OPTIONS reference and defaults

This page lists every keyword the OPTIONS section accepts, with every alias. Each keyword is described with the same fields: value type and unit, default, valid values, the route that consumes it, and an example record. The runnable examples/cabledyn_options_reference.dat shows every syntax form, including commented mutually exclusive alternatives. Every maintained example repeats the common defaults that affect its route and links back to this page. A value labelled absent is not represented by a magic number: omission itself is meaningful.

Record syntax

• Scalar records use the OpenFAST order value keyword. Anything after the keyword is commentary, so 0.05 dtM - Time step (s) and 0.05 dtM time step are both valid.

• Positional records (current, waves) put the model name first and the keyword last: airy 2.0 8.0 0.0 waves. The dynamic_solver record puts its keyword first.

• Descriptions. In every OPTIONS record, the first - that has whitespace on both sides starts a description; it and everything after it are ignored. Negative numbers such as -1.0 are unaffected.

• Keywords are case-insensitive. An unknown keyword is fatal (unknown OPTION keyword "<name>"); CableDyn never silently ignores a misspelling.

• Repeated keywords. Records are applied in order, so the last record for a keyword wins (for example, a subsequent 0 motionFile row disables an earlier path).

• Numbers. Every numeric value must be one plain number with a . decimal point (1e-3, 0.05, -50). A value containing /, , or ;, or written as a repeat count such as 2*0, is rejected with the deck line number instead of being read partially; 1/20 dtM is an error, never dtM = 1. Integer-valued options (for example recovery_max_substeps, the quadrature orders, nModes, StreamOrder and WaveSeed) reject non-integral values.

• Logical values (for example modified_newton, adaptive_mesh, alpha_force_blend and cable_load_feedback) accept, case-insensitively, True/T/yes/y/on/1 and False/F/no/n/off/0. Any other spelling is an error.

• File paths are single whitespace-free tokens, optionally quoted, resolved relative to the deck’s directory. They may contain / or \ separators and may be longer than the 64-character identifier limit. A # or ! starts a comment even inside a path.

In the tables, Standalone means CableDyn_driver.exe; OpenFAST means a CompMooring = 5 (or Mod_SharedMooring = 5) coupled run in OpenFAST, maintained by NLR (National Laboratory of the Rockies, formerly NREL).

