Any Engineers Here????

[SoulWinner]

Hey everybody, I need an engineer who can take an idea I have that could save docks during storms, and test it on a computer to see if my idea is rubbish or not. Is there anybody like that here??

 

[Stratosfied]

Re: Any Engineers Here????

SoulWinner, Sadly no, but I have worked with some very brilliant engineers, and I did stay in a Holiday Inn Express once or twice!

 

[SoulWinner]

Re: Any Engineers Here????

Well, good enough.<br /><br />My idea is this: When building a dock, rather than nailing the planks down, hinge the edge of the plank that faces the water. This way, when big waves come, they will lift the back edge of the plank, and the lifting force on the dock will tremendously reduced. Think it would work?

 

[Barlow]

Re: Any Engineers Here????

SW... try getting ahold of the University there.. <br /><br />they've got the latest technology to run something like this.

 

[Stratosfied]

Re: Any Engineers Here????

I was just egging a little to a local. The hinge on the leading edge is a very good idea. I would think that a dock that is built on a pipe for the verticle support with a larger diameter pipe around it which would be able to allow the bouyancy of the wood the rise with the tides or surges would work. Perhaps we have begun a new industry???

 

[BoatBuoy]

Re: Any Engineers Here????

Seems to me like hinge maintence in salt would be a nightmare. Would SS hinges be prohibitive?

 

[ndemge]

Re: Any Engineers Here????

......a storm rolls in, your beer is sitting on the dock, big wave rolls in and catapults your beer ..... NOOOOOOOOO

 

[roscoe]

Re: Any Engineers Here????

NoelMG... or catapults YOU !!!<br />Sounds dangerous, the lawyers are lining up.

 

[sloopy]

Re: Any Engineers Here????

how would it reduce the lifting force of the dock?

 

[snapperbait]

Re: Any Engineers Here????

SW.. I do believe your onto something there...

 

[notinbig]

Re: Any Engineers Here????

or your on something...... <br /><br /><br />Weight, cost, maintence....etc...?

 

[tylerin]

Re: Any Engineers Here????

Just playing Devils Advocate, what if someone pulls a couple planks up and the next guy falls through

 

[Barlow]

Re: Any Engineers Here????

he gets wet ...

 

[tylerin]

Re: Any Engineers Here????

Originally posted by Barlow:<br /> he gets wet ...

Oh I forgot! He bumped his head on the way through

 

[sloopy]

Re: Any Engineers Here????

Can someone explain to me how hinged planks would make a dock loose buoyancy?

 

[Bass Man Bruce]

Re: Any Engineers Here????

No loss of buancy, but the wave action on the underside of the deck surface would be greatly reduced. Might be a good idea but you've got a lotta little details to work out SW.

 

[TwoBallScrewBall]

Re: Any Engineers Here????

The idea makes sense to me SW. Though I think maybe even though you might save the frame, the abuse that the hinges would take in a storm would probably wreck them. <br /><br />Then again new hinges and top boards is cheaper than an entire new pier. Hmmm.....<br /><br />-edit- I have 2 years of Mechanical and Electrical engineering college but I'm not a mechanical or electrical engineer...

 

[cbnoodles]

Re: Any Engineers Here????

SW,<br />Say a wave is 5 feet high, 20 feet from front to back at the base and is traveling at 20 mph. Also suppose, for the sake of this discussion, the dock in question is 100 feet long and the wave is approaching it sidelong (the wave is 100 feet long).<br /><br />I won't do the math here for you but it is very simple. You've got an effective wall of water 5000 cubic feet moving toward the dock. One cubic foot of water weighs about 62.4 pounds. Sooooooooooooo, the force of the water when it makes contact with the dock is in the neighborhood of 312000 pounds. Here's where the speed comes in: try dropping 312000 pounds of anything onto anything and watch what happens. That's what 20 miles per hour is; dropping something from your hand or just a few feet high.<br /><br />Most docks aint gonna hold up under that kinda load for very long. Even if you can discount part of this by qualifying it with the wave hitting at an angle so it doesn't bear the full force instantaneously, it's the constant repeated pounding that does the dock in. In other words, you can't beat nature. Just salvage what you can and start over.

 

[roscoe]

Re: Any Engineers Here????

Sounds good Noodles, except for the speed of something being dropped. I think you are off by a few feet. And that tthe 312000# force is not gonna hit the pier unless the pier has solid sides. Otherwise, you only have to calculate the surface area of the posts and how much water is going to come in contact with them. Water coming down on top of the pier is a different story, but it is not falling nearly as fast as you think, because it is not in freefall accellerating at 32'/sec/sec.<br /><br />Do 5' waves move at 20mph? Thats 30 feet per second.

 

[cbnoodles]

Re: Any Engineers Here????

Roscoe,<br /><br />The numbers are merely a rough calculation to illustrate a point. Horizontal, vertical, 20 mph, 10 mph...It really doesn't matter. The point is that docks simply cannot be built to withstand the thrashing they are subjected to by hurricane-force driven seas.<br /><br />BTW. Look again at what speed an object will be moving when it hits the ground dropped from only 3 feet. I'll be back later with the formula or you can GOOGLE it if you like. You will be surprised. And it is indeed freefall when a wave hits the ground (shore) in the vertical sense. Horizontally it will depend only on the speed of the wave.