Constrained by Draught and Col Regs Rule 18

SimonFa

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Rule 18 (b) states:

(b) A sailing vessel underway shall keep out of the way of:

(i) a vessel not under command;
(ii) a vessel restricted in her ability to maneuver;
(iii) a vessel engaged in fishing​
.

I know that constrained by draught is covered under restricted ability to maneuver but it got me wondering why we have different symbols for constrained by draft and restricted ability to maneuver?

And couldn't the loose wording there confuse someone in to thinking they don't have to keep out of the way of a vessel constrained by draught?
 
Surely constrained by draught implies that provided the channel is wide enough the other rules apply. On the other hand a vessel unable to manoeuvre could be anywhere. Presumably a vessel can be both constrained by draft AND restricted in its ability to manoeuvre at the same time.
 
Vessels that are restricted in their ability to manoeuvre but are not constrained by draught might include:
Dredgers
Offshore construction vessels operating within a mooring pattern (often guarded in any case)
Offshore construction vessels operating under DP (dynamic positioning) systems
Survey vessels with towed array and /or vessel based active sonar

etc
 
The way I read the rules makes ( 3g ) The nature of her work the defining feature.
Yup, 100% correct, but widely not understood. Many folks incorrectly seem to think that a vessel is RAM if she is merely difficult to manoeuvre and restricted by her design in what manoeuvres she can do.
 
Yup, 100% correct, but widely not understood. Many folks incorrectly seem to think that a vessel is RAM if she is merely difficult to manoeuvre and restricted by her design in what manoeuvres she can do.

You are referring to old long keeld wooden boats I guess.
 
A Sailing Vessel shall keep out of the way of a FV, RAM and NUC. She shall also, where the circumstances of the case admit, avoid impeding the passage of a CBD.
There is a difference between 'Giving Way' and 'Not Impeding'.
A vessel may be directed to Give Way to - or keep out of the way of - another vessel when the two are meeting or crossing in sight of one another and there is a risk of collision - both conditions need apply. In this case one vessel is directed to give way and the other to stand on and it is generally the more manoeuvrable that gives way to the less. So we don't need to give way until there is a risk of collision.
Not impeding is more pro-active. A vessel directed not to impede must not allow a risk of collision to arise in the first place. Not impeding is generally required when the vessel to be avoided would otherwise be the Give Way vessel - a CBD is still a Power Driven Vessel and, if push comes to shove and she is involved in a close quarters situation with a SV then she must still give way - the do not impede requirement is designed to prevent this from happening by requiring the SV (or PDV or FV) to avoid coming into close quarters with the CBD

It is conceivable that a RAM may also be constrained by her draught, but the restriction in her ability to manoeuvre by nature of her work gives her a higher priority than CBD, so declaring herself as such would be superfluous. To be utterly pedantic a RAM is NOT a PDV, she is RAM, and only a PDV may be CBD.

So, per Rule 18, when there is a risk of collision, a SV must give way to FV, RAM and NUC. She shall also, where the circumstances of the case admit, not impede a CBD. But if the circumstances do not admit, if she unavoidably impedes the CBD, the the CBD as a PDV must keep out of the way of the SV.

We also find directions not to impede in Rules 9 and 10 and similar conditions apply.
It's worth remembering that once a vessel is directed not to impede she retains that responsibility even if a risk of collision arises and, in such a case, even though the other vessel must now give way, the vessel directed not to impede does not become a Stand On vessel; she must still do all she can to avoid the other whilst yet being mindful of the other's probable actions to avoid collision.

Incidentally SimonFa, there is no loose wording in the ColRegs, only loose understanding!
 
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