Insights
Pile Run Parachute
A Mitigation Solution for Pile Run of Monopiles and Pin Piles
- Bas van Wuijckhuijse
- 5 May 2026
What is Pile Run?
Pile run happens when a monopile (MP) or pin pile(PP) suddenly sinks into the seabed faster than intended. The pile loses resistance, accelerates downward, and causes effects like hammer/lifting tool shock loads, risking the pile, vessel, equipment, and, most importantly, safety.
As offshore wind moves into tougher seabeds and piles become larger and heavier, the risk and impact of pile run increase significantly.
Pile Run Parachute
The Pile Run Parachute (PRP) is a lightweight, reusable, internal parachute system that slows down a falling pile by restricting water flow through a controlled top orifice.
Its sealed dome shape transfers loads along the pile and avoids interference with hammer blows.
Key features:
- Sealed hemispherical insert in the pile
- Strong hydrodynamic damping, i.e., controlled descent
- Lightweight, removable, reusable
- No negative effect during pile driving
Test-PRP provided by the Unique group.
Experimental Validation Tests
We dropped a 400kg pile with PRP in a basin during a 1:10 scale test at MARIN. There, we verified the PRP’s dynamic behavior and confirmed the accuracy of our simulation models.
More than 30 configurations were tested, varying:
- Pressure‑relief concepts
- Orifice size
- Parachute slackness
- Connection stiffness
Key Takeaways
The PRP drastically reduces pile run speed, up to 26× times. Parachute stiffness and slackness influence the peak load (DAF), while the effect on falling time remains limited.
Test Results
- Terminal velocity drops to safe, crane‑comparable levels
- Orifice size controls the descent speed vs. peak load
- Stiffness and slackness strongly influence initial impact
- Pressure regulator reduces the peak load effectively
- Simulation models match experimental results
Pressure Regulator
A pressure regulator helps reduce the dynamic peak load (DAF) while keeping the pile’s terminal velocity. At the very moment of impact, the regulator briefly opens, allowing extra water flow and limiting the reaction load on the pile, with only minimal effect on fall distance and velocity.
Two concepts were tested: a torsional‑spring regulator (PRTS) and a compressional‑spring regulator (PRCS). Both showed clear potential, as well as opportunities for optimization in the next design phase.
- PRTS: ~10% DAF reduction
- PRCS: ~16% DAF reduction
- Both slightly increase time to terminal velocity.
Pile Driving
During hammer installation, the PRP must not absorbdriving energy.
Tests confirmed the PRP feels only ~0.2% of the pile’sweight during driving (effectively insignificant),ensuring full hammer efficiency.
Key Conclusions
- PRP effectively slows monopiles to operationally acceptable levels.
- Scaled tests closely match simulation results.
- Full‑scale PRP solutions ready to be tailored to pile and site conditions.
Room for Improvement
- Improving the overall PRP sealing
- Further refining pressure‑regulator design for expected loads.
In this video presentation, our R&D Manager, Bas van Wuijckhuijse, provides a more in-depth explanation of the topic. Watch it here:
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