Sea Scout

1 Seascout

If you’re a survey company and you’re out for two weeks at a time mapping the ocean floor, you need a low-speed boat. But if you have a low-speed boat, the last thing you want is to waste 24 hours getting to and from your survey site.

What if you could have two boats in one, a troller and a speed hog? That’s the idea behind Sea Scout, a 134-foot survey vessel built by All American Marine of Bellingham, Wash., for C & C Technologies of Lafayette, La., an international giant in offshore surveying.

The solution is an extremely unusual quad-propeller arrangement in which two Caterpillar C32 diesels spin 42-inch-diameter propellers via ZF 3055A transmissions and two smaller Caterpillar C18s are mated to ZF 550V transmissions to turn 33-inch-diameter props. Fire up the after burners and you’re off to the races at up to 24 knots fully loaded. Power down, and you can troll around for days at 6 to 8 knots.

Brian Gauvin

Survey technicians Jeff Maslak (left) and Riley Chapple deploy side-scan sonar from the stern A-frame.

Scott Croft, C & C’s vice president/geosciences manager admits that when the concept was initially presented, his first thought was of possible complications — “We’ve got to buy four engines instead of two, and we’ve got four propellers to bend instead of two.” But the advantages of the design won him over. So did the chance to build a boat from scratch, especially in a charter market with a dearth of suitable vessels longer than 80 feet.

“It’s a purpose-built research vessel,” he said. “It has a few key pieces that are really hard for me to get out of a normal charter. We’ve got the accommodations; we’ve got a research lab built into the boat so you don’t have to put a container on the back deck.

Brian Gauvin

Capt. Scott Lanclos at the bridge console.

“We’ve also got a lot more power than many boats do. We’ve got 170-kW generators that can be paralleled, so we should never run out of electric, and integrated hydraulics keeps some stuff off deck as well.”

The vessel’s designer, Nic de Waal, of New Zealand’s Teknicraft Design Ltd., said he doesn’t know of any other vessels of Sea Scout’s size with its propeller configuration. “It’s quite unique,” he said. The larger propellers are lower and farther aft than the smaller ones. “They are placed such that the wake of the small propellers merges positively with the larger propellers, thereby increasing the efficiency of the props,” said de Waal.

On either side, one engine faces forward and one aft.

“It is quite common to mount engines facing aft, typically in V-drive configurations, and we have often mounted generators athwartships, so although the mounting was not complicated, the exhaust systems certainly were, partly due to the twin exhaust outlet of the C32,” de Waal said.

“We had to deal with four exhaust outlets and incorporate silencers and feed all the piping into and through the dry stack, all within limited space.”

Sea Scout went to work at Ship Shoal, 90 miles west of the mouth of the Mississippi, collecting side-scan and multibeam data to help the National Oceanic and Atmospheric Administration update its charts. Hurricane Isaac interfered, however, and in September the survey vessel was out checking pipelines after the storm.

Courtesy All American Marine

The quad-propeller arrangement as seen from astern. All American Marine’s Joe Hudspeth calls it “unconventional conventional propulsion — I don’t have a cool term like diesel-electric.”

Croft said Sea Scout can handle deep water — it is SOLAS-compliant and could work in Brazil — but it can also operate in 10 feet of water along the coastline. Crewmembers are typically on board for four weeks at a time, half of them cycling out every two weeks. Crew accommodations occupy the main deck and forecastle, with a commercial galley, lounge, fitness room, laundry, four heads and 12 staterooms. “The creature comfort’s a little better than on some normal boats,” said Croft. “That was probably a big one for me.”

Survey operations are on the 01 deck and the pilothouse is raised for 360-degree visibility, although it still has a low profile.

There is a large moon pool on the centerline aft of the superstructure, but the workhorses of the open deck are two A-frames: a 10,000-pound version on the starboard side and a 14,000-pound one at the stern. The side frame handles non-towing operations, such as bottom sampling or closed-circuit TV. As well as towing, the stern frame can handle static work such as taking piston cores or box cores.

Croft said a few design changes were made along the way — adding extra fuel tanks, for example — and Louisiana has presented a couple of pesky challenges of its own. The heat and humidity have been straining the HVAC system, and the shallow water and slow speed have attracted barnacles. C & C has been working to correct both issues.

Sea Scout is the largest vessel All American has built, and Joe Hudspeth, the shipyard’s business development manager, said it needed every skill in the yard, from electronics to hydraulics to passenger spaces. One skill in less demand than usual was painting; for the first time, All American used vinyl as the exterior coating.

“All of the coatings save the bottom paint are peel-and-stick, including the nonskid on the working deck,” Hudspeth said.

Brian Gauvin

The catamaran’s pontoon configuration.

The supplier was Orca Maritime, a German company that has used its product to clad oil rigs and roll-out graphic designs as large as 43,000 square feet on cruise ships.

“Aluminum is the perfect surface to the ORCA HT film as it will stick extremely strong and straight without any special surface prep,” said Manfred Haack, Orca Maritime’s managing director.

For All American, which has a history of innovative vessel construction — Rich Passage 1, a hydrofoil ferry capable of 40 knots that it built for Kitsap Transit, went into service this June — Sea Scout came along at the perfect time.

“The survey market has been huge for us during this economic slowdown.” Hudspeth said. “It has really been our core market that has kept us afloat, and we still see it growing.”

For now though, it’s back to the future for the shipyard. “Our next two contracts are from private operators in the passenger vessel/passenger ferry market segment, which is back to our core competency and our roots,” said Hudspeth.

By Professional Mariner Staff