Here's my crappy attempt to represent a medium barrel roll in Excel.

EDIT: Okay, now I'm confused. Does a Medium-roll line up the back of the base to the back of the template, or the middle line of the base to the top of the template? The answer will affect the forward and backwards distance it can travel by an amount equal to 1/4 base.

Tough Crowd! Here's a new image that includes the new medium base, and also replaces the U-Wing from the original image with a ship that will remain large-sized in 2nd Edition. (If you're worried about the half-way marks along the bases, don't sweat it: Vassal can place the template midway, as I did to create these images).

3 minutes ago, PhantomFO said:

In a hypothetical situation where a medium-based ship does a barrel roll to its forward right, it will move 1/4 of a small base forward, and will travel a lateral distance equal to two small bases.

I don’t think in those terms, but I am pretty sure it travels half a small base forward, given how the template will be sticking out past the base some in the final position.

Incards looks right, phantomO’s isn’t.

1 minute ago, Forgottenlore said:

Incards looks right, phantomO’s isn’t.

It depends on how the ship gets placed after rolling. Mine was based on the assumption that you line up the back of the base to be flush with the bottom of the template. Incard's appears to be based on lining the center of the base with the top of the template. I don't know which one is actually correct here.

I'll use small bases sb as a unit of length.

A medium base is 1.5 sb long. When a 1 sb template is laid lengthwise next to it, aligning the midway point of the template with the midway point of the base, a small portion of the base "sticks out". The length of these pieces which stick out is 1/4 sb forward and 1/4 sb backward.

The placement rule for the medium base for the 2nd Edition barrel roll follows the same wording as the rule for a large base. Once the template is placed, the player is allowed to line up the newly placed ship so that it's midway point lines up with one of 1) the front edge of the non-moving template, 2) the midway point of the template, or 3) the rear edge of the template.

When barrel rolling forward, the newly placed medium sized ship will be 1/2 sb further forward than its previous position (notice that it will be "sticking out" 3/4 sb , but it was "sticking out" 1/4 sb before).

5 minutes ago, PhantomFO said:

It depends on how the ship gets placed after rolling. Mine was based on the assumption that you line up the back of the base to be flush with the bottom of the template. Incard's appears to be based on lining the center of the base with the top of the template. I don't know which one is actually correct here.

Exactly. That's the point I have been trying to make for days now. I noticed in the TC game with Alex that he was always describing it as lining up with the center hash mark, but they only used small and large bases in that game so it never made a difference. Then another TC video showed a medium based U-Wing and the template hung past the base at the end of the move and I thought "huh, everyone is describing that wrong". Now, this article confirms that you are using the center hash mark to line things up but people keep not paying attention to that.

I am very glad Incard got it right since I am unable to do visuals like that.

2 minutes ago, Forgottenlore said:

Exactly. That's the point I have been trying to make for days now. I noticed in the TC game with Alex that he was always describing it as lining up with the center hash mark, but they only used small and large bases in that game so it never made a difference. Then another TC video showed a medium based U-Wing and the template hung past the base at the end of the move. Now, this article confirms that you are using the center hash mark to line things up but people keep not paying attention to that.

I am very glad Incard got it right since I am unable to do visuals like that.

Yep, I had that wrong. So basically, their lateral movement is on par with a small ship, but their forward movement is on par with a large. I dig it.