Settle a shipboard debate

Got into a debate with a mate on the ship I’m on, and I wanted y’all’s take:

The topic was a two for one. Are DP vessels considered RAM while they are actively working inside the 500M zone around platforms? And if a vessel was on DP while in restricted visibility, which sound signal would they use one for a vessel at anchor, underway making way, or underway not making way?

I said that they would be considered RAM because due to the nature of work being alongside a platform they are restricted in their ability to maneuver to avoid collision. My opinion for the second question was that we should sound a signal for a vessel at anchor to let other vessels know that we are stationary and not moving.

Any and all thoughts are welcome!

I would say RAM, but sound signals for underway and not making way, since that’s what they are. You are not anchored unless physically connected to the bottom.

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Aren’t they technically making way to stay in position? Definitely RAM, but if they’re on station holding position they’re still technically making way right?

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Yea I guess you’re correct. If they were not making way, they’d be drifting off with the wind/current.

Damn 3rd Mate doesn’t know the rules

Psh that’s been made clear in other threads…

It depends.

From Farwell’s:

“A vessel not under command is one which through some exceptional circumstance is unable to maneuver as required by the rules”


“It is important that ships which are genuinely disabled from manoeuvring adequately should have both the right and the duty to advertise that fact by exhibiting appropriate signals and so to make it clear to other ships that they must take steps to keep clear of them.”

“It is equally important that ships which are not genuinely disabled, though they may be under certain difficulties, should not claim this special right and privilege . . . without proper justification.”

Is a ship sitting in DP 20 meters from the quayside considered RAM? No.

Neither is a ship sitting in DP 20 meters from a platform.

If the ship had a hose (bulk, water or fuel etc) connecting it to the platform then it would be RAM.


But the question was about RAM, not NUC.


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All very good information though!

More interesting would be a vessel NOT next to a platform or other fixed or floating structure.

Dive support vessels with divers in the water, vessels operating ROVs, or performing work on subsea structure etc. are defiantly MAR.
If just standing by on DP they are both able to maneuver and to get out of the way in an emergency.

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Who are you going to collide with that would claim to be the stand on vessel within 500m of a platform?

Another vessel with permission to be within the 500m zone?

There is no way just being in DP makes a vessel RAM, there might be other factors to make it RAM, but just being near an installation in DP doesn’t necessarily make it RAM either.

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Farwell’s treats RAM and NUC in the same section.

In general the principle is the question as to if the vessel is excused from it’s duties as a give-way vessel.

Depends on what it is doing there. If it is actively engaged in it’s purpose of work, then I would say yes, it is.

I worked on a DP research ship when I started sailing. We would be on DP all over the place in the middle of nowhere or very close to something with bottom core tubes or various other instruments deployed over the side. At that point we were certainly RAM - I could not maneuver with 3000m (or 30m) of cable out.

If the crew boat is just sitting around for hours next to a rig and doing nothing but waiting, then technically it is not RAM. As soon as they start performing lifts or crew change or attaching a hose or anything like that, they become RAM.

Now realistically speaking, everyone within 500m of a rig is on DP, they all know what the other is doing, and they are in constant communication with each other, so the Rules are circumvented (sort of).

But if the conditions are such that you need to sound fog signals, is the rig going to call the boat in? Or just have them wait until conditions improve? Depends on what the needs are I suppose.

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Agree. If the vessel is sitting alongside a rig or platform doing crane work she can move away in an emergency.
Unless the vessel has some physical connection, like hoses etc. she is not RAM.

PS> If she move away the other ship will probably hit the rig/platform.

In actual practice in this situation it would be expected that vessel free to maneuver would stay clear of the one working near the rig. So that means Rule 2 rather than the steering and sailing rules.

Farwell’s supports this, in cases where ships stopped have been hit courts have found in favor of the stopped ship.

The obligation on the part of free vessels to avoid risk of collision with those incumbered or at rest , is imperative…

A pattern is emerging: Does DP restrict your ability to maneuver? No? Then I guess not.

I’m no kind of lawyer, but you’re clearly describing a barge. Also, while we’re off topic: I thought every red blooded American had an old dragline rusting quietly into the ground on some disused corner of the property. What’s wrong with yours? Didn’t the HOA like it?

In many ways DP can enhance your ability to maneuver not restrict it.