Free plan · 296 sq ft
U-shaped floating boat slip plans
This U-shaped floating boat slip covers 296 sq ft and sits on 22 floats, each 24″ × 48″ × 16″, with a 2x6 rim and 2x6 joists on thirteen 6x6 supports.
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- Computed by the Dock Builder engine
Plan view · framing and floatsU-SHAPE SLIP · 1/1
Spec
U-shape slip at a glance
- Deck area
- 296 sq ft5 sections
- Float count check
- 22 needed · 22 placedRule of thumb (25 psf): 14. Load check: 22. The plan uses the larger number.
- Float top above water
- 11.5″ unloaded · 4″ at full live loadLowest section shown.
- Loads assumed
- 12 psf dead (3,552 lb) + 20 psf live (5,920 lb)Fresh water. At least 3″ of float kept above water under full load.
- Live-load capacity
- About 22.7 psf with 3″ of float dryDock weight uses 28% of the floats’ buoyancy (builders aim for about 40%).
- Framing
- 2x6 rim · 2x6 joists 16″ o.c. · 13 × 6x6 supportsEngine defaults. 11 supports sit over the float rows; 2 short ones go in the knee braces.
- Decking
- 138 boards · 5.5″ face, ¼″ gaps5/4×6 or 2×6 boards, laid across the short side of each section.
- Edge bumper
- 127.3 ft
- Rim, 2x6 (outer frame)
- Joists, 2x6 at 16″ on center
- Supports, 6x6, under the joists
- Floats, under the frame (dashed)
- Deck boards (shown at one end only)
- Dimensions in feet and inches
Material list
What to buy for the U-shaped floating boat slip
Counted by Dock Builder’s take-off, with the cut-list buy list for each lumber size. No prices; for a budget see the dock cost calculator.
| Member | Size | Buy (stock lengths) | Pieces | Cut lengths | Waste |
|---|---|---|---|---|---|
| Rim (outer frame) | 2x6 | 9 × 20′ | 18 | 6 × 20′-0″, 2 × 6′-0″, 2 × 5′-7⅞″, 8 × 4′-0″ | 4.7 ft |
| Joists | 2x6 | 1 × 12′, 8 × 20′ | 12 | 8 × 20′-0″, 4 angled pieces up to 5′-4″ | 0.7 ft |
| Supports | 6x6 | 6 × 10′ or 1 × 8′, 3 × 20′ (8.3 ft waste) | 13 | 5 × 6′-0″, 6 × 4′-0″, 2 × 2′-10″ | 0.3 ft |
Buy lists come from the take-off’s cut-list optimizer, which packs cuts into 8–20 ft stock. Each row leads with the option that wastes least; the “or” line is the other one.
| Item | Buy (stock lengths) | Boards | Cut lengths | Waste |
|---|---|---|---|---|
| Deck boards | 53 × 12′ or 1 × 12′, 32 × 20′ (24.6 ft waste) | 138 | 42 × 6′-0″, 2 × 5′-7⅞″, 84 × 4′-0″, 10 angled pieces up to 4′-9″ | 8.6 ft |
The count is the run of each section divided by one board plus one gap (5¾″), rounded up. Rip the last board to fit. The buy list is the option that wastes least; the “or” line is the other one.
| Section | Float grid | Placed as | Floats |
|---|---|---|---|
| Main leg | 5 across × 2 down | 48″ across × 24″ along | 10 |
| Finger 1 | 2 across × 3 down | 24″ across × 48″ along | 6 |
| Finger 2 | 2 across × 3 down | 24″ across × 48″ along | 6 |
| Total | 22 |
| Part | Code | What it does | Qty |
|---|---|---|---|
| Outside corner bracket | WH-OCE | Wraps each exposed outside corner of the frame. | 6 |
| Inside corner bracket | WH-IC | Reinforces each frame corner from the inside. | 12 |
| Joist-to-support angle | WH-A | One at every joist and support crossing, held by two carriage bolts. | 32 |
| Washer plate | WH-W | Under the nut on the far side of each angle bolt (two per angle). | 64 |
| Corner connector halves (male + female) | WH-OCM / WH-OCF | Join two sections where their corners meet, in place of the outside bracket: a male half on one section mates with a female half on the other. | 6 |
| Connector backing plate | WH-B | Behind each corner connector. | 6 |
| 135° finger stabilizer | WH-FS | Ties the triangle knee braces to the leg and fingers. | 4 |
Codes are the hardware kinds Dock Builder’s take-off counts; match them to your supplier’s equivalent brackets.
| Item | Qty | Notes |
|---|---|---|
| Edge bumper | 127.3 ft | Around every exposed edge (shared edges skipped). |
| Cleats | 17 | Placed about 6 ft apart along both edges of each finger. |
| Carriage bolts (estimate) | ~64 | Two per joist-to-support angle, matching the washer plates. Add the bolts your corner brackets call for. |
| Float lag screws (estimate) | ~88 | Four per float with large washers, or what your float maker specifies. |
| Deck screws (estimate) | ~1,176 | Two per board at every joist and rim crossing; add screws for the two knee braces. |
Fastener counts are estimates worked out from the take-off’s own part counts. The take-off itself doesn’t list fasteners.
