object to you going and messing with the seabed. 10/10 for enthusiasm though. Do a search for artificial reefs and you should come up with everything you need. Except for the money and the nescessary permission of course.
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Re: Building better banks

Postby Mat 'Sonic' Clark » Thu Sep 18, 2008 3:01 pm

I have also spent more time than I should thinking about this subject. Forgetting the rather tricky legal considerations for a moment here are some other things to think about.

Any hand built reef be it made of sandbags or stones would probably be significantly flattened by the first decent swell to break on it. A couple of stormy days would obliterate it. I’m pretty sure the ocean is much stronger than any structure that can be built with human power alone. This means your probably need a JCB to move very heavy sandbags or stones. Sounds both expensive and illegal.

A partial solution to these problems might be a mobile reef built of metal sections that link together. Pin them to the seabed at low tide, Surf through the tide then remove it when the tides gone out again. Days with neap tides and the correct wind and swell conditions would need to be chosen.

Quite a big undertaking but I thought perhaps with the backing of a sponsor this could be viable. The reef would go on tour around the UK and the sponsor could market their product at each location. However the metal would need protecting with some sort of paint (such as used on fishing boats) but this may not be very environmentally friendly.

If you were going to hand build a reef it would need to be on a very small scale and thus designed for small waves. You’d need to do it during the season most likely to have small waves as it would probably be destroyed by the first big swell. You would probably be wise to do it at night when there’s less chance of you be collared by the police. You will probably need the help of many very understanding friends.

I ran this idea past my friends in the form of a ‘beach barbeque and reef building party’ and they told me to fuck off. Can you believe it. It’s almost as if they didn’t want to spend hours lugging rocks about in the dark to create a very small reef break for me to surf.

One other thing to think about is channelling streams/ small rivers. Kids do this every summer at most beaches in Cornwall. Could it be turned to our advantage???
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Re: Building better banks

Postby Ferral » Thu Sep 18, 2008 7:50 pm

Firstly i'd say that putting a reef in is not something you should decide to do without due consideration, there's a fir bit of evidence in the literature that submerged structures (designed for coastal protection) actually often cause erosion in their lee because mass transport of water over the submerged structure casued by breaking waves piles up behind the structure and then need to go somewhere, the seaward driven currents that result then cause erosion. although i doubt a one man band reef building project would manage to create anytihng large enoguh to cause an effect..

secondly the strong feedback loops often occur in changes to the coastal zone s what was a small change can rapidly grow.

However disclaimers aside, much of my time on the shitter is spent pondering such things!! IF i was tasked with building an artifical surfing break id say the best way would be (on an open coastline) to build a carefully designed groyne such that a decent sandbank would form. THe way I imagine doing this would be to build it at an angle inclined in the direction of the longshore sediment transport sand would then be pushed along the jetty and deposited in its lee, this would build out and hopefully produce a mini sand point (some nourishment in the lee wouls seed up this process) kind of like a mini version of sandspit. If you look at lots of waves they are coastal engineering accidents. If people want to build waves maybe they should look at the accidents.

Assuming you dont have a big budget/ the blessing of teh local authority and really do want to try an create your own waves, why not try to dig a bank? I reckon by digging a channel in a line straight out to sea on a closeout bank would give you a wave breaking into the channel on one or both sides. you'll have to do this ona mid tide section really but i think that when waves started to break return flows would 'find' the deeper channel and help scour and maintain the channel and voila your own perfectr wave! THis would work very well in a bank with a trough behind it. you'ld essentailly create your own rip current cell.
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Re: Building better banks

Postby majordom » Thu Sep 18, 2008 10:08 pm

the sandbank is the shape and loation it isbecause of the effet of the ocean

changing it will be very hard as the ocean will just want to push it back to the natural position

the artifiial reef at bournemouth is costing a few million quid - if you have that money
then better to buy a house on maui or your own jet
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Re: Building better banks

Postby Squelchy » Thu Sep 18, 2008 10:45 pm

johnnn why don't you divert a stream/river/sewer for some permanent banks?! :-D
try this :shock: 8) :wink:
http://www.youtube.com/watch?v=Sm7xgPjC ... re=related
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Re: Building better banks

Postby johnnn » Thu Sep 18, 2008 11:15 pm

hughesy wrote:I think you'll find that someone somewhere will object to you going and messing with the seabed.


