FTL jumps, gravitation and oort clouds

On the subject of FTL and system jumps:

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>> On the other hand, as I keep mentioning, there's this thing probably
>> around most systems called an Oort (can't do umlats) Cloud, so, do
you
>> have to move outsystem 1/3 the distance to the closest star before
you can
>> engage FTL? *shrug*

>The gravitional effect of a hollow sphere, experienced anywhere 
>inside the sphere is zero. Now, I can't remember off the top of my 
>head whether the Oort cloud is a ring or a cloud but the same effect 
>applies in either case. (If it is a ring then you'll start to feel a 
>pull only if you leave the plane of the ring.)

>Of course it's rather more likely that considering the density of the 
>Oort cloud (low) and it's distance from the sun/earth (large) that it 
>doesn't produce a large enough gravitational gradient to effect FTL 
>jumps.
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An Oort cloud is not a sphere or disk because of gravitational pull on
itself,  as is the case of water or other liquids in zero gee, in which
case the above is true, The individual particles of the oort cloud are
in orbit around the star not static gravitation and surface tension. The
thickness of a 0G liquid shell is constant, barring outside
intervention. The thickness/density of any star's oort cloud depends on
the timing of the measurement to the orbits of the various particles.

As to ring or sphere, that just depends on the angle of incidence of the
particle to the solar body that captures it, as well as how many
particles the star has captured over its lifetime.

For FTL jumps, civilian ships will jump well inside or well outside the
oort cloud depending on internal and external dameters of the cloud
orbits, and sublight travel the remainder of the way in, (1 week to 1
year depending on world technology and distance of jump point to
destination). Military vessels may try to use the cloud of a paticularly
old star to hide in. The individual effects are dependent on the
scenario.