Marina Design

To build a port

How to create a good port?

The question we shall illustrate in the following pages.



Choose the right location!

Have respect for the forces of nature! One cubic meter of water weighs a ton. Wind loads on a boat can be several hundred kg.Drifting ice has enormous strength and weight. It’s easy to only think of the sunny days when children swim and fish crabs, but then there are autumn storms and ice on some t. Is your port exposed to choppy or long swell? Choppy seas, we can do something about, but also a super tanker rolls in long swell. Long swell looking around rock and stone piers. The “iar” says the ancient fish. A post-stockade looks good, but it does not stop the waves. It takes a thick wall to stop a wave motion. Water depth – think of it along our coast is different about 2m on medium-high and medium-low tide. Water variation varies from place to place. Be realistic and add time studying the place where you want to build your port, choose the right type of brew and a good provider. The customer is always responsible for the site’s geography, which means that you as a customer’s duty of prevailing wave, depth, bottom strength, wind, ice and more. The supplier is responsible for ensuring the product meets the performance he promised. Be honest with yourself – is the location good? Have I assumed the worst case scenario. Will my boat to be safe by a powerful storm. Is the relationship price – reasonable risk? A wrong choice can be costly!

One piece of advice – do not underestimate the forces of nature.

Conditions that must be resolved

  • Water depth along the bridge
  • Bottom Complained-Mud, Sand, Gravel, Rock,
  • Wind conditions – Protected, Exposed, Exposed at certain conditions
  • Water variation between the highest lowest water levels
  • Waves – Blow length & design wave height
  • Current Conditions
  • Ice conditions
  • Type of abutment
  • Anchor type
  • Type of mooring in the bridge-Y boom, aft mount, alongside
  • Boat size and number
  • Bridge, – type, width, length and freeboard height
  • Desired accessories
  • Discharge Requirements for truck
  • Scale drawing of the area
  • Sketch showing the layout
  • Budget
  • Pending state
  • Required delivery time.
  • Possible environmental
  • Terms – eg SBF2005, Swedish Brew Suppliers Association

What is the advantage of a floating bridge?

  • The sea rises and falls. When mooring your boat, you can use fixed ropes. You do not have to worry about the high and low tide.
  • The bridge is always as high above the water, it is always easy to get in the boat.
  • Y-booms are designed to be used on floating docks. Mooring forces distributed always right. Used slipways on solid piers must förtamparna adjusted at high and low tide, otherwise there breaking loads on boat and bominfästningar.
  • When ice forms on pillars freezes solid. Even in winter, we have high and low tide. Do we get a long cold period with the same water level as the ice freezes firmly around all poles. This water is rising or falling field pole with! There will be damage to the harbor. A floating dock comes with the ice up and down.
  • A Y-adapter that is mounted on a fixed bridge must be taken up in the winter, or is it broken down when the float stuck in the ice and the water is rising or falling. A floating dock with cleats come with the ice up and down as a package, there are no stresses.
  • Impregnated bridge pylons leaking toxins, impregnated poles destroyed by shipworm.

What is the disadvantage of a floating bridge?

  • The anchorage must be checked, how often depends on the anchor type is selected.
  • If one chooses a too weak anchoring the bridge can DRAG and anchorage must then be adjusted.

Can ship dock at floating docks?

Yes, provided that the bridge is properly grounded. In many berths have but actually a floating dock / ramp jetty to facilitate the entry and exit.


The design wind load based on the average wind speed. As a reference number may be mentioned that on the West Coast had Gudrun an average wind speed of about 24m / s and a wind gust of about 36m / s

The average windmeasured at +10 m altitude for 10 minutes.Wind gusts are often much higher and measured for 30 seconds. It may be useful to study the most prevailing wind directions and wind speed in the wind rose.


