Floating Dock Systems in South Florida

A float holds up the weight of water it pushes aside, and that depends on its volume — Archimedes, as NOAA puts it. Salt water is denser than fresh. [oceanservice.noaa.gov]

UFC 4-152-07, which applies to Defense Department small craft berthing facilities and not to a private Florida dock, says flotation pontoons should be a foam core completely encapsulated in a protective shell: generally closed-cell EPS, absorption under 3% by ASTM C272/C272M Method C. [wbdg.org]

Encapsulation is the point. We install floats; we do not make them.

Under dead load only the standard wants 16 to 24 inches of freeboard, cross slope no steeper than 2%, and freeboard varying no more than 1 inch from the average; loaded, the floor is 10 inches. The gangway counts: the dock carries its dead load plus 50% of its live load reaction. [wbdg.org]

Cantilever guide piles are the simplest and commonest anchorage, generally preferred where water depth at design high water is under 30 feet, and must be tall enough that the dock cannot float off the top once freeboard, waves and surge are allowed for. [wbdg.org]

The dock grips them through collars faced with ultra-high-molecular-weight polyethylene rub blocks, which wear and are replaced periodically, or rollers in protected basins. [wbdg.org]

Anchor lines of wire rope, cable or chain suit deep water, large water-level fluctuation, or heavy wave exposure, where a compliant anchorage sheds peak loads. The standard's other listed forms are spuds and a strut to shore. [wbdg.org]

A shallow seawalled canal sits inside that case, so guide piles are usually the answer.

FEMA names inadequate anchorage as a primary reason floating docks fail in severe weather. Driving the piles is ordinary work: piling services. [fema.gov]

A hinge at the top takes the vertical swing and the dock's sway; skidplates or rollers carry the bottom. The standard sets a 3 foot minimum width and a maximum 3:1 slope at design low water. [wbdg.org]

Public and commercial facilities are tighter: the US Access Board's guidance for recreational boating facilities sets a 1:12 maximum, not required to run past 80 feet, with steeper slopes allowed under 25 slips if the gangway is 30 feet or longer. [access-board.gov]

The standard puts the choice on water level fluctuation: fixed where the tidal range is under 3 feet, floating at 3 feet or more, and fixed where waves over 2 feet occur. [wbdg.org]

Our tide sits on the fixed side of that line. A floating dock here is bought for one thing: a boarding surface at constant height.

FEMA's case study notes a surge may submerge a stationary dock, washing its deck boards away, while a floating dock rides up and down and anything coming adrift floats off. [fema.gov]

NOAA tidal datums, 1983-2001 epoch, feet.

Section 403.813(1)(b), F.S. exempts a private dock of 1,000 square feet or less of over-water area, 500 or less in Outstanding Florida Waters — and the size is only the first of five conditions, all of which must hold: it is held by pilings, or floating and built with no dredging beyond the pilings; no substantial impeding of flow or navigational hazard; recreational and noncommercial; and the sole dock claimed under that exemption along 65 feet of shoreline. [leg.state.fl.us]

In an artificial waterway, or a residential canal legally in existence, it is a different exemption: rule 62-330.051(5)(c) works from 403.813(1)(i) — a flat 1,000 square feet, no Outstanding Florida Waters cut, and roofs and boat lifts counted inside that same 1,000. [law.cornell.edu]

Floating structures diverge. Section 403.813(1)(s) exempts floating vessel platforms and floating boat lifts on their own conditions: floating at all times solely to support a vessel out of the water when not in use; wholly inside a previously permitted boat slip, or 500 square feet combined — 200 in an Outstanding Florida Water — alongside an exempt or permitted dock or a bulkhead with no other docking structure; not commercial, not for mooring vessels that stay in the water; where seagrasses are least dense. [flsenate.gov]

So a walk-on floating dock you moor alongside is not that exemption: it counts against the dock's own over-water area. A platform that does qualify needs no Board of Trustees permission, and a local government may require only a one-time registration. [flsenate.gov]

Otherwise exemption is not exemption from everything: an exempt dock still needs permission to occupy state-owned submerged land, plus the county and municipal steps below. [leg.state.fl.us]

• Miami-Dade: a Class I Permit before any work in, on, over or upon tidal waters or coastal wetlands. [miamidade.gov]
• Broward: the Aquatic and Wetland Resources Program licenses work in, on, or under the county's surface waters, docks included. [broward.org]
• Palm Beach: the Type 8 checklist warns Army Corps, Florida Inland Navigation District, DEP and county Environmental Resources Management approvals may be needed. [discover.pbc.gov]
• County steps: dock permits; city detail: locations.

Biofouling adds substantial weight to equipment and structures and raises drag on moving parts; growth under the larger foulers drives microbially influenced corrosion. [pmc.ncbi.nlm.nih.gov]

On a float that weight shows as the dock riding lower. Sight the deck edge against the waterline: a low corner means fouling, a waterlogged float or a failed connector.

The standard's own build tolerance is 1 inch of variation from average freeboard, so an obvious dip is worth a call. [wbdg.org]

Viance warns off electro-galvanized, G-90 and G-60 fasteners, recommends Type 316 stainless or higher for salt exposure, and says never to mix metals. [treatedwood.com]

FEMA's loop: monitor against a baseline, inspect after storms, at regular intervals — its example is every two years — and after damage. [fema.gov]

• Guide pile height: it must still clear freeboard, wave motion and surge above extreme high water. [wbdg.org]
• Bolting and hinging of walkways, pontoons and anchorage, the gangway's upper support, bumpers and debris booms: FEMA's retrofit list. [fema.gov]
• Clear the deck; set chain slack for the surge you expect, not today's tide.
• Afterwards: dock repair after a hurricane. Or talk to us first.