I think you're right, which is why I'd like to calculate the likely effects beforehand.

However, I'm still vaguely hopeful that this kind of "surf ramp" might actually _reduce_ erosion, by reducing the power of waves before they hit the coast.

On the other hand, I think the "Law of Unintended Consequences" could be a major factor...
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Re: Building better banks

Postby johnnn » Thu Sep 18, 2008 11:53 pm

Mat 'Sonic' Clark wrote:Any hand built reef be it made of sandbags or stones would probably be significantly flattened by the first decent swell to break on it.


Definitely. I learnt how to surf on a beach where the banks would get obliterated regularly, so I have plenty of respect for the power of the ocean to re-arrange the topography of the bottom. Hopefully, though, the ramp would only be "significantly flattened" and not wiped out completely, so that it could be repaired without too much work.

The area that I have in mind (Shonan) is a big bay that is protected from the winter swells that would probably make this kind of project impossible in a more exposed location. Even during summer, most of the waves are short-period (=low power) windswell, except for the occassional typhoon. And even the typhoons have lost most of their oomph by the time they get here. It does get big sometimes, but rarely for more than a day at a time.

So I haven't given up just yet. If the ramp is small enough and easy enough to build/fix then it might still be a goer.

(And fixing the ramp would give us something to do on the all-to-frequent flat days.)


Mat 'Sonic' Clark wrote:A partial solution to these problems might be a mobile reef built of metal sections that link together.


I like this idea... if you build it, I will come over and surf it :-)

Mat 'Sonic' Clark wrote:One other thing to think about is channelling streams/ small rivers. Kids do this every summer at most beaches in Cornwall. Could it be turned to our advantage???


I went exploring one of the more remote areas of Japan recently, and I stumbled across a break that the locals had created by digging out a river mouth that had become blocked up with sediment. They dug two channels, one on each edge of the river mouth. This created an almost-shaped island in the middle of the river mouth, with banks sloping gently down to the bottom on all sides. The day I surfed there was a bit blown out, but there was still a decent little peak, with a left and right peeling off nicely in each direction.

Apparently it took 20 people about four hours to dig it out.
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Re: Building better banks

Postby Poo Stance » Fri Sep 19, 2008 12:21 am

I think diverting the river is the way to go. I'm guessing that (as stated) any attempt to alter a small aspect of the ocean environment will only lead to the ocean establishing it's equilibrium again. Introducing a river mouth to a beach should have a drastic and lasting effect. And we all know how good the banks around rivers can get.

Either that or sink a ship just offshore and wait for the bugger to rot away. Sand should build up around it if your lucky and hey presto! Or maybe not.

I think one of the reasons the artificial reef in Newquay was rejected was because of the refraction of the waves could significantly change the way water flows into the bays, the results of which could only be guestimated. Ie... all the sand could just bugger off?
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Re: Building better banks

Postby johnnn » Fri Sep 19, 2008 1:20 am

IainF wrote:Firstly i'd say that putting a reef in is not something you should decide to do without due consideration, there's a fir bit of evidence in the literature that submerged structures (designed for coastal protection) actually often cause erosion in their lee ... although i doubt a one man band reef building project would manage to create anytihng large enoguh to cause an effect... the strong feedback loops often occur in changes to the coastal zones what was a small change can rapidly grow.


Yeah, this is what I was worried about, and why I definitely want to consider this carefully. Hopefully, any impact would be small, but I would like to try and work out what the impact would be. Anyone got any suggestions about how to do this?

IainF wrote: IF i was tasked with building an artifical surfing break id say the best way would be (on an open coastline) to build a carefully designed groyne such that a decent sandbank would form. ... If you look at lots of waves they are coastal engineering accidents. If people want to build waves maybe they should look at the accidents.


