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Delta Seiner Sponsoned

A 53-foot by 15-foot fiberglass seiner improved its seakeeping, beam and capacity with a sponsoning and refit at Platypus Marine, in Port Angeles, Washington.


This drawing shows the existing, lighter hull nested in the darker sponson components. Artwork courtesy of Platypus Marine.

Bruce Marifern operates the 1980-built F/V Freedom primarily as a salmon Seiner and contract tender. Marifern has a small family fishing operation out of Petersburg, Alaska and runs equipment in Bristol Bay as well. "I employ neighborhood youth and help them earn college money," he says. "I take them up to fish Bristol Bay and then down to Southeast and they have tuition for the year."

Stability and safety concerns, as well as a desire for more hold capacity led Marifern to consider sponsoning the vessel. He turned to Naval Architect Jonathan Moore, with Tim Nolan Marine Design in Port Townsend, to determine the viability of the widening project, and to Platypus Marine, in Port Angeles, Washington, to perform the work.

A Good Start

The Freedom's hull was built as a 48-foot by Delta Marine Industries in 1980 for a longtime employee as a retirement gift. He finished the house and deck, added machinery and rigging and fished the boat out of Chignik before selling it to Marifern. Marifern removed a tuna bridge and added tripod rigging and a small bulb in the bow, and fished the boat out of Petersburg.

Marifern added five feet to the stern in 2011 and a bow thruster in 2012. Delta Marine did the lengthening work and the thruster was installed by Piston and Rudder, of Petersburg, Alaska. At the same time, Piston and Rudder added an articulated rudder for better handling.

"That rudder made a lot of difference," Marifern says. "The boat could literally turn around in in its own length after that."

Design and Engineering

Jonathan Moore performed the design and engineering work for the sponsoning project and related modifications.

"Jonathan Moore hit the nail on the head," Marifern says. "He and Tim Nolan deserve a lot of credit for how well this project worked out."

Both Moore and Nolan are Sitka-based trollers, and along with their talent in naval architecture, Marifern credits their commercial fishing experience along with their fiberglass skills with the speed of the project and the finished vessel. "The whole project took 4 months," he says. "I can't say enough good things about those two."

After initial design parameters were established, naval architect Moore and owner Marifern worked with Axis Surveying and Mapping who performed a full detailed laser scan of the vessel and mold at Platypus Marine.

The scan information was imported into CAD software, creating 3D computer models, allowing for very precise design and engineering calculations to be produced by Jonathan Moore. The Delta's existing round chine configuration was converted to a hard chine design, which provided a large increase in hold capacity and roll dampening, with the greatest improvement in stability. 3D computer models allowed Jonathan to determine how to locate the new sponsons on the existing vessel, with the goal of blending in the new components, while maintaining fair lines and hiding the fact that the vessel has been sponsoned.

Construction Innovation

Unlike typical one-off projects, the new sponsoning sections were derived from a Platypus-owned 53-foot by 17-foot Hansen boat company mold. "We used the two side parts of the mold and left the bottom and keel," Marifern says. "We also added four feet at the stern."

Platypus hopes this approach will allow future sponsoning projects to be undertaken in a more "Production" atmosphere, resulting in cost and duration efficiencies. The components were built with hand laminated construction methods utilizing vinyl ester resin and biaxle knitted fabrics. New bulkheads, deck sections and stringers are built with foam core construction. Finally, the new hull received an Awlgrip paint job.

The Payoff

This bow-on view shows the hard chine of the new sponson, which will help in seakeeping. Artwork courtesy of Platypus Marine.

The sponsoning modification results in increasing Freedom's beam from 15-feet 5-inches to 20-feet, one inch, a greater beam than existing, conventional Delta 58-foot seiners. The sponsoning also provides a 300 percent increase in the vessel's initial stability and righting energy, while the wider beam and hard chines increase the fish hold capacity from 1,000 cubic feet to 1,250 cubic feet- a 25-percent increase. Although wider and longer, boat can still use the existing 400 HP main. Platypus says this type of modification can bring to an older vessel, more updated capabilities, while avoiding the costly Coast Guard regulations and inspections, on new vessels built after July 1st, 2012.

During the sponsoning and refit, Freedom also had a complete rebuild of her CAT 3406 main and gear box, a complete AC/DC electrical systems and wiring replacement, a new 18 ton refrigerated raw seawater system, refreshed crew quarters and pilot house interiors, along with a new navigation electronics suite.

Marifern is back in Petersburg, having wrapped up the Southeast salmon season and preparing to go out on a tender contract.

"I couldn't be happier with the boat," he says. "When the guys load the hold, the boat goes straight down with no aft drag." Marifern says the boat now handles much better as well. "It has stability up the kazoo."


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