A fixed dock stands on piles and stays at one height. A floating dock rests on floats and rises and falls with the water. That one difference decides most of what follows: how easy it is to board a boat, how deep the water can be and how easily the layout can change later.
What is the difference between a floating dock and a fixed dock?
A fixed dock, or pier, is a deck supported on piles driven into the bed. Its height never changes, so the distance between the deck and the water changes whenever the water level does. A floating dock is supported by buoyant floats, held in position by piles or moorings, and reached from shore by a gangway. Its deck stays at a constant height above the water.
Floating docks vs. fixed docks at a glance
| Factor | Floating dock | Fixed dock |
|---|---|---|
| Changing water levels | Rises and falls with the water, so the deck stays at a constant height above it | Deck height is fixed, so the step to the boat changes with tide, season or reservoir level |
| Boarding | Consistent step from dock to boat | Varies with the water level |
| Water depth | Works in deep water, where it can be held by chain or elastic moorings instead of long piles | Needs piles to the bed across the whole structure, which becomes harder as depth increases |
| Changing the layout | Modular, so sections can be replaced or reconfigured | Permanent |
| Wave exposure | Needs a reasonably protected basin; a floating wave attenuator can provide that protection | Deck must be set above the highest expected water and wave level |
| Access from shore | By gangway, whose slope changes with the water level | Direct |
When a floating dock is the better choice
- Tidal sites, rivers and reservoirs where the water level changes.
- Marinas that berth a range of boat sizes and want the same easy step aboard for all of them.
- Deep water, where long piles are impractical.
- Sites where the layout may need to change as the business grows.
Bellingham Marine engineers each floating dock system with a modular design that moves with changing water levels. Where a site is open to waves or wake, a floating wave attenuator can protect the docks behind it.
When a fixed dock is the better choice
- Sites where the water level barely changes.
- Structures that must carry very heavy loads, such as vehicles or cranes.
- The shore-side approach that floating docks connect to.
Many marinas use both
The two are not rivals. A common marina layout is a fixed approach pier or seawall on shore, a gangway, and floating docks for the berths. The fixed structure handles shore access, and the floating docks keep every boat easy to board at any water level. Bellingham Marine designs and builds complete facilities as a marina construction company.
Frequently asked questions
Do floating docks work in tidal water?
Yes. A floating dock rises and falls with the tide, so the deck stays at the same height above the water and boats are easy to board at any stage of the tide.
Are floating docks stable?
A well-engineered floating dock is stable underfoot. Heavier systems, such as concrete floating docks, move less than lighter ones.
How long does a floating dock last?
It depends on the system. Bellingham Marine’s published service lives range from 20+ years for timber frame docks to 50 to 60+ years for concrete floating docks.
Planning a new dock or replacing an old one? Contact Bellingham Marine to talk through your site.