Environment and seabed

Keyword and aliases	Type, unit	Default	Valid values and rules	Route	Example
g / gravity	real, m/s²	9.80665	finite, > 0	both; OpenFAST host Gravity overrides the deck	9.80665 g
rhoW / WtrDnsty / water_density	real, kg/m³	1025	finite, > 0; also used by EQUIVALENT BUOYANCY conversion	both; OpenFAST host WtrDens overrides the deck	1025.0 rhoW
WtrDpth / water_depth	real, m	absent: no flat seabed	finite, > 0; flat seabed at z = -WtrDpth. Mutually exclusive with a bathymetryFile row. Required by waves	both; OpenFAST uses host WtrDpth unless the deck names a bathymetryFile	200.0 WtrDpth
bathymetryFile / bathymetry_file / seafloorFile / seafloor_file	path	absent	non-empty. The file holds x y depth rows (plain numbers, any order, comments allowed) forming one complete rectangular grid of at least 2 × 2 points with no duplicate x y pair; depths finite and > 0	standalone static EI = 0, independent-line EI = 0 dynamic, Connect/Free point-system, Hermite finite-EI dynamic, free/fixed rod, and Rigid6 decks (not Syrope lines); in OpenFAST the deck file overrides the host flat bed on supported routes (coupled Rigid6 decks require a flat WtrDpth)	site.bty bathymetryFile
kBot / kb	real, Pa/m (N/m³)	1.0e5	finite, > 0 when a seabed is present. Mapped to each line node and rod contact station by local diameter × tributary length; a Rigid6 reference point uses a fixed 1 m² area	both	1.0e5 kBot
cBot / cb	real, Pa·s/m (N·s/m³)	1.0e4	finite, ≥ 0 when a seabed is present; scaled like kBot and acts only on contacted nodes moving downward	both	1.0e4 cBot
frictionMu / mu / frictionCoefficient	real, –	0 (off)	finite, ≥ 0, or none. A positive value needs WtrDpth or bathymetryFile, and dtM/TMax in the standalone driver. Line nodes carry stick-slip friction springs; in a current the static solve holds the line with friction springs from its still-water laid shape, and the march continues them. The isotropic shorthand of frictionMuAxial/frictionMuLateral. Not supported (the deck is rejected) with a FAILURE section, on a deck with Connect/Free points or Point3 buoys, or on a deck whose lines attach to Rigid6 bodies or rods unless it runs on the default standalone monolithic multibody march: staggered bodyScheme, a motionFile, Coupled/Vessel rods and every coupled OpenFAST deck with bodies or rods reject it	both, within the limits in this row	0.5 frictionMu
frictionMuAxial / frictionMuLateral (aliases in the rules)	real, –	frictionMu	finite, ≥ 0. Anisotropic seabed friction of line nodes (the axial/normal pair of OrcaFlex, by Orcina): the coefficient along the line and across it. A row omitted takes frictionMu; both must then be positive, or both zero. An equal pair is the isotropic law bit-for-bit. Rods and bodies, which have no line axis, use the lateral coefficient; the finite-EI two-moving-end route rejects an unequal pair. The route limits of frictionMu apply. Aliases: frictionMu_axial, mu_axial, muaxial for the axial coefficient; frictionMu_lateral, mu_lateral, mulateral, frictionMuNormal, frictionMu_normal for the lateral one. See Theory	both, within the limits of frictionMu	0.2 frictionMuAxial

Clock and initial condition

Keyword and aliases	Type, unit	Default	Valid values and rules	Route	Example
bodyIC	text	static	static: free Rigid6 bodies and free rods, jointly with Free/Connect points, start at their static equilibrium (weight, buoyancy, hydrostatic restoring, steady-current drag, seabed contact, and the attached lines re-solved). A body with no reachable or restrained equilibrium stops with an error naming it. deck: they start at their deck pose, for example to release a body in a free-decay test. Coupled runs solve it with the host’s coupled points at their initial (PtfmInit) pose	both	deck bodyIC
bodyWetting	text	sphere	sphere: a Rigid6 body’s buoyancy, drag, fluid inertia, and added mass scale with the submerged fraction of an equivalent sphere at its centre of buoyancy (a dry body carries none). moordyn: fully wet at any elevation, as in MoorDyn. Bodies with C33/C44/C55 are always fully wet	both	moordyn bodyWetting
rodHydro	text	exact	exact: a surface-piercing rod carries the hydrostatic moment of its displaced volume (waterplane second moment \(\pi d^4/64\)). moordyn: adds MoorDyn’s \(\rho g (\pi d^4/32)\sin\varphi\cos\varphi\) while End A is below the surface and End B above, reproducing MoorDyn-C’s pitch stiffness	both	moordyn rodHydro
bodyHydro	text	morison	morison: Rigid6 bodies carry the fluid inertia \(\rho V (1 + C_a)\dot{u}\). moordyn: they do not, as in MoorDyn	both	moordyn bodyHydro
bodyScheme	text	monolithic	monolithic: free Rigid6 bodies, Point3 buoys, free and pinned rods and Free/Connect points step in one implicit generalised-alpha step with their EI = 0 lines (a Newton iteration on the object accelerations around the line steps); no sub-stepping is needed for stability. A deck without lines keeps its explicit central-difference march unless it names monolithic bodyScheme. staggered: the staggered predictor-corrector, sub-stepped for the stiffest body-mooring mode. Decks with a motionFile or a FAILURE section, and coupled runs, use staggered whatever the value. See Theory	standalone	staggered bodyScheme
bodySubstep	text	accuracy	accuracy: the monolithic step divides each coupling step so that the estimated stiffest body-mooring frequency satisfies \(\omega\,\Delta t \le 0.28\), the accuracy of the staggered scheme’s own sub-steps. none: it takes dtM as given (stable at any dtM; the body-mooring modes are then resolved only as far as dtM allows). Ignored by staggered bodyScheme, which always sub-steps	standalone	none bodySubstep
dtM / dt	real, s	absent (static-only)	finite, > 0. In the standalone driver dtM and TMax are given together or not at all	standalone step; OpenFAST targets 0.1 s when absent, rounds it to at least one whole glue DT, and reports the value used	0.05 dtM
TMax	real, s	absent (static-only)	finite, ≥ 0 and an integer multiple of dtM. TMax = 0 runs the dynamic initialisation and writes the t = 0 row	standalone only; OpenFAST uses the host TMax. Do not copy the host duration into a coupled deck	600.0 TMax
RangeStart / range_start	real, s	0	finite, ≥ 0 and ≤ TMax. First output time accumulated into the range graphs (<out_root>.Line<L>.range.out, LINES Outputs flag r), so a start-up transient is left out. Needs TMax and at least one line with the r flag	standalone only	100.0 RangeStart

