Freighters vs. Sailboats

[Therapy]

Originally Posted by Seaworthy Lass

Hi Cappy
Let's settle a few figures first. The example given by Lodesman was 4-5 knots for the speed of the yacht and 20+ knots for the freighter when he said it was mathematically certain that the angle from the freighter to the yacht would be "fine" if they were to collide (he did not say "dangerously close", just "collide", so I think the argument is at cross purposes ).

Let's say we use the highest yacht speed and lowest freighter speed from Lodesman's figures
ie yacht speed 5 knots and freighter speed 20 knots:
Angle of yacht from freighter = 14.5 degrees max for them to collide (arcsin θ = 5/20) - Paul Elliott was correct with this formula.

The angle will decrease as the speed of the yacht decreases and/or the freighter increases.
eg For 4 knots and 22 knots: angle of yacht from freighter = 10.5 degrees max

I would call of the maximum possible angle of 14.5 degree "fine", so Lodesman is correct on this technical point

In your example of 6 knots and 20 knots the angle of the yacht from the vessel is 17.5 degrees maximum if they were to collide (given small sized vessels). I would still call this moderately "fine".

If the boats are small, they will never collide if they are 30 degree apart as you state in your example (dangerously close and the yacht would stupidly be passing in front of the other boat, yes; collide, no).

NOTE: These figures are for point sized boats (we have not considered boat size in any of these calculations). These maximum angles would of course be higher as the size of the two vessels increased. When we first spot the vessel we have no idea of its size and we haven't allowed for this in the calculations, but in practice we of course need to allow for the worst!

Cappy, I think what your example illustrates is a HIGH RISK OF COLLISION . With that I agree.

Lodesman's statement about "fine angle" related purely to collision, not high risk. No clearances have been taken into account yet so his "fine angle" comment is actually a moot point (nor has anyone taken into account ship size). I will show later that action needs to be taken almost instantly after he has first been able to decide that two boats are on collision course for his example (visually, not using radar), despite him saying he would still continue on course to his destination.

For the example you give, this is the diagram showing the yacht would need to be at 17.5 degrees off the bow of the freighter for them to collide:

Now this picture I can understand!

[Lagoon4us]

Italian helmed ships scare the crap outta us!

Enjoying LEVKAS heading south slowly.........

[Rakuflames]

Originally Posted by Paul Elliott

If you are both head-on, or nearly so, pointing at his stern does nothing for you but ensure a close call at best. "Pointing at his stern" works fine when your relative courses are 90 degrees (plus or minus a whole bunch) and your speeds are comparable (plus or minus something). It works in most situations, but not all.

What exactly is it we are arguing about?

I can't imagine being head on, or nearly head on, with a freighter. It reminds me of an old algebra problem -- if the train to Chicago is traveling at 80 mph and the train to Denver is moving at 60 mph, when will they crash?

They're on different tracks ...

Who would stay on a collision course with a freighter? The only scenario I can imagine is someone who fell asleep at the helm. I know someone who did, and woke up with his windvane pushing him at 6k through a shrimping fleet. Fortunately he woke up in time. He's always imagined dying at the helm -- but not like that.

I think of all the advice I've been given, and none of it was like this at all, and I've had some outstanding advisors (and a few idiots -- I've concluded that true idiots only get more idiotic with time, NOT meaning anyone here!)

I was methodically taught, VERY early on, how to spot a potential collision. A year later another person made sure I knew it. We just watched the movement of that boat -- whether skidoo or freighter -- relative to our boat.

It's not hard. You *can* figure out by how many degrees you will miss the stern or whatever, but you don't *need* to know that to miss the thing. It's big. Unless you fall asleep, everyone in this discussion will miss it, because we all know they move fast.

If this weren't true, it would be in the news all the time -- another sailboat crushed by a freighter, and the news would not shine favorably upon the sailboat.

[Rakuflames]

Originally Posted by Therapy

Yep.

I am going to die because I don't really understand your pictures. Showing my ignorance eh?

Where is the starting point in this essay for each boat? They collide in the center? Red is the slow one right? The arrows are the direction of travel? No, can't be. They are going away from each other?

Almost like math in my head.

Therapy this IS "math in your head." I don't think you're beating yours hard enough just now.

Does anyone know what the longest thread on this boat has been? Because the legs on this one re like teeth in a shark's mouth ...

[Therapy]

Originally Posted by Seaworthy Lass

I think Cappy is getting a bit upset by this statement, as just not running into him is not enough, you need to keep a safe distance away (this distance obviously depends on sea state and weather is impossible to pinpoint). I think Cappy would want you to allow at least 1nm for the closest point of contact (and maybe 2nm in some conditions), so your angle off the freighters bow could easily double in this case and would no longer be considered "fine" for you to be in unsafe territory, it could be quite coarse. (I think I have interpreted him correctly )




.

Then somebody needs to draw me a picture with another circle instead of just an X. And that safety circle will vary depending on who you are right? If any landing walked away from is OK then any crossing not ending in a collision is OK too right? Pucker factor not part of equation.

