Moggy’s Tunaboat Helicopter Manual "GPS 4-2"

Posted on April 13, 2010

Moggy’s Tunaboat Helicopter Manual

Section 4.    GPS Systems and Offshore Navigation Issues

4-2   Hey Moggy,  I can’t find my boat and I’m almost outta gas…!

          It was a pretty horrible day.
When there’s lots of wind, and therefore a rough old sea state, and lots of low, scudding cloud into the bargain, it’s a lot tougher to find fish. It may just not be worth the effort, and the risk. If you had a problem, and the sea state is such that you’re unlikely to float very successfully, then maybe it’s a rest day for the pilot and the observer.
On this particular day in June 1997, I was lying on my bunk, reading a good book. The ship was rockin’ and rollin’ pretty good, and it was decidedly noisy outside. I was perfectly happy not be flying.
Next thing, there came a loud knock on my door, followed by the door bursting open, followed by an excited Taiwanese sailor.
His face showed consternation.
      "Moggy! Captain say you come to bridge!"
With a mental "Now bloody what?", I headed up to see what was going on.
It was a helicopter, a Hughes 500, hovering by the bow, fish tailing unsteadily in the blustery wind.
I grabbed the radio, and made contact.
      "Hey dude, it’s Moggy! What’s up?"
The answer came breathless, and clearly conveyed stress, emotion.
       " Hey Moggy,  I can’t find my boat and I’m almost outta gas…!"

In short order, I established the name of his boat, a Korean ship.
The captain was also on the bridge, and I looked questioningly at him. Typically, captains will know pretty well who is in the area. They make it their business to. Friend or foe.
But this time, the captain just shook his head, looking puzzled. That ship was nowhere near us. I looked on the radar, and in fact couldn’t see anything anywhere near us.
      "Hey guy, how much fuel have you actually got?"
The panicked reply indicated he had maybe twenty minutes left. Not good.
I asked the captain to call the Korean ship. He wasn’t pleased. It was obvious that they were not friends. Contrary to common belief, that all Korean boats hate all Taiwanese boats, and vice versa, the truth is that there are some really good friendships as well. It just depends. But not this particular Korean.
No friend of the captain’s…
Nonetheless, our Taiwanese captain, to his credit, started hailing the Korean vessel, on different frequencies. It took a while. Eventually, a somewhat haughty reply came.  Not friendly. I winced. The captain, again to his credit, remained professional, and merely stated:
"We have your helicopter at my ship! Low on fuel! He ask for your position!"
Now, all of a sudden, the Korean captain adopted a rather more agreeable radio voice.
Yeah, right…
I jotted down the lat and long, and did some quick mental calculations.
Oh, dear…
I passed the lat/long to the Hughes. Back came the immediate reply:
"Errr…. Moggy, I’m not very good with this GPS.  Can you give me a rough idea?"
Oh, dear…
Not good. My GPS was in the helicopter, but a quick mental calculation told me about 120 degrees, and 70 or 80 miles. I passed that information, knowing already what he was going to say. Off mike, I was already asking for my deck helper to be sent for to go up and unstrap my bird.
     "Jeez, Moggy, I don’t have fuel for that…."
I already knew that. He didn’t have much day light for it either. A thought that had not yet occurred to him obviously…
By the time I had lifted off, and he had landed to refuel, his panic had risen to a serious level. I actually started wondering if he was going to refuse to take off my ship. He sounded more and more seriously freaked out. He was having trouble, it seemed, loading his GPS. And he asked me several times what the bearing and range was to his ship. I was now able to tell him exactly, as I was in my bird with my own GPS.  He seemed to be getting a different result. It also seemed that he was arguing furiously with his observer.
In the end, I offered to guide him part of the way. With my Taiwanese captain’s kind blessing. He had long since picked up on the panic in the pilot’s voice.
I flew with him some 40 miles, made sure he was heading in the right direction, and departed back for my boat in the twilight. I got back at about the time he would have been landing, and it was getting pretty dark.
There are a number of lessons here, and further on down in this section, we will spell them all out, one by one.

But first, yet another illustrative anecdote.
This time, it was yours truly, who was beginning to seriously, seriously sweat his fuel. What happened was that we criss-crossed all over the place. Many newbies think there is such a thing as a regular, formal ‘search pattern’. A rectangle, or a circle around the boat, an oval, or a regular four leaf clover shape.
(I’m kidding…)  
Dream on. In truth, the search often goes all over the place. The captain will be watching his bird radar, and if he sees birds gathering somewhere, he will likely call you up and send you to investigate. Where there are birds, there may be fish… You may start off West of the ship. Then go South. Then suddenly East. Then reverse course. Then do a…no, hang on…. over there…. no….go back there.…. oh, what’s that?….. errrr.… let’s head South now……etc, etc.
Meanwhile, the ship, your only landing base, is ALSO often enough zig-zagging. Occasionally they will stay on a steady "zig" heading, but even that may suddenly change. I always asked what their "zag" plans were, but I knew to never rely totally on what they told me.  