Nonlinear solver

Static-solver tolerances are built in and are not deck options; keys such as staticRelTol are rejected as unknown. The dynamic Newton controls are set with dynamic_solver.

Keyword and aliases	Type, unit	Default	Valid values and rules	Route	Example
rhoInf / rho_inf	real, –	0.4	finite, in [0, 1]; generalised-alpha high-frequency spectral radius	both	0.4 rhoInf
maxStrain / max_strain	real, –	0.5	finite, ≥ 0; 0 disables the strain bound. Plausibility guard checked after every committed dynamic step of the EI = 0 lines: a non-finite nodal state, or any element stretched beyond this engineering strain (0.5 = 50 %, several times the breaking strain of steel, polyester, and nylon lines), stops the run with exit code 2 and a message naming the line, element, strain, estimated elastic tension, and time. It catches a numerically unstable march whose Newton residual still converges; a physical run never reaches the default. Finite-EI cables are guarded by tensile_safety instead	both (EI = 0 lines)	0.5 maxStrain
dynamic_solver rel abs max_iter backtracks [rhoInf]	keyword-first record: two reals, two integers, optional real	1e-8 1e-14 30 12	rel and abs finite and > 0; max_iter an integer ≥ 1; backtracks an integer ≥ 0; the optional sixth token sets rhoInf (same range). EI = 0 dynamic solves use all four controls. A standalone finite-EI (Hermite) deck uses only rel and max_iter for each step (abs and backtracks are ignored on this route) and converges its static equilibrium to at least min(1e-6, rel). Finite-EI cables in OpenFAST and in mixed EI = 0 + finite-EI standalone decks do not read rel, abs, max_iter or backtracks: they use a fixed step tolerance (relative 5e-3, 200 Newton iterations) and a 1e-6 static tolerance; only the optional rhoInf token applies to them. Use controls qualified for the mesh and load case; the maintained 952-element Gulf of Maine cable uses 1e-4 1e-14 100 12	both (see rules)	dynamic_solver 1e-8 1e-14 30 12
modified_newton / modifiednewton	logical	False	True enables guarded within-step tangent reuse on every dynamic solver the deck builds. It does not relax convergence tolerances and should be qualified against full Newton	both	False modified_newton
recovery_max_substeps / recoverymaxsubsteps	integer, –	1024	integer from 4 to 65536. Maximum internal subdivisions after a stalled tension-only step or a failed or under-resolved finite-bending interval. The nominal host time grid and output times are unchanged; prescribed position, velocity, and acceleration follow one C2 quintic trajectory inside the interval. The standalone completion summary reports the recovered intervals and the largest subdivision count used	both	1024 recovery_max_substeps

