Forums > Windsurfing   Gps and Speed talk

How to make Australia Great Again?

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Created by Macroscien Sunday, 11 Aug 2019
decrepit
WA, 9275 posts
Wednesday , 14 Aug 2019 5:14PM
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Maybe tidal differences as well?

boardsurfr
WA, 843 posts
Wednesday , 14 Aug 2019 8:50PM
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sailquik said..
I actually like the idea of the water filled plastic tube. I can see it might be feasible to construct it using ultasonic welding and a huge roll of PVC.

The inherent problem with such a structure is that it is water filled, and therefore has the same density as the water it sits in, with the exception of the actual plastic film. This means it need to be anchored to the bottom securely. Not an insurmountable problem, but a complication nonetheless. because, wherever there is strong wind, the surface water will be moving with it, trying to drag you barrier as well.


It has to stick above the water, so there will be a little bit of downforce. But the wind and water will push it downwind. They had some problems with that during the first year. The tube held without problems in 15-20 knots, but started moving when it picked up to 30 knots. They fixed it by adding more anchors. One every 15 ft worked for 30 knots; for 40 knots, you might need more or heavier anchors. Seems solvable, though. And if you curve the tarp a bit to get a deep downwind angle towards the end, most of the anchors will be needed near the front.

If you set up at a place with long shallow areas, the barrier "reef" does not need to be very long, since an approach at decent speed is possible through moderate chop. At the GPS trial in Cervantes, the length of the speed strip was less than 150 m, with sizable chop at the approach and noticeable wind shadow after the first 50 m or so. The spit at Lake George is about 400 m before the trees. A 500 m reef with a 300 m approach through 2 ft water may be too short for official 500 m records, but should be good enough for 50 knot 10-second runs.

sailquik
VIC, 4679 posts
Thursday , 15 Aug 2019 8:17PM
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Check out the Mining ventilation tube halfway down this page. :-)

The question is, would it be strong enough ?? (Inflated with water of course)

Of course, anchor points would have be be added. It has to hold in 40+ knots or it is pointless.

www.derflex.com/m/prodetail.asp?id=115

boardsurfr
WA, 843 posts
Thursday , 15 Aug 2019 8:34PM
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Looks like just the right stuff if they can make bouncy castles out of it. It's probably very similar to what they used in Hatteras. Did you ask them how much a 500 m long, 1.5-2 m diameter tube would cost?

sailquik
VIC, 4679 posts
Thursday , 15 Aug 2019 10:56PM
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boardsurfr said..
Looks like just the right stuff if they can make bouncy castles out of it. It's probably very similar to what they used in Hatteras. Did you ask them how much a 500 m long, 1.5-2 m diameter tube would cost?



Not yet.

Tomorrow.

kato
VIC, 2514 posts
Yesterday , 17 Aug 2019 12:10PM
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I like your thinking Daffy. What about a oil boom with a tail . Cant draw it but think of a sideways P . the top sits at water level and the tail trails out up wind and is anchored into the sand by sand into pockets. The wave action should run up the tarp and be absorbed by the top. It would only work in shallow water. You wouldn't need a great length for some places in Shark bay .

Crasher
WA, 63 posts
3 hours ago , 17 Aug 2019 9:13PM
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I'll do my bit. Drawing up a plan for Sharkbay. Sandbags. Can only try considering the salt mine can buy out certain areas that should not be converted to salt mining. Happening now an done. So 700m sandbag line verses 1000sqkms killed? Salt mine does not bring tourists or money to towns.



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"How to make Australia Great Again?" started by Macroscien