Is it safe to cross astern of a fast ship in open water with a 180 feet CPA

[evm1024]

Originally Posted by Cheechako

I'm not really sure what this question is really about. I have passed close astern of large freighters many times on Puget Sound. They probably weren't doing quite 20 knots in the Sound but it's a non issue. The only large wave produced by these boats seems to be at the bow and dissipates very quickly.

Ignore COLREGS for a moment.

Let's say you there is a 600' long ship inbound in the Straights of Juan de Fuca (in the VTS but we are ignoring COLREGS for this crossing). You want to cross the ships path (why? to get to the other side - Sorry couldn't help myself).

The intersect point is 4 miles from the ship and 1 mile from you at the start of this crossing. The ship is going 20 kts and you 5 kts.

You intend to pass 180' CPA under the ships transom. Can you do this safely?

[evm1024]

Originally Posted by Dave_S

You guys who are saying this is Ok must be imagining some other ship than me. I see a 1000' container ship.

I don't believe anyone would intentionally set a course to pass 180' behind a container ship travelling at 20kn at 90° to it's course.

This would mean when you are 430' from its line you are aiming at the bow of a 200' tall, half a million tons travelling at 20kn.

Nah, not happening.

но да

which translates to - but yes - and means I agree.

It is pronounced much like NO DUH

[Ken Z]

WHY???? It would spill my boat drink!
🍸🍸😁😫

[Dave_S]

I think you would be crossing through aerated and turbulent water and inside the first stern pressure wave (term?). Both of these could cause you all sorts of drama.

[zboss]

Incredibly bad idea. True story... a friend of mine was sailing near Grenada on a night passage and a container ship was closing with him. He made a choice to pass very close to the stern, only to find himself emerge at the bow of another container ship that was hidden behind the one he went astern to. He ended up doing an emergency gybe and almost lost his mast when some rigging broke. So no.... that is stupid.

[Clivevon]

In a crowded sea space (Solent) with slow moving ships, in flat water with good visibility - you might pass pretty close astern of a ship - but 180 feet sounds too close.

In the open sea - why would you do this unless you are some kind of nutter?

At night - I like a CPA of 1 mile minimum.

[Suijin]

Originally Posted by evm1024

The key here is not the exact geometry but rather can you get close to a ship going 4 times your speed and predictable pass under its stern with a CPA of 180'.

Is the question whether you can set your course and not change it and rely on your instruments and your interpretation of them to safely and reliably pass astern by >/= 180'?

You've thrown out close quarters maneuvering, or "darting across the stern".

I'm not sure what the point of this exercise is. If it is to demonstrate that at enough distance instruments do not provide enough accuracy for you to reliably set a course and stick to it, that is obviously true. Is that your point?

[Argyle38]

My response is technically safe, but probably not the best plan.

[Dockhead]

Originally Posted by evm1024

но да

which translates to - but yes - and means I agree.

It is pronounced much like NO DUH

Наш русский чел? Я не знал.

[evm1024]

Originally Posted by Dockhead

Наш русский чел? Я не знал.

Моя жена из Украины. Я только говорю на небольшом русском языке.

[Herb Miller]

Is there any current?

[Jim Cate]

Originally Posted by Dockhead

Наш русский чел? Я не знал.

Oh, shame, DH! TWO forum rule breaches in one post, and you a moderator!

(really kidding, but English is the stipulated language for those who have never read the rules to which they agered when they joined)

Jim

[evm1024]

Originally Posted by Jim Cate

Oh, shame, DH! TWO forum rule breaches in one post, and you a moderator!

(really kidding, but English is the stipulated language for those who have never read the rules to which they agered when they joined)

Jim

I did it too, I did it too. Don't leave me out!

Sorry - I only said that my wife was from Ukraine and that I only spoke a little Russian. (Well I only speak bad Russian)

[crankysailor]

Originally Posted by Argyle38

My response is technically safe, but probably not the best plan.

Ducking a bullet is perfectly safe.. as long as the bullet goes over your head...

Now go try it out.

[Uricanejack]

Originally Posted by evm1024

Ignore COLREGS for a moment.

Let's say you there is a 600' long ship inbound in the Straights of Juan de Fuca (in the VTS but we are ignoring COLREGS for this crossing). You want to cross the ships path (why? to get to the other side - Sorry couldn't help myself).

The intersect point is 4 miles from the ship and 1 mile from you at the start of this crossing. The ship is going 20 kts and you 5 kts.

You intend to pass 180' CPA under the ships transom. Can you do this safely?

Sorry I cant ignore the colregs. It would be fundamentally wrong and unsafe