Promises given in storms are forgotten in calm – English proverb


Water Variation

The water level varies with the weather and the city. People talk about:

HHW = Maximum historical water levels 
MHW = Medium Waterlevel 
MW = Average sea 
MLW = Medium Low tide Stand 
LLW = lowest historical water level

In Swedish Lots Part A (Maritime Administration, 1992) is a summary description of the water and land elevation. Because of the large local variations, the information to be submitted for locations in the table below be interpreted with caution. The table shows that water from 1 m above mean sea level to 1 m below mean sea level is not uncommon.

Calix (1974-1983) +181 +100 0 -80 -140
Furuögrund (1916-1981) +153 +79 0 -70 -120
Ratan (1892-1983) +137 +78 0 -70 -122
Draghällan / Nails (1898-1983) +132 +68 0 -56 -90
Björn (disused) (1892-1975) +136 +73 0 -52 -81
Forsmark (1889-1983) +160 +75 0 -55 -90
Stockholm (1889-1983) +120 +61 0 -46 -68
Rural Area (1887-1983) +99 +54 0 -44 -68
Marviken +101 +60 0 -45 -75
Visby +88 +48 0 -40 -70
North of Öland (1887-1983) +135 +65 0 -42 -80
Kungsholm Fort (1887-1983) +133 +74 0 -65 -94
Simrishamn +160 +85 0 -85 -135
Curdled (1887-1983) +167 +90 0 -93 -144
Klagshamn +140 +86 0 -74 -102
The bay +160 +90 0 -70 -120
Varberg (disused) (1887-1980) +145 +96 0 -64 -116
Ringhals +145 +95 0 -65 -120
Gothenburg / Torshamnen +150 +100 0 -70 -120
Smögen (1911-1983) +148 +94 0 -69 -112
KUNGSVIK +150 +100 0 -70 -120

It is important to check that the pontoon can not hit the bottom at low tide. During a storm rises often water, but it also happens that a storm with land breeze gives high waves and lowered water levels.

Fetch / Strike Length / Height Blow

Fetch is the distance where the wind can create waves. Wind-generated wave height can be calculated by the distance to shore, water depth and wind speed calculations can be very advanced or flashover rate.



A wave is defined with L = length, H = height and T = frequency . Hs = significant wave height, a mean value of the wave height of the pontoon windward side. Ht = transmitted wave height of the pontoon leeward side, i.e. wave height after attenuation.


Criteria for “Good wave climate in the marina”

Wave height Ht in a marina should acc. AS 3962-2001 shall be: – normal: up to about 23cm – for a short period of time, such asa storm about 37cm, but may exceed 1 yr. – 50 years of age is accepted that a storm gives approx 60cm wave heights in the harbor.

At 400m hair length, 5m deep water and average wind speed 20m / s are usually formed about 35cm high waves, ie vågdämpare should be considered. 
At long wavelengths / swell can also be very low wave height be troublesome! 
Each site is unique and must be studied individually.


When the wave hits the bottom

At sea, the wavelengths long and the wave is moving at great speed. Refraction occurs when the wave enters shallow water, wave orbital motion is prevented when the wave slowed down towards the bottom. wave height becomes higher and the wavelength becomes shorter. Refraction occurs when the water depth is less than ½ wavelength. Diffraction occurs when waves bend around islands and headlands.


Diffraction allows the waves that roll diagonally toward a shallow beach bend so that the wave front will finally move perpendicular to the shore. 
Reflection occurs when the wave bounces off a reflective wall, the wave height increases when the two waves meet. Lengthy wavelengths occurs in deep water and tempered with broad and deep pontoons eg SF400. Pontoon width determines the damping. Short wavelengths occurs at 2-5m shallow water, attenuation becomes good with wide and 1m high pontoons eg SF1040. Ponton Width is especially important here in terms of the pontoon self oscillation and wave damping.


Vågtransmission and damping.

Waves attacks a vågdämpare differently. They may be reflected or transmitted over a vågdämpare. Some wave energy can also be taken care of ( energy dissipation ) of the “disorders” as vågdämparen gives the wave motion. The parameters that control and shows vågdämparens efficiency are mainly:

– W / L ratio of the pontoon width and wavelength is the most important factor. – D Depth. Refraction or not? 
- The angle of the incoming wave – Hs / Hp ratio of wave height Hs and the pontoon height Hp 
- Hs / L Libra slope.

