RM ss have good flexibility, good torpedo damage, average tube number(4+4)of all nations except ss6.
 
SS6 is different from ss1~ss5. It have bad flexibility, slow speed (22/37 on surface, 18/31 underwater with almost max displacement)but very powerful firepower (8+6).

NOTE1: divetime: ss4 about 190seconds, ss5 210seconds, pss 222seconds, ss6 227seconds
NOTE2: Planeman ability cap is 4800k

heyho!

bullshit...

RM ss6 is theoreticaly possible to reach 40kn too like allothers except IJN - but only with extremely optimized crew (mega-engies!) or sacrificing handful of torps. just a point of weight...and/or money ;-)

but its very hard to reach...

with that i think its maneuverability is not soo bad.

38kn easy, 39kn no bigger problem... ;-)