Vessel detectors - radar visibility of your own vessel

>Subject: Re: Vessel detectors - radar visibility of your own vessel
>From: "Armond Perretta" newsgroupreader@REMOVE
>Date: 08/24/2003 14:04 Pacific Standard Time
>Message-id: <hf2dnWACq8T7tdSiU-KYuQ@>
>
>Shen44 wrote:
>>
>> Again .... never approach closer than two miles at sea, and if you
>> miss the ship and it's close aboard or within that distance, figure
>> it's up to you to avoid .... worry about some rule later.
>
>Always a sound approach, but consider this. I have a 4 to 4.5 knot
>sailboat. Offshore the commercial traffic I encounter (neglecting for the
>moment commercial fishermen) typically maintains 16 to 24 knots. Even
>should I pick up a target at 8 miles on radar (or otherwise), there is in a
>practical sense very little I can do to _insure_ a CPA of 2 miles or better.
>I am speaking only from the perspective of quite a bit of offshore
>cruising in a small sailing boat, which is not to say I don't realize that
>"big boat always wins."
>

Oh, fiddle faddle. To begin with, not all ships you see out there will be
heading directly at you, so, for the most part, even at 4k, you will have
plenty of time to adjust.
Secondly, on a clear day you should be able to see a ship at 8mi plus and have
a good idea as to it's heading, which means you can take appropriate action to
give it as wide a berth as possible. Hey, if you don't make 2 mi., you
tried..... at least you worked to maximize the passing distance.
From my own standpoint, the "small" boat has a better chance of seeing the"big"
ship sooner (especially at night) and starting to maneuver to maximize the
passing distance .... especially, considering your slower rate of speed.
Don't get me wrong, I don't condone poor watch keeping on ships (visual and
radar) any more than I do so for small boats, but varied experience has taught
me that both have things which must be dealt with/ worked around, when dealing
with the other, and overall, small boaters should always act as if they are not
seen and maneuver accordingly ..... use the radio, shine a bright light on
your sails, use a strobe (short periods) .... do what it takes, never assume.

Shen

>Subject: Re: Vessel detectors - radar visibility of your own vessel
>From: Brian Whatcott betwys1@
>Date: 08/24/2003 18:07 Pacific Standard Time
>Message-id: <9boikvo1svaa2dl1oqqluoi0aqbbiv60d5@>
>
>Single-handed - and asleep?
>
>Brian W
>

Yes .... well, that's a chance you take when doing this, and a whole nuther
argument.

>Subject: Re: Vessel detectors - radar visibility of your own vessel
>From: Rosalie B.
>
>There are some boats, particularly off the FL coast which do not have
>a heading that is stable. They are well lit so we can see them
>(better than the little fishing boats which may be anchored at random
>with no lights at all), but they don't maintain any kind of heading.
>We used to think they got their kicks by heading for any small boat
>they saw.
>
>Actually I think they are gambling ships out just beyond the requisite
>mile limit and aren't going anywhere particular. Bob's method of
>dealing is to head for them at which point they seem to veer off.
>We'd never catch them so that's probably safe.

The one advantage to these types of ships, is they are normally well lit.
Problem is in seeing their running lights and narrowing down their heading at
night (and except for dead ahead, I wouldn't give you much chance of being
visually seen by them).
Hard to give good advice on these .... fraid you will have to take each case as
it comes, but still figure you are your own best solution.
>
>
>How long does it take a large ship going at the rate of speed that
>they normally go at to get from a blip on the horizon to the observer?
>(8 miles? 12 miles?) If the ship is going 24 knots 8 nm would take
>20 minutes. The small boat going 6 knots will take an hour and 20
>minutes to do the same distance if I'm correct (and math isn't really
>my thing) and will be able to separate from the larger ship's course
>(if accurately determined) by two miles in that length of time..
>
>You'd think that would be enough time to get out of the way, but that
>assumes you can accurately tell at that distance what their course is,
>that you are correct in the action that you take, that they maintain
>the course and also that you see them 8 nm away by whatever means. If
>you don't see them until they are 4 nm away, they will be at your boat
>in 10 minutes, and in that length of time you can only get a mile.

The 2mi, is a number to strive for .... it's NOT written in stone.
Also, once again .... how many ships that you meet are heading directly at you?
That is only ONE case.
In many, if not most cases, they will be heading in a direction that crosses
your path, and here, it's important to figure out their "relative motion".
BTW, if you don't see a ship until it's 4 mi from you, on a relatively clear
day, you're not keeping a very good watch.
Normally, from the moment you spot the ship, it should take no more than one to
two minutes to get a good feel for the ship's basic heading and whether the
bearing is steady, opening, or closing .... at which point, your work begins.
Naturally,if you've got radar, this is easier, but if not, you need to do some
"eyeball" calculations, and these need to be watched closely to see if you are
getting the results you wish (probably means a greater course change than if
you had radar)
>
>There was a case here in the bay where a cruising boat running up the
>western shore at night saw a ship on his radar and saw something else
>that he couldn't ID, and apparently went down into the cabin to look
>at a chart or get a cup of coffee or something, and he ran between a
>tug and the tow and his boat sank within a couple of minutes.

Two errors here (well a bunch, actually).
A tug and tow, is normally an easy radar spot (kinda like a triangle small
target leading a larger one, close together, maintaining a same distance
separation) so poor radar interpretation on his part..... and never leave the
radar, till you KNOW what you are seeing and what it's doing.
>
>So it isn't as clear-cut a problem as wanting each ship to keep proper
>lookout IMHO

It's a clear cut problem with BOTH vessels keeping a proper lookout, but not
clearcut as how you should respond for varying conditions .... I'm saying try
to stay at least 2 mi. clear. Well, we all know that's not always possible
.....it's a goal and one which can be attained, frequently, only by very early,
substantial action.

