Sneaking silently:

     The formula for the % chance for a non-thief to sneak undetected is as follows:
Coordination ÷ 2 (rounded down) = the % chance.

 

Note:

A character with the ability to move or sneak without detection may use this as a second chance to remain undetected.

 

Armor penelties for sneaking:
     The following are the penalties for all characters and creatures to sneak silently vs. the type of armor worn. Alloys do not matter; the make of the armor is what causes this penalty as follows:
Penalty to sneak silently vs. armor worn:

 

Leather:   None
Skin:        None
Ring:       -20
Scale:      -25
Chain:     -15
Banded:  -30
Splinted: -30
Plate:      -35