– Ht / Hs transmission coefficient indicates how much the wave is attenuated. An accurate assessment requires the model or field trials.

Liquid vågdämpare

Pontona have built floating docks since 1918. Lars Lindberg built its first liquid foam-filled pontoons wave dampening 1973.Lars pontoons were unique in two ways, the pontoons were foam filled Unlike previous pneumatic kassunpontoner. The pontoons had wings / fins, which increased the pontoon depth and created a turbulence chamber between the wings. It was the foundation for today’s modern pontoons and floating vågdämpare.

1996, SF Marina thorough tests of floating breakwater at Hydrodynamisca Institute in Barcelona. Our calculation of wave attenuation based on these tests. SF Marina continues to work through continuous development and research. Scored installations in Nordic, tropical, arctic and hurricane areas studied. Experience preferred, product development is the result.

Experiment with different types of liquid vågdämpare has lasted as long as shipping. We have experimented with floating walls, wide sections with floating deck, timber bundles, pipes, etc.. The bottom line is that the wave is attenuated in width not in depth, which goes hand in hand with the hydrodynamic studies.

SF Marina floating vågdämpare protects today successfully ports worldwide. Waves damped by wave reflection, turbulence, friction and pontoon movement. 
Floating breakwaters have a work area that is adapted to the coasts. Wave frequencies up to 3-4 seconds suppressed well. Is the frequency anymore, we talk about swell / long lake, which is better handled by permanent structures. 
Floating vågdämpare is adapted to local conditions. It has a specifically designed operating range. 
pontoons are exposed to large forces, force-absorbing structures are required. We have chosen materials and production methods that will provide the best possible product. 
Linkages between the pontoons provide stability and control but also movement ease. 
anchor is an important but underappreciated part of a floating vågdämpares function, significant performance gains can be made ​​here.

When used properly, a floating breakwater is a fantastic product.


Stone pier or pontoon?

Water depth and the wavelength is important in the selection of vågdämpningssystem.

A stone pier is handy to use to dampen waves with very long wavelengths . A solid stone piers will be significantly more expensive with increasing water depth. Is that deep water require a stone pier large quantities of rock. In a normal angle of repose, solid bottom and 10m deep water so it takes about 500kbm stone per meter breakwater. As a comparison, one can think that 100m breakwater which causes 50 000kbm with large stones. If a truck takes about 6kbm stone so it will be more than 8,300 cars. In other words, a lot of stones.


A pontoon is very good vågdämpningsförmåga on waves with short wavelengths, a frequency up to 3.5 second / about 15 m wavelength. 
Up to 75% of the wave height can then be suppressed. 
pontoons can also be anchored on small and large depths.

Ponton Types moderate waves

All helbetongpontoner suppresses waves! There are two main types;

– Average helbetongponton

wave dampening helbetongponton
Wave dampening helbetongponton








– Tube with fins – the fins creates a turbulence chamber.

Wave dampening helbetongponton with flanges
Wave dampening helbetongponton with flanges








Pontoons are the same length, width, height and weight for the same wave attenuation, regardless of the brand! When selecting vågdämpare be to look at: – anchoring system – the pontoon structure and reinforcement – the join between the pontoons

Pontoon width and length

The wider pontoon the better wave attenuation. 
The longer path wave has to go through the pontoon, the better the absorption. It is an advantage if the scale does not hit the pontoon hint right 
The longer vågdämparens total length, the greater the attenuation.


Liquid vågdämpare act as filters for incident waves

Up to 75% attenuation can be obtained at wave frequencies of up to 3.25 sec. If the time between the crests is more than 4 seconds so it swell. At long wavelengths are often too short waves on the highway graphic. A vågdämpare exposed to swell still lowering the short waves, but lets through the swell.


For short waves / choppy water should wave height Ht in a marina be: 
- normal: about 20cm – short period of time , such as a storm: about 35cm

At 400m hair length , 5m deep water and average wind speed 20m / s formed approx 35cm high waves.

