Taxiing and Sailing (ASES, AMES)

The three positions are idling (displacement), plowing, and planing (step) (FAA-H-8083-23, ch. 4):

• Idling (displacement): the buoyancy of the floats supports the entire weight; attitude is similar to at-rest on the water
• Plowing: power application shifts the center of buoyancy aft; the sterns dig in, drag is high, and it is normally just the transition between idle and planing — taxiing in it is not recommended
• Planing (step): most of the weight is supported by hydrodynamic lift rather than buoyancy; the rear portions of the floats ride clear of the water, drastically reducing water drag

A seaplane is virtually always in motion and has no brakes — wind, current, thrust, and inertia keep acting on it from the moment it's untied — so the pilot must know the wind and water conditions, plan the course of action, and stay mentally ahead of the airplane.

• Elevator all the way back to keep the nose high — it minimizes spray damage to the propeller and improves maneuverability by keeping more of the water rudder underwater. The exception: with a strong tailwind component or heavy swells, hold the elevator forward enough to keep the tail down so the wind can't lift it and flip the airplane
• RPM as low as possible — for speed control, engine cooling, and spray
• Keep speeds below 6–7 knots to limit spray to the propeller; in congested or confined areas, low speed also limits the coasting that inertia produces, because even minor collisions cause serious damage
• Cross boat wakes or swells at a 45° angle where possible, to minimize pitching, rolling, and the chance of an upset (FAA-H-8083-23 ch. 4)

Step taxi covers long distances on the water at high speed but well below flying speed — reduce power carefully as the seaplane comes onto the step to stop the acceleration; 65 to 70 percent of maximum power is a good starting point, more when heavy. The rules (FAA-H-8083-23 ch. 4):

• Only where you're confident of sufficient water depth, no floating debris, no hidden obstructions, and no other water traffic nearby — a floating log can tear open a float, and never step taxi in shallow water: floats touching bottom at speed will likely flip the airplane
• Water rudders retracted — at speed the dynamic pressure pounds them and they're ineffective anyway; steer with the air rudder and ailerons, holding a precise planing attitude with elevator
• If a wake crossing is coming, reduce to idle and idle-taxi across it at an angle
• Turns from downwind to upwind at step speed are proportionately more dangerous — centrifugal force and wind gang up on the outside float; if it starts to submerge, immediate full rudder out of the turn and power reduction may save it

Plowing is the high-drag transitional phase — nose high, sterns deep, lots of power for little speed. Prolonged plowing risks engine overheating (high power, low cooling airflow) and spray damage to the propeller despite the nose-high attitude.

Plow turn: exploits the plowing attitude to neutralize weathervaning when turning downwind in strong wind — the exposed forward float area plus the aft-shifted center of buoyancy lets the airplane turn away from the wind, tracing a question-mark path.

Why a last resort: it's only effective in certain seaplanes, and floatplanes are least stable in the plowing attitude and very susceptible to capsizing — never attempt it in rough water or gusty conditions. In most windy situations it is much safer to sail the seaplane backward instead (FAA-H-8083-23 ch. 4).

Sailing is guiding the seaplane on the water using the wind as the main motive force — usually moving backward, since the seaplane weathervanes nose-into-wind. Use it when wind, water conditions, or limited space make a conventional taxi turn impractical or unsafe — maneuvering into docks and confined spaces, and as the safer alternative to a plow turn. The mechanics (FAA-H-8083-23 ch. 4):

• Swing the tail with the air rudder: keel effect pushes the seaplane in the direction the sterns point — so water rudders up, since their action is counter to what you want
• With power balancing the wind so there's no motion through the water, keel effect disappears and the wind pushes the seaplane toward the side the nose is pointed — combining the two techniques sails you diagonally
• With the engine off, lowering flaps and opening doors adds air resistance and sailing speed downwind
• In strong wind, use full forward elevator to keep the float sterns from submerging — combined with wind lift on the wings, a buried stern can conceivably flip the airplane over backward

Wind, current, and space — evaluated before entering a confined area, because afterward the forces are driving you into the obstructions.

• Current: the handbook's benchmark for how much it matters — for an average seaplane at idle, a 5-knot current can offset a wind of 25 knots blowing the opposite direction; the current wins far more than intuition suggests
• Keel effect: only works when the floats move through the water; if the current carries the seaplane, there may be little relative motion and the rudders go quiet even though you're moving over the bottom
• Planning: plan the course using wind, current, and thrust together; remember each type sails differently (flying boats sail backward and toward the side the nose points regardless of wind velocity), and in multiengine seaplanes use differential power to aid steering (FAA-H-8083-23 ch. 4)

A rhythmic pitching motion caused by dynamic instability in the forces along the float bottoms while on the step — an incorrect planing attitude (nose too low or too high, roughly a degree or two beyond the acceptable range) sets off a cyclic oscillation that steadily increases in amplitude unless the proper pitch attitude is reestablished. Uncorrected, it noses the airplane into the water.

Correction: timely back pressure to keep the float bows from digging in, held until the porpoising stops. If it hasn't stopped by the second oscillation, reduce power to idle and hold the elevator firmly back so the seaplane settles on with no further instability — and never chase the oscillations, which amplifies them.

Weight, flap position, and CG all shift the acceptable attitude band; a forward CG increases the tendency (FAA-H-8083-23 ch. 4).

Skipping is a cyclic oscillation entered at the upper trim limit — excessive speed with the nose too high — and it can also be triggered by crossing a boat wake while on the step.

Body-feel distinction: a skip delivers vertical G forces, like bouncing a landplane; porpoising feels like a rocking-chair forward-and-aft motion. Skipping's amplitude doesn't grow the way porpoising does, but the pounding hammers the floats and airframe and can lead to porpoising.

Correction: increase back pressure and add enough power to keep the floats off the water, establish the proper pitch attitude, then reduce power gradually to settle on gently (FAA-H-8083-23 ch. 4).

The land-side lighting and taxi discipline from Task II.C carries over; the water adds an environment that is mostly unlit:

• A lighted seaplane landing area is identified by a rotating beacon alternating white and yellow — a double white flash alternating with yellow marks a military seaplane base (FAA-H-8083-23 ch. 1)
• Usually only the more important buoys are lighted; some unlighted buoys carry red, white, or green reflectors with the same significance as lights. Red buoys carry red or white lights, green/black buoys green or white lights, and a light flashing Morse code "A" marks a mid-channel buoy (ch. 1)
• Anchored craft — including an anchored seaplane — show an anchor light where maritime regulations require it (ch. 6)
• The handbook's night-water caution names the hazard: the difficulty of seeing objects in the water and judging surface conditions (ch. 6) — so at night or in low visibility, slow down, work from lighted and known references, and treat unlighted water as uninspected

Backwards from every landplane instinct: on water, wheels up. A wheels-down landing on water is almost certain to capsize the seaplane — far more serious than a wheels-up landing on pavement. The handbook's technique: make it verbal and visual — many experienced pilots say out loud, "This is a water landing, so the wheels should be up," then confirm each wheel using externally mounted mirrors and other visual indicators, not just the gear position indicators (FAA-H-8083-23 ch. 6). For this task the same check belongs to taxi phases: confirm gear position any time you transition between ramp, land, and water operations, and brief it as a crew callout where a crew exists.