In this thesis, the friction performance of polyurethane tensioner pads used in offshore pipe-laying was investigated. Tensioner pads are used in pipe-lay to create tension in a pipe. The need to understand the pads better is because of the increased use of pipe coatings and pipe lay in deeper waters. Deep water leads to more pipe tension, and polymeric coating reduces friction.

A literature review was conducted on the friction of polyurethane. From the literature review, a few variables that influence polyurethane friction behaviour were summarised into the following research question: What is the influence of normal force on the pads, pad hardness, pad geometry, and pad temperature on the friction performance of polyurethane tensioner pads?

Experiments were performed at a full-scale setup. Polyurethane has a nonlinear coefficient of friction, making it difficult to upscale results from laboratory testing. In the full-scale setup, existing pads can be tested to find the influence of the different variables from the research question. The test setup was found to be flawed. Not only did it deform due to the massive forces, but the data gathered from the hydraulic pressures was not robust and accurate enough to estimate the static coefficient of friction, which is important in tensioners. Therefore, only trends in the pad behaviour were observed.

Increased normal force on the pads was found to increase the coefficient of friction. This contradicted the literature but was likely due to the geometry of flat pads versus round pipes, where the contact surface increased when the pads were loaded. Softer pads were found to yield higher friction than pads made from harder grades of polyurethane. This effect was also found in the literature. The influence of temperature was difficult to test. Since the pads could only be heated externally before testing, temperatures were inconsistent, and test results were inaccurate. The temperature did affect the friction significantly, though, so some newly produced pads were fitted with internal heating.

Next to the experiments, different pad geometries were tested in finite element analysis. A new pad shape was found that decreased stresses, leading to higher friction.

Next to the variables of the polyurethane itself, the relative humidity was recorded. The relative humidity changed significantly during the different tests, and it was found to affect friction more than anticipated.

Three sets of new pads were produced for future testing to validate the influence of geometry and further investigate the influence of the pad temperature. Moreover, a new test setup was designed to test the coefficient of friction more accurately.

This research examines the possible pathways and available technologies that will help the shipping sector to achieve the climate goals set by the IMO. Reaching these goals will require financial incentives and policies regarding sustainability. These policies need to describe regulations at both international and regional level given the maritime sector’s 3% contribution to GHG emissions (Tatar & ÖZER, 2018).Previous research examines only the performances of the new technologies. This research includes both aspects to assess the different options, from the sustainable point of view as the business point of view.The goal of this researchwas to investigate the possibilities to apply renewable energy sources to a vessel that transports polymetallic nodules from the Clarion-Clipperton Zone to Mexico in order to reduce the carbon footprint. Besides this, also look into which of these possibilities has the lowest costs. For this purpose, multiple propulsion drive train systems were examined which were based on the Panamax Leda C. The behavior of these new propulsion systems was examined to answer the following research question: “Which currently existing energy source(s) can be used to transport the polymetallic nodules from the Clarion-Clipperton Fracture zone to the coast of Mexico, a 2200 km route, and whose operational use is technically feasible in five years, in the most sustainable way and with the lowest costs?". To answer this research question, the following steps have been undertaken. First current technologies and their state, were analysed using technology readiness levels (TRLs). The known data was established which included the cargo, the requirements for the fleet, the total days at sea, total amount of nodules collected in one year and the buffer of the mining vessel. With this information an optimal base case was determined in terms of energy consumption and costs. The base case is a Panamax bulk carrier called the Leda C with a deadweight of 81526 dwt.Two different key performance indicators (KPIs) were set to analyse the different performance systems. These KPIs are the emission reduction per tonne collected nodules in %/tonne and the costs per tonne collected nodules in $/tonne.To examine the different propulsion systems, their performances had to be checked for this specific route. In this route analysis there is looked at the probability of the wind, which was necessary to calculate the performances of the wind assisted ship propulsion (WASP) systems. Drive trains of the different propulsion systems were schematically given and analyzed to understand which systems should be implemented for the different propulsion systems. After this, the components of each propulsion was checked, looking at their performance, sizes and costs.The costs of the total drive trains of the different propulsion systems were elaborated. Finally, three different scenarios were chosen to examine the KPIs of the different propulsions.It is concluded that the most cost-effective technology for the RE on board systems is the Flettner rotor and for the alternative fuels this is biofuel (HVO). The propulsion systems discussed in this research will only be attractive when the CO2 tax will increase. It is concluded that the higher the carbon tax, the more attractive the alternative fuels become in terms of cost effectiveness.The advice for Allseas will be, if nothing changes, to not install a sustainable energy propulsion system. Because all systems will be more expensive than the base case. If regulations make it necessary to reduce emissions, it is advised to install the Flettner rotor in hybrid with the current engine.