Superior recently designed and built a pontoon for Sydney’s heritage-listed Chowder Bay Wharf and tenant, Sydney Institute of Marine Sciences (SIMS).
The upgrade works included the extensive replacement of dilapidated wharf piles and decking timbers, as well as the installation of a new steel pile system on the wharf’s western facade to safely accommodate larger vessels.
Located near Mosman on Sydney Harbour, Chowder Bay is exposed to some impacts of weather and also proved a challenge in terms of access.
As Superior Project Manager, Luke Tapfer explains: “The brief was to blend the old with the new and retain the heritage look as close as possible. Access was an issue because the site is so close to the headland. We had to transport the pontoons from Sydney City Marine and cross shipping and ferry channels.”
The location is situated in a marine park, adding to the complexity. “We were unable to use cement blocks, so we employed the Seaflex underwater anchor system, which is environmentally friendly. Superior worked with sub-contractor Anchoring Rope & Rigging on this which was a very smooth process.”
The Seaflex underwater mooring system doesn’t damage the seafloor as the elastic hawsers retain tension on the fixings at all times, thus keep all of the supporting mechanism off the seabed. The anchors used are a Hulk Earth Anchor that uses a harpoon design to fix a “deadman” anchor within the earth and therefore this is very efficient.
All of the Seaflex units were tensioned from the surface using the patented Trumpet Mooring Tube (TMT). This tube provides smooth egress for the ropes through the base of the concrete pontoon and up a polyethylene lined concrete filled tube to an inspection pit in the deck.
This subsea anchoring technology will become increasingly important with wave attenuation, deep water sites and rock issues; where heavy duty installs can be completed without the need for piles.
Superior installed its heavy duty Super Elite™ pontoon system combined with its Capri™ marina system for vessels to berth.
Spear Green Design was responsible for the design and project management of the extension of the existing hardwood wharf facility adjacent to its research centre.
Jeremy Spear, Principal at Spear Green Design said the wind wave data for the site made the project quite difficult. “SGD had previously specified a Seaflex system of floating marina for other projects in the Middle East, so we were familiar with a floating pontoon system with no requirement for piles. This proved attractive to the client, due to the reduced costs and also proved attractive due to not having the visual impact of piles.
“SGD worked with Superior Jetties to complete required engineering to confirm the system was appropriate and the desired result achievable in this tricky location.”
Superior Jetties fabricated the two sections of floating pontoon, a heavy wave attenuating unit and a lighter weight Capri. Once assembled and subsea anchors installed, the units were joined together and secured to the seabed using the Seaflex connection system. A custom built Superior gangway was also installed.
“SIMS now has the capability to moor several research vessels on a floating pontoon system, allowing valuable research to take place more efficiently and safely than before. The facility also had a requirement to open access to the immediate foreshore area, restaurants and event centres by providing access for people with disabilities who may arrive by water – whether ferry or water taxi, when required.”
Sydney Harbour Federation Trust Executive Director, Geoff Bailey said that the opening of this wharf for public access and community use will encourage more people to visit the picturesque harbour side precinct as vessels can use it to drop off and pick up their passengers.
“People can now arrive at Chowder Bay by water taxi or boat to have a meal at Ripples or East Coast Lounge, go to a wedding or function at the Sergeants Mess or visit the new SIMS Discovery Centre in the historic former Submarine Miners’ depot,” Mr Bailey said
“Our recently completed upgrade has improved the wharf’s berthing capacity so that it can accommodate vessels up to the size of Sydney Ferries’ First Fleet class ferries.”