Reflecting on Wind Week 2026 – The Need for Deep Push Seabed CPT

Introduction

Wind Week 2026 is in the history books, and as always this event sparked a healthy amount of debate and interest around the talks. Rather than cramming slides into an 8 minute slot as is often the case at an academic conference, speakers were able to dive deeper into their topics with 25 minute speaking windows providing much greater context and detail.

Of particular interest for the marine geotechnical industry, and Subsea Geo Tools who were an event sponsor, were two talks that both illustrated the need for increased Deep Push seabed CPT systems on the market. Firstly from the Deep Push Joint Industrial Partnership (JIP) presented by Olsi Koreta of Orsted and secondly a presentation from Chris Ruoso of Next Geosciences.

Current Situation and Growth of Offshore Wind

Taking the example of offshore wind we see, as in all branches of engineering, the limits being constantly pushed. Wind turbines are getting larger with one knock on effect being the need for deeper and deeper foundations and therefore ground investigations (GI). This is coupled with the need to embed those foundations into stiffer soils, soils which must be tested.

Thanks to it’s high repeatability, excellent resolution and sensitivity and importantly relevance to foundation design, particularly around cyclic loading, CPT and it’s oft utilized add-on Seismic CPT (SCPT) are often the go to tools for this GI. And the demand is not slowing down. Forecasts from GWEC, Spinergie and 4C Offshore project a growth of offshore wind capacity by 450% by 2035 from 45 to 200 GW (excluding China).

This all sounds like great news for those in the CPT chain from manufacturers and operators to data specialists, and it certainly is, but the consequence is that CPT equipment is also being pushed to its very limit and often beyond.

Limitations of Down the Hole CPT

The need for deeper and deeper CPTs, as well as the drive to push CPTs in less favorable soils, leads to an increase in the use of Down the Hole (DTH) CPT. A method whereby a CPT tool is sent down a borehole to take a discrete, normally up to 3m, CPTs before being retrieved and drilling resumed. The advantage of DTH is obvious, as long as you can drill down to it, soil at essentially any depth below seabed can be tested with CPT.

However the disadvantages are numerous. The most important from a geotechnical point of view is that the data certainly is no longer continuous. Even when a thick soil layer is testable with CPT the DTH device must be retrieved every few meters and the drilling advanced until the previously tested depth is reached by the borehole. These discrete tests must be stitched together and in doing so the effect of the drilling on the immediate soils is obvious, with lost intervals between tests and disturbed soils at the start of each push.

From an operational perspective the limitations are worse. The constant switching from drilling to testing and time spent deploying and retrieving tools means that a deep test (50-70m from seabed to target depth) takes approximately 4-6 times longer utilizing DTH than seabed CPT. And once you factor in the vessel cost comparison between a simple floating vessel that can deploy a seabed CPT system with a drilling vessel required to run a DTH system then you are left with the unfavorable conclusion that DTH costs a lot more per day and a lot more days per test.

Even if money were no issue the availability of geotechnical drillship’s certainly is. The JIP currently project a gap in drilling vessel capacity of 45% by 2030. In a cyclical business, even if upward trending business, investing in drillships that must work 65% of available days to not be a cost burden is clearly a sizeable risk.

The Solution – Deep Push Seabed CPT, but with a Difference

The argument for seabed CPT may then sound overwhelming. But that clear advantage of DTH, a soil at essentially any depth can be tested, remains. Therefore seabed CPT systems must be available that can get the CPT to the deeper target depths that are being specified.

The JIP identified the two main contributors to CPTs not reaching depth as being rod friction and rod buckling. A secondary contributor is lack of pushing force, however if you do not address the other issues, particularly rod buckling, then simply adding pushing force is not enough.