      Now, hear this:  Even if you have a good understanding of latitude and longitude, even if you can visualize where you are in relation to the boat’s position, it is easy to get a little confuddled. The number one trick here is to NOT rely 100% on your GPS! And that of course, is what people do. Yes, many boats have an "auto update system", where you can in effect inquire electronically off the boat what it’s position is. But it may fall out. For several reasons. Line-of-sight being one.  More on this later. You will frequently be 50 miles away from the boat. Occasionally, rarely, on a calm day, I’d go up to 60 or 70 miles. If you are one of those pilots who refuses to go out of sight of the boat, you will get fired. They don’t want you that close. They want you to go and find fish.  I was mostly using the ‘Ross DSC 500’ system, (more on this later) and some days it worked like a charm. Other days, it would reliably fall out once you had gone more than 30 miles from the ship.  Then you could call the ship, and ask for the ship’s position.  And of course, once in a while, nobody would answer.  Annoying. But imagine what happens when a junior Chinese sailor gives you the WRONG latitude and/or longitude! That is exactly what happened to me.

         On this day, the ship had told me they would be steaming steadily on a particular heading. That much I knew. We passed 30 to 35 miles from the ship, and the Ross DSC500 could no longer automatically update the ship’s position. That left me with a shrewd idea of where the ship was, and where it was going, but not an accurate lat/long. Well, we did the old zig-zag here-a-bit and there-a-bit and every-where-a-bit of searching, and then it was time to go home. My observer called for the ship’s position. Silence. No reply. Not unusual. So I set up an approximate heading. I wasn’t worried. Sooner or later, somebody would reply, or we would get close enough to where the Ross DSC500 would automatically update the ship’s position for us. Or I could climb a bit. We flew along, fuel going down, no biggie, and then we finally got a reply. The observer jotted the ship’s position down, and loaded it in the GPS.
Whoa… problem…        
The ship was nowhere near where I was expecting. It would require a significant heading change. I was alarmed. It didn’t make sense. I asked the observer to check with the ship again.
Ship give wrong position. You check. Not possible…
He did, and we got the same answer. I ran the maths. It didn’t make sense. The ship could only do 12 to 14 knots. The purported new latitude and longitude would have meant that they had figured out a way to do more like 35 to 40 knots.
I asked the observer to check for a third time.
Not possible… wrong position…
Now he got mad with me. He checked again, angrily. Same answer. I asked if the ship was indeed maintaining the previously mentioned heading. They said it was.
I shook my head, and refused to obey the GPS indicated heading. Instead, I steered a guess-timated course, to where I calculated the ship had to be. It was significantly different from where the GPS was telling us to go, with the position that my observer had loaded. Based on what he had been told by the ship.
Of course, with my observer’s limited English, he could not understand why I was, in his mind, "refusing to fly to the ship". He became really angry, and was shouting in alarm. I just gritted my teeth, shook my head, and flew my guess-timated heading. But I would lie to you if I told you I wasn’t sweating bricks.  Doubts assailed me. I kept re-running the same mathematics in my head. I kept ending up with the same conclusion: the ship could not have possibly got to that position. But then I would feel the need to re-run the calculations.
Over and over again. Meanwhile, I grimly ignored the GPS purported indicated heading to the ship, despite the loud protests (plus abuse) from beside me. Stress…
You can only imagine my relief, when, at thirty miles range, all of a sudden the Ross DSC500 locked on to the ship’s position, and now we suddenly had a solid lock, pretty damn close to my guess-timated heading! What made it even more beautiful, was the reaction of my observer. He literally shook, his eyes bulged at the screen, and then he turned to me.
"How you know??"
I smiled sweetly, and tapped my head.
"I have big head!"
It was one of my favorite jokes, a twist on the usual meaning. The Taiwanese thought it meant "Really smart dude".   
The Taiwanese’s face went through relief to anger.
"Ship pass wrong position?", he asked.
I nodded.
He said something in Chinese, it sure sounded like a really bad cussword, and spent the rest of the trip back screaming abuse over the radio at the poor unfortunate sailor. He was still yelling when we landed.

       Now, I never did understand what actually happened. If it was an honest error, equipment unfamiliarity, or otherwise. But I think that the Longitude was wrong, and ’19 minutes’ accidentally became ’59 minutes’.
Forty miles…
But I was given assurances it would never happen again, and it didn’t.  
The moral I think though is interesting, right? Yep, it could have been ugly. Running the calculations on board ship, I was pretty soon clear on one thing: I would not have had sufficient fuel to go to the bogus position, realize the error, and then fly to the correct position. It just wouldn’t have been possible in terms of fuel.

I quote these examples to you as a sort of taster, before we dive into the theory in the next chapter. The theory can be a bit dry, and heavy, but I hope you will see the point I am trying to make: it’s super important stuff.  Not just in the Tuna Fields. Anywhere, you use GPS.  

"Don’t be one of those GPS slaves who always meekly fly down the long, dark tunnel"

and hopes…

that there is indeed, light… (your planned destination)….at the end of that tunnel.

There may NOT be.  And then, with your fuel reserves seriously depleted, now what are you gonna do…?

Bad boy, bad boy,
what ya gonna do?
What you gonna do
when the sharks come for you?

Francis Meyrick
      (c)

Last edited by Francis Meyrick on April 13, 2010, 6:43 pm


0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this.
Loading...

Leave a reply

You must be logged in to post a comment.