Fast 90, where am I going wrong.

[Kip336]

It's been a while since I did manual solutions, but the fast 90 is a good way to learn! Soon once you get more comfortable with the process you'll start attacking with other AOBs.

I agree with Zosimus, use the 3,15 timer for better speed estimates.
another thing that helped me was to make a 90degree turn and to keep taking measurements, while also manually drawing bearing lines on the map.

The 90 degree Turn causes the bearing lines to shift, BUT, as the target keeps the same speed and course, there will be one line where the bearing lines are all equidistant from each other.
If this isn't the case, you know your calculations are off.

If I don't forget, I'll post a picture this afternoon after work

[knight76]

Thanks for the tips guys. I am very meticulous in my setups so I can't imagine there would be an issue with the 90 degree setup etc.

I think the problem is going to be the 3 minute timing. I even setup a spreadsheet to enter the data to try to convert distance traveled in 3 minutes to knots, but the game does not give increments only increasing distance in 100m lots. So it's not as accurate.

Can ships in game go 7.5 knots etc or are they always 7 or 8 knots?

I'll give the 3:15 timer a go tonight and see how that works out.

[Kip336]

Only on long distances (1000m + ) should half a knot start to matter.

3:15 is quite easy.
Take a location fix, 3;15 later another one. The distance between both fixes divided by 100 is speed in knots.

1200m travelled in 3:15, speed 12 knots
700m travelled speed 7 knots etc.

If the ship travels 650m, you can set the torpedo to 6,5knots with the dial.

[Pisces]

Just to make sure, did you mix T1 and T2 torpedoes in those tubes? If so then it may be due to a game bug. It doesn't update the torpedo speed calculation when you switch between T1 and T2 tubes. So the torpedo goes to the wrong gyro angle. If you do have both T1 and T2 in the tubes make sure you reset the right speed and re-aim before you shoot.

Other than that it might have been made worse by the 3m vs 3m15s confussion. If you want better resolution in the speed then take multiples of 3m15s: 6m30 and divide by 2, 9m45s and divide by 3, 13m and divide by 4. The latter gets you down to a quarter knot preciscion, which is what the user interface allows you to set visually anyway. You can't see it much more precise.

Target speed isn't always constant though. If it is wrestling with the waves then it temporarily slows down, which might just make it dodge the bullet. Remember that the 3m15s rule is an average speed.

Ships can go at any fractional speed that the campaign designer desires to enter in the editor. (the ship's max speed permitting ofcourse) So it's just a question how lazy he was. Don't count on whole numbered knots if you want to shoot accurate. Nature and physics doesn't count that way either in the real world.

[scott_c2911]

I start from the top of the notepad and work down. Id is first, then range, then AOB. Without that data speed is hard to determine using the in game controls without using 3:15 method. I noticed that the gyro angle didnt change when clicking the tick once after timing the target and gaining speed data. I realised that I was just accepting the speed and not the solution. I clicked the tick again and the gyro angle was altered. This is a bit controversial but I consider the 3:15 method cheating but then Im being hypocritical as I play with map contacts on too, which is also cheating a bit. I can plot perfect intercepts exactly 90' to the targets track. At the end of the day its whatever you feel comfortable with and you enjoy. Theres no fun in sitting there for ages searching for contacts and finally missing it all together. The important thing is that the built in method for gathering speed data doesnt work unless you are practically stationary where the 3:15 method still works at flank speed. I can understand why its so popular but I have missed everytime I tried it.

[Zosimus]

Originally Posted by scott_c2911

I start from the top of the notepad and work down. Id is first, then range, then AOB. Without that data speed is hard to determine using the in game controls without using 3:15 method. I noticed that the gyro angle didnt change when clicking the tick once after timing the target and gaining speed data. I realised that I was just accepting the speed and not the solution. I clicked the tick again and the gyro angle was altered. This is a bit controversial but I consider the 3:15 method cheating but then Im being hypocritical as I play with map contacts on too, which is also cheating a bit. I can plot perfect intercepts exactly 90' to the targets track. At the end of the day its whatever you feel comfortable with and you enjoy. Theres no fun in sitting there for ages searching for contacts and finally missing it all together. The important thing is that the built in method for gathering speed data doesnt work unless you are practically stationary where the 3:15 method still works at flank speed. I can understand why its so popular but I have missed everytime I tried it.

I have no idea why you, or anyone else, would think that the 3:14.4 method is cheating. I also don't understand why people say it's 3:15. Doesn't 3:14.4 round down to 3:14? Not that it really matters.

You should easily be able to use the three-bearing method to get the target's exact course, and if you get a fourth bearing, you'll know his exact range, too. From there it's simple to plot his speed by measuring two points 6:29 apart. Multiply the distance in kilometers by 5 to get the speed. For example, if the ship has covered 1.4 km then you'll know his speed is 7 knots.

Personally I have found the two-bearing method to be good enough. Even from a hydrophone, the two-bearing method gives a course and range that's close enough for government work. Range, generally speaking, has a negligible effect on torpedo solutions. It's only important for setting the spread angle on salvos.

[Pisces]

Originally Posted by Zosimus

... I also don't understand why people say it's 3:15. Doesn't 3:14.4 round down to 3:14? Not that it really matters.

The 15 seconds is easy to see on the clock and add multiples in your head. It's easier to handle quarters of a minute than mentaly adding .23333 every time. That 1 second in 195 seconds total that it is off is insignificant.

You should easily be able to use the three-bearing method to get the target's exact course, ....

And I don't understand why you say "exact" here. As the 3 bearing method is far from exact as a practical method. To get an exact course you need to know the precise bearings (at least 1 fractional decimal), otherwise it results in a range of courses tens of degrees wide. It tested this with my 3-bearing AOB slideruler, only using bearings rounded to the degree as the crew reports them. This depends much on how long the time intervals were. Longer time intervals results in more degrees between the bearings and makes the result more granular. Also the problem in is you are using intersections of lines that are almost parallel, and that can result in wildly varying course and range results. Doesn't matter if you use the formula, or do it graphically. If you rely on the map plotting the exact thin line bearing then this could be somewhat of a cheat, similarly to using the target icon markers when plotting, as it seems to be fairly precise. In reality hydrophone set could not give that level of precision.

Personally I have found the two-bearing method to be good enough. Even from a hydrophone, the two-bearing method gives a course and range that's close enough for government work. Range, generally speaking, has a negligible effect on torpedo solutions. It's only important for setting the spread angle on salvos.

To my knowledge, there is no 2-bearing method that can give that level of information (course and range). Course needs at least 3 bearings. Otherwise you are assuming things that might not be true. Please explain how it works. Unless you mean 2 bearings with range measurements like the SH4 TDC does, or as on a maneuvering board is done. But that does not apply to SH3.

[knight76]

No not mixing torpedoes just using the standard loadout.

I've been on my next patrol now just arrived on station, on the way had good weather so the 4 merchants I attacked were with deck guns. Still early war so they aren't armed yet.

At the moment I am lying in wait ahead of a convoy with a destroyer way out front and one way in the rear but none flanking the convoy. This will be a longer distance shot so I guess we will see if I score any hits

[Kip336]

Take out the rear DD, hide and take out the front. You'll have ample time to set up torpedo attacks and use a deck gun on the convoy from a few hundred meter :p