Manoeuvring and Warning Signals [Rule 34]

[Polaris]

So, I'm wondering if someone can help me out here.

Rule 34 parts A, B, C & D states that manoeuvring and warning signals are only used "When vessels are in sight of one another."

"e) A vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction."

Rule 35 Sound Signals in restricted visibility
a) A power-driven vessel making way through the water shall sound at intervals of not more than 2 minutes on prolonged blast.

So both rules state using one prolonged blast where the situation is aboard a vessel when nearing a bend in a channel in fog. Reading this I can see where there could be confusion on the bridge where an undetected ship on radar, using their making way fog signal per 35a being mistaken for an answered signal in reply to another ships sounds signal as per 34e.

I have experience in res viz, I know the practical implications of using fog signals but am I reading this incorrectly or can anyone share their opinion?

[CharlieDelta]

I may be wrong, but the purpose of both is to indicate the presence of another vessel. The answering signal does not indicate any form of consent, it's simply a "hey, yeah, there IS someone around the corner". Think of it like this - the prolonged blast is like "Marco" and the returned prolonged blast is like "Polo" (http://en.wikipedia.org/wiki/Marco_Polo_(game)). In good visibility you use it when you need to. In RV, you're already Marco-ing and Polo-ing at least every two minutes anyway.

If you don't have them on radar, you follow 19(e) and reduce your speed to minimum steerage. You'd be proceeding at a safe speed anyway given the limitations of your radar (can't see around corners).

[alistairuk]

As CD says all your doing in both cases is indicating your prescence to another vessel.