Weight and Trim Procedure

GreyLynx · 01-26-20, 04:45 PM

Before heading to the open sea / combat area, the Weight and Trim Procedure should be carried out (Sea Trials) as described in the "Diving Regulations for U-boats" document (uboatarchive.net/Diving/DivingRegulations.htm).

In the Wolfpack game, this is how I do it:
1. On the surface, Conning Tower Hatch closed, engines stopped, I flood the Main Tank Ballasts, I purge the Trim Tank and the Negative tank if necessary.
2. I check the depth on the "Water above base of keel Meter" next to the Trim Meter. This is the Base Depth which is proportional to the weight of the boat (Archimedes principle). In the game, it varies randomly from 7.6 m to 9.8 m, based mainly on the amount of fuel on board. I assume that at a Base Depth of 9.8m, the boat is fully loaded.
3. I adjust the Trim Tank to lower the boat to a depth of exactly 11.6 m, which is the Neutral Buoyancy setting. Beyond this point, the boat has a Negative Buoyancy and starts sinking. BTW at the beginning of the game, the Trim setting is automatically set to this value (more or less).
4. The Base Depth and Trim Setting are kept in the Diving logbook (for those who play by the book).

If the Base Depth is 9.8, then the Neutral Buoyancy Trim setting is 4 m³. If the sub weights 761 tons on the surface and 865 tons submerged, then adding 100 m in the MBTs will add 100 tons to the surfaced sub, and the Trim tank will add 4 more tons.

Note: When torpedoes are fired, the boat becomes lighter, therefore the Dive Officer must adjust the trim setting accordingly to maintain Neutral Buoyancy. The trim setting may also need adjustment based on speed and Dive Planes positions. On the other hand, water density (salinity) is not taken into consideration in the game (yet).

The following table shows the Base Depth / Trim setting I measured during testing:

Base
Depth Trim
----- -----
7.6 m - 11 m³
7.9 m - 9 m³
8.2 m - 8 m³
8.5 m - 7 m³
8.9 m - 6 m³
9.4 m - 5 m³
9.8 m - 4 m³

May I suggest that this procedure be added to the responsibilities of the Dive Officer.

01-26-20, 04:45 PM	#1
GreyLynx Watch Join Date: Mar 2019 Location: The Great White North Posts: 18 Downloads: 22 Uploads: 0	Weight and Trim Procedure Before heading to the open sea / combat area, the Weight and Trim Procedure should be carried out (Sea Trials) as described in the "Diving Regulations for U-boats" document (uboatarchive.net/Diving/DivingRegulations.htm). In the Wolfpack game, this is how I do it: 1. On the surface, Conning Tower Hatch closed, engines stopped, I flood the Main Tank Ballasts, I purge the Trim Tank and the Negative tank if necessary. 2. I check the depth on the "Water above base of keel Meter" next to the Trim Meter. This is the Base Depth which is proportional to the weight of the boat (Archimedes principle). In the game, it varies randomly from 7.6 m to 9.8 m, based mainly on the amount of fuel on board. I assume that at a Base Depth of 9.8m, the boat is fully loaded. 3. I adjust the Trim Tank to lower the boat to a depth of exactly 11.6 m, which is the Neutral Buoyancy setting. Beyond this point, the boat has a Negative Buoyancy and starts sinking. BTW at the beginning of the game, the Trim setting is automatically set to this value (more or less). 4. The Base Depth and Trim Setting are kept in the Diving logbook (for those who play by the book). If the Base Depth is 9.8, then the Neutral Buoyancy Trim setting is 4 m³. If the sub weights 761 tons on the surface and 865 tons submerged, then adding 100 m in the MBTs will add 100 tons to the surfaced sub, and the Trim tank will add 4 more tons. Note: When torpedoes are fired, the boat becomes lighter, therefore the Dive Officer must adjust the trim setting accordingly to maintain Neutral Buoyancy. The trim setting may also need adjustment based on speed and Dive Planes positions. On the other hand, water density (salinity) is not taken into consideration in the game (yet). The following table shows the Base Depth / Trim setting I measured during testing: Base Depth Trim ----- ----- 7.6 m - 11 m³ 7.9 m - 9 m³ 8.2 m - 8 m³ 8.5 m - 7 m³ 8.9 m - 6 m³ 9.4 m - 5 m³ 9.8 m - 4 m³ May I suggest that this procedure be added to the responsibilities of the Dive Officer.