[ericbsmith]

The major effects are much as people have already described.

• Acceleration will be directly impacted and reduced. Delta-V will need to be significantly recalculated, since the Delta-V multiplier is based on the percentage of the ships mass that is fuel and that percentage is going to change due to the overloading.
• Handling and Stability Rating should be impacted. Handling should be reduced, SR would probably actually get a bonus since a more massive ship is more stable.
• In an atmosphere and a gravity well a temporary reduction of HT would be in order, since you will be overstressing the hull. Continual overloading of the ship may call for a permanent reduction in HT as damage is actually done to the hull. These won't really affect space or interstellar operations, since any overstressing is likely countered by the lower acceleration.
• Even in space, it is possible a poorly loaded and imbalanced load could do damage to the hull, but this is true even if loaded within mass limits. Overloading just exacerbates the problem. Freight Handling skill is important here.
• FTL drives may not work as efficiently, or may not work at all, depending on how FTL works in the campaign. An FTL-2 drive may only be able to make FTL-1 speeds, or it may not be able to travel in FTL at all.