This topic is about how to measure properly the fleet &objects in SH5 and not about how wrong the scaling is done compared to the real ships, right? Because ship scaling is another fine example of how bad this game was done.
Lets take 2 example of most common merchants, Cimmarion and Liberty cargo. SH5 vs reality:
=========Cimmarion tanker=============
Stock dimensions - ClassName=T3Cimmaron
MaxSpeed=12
Length=139.6
Width=18.5
Draft=7.3
Displacement=7600
Tonilo Real_Dimensions_Cfgs - ClassName=T3Cimmaron
MaxSpeed=12
Length=190.57
Width=41.83
Draft=10.50
Displacement=7600
Real life dimensions - USS Cimarron (AO-22)
Speed: 18 knots (21 mph; 33 km/h)
Length: 169 m (553 ft)
Beam: 23 m (75 ft)
Draft: 9.86 m (32 ft 4 in)
Displacement: 7,470 long tons (7,590 t) light | 24,830 long tons (25,228 t) full load
=========Liberty cargo=============
Stock dimensions - ClassName=LL
MaxSpeed=13
Length=147
Width=18.1
Draft=5.8
Displacement=7170
Tonilo Real_Dimensions_Cfgs - ClassName=LL
MaxSpeed=13
Length=140.91
Width=21.35
Draft=8.20
Displacement=7170
Real life dimensions - Liberty ship
Speed: 11 to 11.5 knots (20 to 21 km/h)
Length: 135 m (441 ft 6 in)
Beam: 17.3 m (56 ft 10.75 in)
Draft: 8.5 m (27 ft 9.25 in)
Displacement: 14,245 long tons (14,474 t)
And these are only the merchants. The capital ships are another story.. just look at the crew on deck and considering they are around 1.8m, see how many times they will fit into the ship visible height. Then look at pictures made in ports and compare the ship body to the people near them. No rocket science needed to see that the ship scaling in SH5 is a joke.
And I dont think this part will be ever fixed, at least not my modders.