NOTE! At long wavelengths / swell can also be very low wave height be troublesome!

Ship-generated waves contain both short and long wavelengths that best tempered with broad and deep pontoons.


Mooring at vågdämpare

Vågdämparen is the port’s most vulnerable pontoon and it moves. 
Avoid therefore permanently moor large boats at a vågdämpare, then boat and pontoon may have different patterns of movement and the dynamic load can be great. 
Same goes for non self-bailing small boats to water splashes.


Select pontontyp


Deep vågdämpare

Helbetongpontoner for attenuation of long wavelengths. Broad scope provides great cushioning. Same Coupled with strong couplings, require heavy anchor. Beam 3, 4, 5, 6m


For residential and commercial use, are used for wave attenuation. Withstands slipways and icy winters. Linked together as desired. Width: 2.4, 3, 4, 5m length: 10, 12, 15, 20, 25m



 Wood & Concrete Bridges

Wooden decks of concrete-filled floats. For private or commercial use in protected waters. A heavy and sturdy bridge built slipways and icy winters. Width: 2.4m or 3m. Built in continuous length from 8m.



 Simple bath and småbåtsbrygga

Wooden decking of filled plastic floats. The bridge sections that can be assembled into L-, T-and I-bridges. Ready to launch, easy to anchor itself. Should be up in the winter. Gangway in different lengths. The bridge width: 1.1m – 2.4m




 Operating space between moored boats

Free maneuver – minimum 1.5x largest boat length


Anchoring System


The purpose of the anchor is to keep the floating pontoons in place when exposed to wind, current, waves, ice and loads of moored boats and to relieve the links between the pontoons.

Wave forces on the pontoon can be estimated by taking the effect of a full wave reflection. Waves are distributed in reality irregularly along a long construction, which reduces the total force.

Iskra which of various types can also occur at sea lanes and other places where the ice is lost during winter. Ice can accumulate and by the wind to push a design. An ice cap permanently frozen (clamped) indicates a large water level variations difficult to estimate loads.

Other loads on the anchor since primarily from streams and water level variations and wind, and operating load from moored boats.

A vågdämpare is not stationary. The movement that occurs and external forces that affect determines mooring system characteristics. loose tie gives pontoon large movements (drift), while a tight anchorage considerably limits the pontoon business opportunity.

A tight anchorage is achieved by tensioning the anchor. An optimal bias and a heavy anchoring system provides a minimum anchorage force and motion. Path loss can then be improved by up to 25%.

Commonly, anchor with chain and anchor .

The chain must be heavy and have a length of at least 3-4 times the water so that the pulling force at the anchor is horizontal and so that the anchor easier digging into the ground. 
Chains must therefore by its own weight curve down so much that it becomes almost horizontal anchor . 
Vågdämparsystem should be maintained when the anchors sat down by the chains efterspäns.


None crossed chain for vågdämpare


Crossed chains for anchoring in protected mode

The chains on a vågdämpare should not be crossed under the pontoon, then this lowers the damping performance and increases the pontoon rolling. 
in protected areas can benefit chains with cross brace, which reduces påseglingsrisken.

Seaflex is a good alternative, and corrosion-resistant anchoring system where the anchor is made ​​of prestressed polyester rope and special springs.

Anchors are dictated by the Bottens condition for achieving a safe anchorage. 
If armature is released / lifted up instead of burying into the ground so dragnetting plant. 
Adding a couple of anchors in series or parallel connection, you can hold the power to improve. 
anchor “holding power “depends on the seabed and the anchor weight, best bottom is a hard clay base, a sand or rock bottom may be” slippery “with SWEEP as a result, the resolve and gaseous bottoms can be very difficult to get the required resistance for the anchors. 
To calculate an armature holding force requires a geotechnical test, which is costly. Normally, therefore, based on design experience-based values ​​for “a normal bottom.” Liability-wise, it is the client who is responsible for the ground conditions and the preparation of geotechnical data for design. 
A concrete anchor loses about 40% of the dry weight in water.



