– Frequently asked questions


What is an accredited mooring analysis in accordance with the Norwegian standard?

In Norway, the NYTEK23 regulation requires that mooring analyses must be in accordance with the Norwegian Standard, NS 9415. The standard sets the requirements for the dimensioning of the mooring system in terms of Ultimate limit states, Accidental limit states, Fatigue limit states, safety factors etc.

Aquastructures is accredited by the Norwegian government to perform mooring analysis for the aquaculture industry, in accordance with the NYTEK23-regulations.

What is anchor holding power?

An anchor holding power is the resistant of the anchor to prevent drift. The holding power is dependent on the type of anchor, topography and the type of seabed. The holding power of the anchor must always be larger than the dimensional force in the anchor line.

What is pre-tension?

Pre-tension is the force in the mooring line in static condition i.e. without environmental forces such as waves and current.

What is a grid?

A grid is a part of the mooring system. The grid provides a safe distance between the floating collars, and connects them to one system.

What is a bridle?

A bridle is the part that connects the floating collar to the grid.

What is a local analysis?

A local analysis determines the capacity of local details. The analysis provides an accurate view of the stresses around structural connections, hubs hinges etc. 



How to get product certification?

Contact Aquastructures. We are happy to assist you.

What is a product certificate?

 A product certificate is a document that authorizes a producer to supply a product within the aquaculture industry, in accordance with the NYTEK23-regulations and the Norwegian Standard, NS 9415.

What is a risk analysis?

A risk analysis involves a series of three steps:

1) Identifying potential events/risks
2) Evaluating the likelihood and potential consequences of these events 
3) Prioritizing and determining which events that require mitigation

What is a mooring report?

A mooring report must provide a detailed description of the installed mooring system, including the following details:

o Description of the mooring system components
o Coordinates of the bottom mooring points
o Any deviations from the mooring analysis
o Documentation of the holding power of the bottom mooring points
o Installation date of the structure
o Map of the mooring system

What is extra equipment?

Extra equipment is a fixed or movable equipment, which is not a main component, but can lead to escape of fish. 

What contains the report of mooring inspection?

After the installation of the fish farm, a ROV inspection will be conducted to determine the following:

o The heading on mooring lines
o The depth of bottom mooring points
o Any deviations from the mooring report 

Land-based fish farms

Which components must be certified in land-based fish farms in Norway?

The regulation for land-based fish farms demands that following components must be certified:

o Pipes
o Tubes 
o Tanks 

For components in new facilities or newly bought components in old facilities, the producer must have a certificate of the products. The certificate is issued by an accredited company like Aquastructures.

What is a state analysis of land-based fish farms?

A state analysis is a part of the technical escape report which must be delivered to the Directorate of Fisheries. It determines the duration of the license of use. Aquastructures has contributed in coorporation with the Directorate of fisheries to make a guide for state analysis.

A land-based fish farm is divided into departments in the state analysis, based on for example area or type of component. Each department will get its own state level, based on the state of the components in the department. The lowest state level determines the total state level  of the structure and the duration of the license.

Do old land-based fish farms need product certificate?

Only new components such as pipes, tubes and tanks that are installed on the structure built before 01.01.2018 must be product certified. Structures, built after 01.01.2018, can only have product certified components.

Wht is the content of a technical escape report?

A technical escape report is required to be granted a license. The license is issued by the Directorate of Fisheries. The report should contain the following:

o A state analysis of the structure
o A sketch of the sewerage- and the delivery system
o Risk assessment for operation and delivery of fish
o Geotechnical review
o Maintenance plan 

Site survey

What is a site survey?

In site survey design, wind, wave height and current velocity is calculated. Wind is determined by the national wind standard, NS-EN-1991-1-4.  Waves are determined by numerical methods and current is meassured by means of Doppler or rotor meter.  In addition, conditions like icing, mapping of seabed and tidal level are documented. 

What is a significant wave height, Hs?

The significant wave height is defined as the average height of the highest 1/3 waves in a wave spectrum.

What is a wave height?

Wave height is the vertical distance between the wave crest and the wave trough.

What is maximum wave height, Hmax?

Maximum wave height is the highest wave in a time series. From NS 9415 this is defined as: Hmax = 1.9 x Hs. 


What is stability calculation?

Stability calculations  indicate how a floating object behaves in waves and still water, both in intact and damage condition. Important parameters in stability calculations are the centre of gravity, centre of buoyancy and the metacenter of the object. The stability calculations are performed for different load conditions.  

What does the Norwegian Standard say about stability calculations?

The Norwegian standard states that stability calculations must be performed for all barges for intact condition and damage condition. There are specific requirements and minimum criteria that need to be fulfilled.  

When is a new stability calculation required?

New stability calculations need do be performed when there are significant changes on the barge that can influence the behaviour of the barge in water. For example, new equipment with significant weight or different load conditions. 

What is the freeboard dimensional water-line?

The freeboard dimensional water-line is the allowed freeboard of the barge. It is determined by the stability of the barge, and the strength of the hull. This limit must be marked on the hull of the barge with a white line. Loading beyond this mark may lead to instability and in worst-case capsizing.

Do not hesitate to contact us:

Aquastructures AS
Email: mail@aquastructures.no
Phone: +47 73 83 17 47
Adr: Kjøpmannsgata 21, 7013 Trondheim