[Seaworthy Lass]

Originally Posted by Therapy

Then somebody needs to draw me a picture with another circle instead of just an X. And that safety circle will vary depending on who you are right? If any landing walked away from is OK then any crossing not ending in a collision is OK too right? Pucker factor not part of equation.

Will give it a go for you

[Therapy]

Originally Posted by Seaworthy Lass

Will give it a go for you

Don't bother.

By the time I get a boat, get it on the water and see a freighter........well it may never happen.................in this lifetime.

Better to just post a picture of your nice anchorage.

It can have a freighter in the background if you choose.

[Seaworthy Lass]

Originally Posted by Therapy

Better to just post a picture of your nice anchorage.

It can have a freighter in the background if you choose.

Thread drift warning

Not another boat or freighter in sight:

[Capt Phil]

Seems most of the discussion revolves around one freighter/towboat vs one sailboat either within coastal inland waters or in open ocean at normal speed. When you introduce reality such as a Separation Zone coming into or out of a busy harbor like LA or San Francisco and are dealing with 5-10 freighters, tankers, commercial vessels of all shapes and sizes and speed configuration along with pleasure craft, both power and sail all going in different directions, you will find the ColRegs a handy set of rules for guidance... indispensable, actually. That is not the time to start reading them... you should have them pretty well sorted in your mind already.
You should also expect other mariners not to behave in accordance with the regs through ignorance or lack of attention. It is far better to consider all are idiots until they prove you wrong.
Be careful out there! Phil

[Paul Elliott]

Originally Posted by Rakuflames

I can't imagine being head on, or nearly head on, with a freighter.

Well, it happens. You're sailing on the open ocean, nothing but blue water around you. You see a dot on the horizon -- it's a ship! At night you may be able to see his running lights, but unless conditions are perfect this is pretty tough to do until it gets a little closer. With luck you see his masthead lights, and they show that the ship is heading to your port or starboard and there is no possibility of collision. Or, you see one on top of the other and he's heading towards you.

In the daylight you can't tell which way the ship is going until you take some bearings and see if you are on a converging course (or you use AIS or radar).

Or, if you are in a harbor or entrance, ships are turning all the time. Sometimes you don't know which way they will turn until you see their bow pointing straight at you. You need to scurry out of their way ASAP, since they are constrained in their ability to maneuver. Fortunately they're not doing 20 kts in the harbor! This is what happens when we share the water with ships.

So it's entirely possible to find yourself head-on with a freighter, through no fault of your own. If you've been paying attention you should have time to deal with it (as long as you have some boatspeed).

[CPseudonym]

Originally Posted by Capt Phil

It is far better to consider all are idiots until they prove you wrong.

Words to stay alive by.

[Therapy]

Originally Posted by Capt Phil

. It is far better to consider all are idiots until they prove you wrong.
Be careful out there! Phil

Originally Posted by CPseudonym

Words to stay alive by.

Like ridin' a motorcycle.

[chrisjs]

You sailboat guys are so intellectual!! Us trawler types just keep out of the way.
It is not rocket science, so do not try to make it so. You are not trying to get the closest pass to the noxious freighter, either in front or off its stern, just trying to avoid a collision that will destroy your boat and may kill you or your crew. And as somebody stated so adroitly (I think much earlier on this thread) figure that half the boating population is below average intelligence, and be safe

[psneeld]

I've been away from this forum for a bit...but I see it's up to the same old stuff...

There's the NAVRULES ...and there's the common sense part of the NAVRULEs which works for those that truly understand them and then there's just common sense (which I know all the trivial comments about common sense but some actually have it and use it.)

The overarching rule about the collision regs is that they are there to prevent collisions...not becasuse one boat is anything more or less than any other boat(size, maneuverability, importance)...although there are rules that do get very specific as to maneuverability...but not generally applied. To start pontificating about what's more maneuverable and how that changes the rules just shows ignorance of the rules unless using that lack of maneuverability when applying a rule...not just because "you think so". A good example is a tug/tow...if not declaring RAM...then it's just another power driven vessel.

The best piece of advice in the rules is "Rule 8 - Action to Avoid Collision
(a) Any action shall [be taken in accordance with the Rules of this Part and], if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship."

Unless you are in the intracoastal...or a sailing/power regatta (marine parade)...the prudent skipper alters course far enough in advance NO RULES apply...

[Bash]

Originally Posted by goboatingnow

Racing teaches you nothing about COLREGS or the wisdom and experience around then. If anything racers underestimate situations with large racers , sail too close and leave everything to the last minute.

Gotta disagree. A racer will be involved in more crossing situations than anyone else, and needs to learn quickly how to make best speed in such situations. Very few cruisers will have a fraction of the experience with a hand-bearing compass of a race tactician. We use them not just to judge crossing situations, but also to determine the relative speed of the opposition.

In my home waters, anyone violating COLREGS Rule 9 is automatically DSQ. You learn pretty quick not to make that mistake.