kcrane
Well-Known Member
Good question. You should assume that from at least 6 miles, the bridge crew is watching you and making plans to avoid you. That said, the average range at which a manoeuvre is made, is closer to 2-3 miles - this accounts plotting your movements, planning a solution, trialling on ARPA, informing the captain if necessary, etc, etc. There are sometimes other anti-collision situations also at play - this could cause the ship to alter earlier, or later than the rough 2-3 mile average.
In answer to your question, you can probably take action as close as 4 miles without perturbing the big ship too much, as long as it is bold and plainly obvious (30° or more). This is not strictly in accordance with colregs, so if you made your move sooner, it would be better.
Ah ha, I'm feeling better about this thread now.
I'm trying to remember how far away we would be when we make our changes and about 5 miles seems likely, that would be about 10 minutes away at 30knts.
If we took care to make a call before the 6 mile mark (which happens to fit nicely to my radar marker rings) then everyone should be happy.
Having said that I'm using radar and AIS with a fairly modern plotter on a fast boat. The kit works it out for me.
Quite what I'd do in limited vis on a 5knt sailing boat, hard on the wind, in iffy sea conditions while feeling a bit seasick I hesitate to consider. But then that's probably why I switched to a mobo.