
ID	0103
Class	KNOWN-LIMITATION
Severity	1
Status	blocked

Models: none on main; the 2.x model TrawlDoorCtrlLiftMass on branch origin/environment_from_marenv

Found: 2026-10-06, feature trawlwriter (owner ruling: not ported, file an issue)

Decision needed: Owner: is the door with controlled mass wanted on the 3.x line, and is the 2025 work (commit 194506e, "Work on trawl door with mass proportional to lift") finished?

Evidence

git show origin/environment_from_marenv:src/trawl/TrawlDoorCtrlLiftMass.cpp: registered as Trawl/TrawlDoorControlledLiftAndMass, while its header documents Trawl/TrawlDoorControlledLiftMass.
The mass is a state that follows the input MassGoal (XDot = -(mass - MassGoal), bounded by MassMin/MassMax); the weight in water is 9.81 * mass * 0.87, assuming a steel door.
The rest is Trawl/TrawlDoorControlledLift (src/trawl/TrawlDoorControlledLift.cpp), ported to main in feature trawlwriter, with its width-mode sign fix.

Effect

No 3.x door whose mass, rather than its weight, is controlled. FhSim_trawlwriter does not use it.

Possible fix

Port it on top of TrawlDoorControlledLift (a MassGoal input and a mass state in place of the weight controller), registered under one name.

Test that would prove it

A scenario where MassGoal steps: the mass follows with time constant 1 s and the weight is 9.81 * 0.87 * mass.

Risk

None for existing inputs; it adds a model.