An assessment of the feasibility of using skirt containment boom together with paravanes for offshore response

The use of conventional offshore containment boom is a recognised way of containing and recovering oil spilt at sea. However, there are various operational and logistical challenges with their use. One of the largest being that their containment becomes ineffective when towed through the water at speeds of greater than 0.75 knots. Containment and collection of oil using high speed systems allows for greater tow speeds (2–3 knots) without failure and can be operated with a paravane as a single ship system. Oil Spill Response Limited (OSRL) have had numerous requests from its members to supply offshore containment and recovery systems suitable for a single vessel deployment. The reason for this was to help with the challenges of low availability of vessels suitable for offshore operations and to reduce high costs. OSRL have used manufacturers guidance to advise its members on the best options however wished to have its own data to further support this guidance and provide user-validated recommendations to its members. OSRL have investigated the viability of using a paravane with a conventional offshore boom using field tests. These tests focused on vessel tow speed, current speed, boom containment effectiveness and encounter area. A number of deployments were carried out using conventional inflation boom and a medium sized paravane in Southampton Water, UK in 2018 (Figure 1). Observations were gathered to identify the point of boom failure when towed at different speeds and whether a suitable encounter area could be achieved. This poster will provide the detail on the feasibility of towing a conventional offshore boom with a single vessel and paravane, see boom configuration in Figure 2. It will outline specifications and parameters which make for a successful / unsuccessful deployment of conventional boom with paravane and provide recommendations for Tier 1 single vessel deployment equipment.

THE SIGNIFICANCE OF WAVE REFLECTION ON THE MORPHOLOGY OF INTERTIDAL MUDFLATS

The influence of seawalls in modifying the equilibrium form of a shoreline has previously caused extensive debate. A numerical model was used to predict the equilibrium form of muddy intertidal profiles, along a shoreline in Southampton Water, UK. It was found that the profile containing a seawall had a very different profile form to the undefended sites, and that this seawall profile could not be accurately represented in the model. The model was extended to include wave reflection from the seawall, producing a new prediction with a much improved resemblance of the observed profile. It was concluded that the likely cause of the different profile form at the site of the seawall in this case, is due incident and reflected wave interaction.

Metabolic rate and growth in the temperate bivalve Mercenaria mercenaria at a biogeographical limit, from the English Channel

Metabolism and growth rate of the hard clam, Mercenaria mercenaria, were investigated in a population invasive to Southampton Water, southern England. An individual metabolic model expressed as a function of soft tissue dry mass was fitted to data of 18 individuals (log (VO2) = −1.952 + 0.543 • log (DM); F1,16 = 201.18, P < 0.001, r2 = 0.926). A von Bertalanffy growth function was fitted to 227 size-at-age data pairs of 18 individuals (Ht = 80.13 • (1 − e−0.149 • (t−0.542)); r2 = 0.927). Individual age-specific somatic production was calculated, demonstrating increase with age to a maximum of 3.88 kJ y−1 at ten years old followed by decrease, and individual age-specific annual respiration was calculated, demonstrating asymptotic increase with age to 231.37 kJ y−1 at 30 years old. Results found here lie within the physiological tolerances reported across the biogeographical range, suggesting that the species' biogeographical limitation in the UK to Southampton Water results from ecological rather than physiological factors.