Offshore (SSS/SHS)

Offshore certificate (SSS): entry & examination

The certificate for coastal waters out to 30 nm — with a substantial mileage hurdle before the theory.

You need the SBF See plus 1,000 nautical miles on yachts in coastal waters, at least 500 nm of them as watch leader or equivalent. Holders of the SKS (or the older DSV BR certificate issued before October 1999) need only 700 nm in the corresponding type of propulsion. Minimum age 16.

Theory

Four written subjects: maritime law including radar plotting (60 min), seamanship (60 min), navigation without astronavigation but including tidal calculations and electronic navigation (120 min), meteorology (45 min).

In practice

The practical examination takes place on a seagoing yacht and is considerably more demanding than the SKS — boat handling, radar, seamanship, crew management and yacht systems.

See alsoRadar plotting (the principle) · Tidal calculations with the Admiralty Tide Tables · Ocean certificate (SHS): entry & examination

Ocean certificate (SHS): entry & examination

The top tier — worldwide voyaging, with astronavigation at its core.

The SHS builds on the SSS and is intended for voyages in any sea area worldwide. The theory consists of four separate examinations — three written, one oral — which may be taken in any order within 24 months.

Subjects

Navigation (focused on astronavigation including the sextant), maritime law (including international law of the sea and customs matters) and meteorology (extended to the global wind system and tropical revolving storms).

See alsoAstronavigation: the principle of the position line · Conduct in areas prone to revolving storms · Offshore certificate (SSS): entry & examination

Radar plotting (the principle)

Deriving a target's true course and closest approach from its relative motion.

At first the radar shows only a target's motion relative to your own ship. By plotting several bearings and ranges over time, the relative motion line can be established — and from it, taking your own course and speed into account, the true course and true speed of the other vessel.

CPA & TCPA

The plot yields the Closest Point of Approach (CPA) and the Time to CPA (TCPA) — the key figures for judging a risk of collision and the right avoiding action.

See alsoOffshore certificate (SSS): entry & examination · Responsibilities between vessels (Rule 18)

Tidal calculations with the Admiralty Tide Tables

The Admiralty Tide Tables (ATT) — standard ports read off directly, secondary ports via time and height differences.

The Admiralty Tide Tables (ATT) are the international standard work for tidal calculation. For standard ports the times and heights of high and low water are tabulated directly. For the many secondary ports, time and height differences from the relevant standard port are given and interpolated from there.

Why it matters

Depth under the keel and clearance under bridges depend directly on the current state of tide — in tidal waters a safety calculation, not merely examination material.

See alsoOffshore certificate (SSS): entry & examination

Astronavigation: the principle of the position line

Constructing a position line from the measured altitude of a heavenly body above the horizon.

With the sextant you measure the altitude of a heavenly body (sun, star, planet, moon) above the visible horizon and note the exact time. From the almanac and sight reduction tables the altitude theoretically expected for an assumed position can then be calculated.

Position line

The difference between the observed and the calculated altitude gives an intercept perpendicular to the direction of the body — the position line. Two or more position lines, taken at different times or from different bodies, intersect at the actual position.

In the SHS examination

Handling the sextant and the full calculation (meridian altitude, azimuth, sight reduction) are extensive subjects in their own right — this is only the basic principle as a starting point.

See alsoOcean certificate (SHS): entry & examination

Conduct in areas prone to revolving storms

Semicircle rules: keeping out of the dangerous semicircle of a tropical revolving storm.

Tropical revolving storms (hurricane, typhoon or cyclone depending on the sea area) rotate anticlockwise in the northern hemisphere and clockwise in the southern, and generally travel with the large-scale wind system of the zone, such as the trade winds.

The dangerous semicircle

If you are on the side where the storm's speed of travel adds to the wind speed (in the northern hemisphere usually to the right of its track), you are in the dangerous semicircle. The correct avoiding manoeuvre depends on your own position relative to the track — a core topic of the extended meteorology in the SHS.

See alsoOcean certificate (SHS): entry & examination

International law of the sea & clearing in

On a long voyage more than the COLREGs applies — flag state law, territorial waters, customs.

Beyond the collision regulations (COLREG), the law of the countries you visit becomes relevant on a long voyage: territorial waters and the contiguous zone (12 and 24 nm respectively), the right of innocent passage, and the duty to clear in (customs, border police, harbour authority) on arrival in a new country.

The vessel flies the flag of her state of registration — which determines the law that applies on board in principle. For the examination what counts is a basic grasp of these relationships, not detailed knowledge of individual countries.

See alsoOcean certificate (SHS): entry & examination · Offshore certificate (SSS): entry & examination