It begins life as a collection of tubes in the fabrication yard. As it is assembled, the pieces are moved about and connected until a complete jacket and deck are formed. These structures are then moved along a set of ways until they reach a bulkhead. There they move onto transportation barges. During each structure's travels along the barge, the ballast configuration in the barge must be continually changed to keep the structure from breaking. After a structure is completely on the barge, some sort of seafastening is attached, the barge ballast condition is changed for tow, and the barge is towed from the fabrication yard to the place where the structure will be installed.

Upon arrival at the installation site, the jacket must be moved from the barge to an upright postion sitting on the sea floor. This can occur in different ways:

• The jacket can be launched. Here, the barge ballast is again changed, the jacket winched until it begins to slide, it tips on the tilt beams, dives into the water and comes to rest. The jacket must then be rotated from its resting position to an upright one and set on the bottom. This is normally done by connecting the jacket to a crane vessel with a sling and uprighting via a combination of ballasting the jacket and lifting the crane.
• Alternatively, the jacket can be lifted from the barge directly by a crane vessel. In this case, there are normally two slings attached to the jacket so that it can be rotated.

Now, the deck must be installed. This can be accomplished in two ways:

• The traditional way is to pick up the deck with a crane vessel and lower it onto the jacket.
• Alternatively, the deck can be designed so that the transport barge can be maneuvered over the jacket and the deck placed on the jacket by deballasting the barge.

Throughout this whole process, the objective is to minimize the chance of failure. Failure here can be viewed in several ways:

• A complete loss of either the jacket or the deck,
• Damage to either structure, or
• Injury to some personnel.

• The structures themselves must the designed for each phase of this operation, and
• The operation must be designed so that as few things can go wrong as possible.

If one looks at all of the things that must be considered which were defined above, it becomes obvious that consideration of all these things is quite complicated. One is faced with both simulating what will happen based on the design of the operation and analyzing the integrity of the structures. In addition, the participants in this analysis (crane barge, jacket deck, cargo barge and launch barge) are definitely not the same in any way. Thus, MOSES must be able to mathematically consider all types of structures and perform quite different types of analyses.

The result of these diverse demands is a tool which is rightfully complicated. MOSES is not easy to learn. The learning is made more difficult by the fact that different types of engineers are involved, each of which have their own vocabulary and ingrained way of doing things. Believe me, we have tried to make this as easy as possible, but when decisions must be made, we will always choose to give one the ability to do things correctly at the expense of ease of understanding. MOSES is complicated not because of a lack of effort but because you demand sophisticated analyses. It is always easier to do things half way than to do them right.

MOSES is complicated, but it is not hard to use. It is hard to learn to use. To intelligently use MOSES, one must first understand

• The situation being analyzed,
• What one can change in the operation, and
• What one wants to accomplish.