USN/DTRC Low Observable Force [Fleet Concept 13]

Here's a late 80's/early 90's concept from the David Taylor Research Center (now Carderock Division, NSWC) for a semi-submersible warship. Looks like it was intended to be nuclear powered, using waterjet propulsion. Also referred to as the Low Observer Force. With the intention of being able to operate in an enemy's own backyard, it was primarily designed for ASuW and Land Attack. The design was suited for use with Ambush, Surprise Attack & Hit and Run tactics in particular. At this remove, they appear to have been aiming at a operational displacement in the 4,000 ton range. Frigate sized in other words, but packing a heavy offensive punch.

Edit: Before you ask, I have been wondering what it's planned secondary armament would have been, ASW and AA wise. One highly likely possibility for ASW would have been a VL variant of the UUM-125A.

Originally found this in a paper linked to by TomS over in another thread [second link in post]):

A later, separate French concept.

Is this a believable shape for a hull meant to move under the sea surface ? It probably would stay semi submerged
for most of his mission. Reminds me of WW II/pre WW II subs, but those were mainly meant to stay on the surface
on submereg only for a realtively short time.

The BMG SSGT is worth a look from that perspective - its' unusual inverted-vee hullform was apparently the result of studies into the optimum shape for operating just below the waves.