Tech Tips

There's a lot of thinking and design that goes into any yacht as sophisticated as a Selene Ocean Trawler. When you think about it, your Selene is really comparable in systems to a small city—but a city that also moves! In addition to propulsion, there is energy management, power generation, water treatment, sewage, food distribution, emergency services, fire protection, and a plethora of integrated mechanics and systems. Though these systems can be daunting in their complexity, they can, and should, be easily understood.

Selene Ocean Trawlers are built by Jet Tern Marine  with a commitment to delivering "Safe and Comfortable Passagemakers," and how a Selene is designed to move with the way its hull efficiency is measured are fundamental factors in meeting that commitment. Following are some notes of introduction to complicated subjects that invite uncomplicated explanations. If you have a question about any of the technical components of a Selene that you don’t see answered here, please This e-mail address is being protected from spambots. You need JavaScript enabled to view it   so we can address your technical question.



Marine Batteries

Modern ocean trawlers have large and complex electrical systems, with large battery banks as the foundation for the system. The batteries generally supply two types of loads:

 
Fuel Polishing

Ninety percent of all diesel engine failures are fuel related. Microorganisms, dirt, water and other contaminants can cause everything from annoying plugged filters to major engine damage. Passage-making trawlers typically carry large quantities of fuel, and often store that fuel for relatively long periods of time with little turnover, compounding the problems of fuel contamination. Selene Trawlers are equipped with an ESI fuel polishing system as standard equipment. The system is designed to keep fuel clean and eliminate the sources of most fuel-related problems.

 
Bottom Paint

Osmotic blistering is the nightmare of very fiberglass boat owner. Modern materials, such as vinylester resins as well as careful process control during layup have substantially reduced the incidence of osmotic blistering. However, the high cost of repairing osmotic blisters justifies extra diligence in protecting the hull.

 
Hydrostatic Data

Jet Tern Marine publishes detailed specifications for all of the Selene Trawlers. Most of the published specifications are pretty obvious—providing key dimensions for the Trawler, such as LOA: Length Over All. There is also a wealth of information in the hydrostatic data, but the definitions of many of these terms is not as widely understood, let alone their significance to the performance of the vessel.

 
Full and Semi Displacement Hulls

A Full Displacement hull is the theoretically purest of designs meant to travel efficiently through water by gently displacing the liquid in which it floats. Importantly, the chines of true displacement hulls are rounded the entire length of the vessel. This roundness offers little resistance to forces which is critical to its efficiency. However, forces intent on inducing roll, whether under way or at anchor, can have their way. In following seas, they handle well. Krogen and Nordhavn brands are examples of this design.

 
Hull Design Considerations

Bulbous Bow
Anyone who spends much time around large ships has noticed the bulb-shaped protrusions that are common on bows of large ships. To understand the purpose of the bulbous bow, we have to briefly review the characteristics of a displacement hull as it moves through the water.

 
Sound Insulation

Modern ocean-going trawlers are virtually all powered by diesel engines, which are very reliable and efficient, but also quite noisy. Controlling engine noise is an important part of a safe and comfortable passage. Excessive engine noise is not only annoying, but it can impair communication between crew members, cause headaches, and hinder sleep. Inadequate rest can lead to fatigue and poor decision making at sea. Long-term exposure to excessive noise can damage hearing.