How about a submerged groyne (like an artificial bank extending from the shore)? If the sediment is drifting from east to west (as it does on this south-facing beach) then your groyne would be angled off to the west, and you'd be hoping to create a left in the lee. But if the groyne was also submerged then you might also get a right breaking back the other way.

There are lots of groynes on the east coast of Chiba Prefecture, and I'm told that the banks can sometimes get really good there, although I'm yet to see it. If only they would build them on an angle! Actually, one of my other crazy ideas was to try to seed some decent banks coming off these groynes by building a row of sand bags, starting at the edge of a groyne. Hopefully the sand would get trapped behind it.

IainF wrote: I reckon by digging a channel in a line straight out to sea on a closeout bank would give you a wave breaking into the channel on one or both sides... i think that when waves started to break return flows would 'find' the deeper channel and help scour and maintain the channel ...you'ld essentailly create your own rip current cell.


Which brings me to my other crazy idea. I thinking digging a channel would be seriously hard work - altho maybe no harder than building a ramp out of sand bags. But like you said, once a bit of a channel was established the return flows might take over and do the rest of the work.

One easy way of "digging" a channel might be to use a pump. The idea is to collect water from out the back (where there isn't as much sediment in the water) and then pin the outlet hose to the bottom of the bank. Hopefully the focused water coming out of the hose would carve a small channel in the bank, which would then get re-inforced by the return flows.

Not sure how long this would take, or even if it would make a noticeable difference. But one of these days I might just get round to trying it...
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Re: Building better banks

Postby johnnn » Fri Sep 19, 2008 2:43 am

majordom wrote:the sandbank is the shape and loation it isbecause of the effet of the ocean

changing it will be very hard as the ocean will just want to push it back to the natural position


Actually, the shape of the sandbank is due to a lot more factors than just the ocean (altho obviously the ocean is a pretty big factor). Rainfall, sand drifting in from hundreds of kms down the coast, the new bike path behind the dunes -- all of these things play a part. And one of the biggest factors is the existing shape of the coast, which is part of a feedback loop that determines the future shape of the coast.

That's why I want to be careful, but I suspect that there may be no real way of knowing for sure. Then again, people have been studying this kind of thing for decades now, so maybe someone might be able to give us some idea of the likely consequences.

By the way, I've made an estimate of the amount of work involved. This kind of ramp is not at the same scale as the reef at bournemouth, or other similar reefs, so it might actually be do-able.

Assuming that the water just behind the closeout bank is about 3 m deep, then the ramp will need to be about 2 m high in order to reach to 1 m below the surface. If the ramp is in the shape of an truncated cone, 6 m in diameter at the base and 3 m in diameter at the top, then the ramp will need about 33 cubic metres of sand.

(See http://wiki.answers.com/Q/Formula_for_c ... cated_cone)

Using bags that are 1 m x 0.5 m 0.2 m when full of sand would require 10 bags per cubic metre, or 330 bags in total.

Bigger bags would be more stable, but would be much harder to transport. Bags of this size would weigh about 178 kg (based on http://wiki.answers.com/Q/What_is_the_density_of_sand) which is a lot, but if the bags were placed in a wheelbarrow before they were filled with sand, and then wheeled to a longboard or surfski waiting in the shallows then this should be doable by two people.

If it takes ten minutes to fill a bag and manouevre it into position, then that's 55 hours of work per pair - which is a lot of work, I admit. But if there were eight people involved, with two wheelbarrows and two surfskis (specialized into two barrow teams and two dive teams) then the number of hours drops to about 14 hours. There's a lot guesswork in these times, but five shifts of three hours should do it. A lot of work, but not impossible.