When anchoring a floating breakwater is always certified shackles used. Otherwise we do not know with certainty what load shackle tolerate and what kind of iron it contains. 
classification is stamped on the shackle. Use certified shackle with nut and safety pin so reduces the risk of failure. 
Bunch canal between sprint and jumper is important to inspect for maintenance, when corrosion takes the threads first.




Tamp & Chain

The rope and chain anchor is a shorter chain closest to the pontoon, to weigh down the anchorage. Rope first reef since the chain and the anchor – so that abrasion wear can not occur. Tamp and chain anchor should be avoided vågdämpare. 
could be envisaged rope and chain at less exposed locations with large water depths. Anchor weight must be increased by rope and chain anchor when the anchor tensile direction are not parallel to the ground. A rope lifting anchor then easier dragnetting, while anchoring the whole chain pulls the anchor into the ground. 
rope is in vulnerable positions to be Type Poyestersilke and 8-strand. 
Polyethylene Tamp is quite unsuitable for breakwaters as it will stretch too much. Three-strand rope spins under load, which is 8-strand does not. 
Tamp and chain anchor has the environmental benefit of the anchor not touch the bottom.

Clutch System

A vågdämparkoppling subjected to high loads. NOTE! Are chains poorly clamped so will load on pontoon joints very large. It is the anchor in the first place to take up the loads, not connections. A symmetric input is important.

Benefits the total drawbar load by having individual connections in each joint. The load on the clutch then related to the current floating joint, unlike continuous wires. 
Individual connections are to service. 
if a cable break in the unlikely occurs when an individual switch is used, suffer only a pontoon seam instead of all pontoons.








In very exposed locations, in broad vågdämpare, the center clutch used on each other to four joints to absorb torsional forces(torque) in a series of wave dampening pontoons.

By putting ” bridelrings “between pontoons förankringsbyglar you get a bridle that narrows the pontoons. Coupling load allocation and security become double.


Pontoon equipment



Suitable width is 1.2 m or wider. 
use 1st railing for gangways 6m or longer. In exposed locations or ferry etc. are railing on both sides. 
railing must withstand 35kg Lateral load and be 90cm high. 
Landgången may as optional accessories provided with plates to hide the gap between the dock and gangway, and between the gangway and pontoon. 
slide plate may be considered the gangway on the pontoon, especially gangway lands on the timber.

Slope should be the max 1:5. The illustration below refer to water variation in Gothenburg. A short gangway gives steep slope at low tide.


Gangway mounts

Gangway Brackets can be made ​​of wood or concrete, and should be so high that the gangway at MHW (medium water) lies horizontally. 
attachment should be articulated / hanging to avoid biting forces.






Anchor Bars

There are two main types of single-tube barriers and viable double pipe booms.




Classic 2 Outriggers Walkable Single pipe Dubbelrörsbom

A förtöjningsbom should be shorter than the boat, optimally 20%. 
All mooring lines must be fixed to the boom mooring loops.

Modern booms have large foam-filled floats integrated, nylon stored hinges, mooring rings and optional bridge mounts as standard. All steel is galvanized. Protection Reinforced plastic is available in several models.

Combination bar has a support leg and fits in protected and semi-protected areas.


The short base for attachment of the boom gives large loads on the bridge. 
Having two legs, the load on the bridge attachment less. 
With sträckmetalldfylld Y-piece boom is convenient. 
For added comfort, select viable booms. 
in vulnerable locations and for large boats required double pipe booms.

The most common is the gooseneck angle bracket.

The pictures show Rollytechs mounts. Bracket Rail Mount Clamp Fix Anchor rail bracket U-bracket If booms mounted only on a pontoon side must bomvikten compensated for pontoon not to fall. Booms mounted on a fixed bridge must be removed during the winter, that is mounted on a floating pier can do but to avoid isskaderisk the boom loosened.

Boating Width

Site width specified as cc dimension between the bars. 
Free space width in the length to the boat between the booms.

