UBOOT takes observation position off eastern approach to Scapa Flow Naval Base.
Periscope depth, water under keel measured around 180 meters.
Hydrophone and periscope operators active.
VIDEO OF ENEMY ACTIVITY - 24 hours, general presentation
DETAILED ANALYSIS OF OBSERVED ENEMY ACTIVITY
#1 - Periscope sighting of small vessel coming towards land from NE; Watch Officer draws in periscope and takes UBOOT down to 100 meters. Hydrophone keeps listening and tracking the vessel: slow sleep, one slow screw, passing north of UBOOT position, no sign of alarm. Vessel continues toward land and disappears into narrow sound (salmi) between SOUTH TOWN and RUMLEY POINT.
#2 - same time as fishing boat is going into narrow sound, Hydrophone picks up another observation in direction SW from UBOOT position, at distance of maybe 8 NM (nautical miles). Fast small vessel… appearing from behind the LYTHE point… then suddenly slows down and continues to arc slowly…
Sea is quiet all around.
UBOOT comes back up to periscope depth (20m)
#3 - ... small vessel continues in halfcircle and goes back, accelerates to fast speed again, ata same time Hydrophone picks up signal of slow big screw… large vessel, heading toward NE somewhere maybe 10 NM distance.
#4 - soon after, Hydrophone picks up yet another similar slow single screw, large vessel, heading toward NE behind the previous spotting.
No periscope sighting yet of either one.
PERISCOPE SIGHTING of lighthouse coming to light south of LYTHE point, light stays on for 20 minutes.
Hydrophone can hear vessel #3 changing speed and adjusting course around somewhere close to LYTHE point.
#4 still coming on behind vessel #3.
ship #3 moves toward EAST and slowly accelerates.
ship #4 can be heard changing speed and course close to LYTHE point.
AIR#1 - Periscope sighting of airplane coming out from the direction of Scapa Flow Naval Base.
Officers identify Airplane as
Watch Officer takes UBOOT down to 150 meters, so as not to be spotted from air.
Airplane can be heard flying wide circles around the outgoing vessels: ship#4 moves toward NE, ship#3 moves EAST.
at 1245 Airplane flies back toward Scapa Flow Base and disappears over land.
UBOOT comes back up to periscope depth.
PERISCOPE SIGHTING lighthouse comes into light NE from UBOOT position, light stays on for 15 minutes.
PERISCOPE sighting of ship#4 from behind, going toward NE.
Browsing through Lloyd’s Ship Register, Officers identify ship as
TIME 1315 vessel can be observed to change course slightly and heard to accelerate speed.
Hydrophone reports sound of LARGE VESSEL GROUP at direction NE from UBOOT position, at distance more than 60 NM. Possible convoy formation.
HYDROPHONE starts cranking up and breaking sound.
Needs readjusting. Watch Officer orders repairs, adjustments estimated for 60 minutes.
Hydrophone still under adjustments.
PERISCOPE sighting of lighthouse at NE coming to light.
PERISCOPE sighting of Coastal Patrol Airplane
#5 - PERISCOPE sighting of large vessel coming toward land., at direction EAST from UBOOT position, distance 3 NM.
Vessel estimated to be most likely TOWN CLASS destroyer…
PERISCOPE sighting of Coastal Patrol Airplane.
Watch Officer takes UBOOT down to 150 meters.
Hydrophone still under adjustments..
Hydrophone adjusted and operational.
#6 - Hydrophone picks up sound of one big screw going north, at distance 7 NM, approximately NE from UBOOT position.
Coastal Airplane flies wide circle and disappears below LYTHE point.
#5 - Hydrophone can hear ship#5 moving toward LYTHE point.
PERISCOPE sighting of warship from behind, and Officers recognize vessel most likely as:
periscope sighting of lighthouse coming to light SOUTH of LYTHE point, for 20 minutes.
Hydrophone can hear #5 decreasing speed and making slight course change close to LYTHE point. Vessel disappears behind landmass around 1700 hours.
Hydrophone malfunctions. Checkup reveals broken wires which need to be replaced. Watch Officer orders repairs underway.
Weather: starts to rain, slightly. Sea state calm.
UBOOT floating at periscope depth.
#7 - PERISCOPE sighting of fast small boat.
Officers identify boat as:
Course heading toward UBOOT position - but quick course change at 2 NM from UBOOT position, continues toward land and disappears into narrow sound between SOUTH TOWN and RUMLEY POINT.
TIME 1915 - Hydrophone repaired and in good working order.
TIME 1940 - Sunset
#8 - periscope sighting of small boat coming out from narrow sound.
Course heading directly toward UBOOT position.
Watch Officer draws in periscope and takes UBOOT down to 120 meters.
Hydrophone keeps following vessel… one slow screw… as it comes directly toward UBOOT.
Vessel passes approximately 0,5 NM NORTH of UBOOT position,
Hydrophone can hear second diesel screw engaging - so small vessel with twin diesel engine… boat accelerates to 8 knots and disappears toward NE / NORTH
UBOOT floating at periscope depth 20 meters.
Sea is calm, and quiet all around
REWARDS FOR SUCCESSFUL IDENTIFICATIONS:
ID REWARDS: FIRSTOFFICER, NAVIGATOR and ENGINEER get 2 FREE ACTIVATIONS next session.
Based on observations of enemy movements,
OFFICERS WRITE RECOMMENDATIONS FOR CAPTAIN:
Officer’s Recommendation: In respect to a eastern approach to the basin, the southeastern approach appears to be used by smaller boats. No ships observed going through the Northeastern approach. Enemy appears to use lighthouses on rocky outcrops to guide what appears to be convoys east of the Scapa Basin. Movement of large vessels is covered by probable torpedo-armed aerial surveillance craft. Our conclusion is that the best approach would be from the south, by following in larger ships’ wakes.