drifting

[comet61]

Sometimes if I am patrolling in a grid area I will not use the plotting tool but steer manually or set the course using the pop-out compass. (I use the most recent version of GWX). I have noticed that after about an hour I have a significant change in course. Last night I set a course on relative calm seas at 30° @ 8k. In one hour my course heading was @ 22°. Usually I use time and speed for calculated distance which pretty much works for me, however I was wondering about the drifting. Is there a ocean current influence in SHIII and if so is there usually a course correcting time-table if in manual steering? I didn't take heed about wind variations, so next time I'll need to pay attention and see if that is it also. But no wind and calm seas?

FYI: I do use the plotting tool for my longer trips to an area or going home, but I like using manual/course settings when in "search mode"...

[Tom]

I think that if you just order a heading (instead of using the course plotting tool) the submarine turns towards that heading and then continues with rudder amidships. The waves (and possibly the wind too, not sure about this) will cause slight deflections to your course and these will not be corrected, thus changing your heading over time.

When you use the course plotting tool, your heading is constantly corrected, so that you are always moving towards the next waypoint. If you closely watch the rudder dial, you will often see a 1-3 degree deflection, especially in rough weather.

[irish1958]

Originally Posted by Tom

I think that if you just order a heading (instead of using the course plotting tool) the submarine turns towards that heading and then continues with rudder amidships. The waves (and possibly the wind too, not sure about this) will cause slight deflections to your course and these will not be corrected, thus changing your heading over time.

When you use the course plotting tool, your heading is constantly corrected, so that you are always moving towards the next waypoint. If you closely watch the rudder dial, you will often see a 1-3 degree deflection, especially in rough weather.

That is correct (just as it is in real life).

[comet61]

Since I posted... I noticed the "deflection" every hour. In the calm seas I get almost 1° an hour of deviation hence the 8° difference in a 8 hour time span. I can only imagine what it would be in 15km winds in 10ft swells. Thanks!!

[Sea Sap]

I've recently stopped using waypoints for everything except the Kiel Canal and I find it adds to the immersion. The weather altered my course 10 degrees during a four hour period today.

[Sailor Steve]

No, this is NOT just as in real life. It is a major bug in the game, and one I'm hoping is fixed in SH5.

The boat will wander due to tides, currents and wind, but if you give your helmsman a heading ("One six five!") he will gold to that course come hell or high water. You will drift, but your heading should never change. That's the helmsman's job, and if he can't do it you replace him with someone who can.

[irish1958]

Originally Posted by Sailor Steve

No, this is NOT just as in real life. It is a major bug in the game, and one I'm hoping is fixed in SH5.

The boat will wander due to tides, currents, and wind, but if you give your helmsman a heading ("One six five!") he will gold to that course come hell or high water. You will drift, but your heading should never change. That's the helmsman's job, and if he can't do it you replace him with someone who can.

Steve, it might be a bug in the game. But how else could you model the effect of tides, currents, wind, waves, water density, water temperature, etc. on the boat? For example, the Gulf Stream has a velocity of almost 5 knots. If you set a course, say for the Carolina coast near Chareston of, at, say, 270 degrees. You could hold that course, but by crossing the gulf steam at 12 knots and holding your course, you would be 30 miles/12 knots x 5 knots=12.5 miles North of Charleston, and that doesn't consider the effect of wind and waves of the boat. Using way-points solves the problem with periodic (in real life) corrections.
The Arctic Stream is even faster
I think the periodic drifting is a good compromise in the game.
This is no longer a problem with GPS navigation.

Originally Posted by irish1958

Steve, it might be a bug in the game. But how else could you model the effect of tides, currents, wind, waves, water density, water temperature, etc. on the boat? For example, the Gulf Stream has a velocity of almost 5 knots. If you set a course, say for the Carolina coast near Chareston of, at, say, 270 degrees. You could hold that course, but by crossing the gulf steam at 12 knots and holding your course, you would be 30 miles/12 knots x 5 knots=12.5 miles North of Charleston, and that doesn't consider the effect of wind and waves of the boat. Using way-points solves the problem with periodic (in real life) corrections.
The Arctic Stream is even faster
I think the periodic drifting is a good compromise in the game.
This is no longer a problem with GPS navigation.

Steve is right, and has it right (as usual).

Remember that Course and Heading are not the same thing.

One holds a specific Heading while conducting a torpedo attack.
The only Course of interest, is that of the target(s).

[Sea Sap]

Originally Posted by Sailor Steve

No, this is NOT just as in real life. It is a major bug in the game, and one I'm hoping is fixed in SH5.

The boat will wander due to tides, currents and wind, but if you give your helmsman a heading ("One six five!&quot he will gold to that course come hell or high water. You will drift, but your heading should never change. That's the helmsman's job, and if he can't do it you replace him with someone who can.