Shen
>

>ubject: Re: Vessel detectors - radar visibility of your own vessel
>From: Rosalie B.


>I was driving the boat down along the coast from Ft. Pierce to Miami
>at night - trying to keep out of the Gulf Stream and also out of the
>zone where the Navy was doing underwater tests (i.e. staying in less
>than 100 feet of water) while sailing which meant some tacking. I
>could see some ships between me and the shore only because they were
>dark shapes against the lights.

Never an easy task.

>
>And one big cargo ship was coming north. I saw the red, white and
>green lights. I moved out from shore a bit, but didn't want to go too
>far out because of the Navy stuff. Then I saw just the white and
>green, so I figured they were going in the inlet. Then they shut off
>the green light and appeared to stop. A little bit later they turned
>on the deck lights. I guess they anchored or picked up a mooring.

Anchored. If you see a ship heading North, close inshore in that area, he's
(probably) bound for a port or anchorage. Normally, ships Northbound will stay
well offshore in the axis of the Stream.
>
>I've also been at the wheel following a big ship into an inlet, when
>the ship stopped and started to back up (in daylight - I don't know
>what I would have done at night).
>>>
>>>There was a case here in the bay where a cruising boat running up the
>>>western shore at night saw a ship on his radar and saw something else
>>>that he couldn't ID, and apparently went down into the cabin to look
>>>at a chart or get a cup of coffee or something, and he ran between a
>>>tug and the tow and his boat sank within a couple of minutes.
>>
>>Two errors here (well a bunch, actually).
>>A tug and tow, is normally an easy radar spot (kinda like a triangle small
>>target leading a larger one, close together, maintaining a same distance
>>separation) so poor radar interpretation on his part..... and never leave
>the
>>radar, till you KNOW what you are seeing and what it's doing.
>
>I agree with this, but this tug was towing on a long line and I gather
>he made no connection between the two blips. I've also seen tugs
>towing stuff like pipes so the tow doesn't have much of a radar or
>sight profile at all.

Almost sounds like he was on too low a range scale. For normal viewing, at sea,
I'd suggest 6-12mi (and no lower than 3) to give the best overall picture
(naturally reducing from that if you are working a particular target or feel
the need to check the lower ranges, for numerous reasons).
Most tugs at sea will have 600-1200 feet of cable out (varies), but on the
longer range scales, after some experience, it will still be obvious as to what
they are.
>
>In any case, they lost their boat and everything they owned and were
>lucky to escape with their lives, although the Calvert Co Volunteer
>Fire Department picked them up out of their dinghy within 15 minutes.

This is a shame, but at least they lived. Many in this case, don't.

Shen

>ubject: Re: Vessel detectors - radar visibility of your own vessel
>From: "Armond Perretta" newsgroupreader@REMOVE
>Date: 08/25/2003 02:52 Pacific Standard Time
>Message-id: <1NOcnfF4p9bnQdSiXTWJiA@>
>
>Shen44 wrote:
>>> From: "Armond Perretta" newsgroupreader@REMOVE
>>> Shen44 wrote:
>>>>
>>>> Again .... never approach closer than two miles at sea, and if you
>>>> miss the ship and it's close aboard or within that distance,
>>>> figure it's up to you to avoid .... worry about some rule later.
>>>
>>> Always a sound approach, but consider this. I have a 4 to 4.5 knot
>>> sailboat. Offshore the commercial traffic I encounter (neglecting
>>> for the moment commercial fishermen) typically maintains 16 to 24
>>> knots. Even should I pick up a target at 8 miles on radar (or
>>> otherwise), there is in a practical sense very little I can do to
>>> _insure_ a CPA of 2 miles or better. I am speaking only from the
>>> perspective of quite a bit of offshore cruising in a small sailing
>>> boat, which is not to say I don't realize that "big boat always
>>> wins."
>>
>> Oh, fiddle faddle.
>
>Which part is "fiddle" and which part is "faddle"?

Both. You're trying to make more of this than there is. I said it before, I'll
say it again .... The 2mi. figure is one you strive for, but don't always
achieve, and I would disagree, that even at your speed, that for MOST
situations you couldn't attain this or something approaching it.
>
>When push comes, etc., the little boat gets out of the way or else. It
>matters very little whether a ship missed you by 100 meters or 100 miles,
>although I do in fact have a preference.
>
>Nonetheless, what you suggest is not always (and in fact not even in the
>majority of cases) possible.

Disagree

In addition one will _always_ have a difficult
>time explaining maneuvering that is not allowed in the COLREGS should it
>come to that (no matter what the General Prudential Rule states).

If you don't have a collision, what and to whom do you have to explain
anything? If you start your maneuver early enough and monitor it's
effectiveness, why should you ever need to worry about a close situation?
>
>Placing the entire onus on the small boat is just as much an error as
>placing the entire onus on the big boat.

The idea of what I'm talking about, is not placing the "onus" on the small
boat, as such. It's telling the "small boater"...Hey! You can have some
problems with large ships .... some of them your doing, some of them the
ships..... so, from experience and having been on both sides of the coin, I
reccommend ..... Now .... it may not always be technically legal and/or
convenient, but for the most part it might keep you out of trouble, more often
than not.

Shen