Finite-EI cable controls

Keyword and aliases	Type, unit	Default	Valid values and rules	Route	Example
adaptive_mesh / adaptivemesh	logical	False	Permits finite-EI refinement when the static curvature diagnosis or mesh-scale contact chatter is fragile. Multiple adequately sampled grounded runs are allowed and are not treated as chatter merely because the contact topology has several islands. False keeps the declared NumSegs authoritative but does not disable the folded-element safety check, nor the automatic refinement of a deck mesh that cannot resolve the curvature of the equilibrium (reported). When True, reaching the refinement cap while the mesh remains fragile is reported	both (finite-EI lines)	True adaptive_mesh
alpha_force_blend / alphaforceblend	logical	True	Generalised-α blend of the finite-EI dynamics. True blends the forces of the two step ends; False evaluates the forces at the blended configuration \(q_{\alpha_f}\) (Chung and Hulbert), whose blended tangent vectors are shortened while the line rotates and raise the mean tension at large dtM: on the Lozon Gulf of Mexico 80 m cable in 3 m surge the mean hang-off tension is 12511 / 10097 / 9507 / 9360 N at dtM 0.1 / 0.05 / 0.025 / 0.0125 s with False and 9424 / 9322 / 9314 / 9311 N with True. A run prints a note when a nodal tangent turns by more than 0.25 deg (True) or 0.1 deg (False) in one step. A dynamic run with a torsional line (END CONNECTIONS TorsStiffness at both ends) needs True	standalone and coupled (finite-EI lines)	False alpha_force_blend
cable_statics / cablestatics	mode	continuation	continuation solves a finite-EI cable from its exact EI = 0 catenary by continuation in EI and falls back to the mesh-sequenced route; sequenced runs the mesh-sequenced route (coarse section-preserving hierarchy, EI and buoyancy continuation, prolongation) first and the continuation route as its fallback. Both results are audited; on the Lozon cables the two routes agree to the solver tolerance (see Theory)	both (finite-EI lines)	sequenced cable_statics
axial_quadrature_order / axialquadratureorder / axial_quadrature	integer, –	4	integer from 1 to 6; Gauss order for the finite-EI axial energy. A value different from the bending order gives selective integration	both (finite-EI lines)	4 axial_quadrature_order
bending_quadrature_order / bendingquadratureorder / bending_quadrature	integer, –	4	integer from 1 to 6; Gauss order for the finite-EI curvature energy	both (finite-EI lines)	4 bending_quadrature_order
tensile_safety / tensilesafety	mode	False	True/T/yes/y/on/1/error reject axial compression outside the tolerance, judged on the element-mean axial force averaged over three elements (see Theory); warn/warning/monitor commit the state, count accepted integration-step events, and report the worst force, threshold, element and time after a standalone run (the printed xi is always 0.5, the centre of the three-element window, because the audit judges element means); False/F/no/n/off/0 disable the audit (case-insensitive). A response diagnostic, not a tension-only constitutive law	both (finite-EI lines)	warn tensile_safety
tensile_strain_tolerance / tensilestraintolerance	real, –	2e-6	finite, ≥ 0; strain band used by the tensile audit. Changes require an engineering basis and should be recorded with the run settings	both (finite-EI lines)	2e-6 tensile_strain_tolerance
cable_load_feedback / cableloadfeedback	logical	True	False keeps the cable march, prescribed platform kinematics, host SeaState fields, and response channels active, but returns zero cable force and moment to the host: a controlled one-way comparison, not a physical operating configuration	OpenFAST (coupled finite-EI cables)	True cable_load_feedback

