# SEA ROOM

A safe distance from the shore or other hazards.

## Related Terms

### MOMENT OF INERTIA

The quantity obtained by multiplying the mass of each small part of a body by the square of its distance from an axis, and adding all the results.

### GREENWICH HOUR ANGLE

Angular distance west of the Greenwich celestial meridian; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of the Greenwich celestial meridian and the hour circle of a point on the celestial sphere, measured westward from the Greenwich celestial meridian throug

### HARPOON LOG

A log which consists of a rotator and distance registering device combined in a single unit, which is towed through the water. The TAFFRAIL LOG is similar except that the registering device is located at the taffrail, with only the rotator in the water.

### HORIZONTAL DANGER ANGLE

The maximum or minimum angle between two points on a chart, as observed from a vessel, indicating the limit of safe approach to an off-lying danger.

### SHEAR RATE

The difference between the velocities along the parallel faces of a fluid element divided by the distance between the faces.

### GROIN

A structure (usually one of a group) extending approximately perpendicular from a shore to protect the shore from erosion by tides currents, or waves or to trap sand for making a beach.

### HEIGHT OF TIDE

Vertical distance from the chart sounding datum to the water surface at any stage of the tide. It is positive if the water level is higher than the chart sounding datum. The vertical distance from the chart sounding datum to a high water datum is called RISE OF TIDE.

### HIGH WATER LINE

1. The intersection of the land with the water surface at an elevation of high water. 2. The line along the shore to which the waters normally reach at high water

### HOUR ANGLE

Angular distance west of a celestial meridian or hour circle; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian or hour circle and the hour circl

### INDIRECT ECHO

A radar echo which is caused by the electromagnetic energy being transmitted to the target by an indirect path and returned as an echo along the same path. An indirect echo may appear on the radar display when the main lobe of the radar beam is reflected off part of the structure of the ship (the stack for example) from which it is reflected to the target. Returning to own ship by the same indirect path, the echo appears on the PPI at the bearing of the reflecting surface. Assuming that the additional distance by the indirect path is negligible, the indirect echo appears on the PPI at the same range as the direct echo received. Also called FALSE ECHO.

### Related questions

MarineProHelp 2018 - 2022