I didn't claim it was as in real life, I said it added to the immersion. I doubt many of us would want all the hassle of real wartime navigation and in my opinion it is nearer to real life then always being exactly where you want to be in the vast ocean by use of waypoints.

[irish1958]

Originally Posted by Snestorm

Steve is right, and has it right (as usual).

Remember that Course and Heading are not the same thing.

One holds a specific Heading while conducting a torpedo attack.
The only Course of interest, is that of the target(s).

I never said Steve was wrong. I said that if you maintain a particular heading, you won't get to where you want to go. How would you model this in the game? The only (easy) way to do it, in my opinion, is to have the boat wander a bit and require periodic corrections. Otherwise you would need a supercomputer to crunch all the data.

Originally Posted by irish1958

I never said Steve was wrong. I said that if you maintain a particular heading, you won't get to where you want to go. How would you model this in the game? The only (easy) way to do it, in my opinion, is to have the boat wander a bit and require periodic corrections. Otherwise you would need a supercomputer to crunch all the data.

This is also 100% corect.

My reinforcement of Steve's comments was not intended to infer that those of Irish were wrong. They aren't. And accurate information is given in the post.

It is the inability of the Helmsman to hold an ordered Heading that is problematic and incorrect. Keeping a vessel on Course is an entirely different issue.

The OOD is responsible for keeping a vessel on Course.
He may change Heading many times in order to achieve this end.

F.eks., if the Helmsman is ordered to hold Heading 090 for an extended period of time, the vessel should, and will drift off Course. However, this is the OOD's concern, not the Helmsman's.

The constant changing of Heading required to stay on Course is solved by Waypoints.
The automated Heading changes ordered by the OOD, and carried out by the Helmsman works well.

When not using this automated system, the Helmsman had better be holding whatever Heading is ordered. If unable to do so, he must be replaced.

[Draka]

In navigation, Heading is the direction the bow is pointing - the helmsman will attempt to maintain that based on his compass. Be advised that a VERY good helmsman will still stray 3-5 degrees at best from that depending on sea state, etc. The actual course made over the ground will vary from that based on wind, current and sea state.

I agree that the use of waypoints simulates the entire chain of the Helmsman, Officer of the Deck and the Navigator all inputting their functions into the maintaining of a plotted course. However, once you are on manual it SHOULD vary based on all the above - but as also been stated it would take a lot of CPU cycles and code to do anything like a good job at simulating ALL the effects.

Just as a case in point - the helmsman was maintaining his plotted course, but the navigator didn't correctly factor in a current - and the result was seven US destroyers out of action. See http://www.pointhondamemorial.org/.

Originally Posted by Draka

In navigation, Heading is the direction the bow is pointing - the helmsman will attempt to maintain that based on his compass. Be advised that a VERY good helmsman will still stray 3-5 degrees at best from that depending on sea state, etc. The actual course made over the ground will vary from that based on wind, current and sea state.

I agree that the use of waypoints simulates the entire chain of the Helmsman, Officer of the Deck and the Navigator all inputting their functions into the maintaining of a plotted course. However, once you are on manual it SHOULD vary based on all the above - but as also been stated it would take a lot of CPU cycles and code to do anything like a good job at simulating ALL the effects.

Just as a case in point - the helmsman was maintaining his plotted course, but the navigator didn't correctly factor in a current - and the result was seven US destroyers out of action. See http://www.pointhondamemorial.org/.

Excellent post.
The event in your link has been referred to as Whiskey On The Rocks.
From that moment on all USN ships in in any and all formations were responsible for maintaining their own plot.
An interesting side note is that in situations such as this, the QM stands before a Court Martial, right beside the CO.

Straying 3 - 5 degrees during an UNREP could have very seriouse and possibly fatal consequenses. That's UNSAT. There are certain situations when very good isn't good enough and only the best will do.

[Sailor Steve]

Originally Posted by Sea Sap

I didn't claim it was as in real life, I said it added to the immersion.

I didn't say you did. Irish did.

It's the same problem with flying a plane. You keep to the same compass heading and find that the wind has carried you off course. If you want to head 090, and the wind is blowing from 010, you're going to have to calculate the actual heading needed to maintain the proper course.

I don't want to do all the navigating either, and it is true that the waypoint system gets you where you want to go, but as with other components of the game (Weapons Officer Assistance) it's too perfect. You can't get off course at all if you use waypoints. On the other hand, if you set the compass for 090 you shouldn't suddenly find yourself on a heading of 155. It just doesn't work that way.

The ideal medium would be to set a course using waypoints, and at a set time each day have the Navigator take a sighting, at which time you would see that you were at a different spot than you thought you'd be, or not, depending on random factors. If the day was overcast, then you would have to navigate by dead reckoning, or have the Navigator do it for you. When the sun finally showed up again you would find exactly how far off course you had wandered.

Of course this would require that the crew be able to spot land, and the game would kick you to real time anytime land was spotted, so you wouldn't just run aground. But that is something the game should have anyway, and doesn't.