Ambient fluid and prescribed motion

Keyword and aliases	Type, unit	Default	Valid values and rules	Route	Example
current	positional record, m and m/s	none	none current; uniform vx vy vz current; or the two-level profile z1 vx1 vy1 vz1 z2 vx2 vy2 vz2 current. Values finite; the two profile levels may be given in either order, are sorted by z, and must differ. The static initial condition includes the steady drag of the current on the line at rest. Requires dtM/TMax in the standalone driver; a coupled deck takes its clock from the host. Use a WaterKin CurrentMod 1 table for more levels; a deck with both is rejected	standalone; in OpenFAST, a single-turbine pure EI = 0 deck without Rigid6 bodies or rods keeps it as a steady current when SeaState carries no waves or current. It is rejected when SeaState carries waves or current (double counting), in FAST.Farm, and on a deck with finite-EI cables, Rigid6 bodies or rods. On a pure EI = 0 deck, a WaterKin CurrentMod 1 table is the deck-side current that combines with a SeaState field	uniform 0.5 0 0 current
waves / wave	positional record, m, s, deg	none	none waves; airy H T direction waves; stream H T direction waves (alias dean: the regular nonlinear stream-function wave, see StreamOrder); jonswap Hs Tp gamma direction waves; pm Hs Tp direction waves (aliases issc, bretschneider); torsethaugen Hs Tp direction waves; or ochihubble Hs1 Tp1 lambda1 Hs2 Tp2 lambda2 direction waves (see Theory). Height and period finite and > 0; gamma finite and ≥ 1; direction finite, in degrees. WaveSpreading spreads a spectral row. Requires dtM/TMax and WtrDpth (a bathymetryFile does not satisfy it). Not combinable with WaterKin WaveKinMod 1. A jonswap sea is synthesised from 200 long-crested components over [0.2, 5] times the peak frequency: one component per equal-width frequency bin, placed at a random frequency inside its bin with a random phase (see WaveSeed), and scaled so the discrete spectrum gives exactly Hs. The frequencies are not equally spaced, so the record does not repeat	standalone only; always rejected in a coupled OpenFAST or FAST.Farm deck, because the host SeaState supplies the waves	airy 2.0 8.0 0.0 waves
StreamOrder / stream_order	integer, –	0 (20 terms)	0 or an integer from 2 to 60: the number of Fourier terms of a stream wave. A wave higher than 0.8 d or steeper than H/L = 0.142 is rejected, and a solution that does not converge fails with a named error	standalone stream waves	30 StreamOrder
nModes / n_modes / modes	integer, –	0 (off)	integer from 0 to 1000. Modal analysis of every line about its static equilibrium: the nModes lowest natural frequencies and mode shapes of K φ = ω² M φ (static tangent stiffness, structural plus added mass, ends held), written to <root>.modes.out before any dynamic march. Decks of lines between Fixed and Coupled/Vessel points on a flat WtrDpth seabed: all EI = 0 lines (static or dynamic deck), or all finite-EI lines on the cubic-Hermite route (dynamic deck, every End B Fixed). Other decks are rejected; a deck that mixes EI = 0 and finite-EI lines stops with OPTION nModes is not supported for mixed EI=0/finite-EI decks; remove it or set it to 0; a deck with a torsional line stops with modal analysis (OPTION nModes) of a line with torsion is not yet supported. The banded solver has no line-length limit: a 1024-element finite-EI cable takes a few seconds. See Theory	standalone	10 nModes
WaveSeed / wave_seed	integer, –	1	integer from 1 to 2147483646. Seed of the jonswap component frequencies and phases: the same seed always gives the same sea on every platform, and a different seed gives an independent realisation. The stream is the Park–Miller MINSTD generator (multiplier 48271, modulus 231 − 1) started from the seed scrambled by three rounds of a 31-bit xorshift and one MINSTD step; each component draws its frequency offset, then its phase. Run several seeds for extreme-value statistics	standalone spectral waves and wave trains (train i uses seed + 7919 (i − 1))	7 WaveSeed
wavetrain / wave_train	positional record, m, s, deg, –	none	one wave train of a multi-train sea; the rows add up (at most 16): airy H T direction wavetrain, jonswap Hs Tp gamma direction s wavetrain, pm Hs Tp direction s wavetrain, torsethaugen Hs Tp direction s wavetrain, ochihubble Hs1 Tp1 lambda1 Hs2 Tp2 lambda2 direction s wavetrain. s is the cos-2s spreading exponent in [0, 1000]; 0 gives a long-crested train. Each train has its own heading. Not combinable with a waves row or WaveSpreading. Same requirements as waves	standalone; in OpenFAST rejected like waves	jonswap 4 9 3.3 0 4 wavetrain
