The text provided appears to be an excerpt from a larger engineering manual, specifically dealing with the design and construction of various types of coastal structures for shore protection.

Based on the context clues within the passage, it seems that three main topics are being discussed:

1. Bulkheads: These are soil retaining walls used primarily in relatively sheltered areas not subject to significant wave attack. They serve as berthing facilities and help establish elevated grades along shorelines.

2. Quaywalls: Similar in function to bulkheads but designed for more demanding conditions, such as higher water levels or severe wave environments. They double as gravity wall structures that provide both protection against moderate wave action and a berthing face for ships.

3. Seawalls: These are forms of coastal defense structures intended specifically for protecting shorelines from erosion due to waves rather than being used as berthing facilities like bulkheads or quaywalls.

Key points about each structure include:

- Bulkheads rely on mobilizing passive earth pressures between the mudline and embedded tip, along with lateral support systems above mean low water (MLW), for their stability.

- Quaywalls are designed to handle higher loads than typical bulkhead constructions due to factors like greater height requirements or more severe wave conditions.

The passage also differentiates these structures from others mentioned:

1. Breakwaters: While they share some similarities with bulkheads and quaywalls in terms of providing protection against waves, breakwaters differ primarily because their primary purpose is not as a soil retention structure but rather for reducing the impact of incoming waves on shorelines or harbor areas.

2. Sheet pile breakwater design: This term seems to refer specifically to a type of bulkhead constructed using sheet piles (vertically spanning flexible members) that provides both structural support and resistance against water pressure.

The text also references external documents, such as NAVFAC DM-26.2 for more comprehensive information on coastal protection matters.