Not Your Grandfather’s Unifloat Floating Dock System
July 1, 2014
Typically on our blog I like to write technical or educational pieces that have an overall focus on marina design best practice, innovation and industry trends.
I make a conscious effort to stay away from brand specific pieces as I do not want to compromise the credibility of our blog by including sales pitches.
This article strays a bit from my traditional focus but I thought it still worthwhile to share as many of our readers are familiar with the Unifloat concrete dock system and may have the same question one of our recent clients had – What is the difference between the Unifloat system you produce today vs. the one you manufactured thirty to forty years ago?
For all intents and purposes, to the untrained eye, today’s Unifloat dock system looks very similar to the ones manufactured by the company in the mid to late 1900’s – after all, today’s Unifloat is characterized by the same overall design concept as the original. The modules are still made from concrete, most commonly connected by treated timber walers, which are held in place by through-rods.
The truth is, over the past 30 to 40 years there have been many improvements made to the Unifloat concrete dock system, which have improved the system’s durability, longevity, and performance especially at sites where docks are exposed to more extreme conditions. These improvements can be seen in the overall system, the individual float modules, the dock components, the anchorage system, and in the manufacturing process. Below is a partial list of some of the improvements that have been made.
The Float System
A 12” freeboard was standard for the Unifloat dock system into the late 80’s. Today, the system typically features a freeboard of 18” or higher. The higher freeboard provides far greater protection from saltwater splash zone deterioration making the system’s thru-rods, weldments, and walers last much longer.
The length of walkway modules has been increased significantly from 8 or 10 feet to a maximum of 20 feet. This improvement has reduced the number of float joints by more than 50% and has allowed for the use of a single waler system that is much stronger and more cost effective than in the past.
Finger Modules have also been increased in length from 8 to 12 feet to full finger length (up to 50’ or so). This provides a much more stable finger and eliminates float joints. Single piece fingers provide a much stiffer, structural float module and prevent fingers from twisting.
Up till the late 80’s, the utilities were often run under the walers; this left them vulnerable and more susceptible to damage. The modern Unifloat system utilizes a cast-in raceway system, which is accessed through junction boxes at required locations. This provides full protection for the electrical system from both the elements and the marina users. This is the safest form of electrical installation possible.
The Float Modules
The concrete mix design used today in the Unifloat dock system is much heavier and more durable than that used thirty years ago. Lightweight fines have been replaced with hard rock pea gravel and builder’s sand. Current mix designs provide greater compressive strength and also include other components that improve the longevity of the concrete in certain climates.
Concrete admixtures for corrosion protection, such as DCI®, are now used in areas with aggressive environments or when requested by BMI or the owner. Additional admixtures are used as appropriate for durability, cold weather, and extreme exposure to the marine environment.
Fiber reinforcing has been added to the mix design for all float decks. Testing done on the use of polypropylene fibers in concrete shows that the fibers aid in crack prevention.
The strength of the concrete used has also been increased dramatically providing a much harder and stronger concrete dock that is more durable and long lasting than earlier Unifloat dock systems.
Concrete reinforcing protection is now provided with the use of galvanizing or epoxy coating. Thus, if salt water should penetrate the concrete sufficiently to keep the reinforcing steel wet, it will still be fully protected.
The minimum deck thickness of the concrete modules has been almost doubled. This provides additional coverage for the reinforcing and helps reduce cracking. A thicker deck also means a stronger float module.
The dock’s primary reinforcing has been substantially increased in the tops, bottoms and sidewalls. Sidewall reinforcing was not used prior to the late 80’s but now consists of vertical bars on both fingers and walkways. The dock’s secondary reinforcement has been greatly increased. These improvements help crack prevention and lend to a stronger dock system.
A penetrating sealer is now applied to all deck and sidewalls during the curing process. This provides a layer of protection against dirt and spills on the concrete and helps prevent penetration of foreign substances such as petroleum products.
The Dock Components
Finger to walk connections have been made much stronger through the use of heavy duty triangle frames. Today’s finger attachment brackets are computer modeled and in some cases have undergone full scale destructive testing.
The size of thru-rods has been increased resulting in rods that are 40% stronger.
The addition of shear plates has created a walkway waler system with a much higher level of strength than was achieved prior to their use.
The minimum waler size for both the walkway and finger piers has been increased. All timber components are fabricated prior to treatment to insure longevity and maximum resistance to rot and decay.
Today, Bellingham Marine is proud to say that all of their manufacturing plants are certified by a third party quality control organization. ISO and PCI are the industry’s most comprehensive certification programs for quality control. By developing a robust quality management system and mapping our processes, Bellingham Marine has been able to identify and eliminate waste and non-value added steps. This is passed along to the customers in cost savings as well as on-time delivery and superior product quality.
As mentioned above, this list includes just a sampling of the improvements that have been to the Unifloat concrete dock system over the past thirty – forty years. Just think, if Unifloats that were built 30 years ago are still functioning well, how long will today’s product last with all these improvements? Probably only our children or grandchildren will know.
If you are interested in hearing more about the evolution of the Unifloat concrete dock system and how it has become a world standard for dock design, we’d love to share more of its story with you. Please contact us at firstname.lastname@example.org