WaveSpreading / wave_spreading	real, –	0	cos-2s exponent in [0, 1000] of the spectral waves row: the energy is spread over direction ± 90° with D(θ) = K(s) cos^2s(θ − direction). 0 keeps the sea long-crested. Rejected with a regular (airy) wave, without waves, or with wavetrain rows	standalone spectral waves	4 WaveSpreading
WaveDirections / wave_directions	integer, –	9	integer ≥ 1; equal-angle direction bins of a spread train (each with its own frequency set). Long-crested trains use one direction	standalone spread seas	15 WaveDirections
WaveComponents / wave_components	integer, –	200	integer ≥ 2; frequency components per train and direction. A jonswap waves row with the default 200 and no spreading keeps the original JONSWAP synthesis; any other value moves it to the spectral-sea synthesis. At most 100000 components in all	standalone spectral waves	400 WaveComponents
rampTime / ramp_time / tRamp	real, s	0	finite, ≥ 0; 0 disables the ramp. Scales every wave amplitude by the half-cosine r(t) = (1 − cos(πt/rampTime))/2 from still water at t = 0 to full height at t = rampTime; the fluid acceleration includes the ramp rate, so the ramped field is kinematically consistent. The current is not ramped: the static initial condition already carries it, so ramping it would start the line out of equilibrium. Recommended for wave runs, which otherwise switch the full sea on at t = 0 against a still-water static shape; one to two peak periods is typical	standalone waves, wavetrain, and WaterKin WaveKinMod 1 waves	20.0 rampTime
motionFile	path, or 0/none	absent	an active path requires dtM and TMax; 0 or case-insensitive none disables it. On a deck with a line restrained in torsion at both ends, an optional twelfth column rolls that line’s End A frame (degrees, 0 at t = 0). See the file grammar in Auxiliary input files	standalone Coupled/Vessel points, prescribed rods, and Rigid6 bodies; rejected on Connect/Free point-system, FAILURE, and mixed decks; forbidden in OpenFAST, where the host owns coupled motion	motion.dat motionFile
vesselMotion	path, or 0/none	absent	a 6-DOF vessel record (19 values per row with roll/pitch/yaw, or 20 with a unit quaternion) on the dtM grid; every Coupled/Vessel point moves rigidly with the vessel from its deck position, and a finite or Rigid END CONNECTION at such a point turns with the vessel. An alternative to motionFile and vesselRAO (only one may be active); requires dtM and TMax. Grammar in Deck format reference (.dat)	standalone line decks accepted with a motionFile; rejected on rod, Rigid6 and TURBINES decks and in OpenFAST	vessel.dat vesselMotion
vesselRAO	path, or 0/none	absent	a displacement RAO table (amplitude and phase lag per DOF, per period and relative heading). The vessel motion is the RAO response to the deck linear waves (airy, spectral rows with WaveSpreading, wavetrain rows, or a WaterKin WaveKinMod 1 file), each component at its own heading and phase, with rampTime; a stream wave is rejected. Otherwise as vesselMotion	as vesselMotion, with deck waves	rao.dat vesselRAO
vesselRef	x|y|z, m	0|0|0	three finite values: the vessel reference point at its reference pose, which is the rotation centre of vesselMotion/vesselRAO and the RAO origin (the point at which the wave phase is referenced)	vesselMotion, vesselRAO	90.0|0.0|-14.0 vesselRef
WaterKin / WaveKin	0/none, 3, 7, path, or SEASTATE	0 (no WaterKin policy)	0 or none means still water from this record; 3 and 7 are the MoorDyn-C modes that read wave_elevation.txt and wave_frequencies.txt in the deck folder; a value containing a letter (other than an exponent e) is a MoorDyn-F WaterKin filename; SEASTATE selects the host field. The other MoorDyn-C modes fail closed by name. Mode rules are in MoorDyn-C WaveKin and Currents modes and MoorDyn-F WaterKin file modes	3/7 and file WaveKinMod 1: standalone decks only; SEASTATE, WaveKinMod 2, and CurrentMod 2: OpenFAST only	waterkin.dat WaterKin
dtWave	positive number [s]	0.25	the step at which WaveKin 3 resamples wave_elevation.txt (MoorDyn-C)	standalone	0.1 dtWave
Currents	0 or 1	0	1 reads the MoorDyn-C steady profile current_profile.txt in the deck folder; the other MoorDyn-C modes fail closed by name. current and a WaterKin table are the other sources; two sources in one deck are rejected	standalone	1 Currents

