HELP NEEDED ON HARBOUR DESIGN 2

[nedians]

What are most important things which one should consider while finding a location for a new harbour ?

2) What is Squat ? any formula for calculating it?

3)What are the requirement of a good habour?

4)What is Littorial Drift and what one should do in order to avoid LIttoral drift?

any website which contains information on this

 

[sfamularo]

All of the questions asked are very broad in their scope. I will do my best to answer each on some level...

1. Almost everything needs to be taken into account when designing a new harbor! Global Scale - defining the purpose of the facility...is it for local fisherman, for a specific maritime purpose, or a global trade center. Local - define the existing site characteristics - soil good for foundation, is the site permittable, is skilled labor available nearby. Coastal and Marine - What are the water depths near the site - can the ships of the harbor pass safely under all tidal, storm and wave conditions? Is the site protected from the dominant waves...from small waves?

2. Squat is the downward displacement of a vessel while it travels in shallow water. If you look at the Bernouli equation - if no energy loss is assumed, then the total energy must stay the same throughout the fluid. Under a ship with low clearance, the water must move faster under the ship than at the sides or adjacent to it. As the velocty increases the hydrostatic pressure decreases effectivey sucking the vessels down. It is not very pronounced at slow speeds. There is a formula for it (I think). I'll post that later.

3. The requirements of a good harbor are difficult to define. There are so many! Reply to this post with more specific questions. A few are: Little wave distrubance, well maintainted structures, capable land based cranes and offloading equipment.

4. Littoral drift is the transport of sand and sediments due to the action of waves on beaches...in the general alongshore direction. Onshore-Offshore movement is called the cross-shore direction and typically associated with erosion/deposition from storms and incident wave energy. Littoral drift can clog the entrance channels and cause unnvaigable waters as well as dangerous wave conditions.

There aren't many good websites for all this but there are plenty of good books:

Kollmeyer and Tobiasson - Marinas and Small Craft Harbors
Gaythwate - Design of Marine Facilities for the Ebrthing and Mooring of Ships
Tsinker, Gregory - He has a couple and I can't rememeber the names. Look under floating ports or marine structures.

Look these books up on Amazon for better info.

Any questions, e-mail me at stevef@ocean-coastal.com

Steve

 

[grrams]

I used to work for a facility that conducted port expansions research project via computer simulation. This is not an advertisement but a location of a resource for your endeavour.

http://www.starcenter.com

 

[jhambone]

I have been asked to check out the largest ship a certain dock can handle. I have never dealt with dock design, and I was wondering where I might look for design guides. Also, is there any special code or anything else I need to know about the design. I really need to know how to determine the loads applied to the dock by different sized boats, such as wind loads and wave interaction.

 

[PM]

sfamularo's response was very good considering the bredth of the question. I'm sure I couldn't do better, but I'd like to add one small, if not triffling, correction.
Snipped from sfamularo (Marine/Ocean):"4. Littoral drift is the transport of sand and sediments due to the . . . Actually Littoral Drift is the material moved and Littoral Transport is the mechanisim of moving Littoral Drift.

jhambone (Structural) You have a simple question with a complex answer.

Any given dock will have limits on depth along side, beam, wind loads on bollards, berthing loads on breasting dolphins, etc. not to mention complicated stuff like sieche (standing waves in artificial basins). Start with vessel draft and beam and you should be able to compare these dimensions against ship sizes to roughly establish max DWT. Obviously, if you are prepared to dredge, you might be able increase vessel size, but there are limits to how much you can safely increase the unbraced length of existing piles or undermine gravity based structures. You have to assess the wind loads on bollards from a product of max. permitted windage pressure times the exposed windage area of the max. vessel. Individual hawser loads can be estimated from a consideration of proximity of the hawser to the center of wind load as well as the stiffness of the hawser. Likewise you can calculate the maximum safe lateral deflection of the dock / fendering system and convert that into berthing energy to compare to maximum kinetic energy applied by a vessel berthing at say 1.5 feet per second.

The US Navy has quite a few good manuals on this type of work refered to as NAVDOCS.

Good luck,

 

[sfamularo]

My bust on the littoral thing...

About the Navy Manuals that PM mentioned, they are available online here:

http://www.efdlant.navfac.navy.mil/criteria/tools/waters_toolbox.htm

It's a 28 Mb download so hopefully you will be downloading faster than 56kbps...

Hope this helps.