And speaking of work, I should probably do some... :?
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Re: Building better banks

Postby jon-rn » Sun Oct 05, 2008 10:26 pm

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Re: Building better banks

Postby Squelchy » Sun Oct 05, 2008 11:08 pm

before anyone else wastes 3 mins of their life watching that link
nothing funny or strange happens
just watch water going downhill for 3 mins

:offtheair: :munky2: :confused1:
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Re: Building better banks

Postby kieran100 » Mon Oct 20, 2008 2:47 pm

This idea may be even more crazy, expensive and highly illegal but what about controlled underwater explosions shaping a dodgy cloeout slab near a cliff where no one will notice?!!! Porthleven reef was apparently created by dynamite 100 years ago when they tried to expand the entrance to the harbour (wavelentgth article a few years ago.) It seems that we got lucky with the creation of a good wave. Why not do it again?! You would need someone like Dr Kerry Black, an underwater contruction engineer and someone in the Special Boats Service with experiance in blasting away large quantities of rock. You could have a perfect A-frame peak at the base of a cliff or just off-shore out of site, on a rock like granite the reef would last for our lifetime. Would this idea ever become a legal possiblilty?
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Re: Building better banks

Postby sandybottom » Wed Oct 22, 2008 10:30 am

hey johnn
also do a search on us patents for artificial surfing reefs , theres some expired patents and others that can be used if noone profits from them -ask first though.
Ideas abound in these and you have to study closely.
BUT -seriously the funs in the learning as the implementation is just too seriously hard and those that have tried have made a lot of money but not produced any results -google openake , mount manganui, artificial surfing reefs -particularly International coastal management and their Research and development site.
The worlds first and most sucessfull cost/benefit man made reef was in Bagara in queensland au. a few rocks were moved around for a few bucks and it works well when there is swell.
forget playing with particles of sand unless you want to go back each day and tweek them again - thats ok to and theres ways of doing that -japan has a underwater "bulldozer" and its just a trench thru the stormbank at the right angle with the excess material forming the "ramp" - only moves material that has moved over the last day anyway.
a buldozer on standby and a few litres of diesel each day for a few cubcs of sand shaped around

dont talk artificial surfing reef in India though as a group of Kiwis are "most wanted ' there so that a crowd can tear them "limb from limb" , 5000 protesters against tsunami fund diversion (they were fishermen that wanted nets and boats and food not surfing reefs) got arrested -so how many were protesting??

There should be an international warning out against going to anywhere there was a tsunami as the locals might confuse you for the kiwis who want $millions of the relief money for designing and building surfing reefs ,

STAY AWAY FROM INDIA WITH A SURFBOARD (NEAR THE COAST ANYWAY)

just google tsunami fund diversion with and without ASR included and see for yourself.
I think the underwater engineer mentioned in a post here is mentioned also in the newspaper reports. For gods sake if you go to India dont mention his name if you want to be healthy.

good luck and keep learning
dont hesitate to ask if i can elaborate on anything (except what the Indian newspapers report -thats self explainetory)
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Re: Building better banks

Postby weaver » Sun Mar 08, 2009 2:58 pm

Does anyone know if a temp inflatable bank anchored to the sea bed has been thought about? It would'nt have to be all that big, as long as it was placed at the right angle to the incoming swell. More like a long sausage really and the anchor points could be left in situ, perhaps mulitiple points to accomodate various angles. The whole thing could be deployed from the shore, much like an oil containment boom and removed if storms were forecast? Or has it been looked at and discarded as impractical?
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Re: Building better banks

Postby surfrat » Tue Mar 17, 2009 3:14 pm

everyone is missing the point here....you can't build a sandbank
what you need to do is build a pier or a jetty that will be resistant to weather and wave damage and will over time create banks for you. Tried and tested.

I'd go with jetty over pier cos pier's seem to burn down after a while......
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Re: Building better banks

Postby savvy » Tue Mar 17, 2009 6:14 pm

surfrat wrote:everyone is missing the point here....you can't build a sandbank


http://www.youtube.com/watch?v=eUQ2-8iuQZA

http://www.snapperrocks.com/

:)
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Re: Building better banks

Postby surfrat » Wed Mar 18, 2009 10:53 am

fair point, the superbank was "built" but not on purpose and i doubt the sand would have stayed where it was without the river mouth, and various jetties and rocky point giving it some form.

but on a flat long beach you cannot dump a load of sand bags and/or sand and build a sand bank.

there's been talk of an artificial reef as sea defense where i live for ages now. maybe with surfing in mind....

but my favourite scheme is the one to restore a canalised river to it original course and have an interesting new rivermouth half way along the beach........now that'd make some sand banks for sure
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Re: Building better banks