When conducting a marine CPT, particularly in deep water, the seabed system will often be deployed onto very soft marine sediments. These near-surface deposits can be so soft that defining a distinct seabed interface, the point at which the water column ends and the soil begins, can itself be challenging. Although steadily increasing in strength with depth, due to the overburden pressure, the soft marine deposits may be around 10 – 20m thick. This creates a significant portion of the marine CPT in which the rods have very little lateral support. Pushing into stiff underlying soils becomes a recipe for disaster as the applied pushing force results in bending of the CPT tubes, rather than penetration into the hard soil layers. Increasing pushing force will not solve this issue. The CPT tubes must be supported through the softest material, which is normally conducted by deploying casing. CPT casing is typically 55mm diameter and in some cases even this provides in sufficient lateral support.

Deploying high push capacity can help overcome rod friction, but it is only part of the solution. Minimizing rod friction is also critical to achieving deeper CPT penetration. This may be achieved using a mechanical friction reducer and, in some enhanced systems, by injecting water or another medium such as drilling mud along the rods. This reduces friction at the soil–rod interface, allowing more of the available thrust to be used for forward penetration rather than being lost to side friction. Rod lubrication is often particularly effective in stiff cohesive soils such as over consolidated clays, whereas in dense sands its benefit may be more limited and additional measures, such as increased push capacity, may be required.

The Pioneer CPT300 – Designed for Deep Push from Inception

Subsea Geo Tools recognized the limitations of both existing seabed CPT systems and DTH CPT for seriously addressing the growing demand for not only CPT quantity but also target pushing depth and the ever increasing strength of soils being tested.

The result is the Pioneer CPT300 a next generation deep push seabed CPT system designed from the ground up to address the limitations of existing CPT equipment.

Most powerful seabed CPT system

The Pioneer is built around our continuous dual pusher, Gemini, this allows the Pioneer to push a continuous CPT up to 6 cm/sec as well as utilizing both pushers to achieve more than 300 kN of pushing force. This makes the Pioneer the most powerful seabed CPT system in it’s standard configuration on the market. Importantly the Gemini has an integrated third clamp allowing the Pioneer to push casing through the soft seabed material to prevent rod buckling when pushing into underlying hard soils. The Pioneer is the only system on the market that can push casing up to 90 mm in diameter. Gemini is also built around the proven technology of hydraulic pushers rather than wheels or chains, both of which need to be stacked to achieve the same pushing forces as Gemini can. This also avoids the downtime associated with a system with as many moving parts as a drive chain.

Reducing rod friction

The Pioneer can also deploy a rod lubrication system for reducing rod friction. Due to our partnership with Royal Eijkelkamp we also have access to their unique SonicCPT  technology in which rod friction is also eliminated.

Not only is it important that the CPT cone reaches target depth, but if Seismic CPT (SCPT) is specified then the generated seismic waves must also reach that depth. The same marine deposits that can lead to rod buckling are also problematic for transmitting seismic waves. Instead of being propagated through the soil and down to the probe, in very soft materials seismic energy is dissipated and lost in the surface deposits. The Pioneer can deploy our unique push in SCPT source that allows the wave generator to be driven into the seabed, past the softest materials, into more competent layers. This increases the proportion of wave energy propagated through the soil results in stronger, cleaner seismic signal and improved confidence at depth.

Summary

The offshore wind industry is demanding more from marine geotechnical investigations than ever before. Foundations are becoming deeper, target soils are becoming stronger, and the volume of testing required is increasing rapidly. While Down the Hole CPT can provide access to great depths, its operational complexity, discontinuous data and reliance on expensive geotechnical drilling vessels make it difficult to scale efficiently.

Deep Push seabed CPT offers a compelling alternative, but only when the equipment is designed to address the real limitations that prevent conventional systems from reaching target depth. High pushing force alone is not enough. Rod buckling, insufficient lateral support, rod friction and seismic signal quality must all be considered as part of the same system.

The Pioneer CPT300 was developed specifically around these challenges. With more than 300 kN of push capacity, continuous dual pushing, large-diameter casing capability, rod lubrication options, access to SonicCPT technology and a push-in SCPT source, the Pioneer provides a complete approach to Deep Push CPT rather than simply adding more thrust to a conventional seabed system.

As offshore wind moves into deeper foundations and increasingly challenging ground conditions, the industry will need seabed CPT systems capable not only of collecting more data, but of reliably reaching the depths where that data is needed.