Free space width at bomförtöjning for boats: 
less than 5m = båtbredd + 30cm 
longer than 5m-10m = båtbredd + 50cm 
in exposed positions should place the width is slightly increased. 
Measure of free space width in relation to boat length that are common today.

Piles & Aft Buoys

If stern posts or stern buoys used longer needed places than at Y-bar. 
spacing between piers must thus be larger.

Faith Load on cleats, rings and Palare.

A large cleat signaling that large boats can add, a small cleat ….. 
What is cleat rated for? 1-ton, 3-ton, 5-ton? 
use through bolts with nuts and large washers when mounting.


Mooring at the boom

Is your boat at a floating pier in a vulnerable position, then it is important that the distance between the bars is not too small. 
You should have about 25 cm fender space between the boom and the boat on each side. 
use bomfendrar to protect the boat.

The boom should be 20% faster than the boat (1.5-2m) so that the stern line gets a good angle. stern ropes must be tensioned.A rope before, a rope astern! Stern must be locked in position between the booms. No movement in the boat’s rear.

Förtampen should be a little looser and keep the bow in place laterally. 
bow of the boat will be able to move easily up and down the lakes in Wheel. 
Wear rubber spring on förtampen to counteract dumb jerk.

The boat will float like a duck on the waves. Bring shall move up and down and the stern stuck.

Moor the storm, whatever weather. You never know when it turns.


Post spacing for electricity

An extension cord should be a maximum of 25m, giving a maximum of 20m distance from the nearest power pole (max 40m between the posts)


Electrical Safety

Regulations governing electrical installations in the marina and recreational boating is controlled by ELSÄK-FS and installation rules Chap. 709. By and large, the same rules that were in ELSÄK-FS 1994:7






Safety and accessibility

– Distance between rescue ladders
rescue ladders / ladders should be on every bridge cam, plus there should be rescue ladders tentatively every 60 meters. 
Steps shall be accessible from the water and always be mounted.

– Highlighting of rescue equipment

mark must sit 2-3 m above the equipment and have a red / orange color. 
Mobile and fixed rescue ladders should also be painted.

– Fire fighting equipment
Current regulations from the State Fire Board 1983 is not adapted to today’s reality. 
New regulations are in the pipeline. Still recommends the rescue in such Karlskrona follows;

Fire extinguishers class N3, 6kg, shall be every 50 meters (25 +25 m). 
place to be excellent. No requirement for water quenching is. 
Other extinguishers within the port facility shall be marked in a position to plan centrally located eg at the port office / service areas.

In case of fire in the boat is recommended to move the boats around the burning boat in the first place.

– Disabled
Transition between piers, docks, gangways and pontoons should have minimal level differences and gaps, to allow access by wheelchair, walker, etc. 
Gradients should not exceed 1:12


Calculation of wave climate and dynamic properties of a liquid vågdämparsystem becomes to some extent uncertain, since real-world conditions need to be simplified. 
, it is of great value to study in situ wave climate in the area before the breakwater is placed and after immersion register breakwater vågbrytarfunktion and dynamic behavior at different vågpåkänningar.

An essential component of such a study is to develop solid wavemeters showing wave data from a few selected points in the water sector. Video filming and photography of the breakwater and the current catchment during different storm and issituationer then provide valuable information. Write a logbook.





A vågdämpare actively, at times under heavy load. Ocular inspections should be made ​​frequently. Refer to the pontoon is in the correct position, the chains are taut, the shackles are OK and that gangways sitting as they should. dive and maintenance inspections are made ​​regularly, at least once a year. During the inspection check it so that the anchors are not moved, wear and corrosion on the clamps, chains and shackles. , the largest corrosion are usually found in surface water that is oxygen richest. Improperly grounded electrical cables and mineral-rich ground can also provide great corrosion, sometimes unexpected way. Anchoring wells shall be opened and inspected connections. Bolts to träfendrar checked. Write log on carried out work.

Propellergangen 4 417 64 GOTHENBURG SWEDEN | Tel: +46(0)31-779 07 65 | Fax: +46(0)31-779 07 35