Postby JoeHart » Wed Apr 08, 2009 8:28 pm

forget about artifical reefs, they a big headache. I'll been involved with the bournemouth reef for the last 15 years. Best thing to do is find a sight an dump a load of rocks in. Save the heart ache and the money

cheers Joe
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Re: Building better banks

Postby danny1 » Sat May 09, 2009 8:48 am

why donr you go surf a reef or somewhere with decent beach break??????????????????? explore!
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Re: Building better banks

Postby Noserope » Tue Jul 07, 2009 10:31 pm

I did it. My pal Pete and I lugged out rocks from the sea wall as heavy as we could carry as far as we could hold our breath and deposited them in a pile outside of a spot that reeled off too fast to get into. What we accomplished was we made a take off spot that stood up long enough for you to paddle into it. It was a crazy break where a head high wave would be past vertical one foot up the face that usually had a three foot thick lip that would throw six feet horizontally, that was usually over only about one foot of water. Sometimes the wave went dry at the bottom and got ugly. I broke both both my thumbs there once doing a superman dive off the front of my board. The next winter a big storm swell took the rocks away. It was worth it I got some of the best tubes of my whole life there. Over a hundred yard long barrels easy. Only we knew that you had to line up exactly with the antenna from the coast guard station across the street to make the drop and we didn't tell anybody.
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Re: Building better banks

Postby Vince Noir » Fri Jul 10, 2009 3:43 pm

^ so your saying that by dumping rocks into the waves path, you effectively made the wave slow down enough for you to paddle into it ?

Im no expert in surf science , but that doesnt make any sense what so ever.....by making it shallower/giving something the waves to break over, your doing the opposite of what you set out to acheive


unless the wave suddenly hits the reef and reels off too fast, and what you did was make it shallower just before this point, so that it broke slow enough to get into the wave as it hit the natural reef

no personal offence, but i'd be highly skeptical that you and a mate would be able to do that by swimming rocks out..take alook at how long proper artifical construction projects take... :roll:

Prehaps you were always able to get into the wave in the first place ?
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Re: Building better banks

Postby FTURUE » Sat Jul 11, 2009 3:47 pm

Noserope wrote:I did it. My pal Pete and I lugged out rocks from the sea wall as heavy as we could carry as far as we could hold our breath and deposited them in a pile outside of a spot that reeled off too fast to get into. What we accomplished was we made a take off spot that stood up long enough for you to paddle into it. It was a crazy break where a head high wave would be past vertical one foot up the face that usually had a three foot thick lip that would throw six feet horizontally, that was usually over only about one foot of water. Sometimes the wave went dry at the bottom and got ugly. I broke both both my thumbs there once doing a superman dive off the front of my board. The next winter a big storm swell took the rocks away. It was worth it I got some of the best tubes of my whole life there. Over a hundred yard long barrels easy. Only we knew that you had to line up exactly with the antenna from the coast guard station across the street to make the drop and we didn't tell anybody.


you took on the power of the ocean, you are my hero (L)
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Re: Building better banks

Postby Noserope » Tue Jul 28, 2009 1:49 am

Vince Noir wrote:^ so your saying that by dumping rocks into the waves path, you effectively made the wave slow down enough for you to paddle into it ?

Im no expert in surf science , but that doesnt make any sense what so ever.....by making it shallower/giving something the waves to break over, your doing the opposite of what you set out to acheive


unless the wave suddenly hits the reef and reels off too fast, and what you did was make it shallower just before this point, so that it broke slow enough to get into the wave as it hit the natural reef

no personal offence, but i'd be highly skeptical that you and a mate would be able to do that by swimming rocks out..take alook at how long proper artifical construction projects take... :roll:

Prehaps you were always able to get into the wave in the first place ?



