Solas requirements, chapter V annex 13, can be summarized in their main points as follows:

1)”All ships (excluding fishing vessels and pleasure craft under 150 gross tons) to be fitted with a magnetic compass or other means to determine and display the vessel’s heading independent of any power supply. ”

2) “They must also be fitted with a pelorus, or other means to take bearings over an arc of 360° of the horizon and a means for correcting heading and bearings to true at all times”

3)”all ships of 150 gross tons and over and all passenger vessels carry a spare magnetic compass stowed away from the bridge structure”.

The proper way to comply with these regulations is to be fitted with a reflector binnacle above the pilot house, the heading visible from the helm station below my means of a mirror.  This also satisfies the pelorus requrement, because bearings can be taken directly from the compass, and the errors of the compass conveniently found.  Stow a spare compass away from the bridge and you are SOLAS compliant.

A compass in a reflector binnacle above the pilot house works better than a compass mounted inside a steel pilot house because:

1) It receives the full strength of the earth’s magnetic field because it is not surrounded with steel.

2) Its errors are conveniently found by direct compass bearings

3) correcting the compass is convenient because the binnacle is supplied with B and C magnets, heeling magnet, quadrantal spheres, and flinder’s bar.

Some designers of tugboats don’t seem to understand these SOLAS requirements.  I have seen several tugboats with a standard compass reflector binnacle but no way to read it from the helm, and a second compass mounted at the helm station, usually on top of a steel plate.   This does not meet the “stowed away from the bridge structure” requirement, and these inside compasses are difficult to adjust and not as reliable as the standard compass above.  This is an illogical and unseamanlike arrangement, and does not meet SOLAS.  Of the many seagoing ships I have been aboard, none of them have a compass inside the pilot house.  A standard compass binnacle above the pilot house is all that is needed.