10th Patrol of U-53
Sept 28th, 1940
Radio Contact Intercept Part 1
Time 14:53
Four days into our 10th patrol we get a radio contact from BdU. A lone ship is moving slow and heading in our direction.
Actually, it's not too far off our intended course. Like a gift... These are my favorite types of intercepts because the ship is playing right into my hands. I don't have to do any end-around or stationing plotting. I can procede on a direct intercept course and as I make contact at distance I'll be able to easily maneuver into my favorite 90° firing position as the target closes the gap.
I grab a screen print and pull the image into MoBo. After plotting my subs position and the contact position atop the nav map graphics I hover over the contact and press the "I" button to generate the intercept point.
Plotting a blue node on the intercept point and connecting to sub gives me a line that I can display the intercept bearing on. Hmmm... given our present speed of 9kts, looks like 259° is the course we need to take eh Wolf.
Aye sir. Uh, that's Wolfgang my XO. Set course 259° speed 9kts for intercept.
Hmmm... 42 km away... it's 14:53 now... let's see 42km and 9kts should be like 4 hours or so traveling time? An early evening attack. Wolf double-check that.
Ooof! I guess I meant 2.5 hrs, bah! forgot about the knot to km conversion; too many hours without sleep.
You should get some rest sir. So let's see it's almost 3:00pm, maybe around 5:30 we'll make contact. Wolf, have the cook prepare an early dinner... Seas are relatively calm, we should make consistent time/speed... and so should our dinner guest.
Time 16:20
BdU reports an update on the target position. Amazing the intel they have these days. We'll win this war in no time!
Hmmm... interesting, he's pretty much where we expected him to be. Wolf, that previous contact position was plotted at 14:50 can we get a speed estimate a little better than "slow" based on the new position at 16:20? I had assumed 6, but he's a little further along than I expected. Ahhh maybe it's my eyes... let's just confirm the speed.
Aye sir.
...for the distance covered in 1.5hrs I estimate a target speed of 6.1kts. Wolf yer killin me with the tenth of a knot. Let's just assume that tenth is just BdU position plotting error and make it an even 6.
Aye sir
We still have an hour to go before we run into em... I'm thinking this might be a good opportunity for a submerged approach. At 1/3 speed we'll make 4kts submerged. Let's see if we can intercept from current position at 4kts.
Mmmm... I like that approach angle. Take her down to 25 meters, maintain 1/3 speed, and set course 219°.
Navigator lay a course for 219°
This slower approach should get us in range in about an hour or so. We're going slower but we've cut the distance.
Time 17:15
Sir, hydrophone reports contact bearing 050° long range.
Time 17:20
Let's setup for an attack position at 1500 meters and 90° abeam.
Give me a 1500 meter radius...
Time 17:26
Let's adjust course for a 90° approach angle. Bring us up to parascope depth.
Time 17:38
Let's set the TDC for our known attack position. Wolf, double-check the attack scope and make sure it's still pointing at 0°, do not let the scope break surface.
Aye sir, scope wire on 0°.
Come here Wolf I wanna show you something. Your solutions have been off lately. Let's review the process. Do you remember Fast-90?
Alright, TDC switch OFF...
Leave bearing pointing at 0°
Range = 1500 meters
AoB = 90° port
Speed = 6kts
For this 90° abeam shot I've set the attack scope pointing at a phantom ship bearing 0° on the targets path. The AoB in this case will always be 90° port or starboard. All you have to do is determine which direction the ship is headed. Conveniently enough, the AoB arrow points in the same direction as the ships heading. If the ship is approaching from your right the arrow would point to the left and vice-versa.
TDC switch ON
...the TDC is now calibrated! When you move the scope the AoB will adjust automatically. This allows you to aim at specific points and fire without having to reset the TDC. Works great on multiple ships that are moving along the same path (ahem, convoys).
(continued)