Well maybe I figured out my own question.. instead of a extrusion by distance, I used vector and extruded to a fixed point at the desired distance.. worked fine.

But.. I'm still curious why one profile using the distance method decided to follow the wrong direction?

oh. i definitely had that happen to me before and it drove me crazy! This is when we select/extrude a bunch at the same time. Some will go this way and some the other way (for the strangest reason :)) Sometimes they behave well/good though.

Just last night/this AM, I was trying to do the same thing, to extend five surfaces along the x axis to represent decks/flooring. I then offset-copied the construction lines to the next distance, re-drew surfaces in a rectangle, and then thickened those.

I ended up just using the thicken tool and thickened them to the distance needed. After a while, getting tired of that approach and just thickened the next 5 surfaces most of the total distance and then used a surface to trim them. Tiring of that, I used a solid (a circle's surface thickened) to intersect trim the plate and then selected and discarded the 5 thin slivers of steel.

I then realized that I didn't correctly place my solid. Rather than futz about deleting and retrawing, I calculated the gap I needed to make up for and then moved the faces. I did it with a face offset or similar tool. I find this is much faster than what I was donig 1.5 years ago. Fortunately, VCP 7 now auto joints surfaces after a mesh is converted to surfaces-- quite a time saver.

clarification of what my poor approach was before:

I drew lines for each deck and then created surfaces from them, then joined the surfaces, and then stitched them. When I ddn't correctly or completely make an enclosed or tolerantly closed box, I failed to obtain solids. Extruding or thickening surfaces seems MUCH cleaner a way to get the solid.. Then obtain the outside hull piece by copying the hull sideshell and hiding the original. I then take the 5 deck plates that originaly extend past the hull sideshell and then trim those thickened decks with the sideshell.

When I need to form fuel or ballast tanks, i use a copy of the sideshell, break it with a surface that is part of the inside boundary of the volume, join the generally neat surfaces, and join that join to the other sides made of boundary surfaces, and then stitch to make a solid.

If you're using VCP to create tanks, DO NO USE SOLIDS AS ANY PART OF THE TANK. You will get wrong volume values for fuel or ballast or potable water because VCP will see the solids present and calculate THOSE volumes instead. At least, that is what I saw. It reported 1.2 some odd tons when I knew the volume should have been nearer to 58 tons.

If you're using VCP to design ships, keep a separate dxf or similar source model and separately use THAT one for making liquids tanks so you have a cleaner model.