OK, I'll explain it again. The break was essentially a close out that slapped over virtually all at once but not quite. Our rock pile was out beyond the part of the wave that broke first. Our pile did not make it break differently, what it did was take the deep water outside the break and make it shallower in one single spot. The wave broke in about three feet of water. Out past that it immediately dropped to eight feet and that was too deep for the wave to stand up and start to break so it just all fell over too quick to get into. Waves grow taller as they near shore unless it gets too shallow too quick. That's why the big island of Hawaii has crappy waves, it's too young to have reefs off shore. By piling rocks where it was eight feet deep until it turned six feet deep we made a point where the wave stood up taller preparing to break for a moment before it threw over when it came into the three foot ledge. This was all we needed to slide down the face, collect enough speed and turn right before the whole thing threw. With out that peak you had to make a drop that went immediatly to past vertical and be going down the beach 30 mph which was impossible. It's basic fist year oceanography, waves get taller and slow down as they near shore and feel shallow water. I took that class in college and learned that lesson. We didn't make the wave slow down, that takes more time but we did make it start to break. A six foot wave will start to break in six feet of water according to the book. Oh and we didn't "swim" heavy rocks out, we walked the bottom holding our breath.
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Re: Building better banks

Postby danny1 » Sat Aug 21, 2010 8:10 pm

yes mate...this is the best thread on here...
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Re: Building better banks

Postby johnnn » Sun Aug 29, 2010 12:53 pm

I haven't checked in on this thread for more than a year, but I'm glad this discussion is still alive, and even more glad to hear that someone has actually tried out basically the same idea.

Noserope wrote: The break was essentially a close out that slapped over virtually all at once but not quite.


This is exactly the kind of setup that I was talking about. Glad someone else has tried this.

Noserope wrote: Our rock pile was out beyond the part of the wave that broke first. Our pile did not make it break differently, what it did was take the deep water outside the break and make it shallower in one single spot.


So your rock pile was a kind of 'ramp'. You said the pile was about two feet high.. How wide did you make it? And how far back from the natural bank did you build it?

Noserope wrote:(Before they built the rock pile) The wave broke in about three feet of water. Out past that it immediately dropped to eight feet and that was too deep for the wave to stand up and start to break so it just all fell over too quick to get into. By piling rocks where it was eight feet deep until it turned six feet deep we made a point where the wave stood up taller preparing to break for a moment before it threw over when it came into the three foot ledge. This was all we needed to slide down the face, collect enough speed and turn right before the whole thing threw.


That's exactly the kind of effect I was hoping for.

Noserope wrote:We didn't make the wave slow down, that takes more time but we did make it start to break.


When I said "slow the wave down", I meant "slow down the speed at which the wave is breaking" rather than "slow down the speed at which the wave is travelling". Actually, what I meant was "create one small section that breaks slowly enough to take off on". This is easier to achieve in deeper water, where the depth of the bottom is closer to the depth of the swell.

The set up that you created is basically the same as one of my favorite waves on the whole planet (whose location shall remain top secret). At that spot, there is a dead-straight, shallow coral reef that drops of suddenly into deep water. The angle of the reef is at a favorable angle to the incoming swell, but the wave still breaks way too quickly, too quickly for a kook like me to get into anyway. Fortunately, however, there is a coral 'ramp' in deep water a few meters back from the dead-straight reef, and the wave starts to stand up and peak when it hits the ramp, a second or two before it hits the 'bank' of the reef. The drop from the ramp is still fairly intense because it jacks up so quickly, but it's a whole lot more makeable than any other section, and once you get to your feet it doesn't really matter that the rest of the wave is super-fast.. that just makes it more exciting.

I think a few of the replies on this thread have missed the point of what I wanted to achieve. I'm not interested in trying to create the perfect wave. That would be difficult, time consuming and expensive, and - judging from this forum - in the end everyone would winge when it didn't live up to their fantasies.

The problem with 'perfect waves' is that once the word is out every man and his dog wants part of the action, so that paradise turns into a shit fight. (There are some perfect waves out there that aren't crowded, but they only stay secret if the conditions that they need to work don't happen very often.)

But at the other end of the spectrum there are unsurfable closeouts. Sometimes there might be swell, and there might be banks, but nature just hasn't managed to get its act together. I have the feeling that a few well-placed piles of rock producing waves that are at least surfable (altho maybe a long way from perfect) might be a better way of catering for the growing number of surfers than big expensive projects that either fail or get crowded if they do succeed.
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