Stability calculations that hold for a tracked machine do not transfer to an amphibious one, and the difference is larger than most operators expect.
Why the difference
A tracked machine resists tipping through the reaction of a rigid track frame against solid ground. A floating machine resists it through buoyancy distribution across the pontoons. Buoyant restoring force builds progressively as the machine heels, rather than being available immediately. The practical result is that a floating machine tolerates less overturning moment, and gives less warning as it approaches the limit.
What this means in practice
- Attachment weight at full reach is the governing figure, not attachment weight alone.
- Buckets specified for amphibious and long-reach work are deliberately smaller and lighter. Fitting a standard bucket because it is available is a common and dangerous substitution.
- Slewing with a loaded attachment at reach is the highest-risk moment in the cycle, particularly with any list already present.
- Wet material weighs substantially more than the same material dry. Dredged silt is not the density of the soil it came from.
Before fitting anything
Confirm attachment weight against the rated capacity for the specific pontoon configuration, at the radius the work requires. If that information is not to hand, ask before fitting rather than after.