Wheel-Over Point • Rate of Turn • Turning Radius • Course Alteration • Advance • Transfer • Head Reach • Manoeuvring Data • Multi-Turn Passage

Wheel-Over Point Tool Rate of Turn, Turning Radius & Course Alteration

Plan a course alteration using steady-turn geometry and ship-response allowance rather than treating the vessel as if it could turn instantly. Simple mode solves radius, tangent distance, practical wheel-over distance, turn time, advance and transfer from speed and target ROT. Advanced adds vessel-specific manoeuvring-booklet data, steering response, shallow-water allowance, turn-speed loss, current translation, ROT limits, available run-in, maximum turn-radius constraints and a multi-turn passage register.

Figures represent
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Need ship-specific trial data, shallow-water/current allowances or multiple turns? Click Advanced above.Advanced is a substantially deeper passage-planning model with manoeuvring-booklet inputs, response/head-reach modeling, route constraints and a multi-turn register.
Fast7 primary inputs
Core answerWheel-over distance before PI
ImportantGeometry + response kept separate

Single Turn Wheel-Over Solution

°T.
°T.
knots.
degrees per minute.
seconds from wheel/helm order to established turn effect.
NM added before the geometric tangent point.
NM along inbound track.

Vessel & Manoeuvring Model

Choose how the base turn radius is obtained. “Target ROT” uses steady circular-turn kinematics. “Specified radius” uses an entered radius. “Booklet” uses ship-specific 90° transfer and/or tactical diameter, with head reach inferred separately from trial advance.

m, for manoeuvrability reference ratios.
m.
m.
knots.
deg/min, used in ROT model.
NM, used in radius model.
deg/min, company/pilot/ship planning limit.
% of approach STW used for arc-time estimate.

Ship Response & Environmental Allowances

seconds.
seconds.
seconds.
NM, add only when supported by ship/pilot data.
% of deep-water/model radius. User-entered planning factor.
NM.
°T, direction current flows toward.
knots.
NM during response + turn.

Ship-Specific Turning-Circle / Booklet Data

Enter actual trial/booklet values if available. In Booklet mode, 90° transfer represents the effective circular radius; tactical diameter/2 can be used as a second radius estimate. Trial advance minus selected radius is used as an inferred response/head-reach distance where positive.

knots.
NM from rudder order.
NM.
NM.

Multi-Turn Passage Register

Each turn can override speed, ROT, safety buffer and route-space constraints. “Max radius available” represents a chart/pilotage planning limit from the route geometry. “Run-in available” is distance from the current approach position/reference to the planned PI.

Inbound °TOutbound °TDirectionSTW knROT overrideBuffer NMRun-in avail NMMax radius avail NMInside clearance NM

Passage Planning & Manoeuvring Checks

Navigation limitation: this is a passage-planning and geometry cross-check, not an automatic conning or safe-water decision system. A real ship does not instantly enter a perfect circle. Rudder/propulsion response, loading, trim, bank effect, squat, shallow water, wind, current, tug use, pilot orders and speed changes can materially alter the path. Vessel-specific manoeuvring data, pilotage requirements, ECDIS/charted safety margins and actual monitoring remain controlling.
Method basis: IMO radar-navigation training material gives wheel-over tangent distance approximately as R × tan(ΔC/2) and notes that a ship cannot alter course instantaneously, shallow water increases turning diameter and speed falls during a turn. This tool therefore keeps geometric tangent distance separate from ship-response/head-reach and safety allowances. IMO MSC.137(76) defines turning-circle advance and tactical diameter and, as a manoeuvrability reference, sets full-scale criteria of advance not exceeding 4.5L and tactical diameter not exceeding 5L for applicable ships under specified trial conditions.
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