MoorDyn compatibility-only keywords

These names exist so a migrated MoorDyn deck fails less often at the syntax boundary. They do not tune CableDyn physics and should not be added to a new CableDyn model.

Keyword	Value	CableDyn behaviour
tScheme	any token	Accepted and ignored; CableDyn always uses implicit generalised-alpha.
dtIC, TmaxIC, CdScaleIC, threshIC	plain number	Parsed strictly and ignored; CableDyn uses a Newton static initial condition rather than MoorDyn dynamic relaxation.
WriteLog	plain number	Parsed strictly and ignored; reporting uses the normal CableDyn/OpenFAST diagnostics.
dtOut	plain number	Parsed strictly and ignored. Standalone output follows dtM; coupled .CD.out follows committed CableDyn solves; OpenFAST’s main table follows host DT_Out.
mu_kT, mu_kA	any	Rejected by name: the MoorDyn-F seabed friction coefficients map to frictionMu with frictionMuLateral (for mu_kT) and frictionMuAxial (for mu_kA).
mc, cv, FricDamp, StatDynFricScale	any	Rejected by name: CableDyn applies one regularised Coulomb friction set by frictionMu, frictionMuLateral and frictionMuAxial, with no static-to-kinetic ratio or friction damping. Remove the row.

Other MoorDyn constructs that fail by name rather than as unknown input: CoupledPinned and VesselPinned rods, and CoupledPinned bodies. Line-node output channels start at node 1 (N0 is rejected), and a number with a sign inside its mantissa (such as 1+2) is rejected instead of being read up to the sign.

Water-kinematics sources

A WaterKin file keeps its independent WaveKinMod and CurrentMod selectors. Host modes require the OpenFAST aggregate and a compatible SeaState field; the standalone driver rejects them with WaterKin WaveKinMod 2/SEASTATE is coupled-only. The detailed supported matrix is in MoorDyn-F WaterKin file modes in Deck format reference (.dat).

With no WaterKin policy, OpenFAST uses its complete SeaState field when one exists. Explicit file selectors are authoritative: for example, file WaveKinMod=0 and CurrentMod=1 means no host waves and only the file current profile. A coupled deck cannot carry inline waves or wavetrain rows: the host SeaState supplies the waves, so such a deck is rejected at initialisation. An inline current row is kept as a steady current only on a single-turbine, pure EI = 0 deck without Rigid6 bodies or rods whose SeaState carries no waves or current; it is rejected when SeaState carries waves or current, in FAST.Farm, and on a deck with finite-EI cables, Rigid6 bodies or rods.

Standalone versus OpenFAST checklist

For a standalone static calculation, omit both dtM and TMax or set a deliberate pair with TMax=0 when exercising the dynamic initialisation route. For standalone dynamics, provide both and ensure TMax/dtM is integral. current, waves, motionFile, a positive frictionMu, rods, bodies, Connect/Free points, and finite-EI sections (outside a mixed deck) all need the dtM/TMax pair. File paths are resolved relative to the deck and may use ordinary nested paths longer than the 64-character deck-identifier limit.

For CompMooring = 5, OpenFAST owns gravity, density, flat depth, platform motion, run duration, and its output clock. The CableDyn deck owns line properties, mesh, contact coefficients, rhoInf, Newton policy, optional dtM, and CableDyn output channels. The console prints the actual dtM and its integer ratio to glue DT; archive that line with production results.