Build sequence
How it goes together
A 6×20 main leg with two 4×20 fingers makes a slip 12 feet wide and 20 feet deep, with triangular knee braces in the two inside corners. The 4 ft fingers are narrower than the 5 ft we suggest for a floating section on its own: they rely on being bolted to the main leg and held by the knee braces, so don’t build a finger as a freestanding dock. Measure your boat’s beam and length, plus room for fenders, before you settle on the slip size.
Cut and frame each section
Cut 18 rim boards and 12 joists from the lists above. Build each section’s frame upside down on a flat surface: rim around the outside, joists at 16″ on center. Check it is square by measuring both diagonals; Multinautic’s guide asks for them to match within ⅛″.[8]Add the supports
Lay the eleven 6x6 supports across the joists, one over each row of floats (positions are on the drawing), plus two short ones in the knee braces. Fit a joist-to-support angle at each of the 32 crossings with two carriage bolts and a washer plate under each nut.Fit the corner hardware
Bolt an outside corner bracket and an inside corner bracket at every frame corner. Where two sections share a corner, a corner connector half replaces the outside bracket on each section, with a backing plate behind it. Frame the two triangle knee braces and tie them in with the 135° finger stabilizers.Attach the floats
Set the 22 floats on the supports as drawn (main leg: 5 across by 2 down, 48″ side across; finger 1: 2 across by 3 down, 24″ side across; finger 2: 2 across by 3 down, 24″ side across). Lag each one down with large washers. Multinautic uses at least four lag screws per float; follow your float maker’s instructions.[8]Flip and launch
Turn the frame float-side down. Multinautic says it takes at least two adults to build and move a section.[8] Flipping before you deck keeps the frame light. The finished layout weighs roughly 3,552 lb by the 12 psf dead-load estimate, so decide early whether you deck it on shore or in the water.Deck it
Screw the 138 deck boards across the short side of each section with ¼″ gaps, two screws at every joist and rim board. Rip the last board to fit.Bumper, join and anchor
Run 127.3 ft of edge bumper around the exposed edges. Bolt the sections together at their shared corners. Then anchor the dock or tie it to pilings; see anchoring a floating dock.
Recreate it in the designer
Add the slip, then set each section
In Add dock, choose Boat Slip Layout → Floating dock → Float supported. Set Number of slips 1, Main leg width 6, Slip width 12, Finger width 4 and Finger length 20. Turn on Cleats at 6 ft and leave Boat lift in each slip off. Then set each section’s floats and supports below.
- Main leg: 6′-0″ × 20′-0″ (runs across the slip)
- Float type
- Poly drum
- Drum
- W 48 in · L 24 in · H 16 in
- Grid
- Across 5 · Down 2 (10 floats)
- Supports
- Count 5 · Inset 2 ft
- Decking direction
- Along length (boards run across)
- Finger 1: 4′-0″ × 20′-0″
- Float type
- Poly drum
- Drum
- W 24 in · L 48 in · H 16 in
- Grid
- Across 2 · Down 3 (6 floats)
- Supports
- Count 3 · Inset 2 ft
- Decking direction
- Across width
- Finger 2: 4′-0″ × 20′-0″
- Float type
- Poly drum
- Drum
- W 24 in · L 48 in · H 16 in
- Grid
- Across 2 · Down 3 (6 floats)
- Supports
- Count 3 · Inset 2 ft
- Decking direction
- Across width
Assumptions & limits
Read this before you build
- Loads. 12 psf of dead load (lumber docks typically weigh 10–15 psf[4]) plus 20 psf of live load, the figure building-code guidance uses for private floating docks, with at least 3″ of float left above the water under both.[5,6] Fresh water; salt water lifts about 2.6% more.
- Floats. Rated 598 lb at full submersion, the lower of the published ratings for this size.[1,2] The float-top heights assume straight-sided floats; real floats taper, so they sit a little lower. The plan also shows the retail rule of thumb (25 lb of buoyancy per sq ft[3]) and uses whichever count is higher.
- Framing. The engine’s default framing: 2x6 rim, 2x6 joists at 16″ on center, and 6x6 supports, here lined up over the float rows. Many builders use a 2x8 outer rim for a stiffer frame and a higher deck.[7,3]
- Deck height. It depends on how the floats mount. Bolted under the supports, the deck surface sits about 12″ above the float top (a 5½″ support, a 5½″ joist and 1″ of decking); mounted up inside the frame, less.
- Not checked. Wind, waves, ice, snow, boat wakes, point loads, tilt and anchoring. Keep single sections to 20 ft or less and at least 5 ft wide, and hinge longer runs.[7]
How these numbers are worked out, step by step, is on our floating dock design guide. To try a different float or load, use the dock float calculator.
Free account
Change the size. The material list follows.
Draw this dock in the designer, no account needed. A free account adds the take-off with its cut list, a quote and printable PDF drawings.
Material take-off · Lakeside L-Dock (demo)4 sections · 480 sq ft
- 0158 floatsCounted from each section’s float grid
- 02Rim 2x10 WeardeckBought as 12 × 20′. Framing follows the lumber you pick.
- 0310′ joists · 0% wasteBest of six stock lengths
- 58 floatsCounted from each section’s float grid
- Rim 2x10 WeardeckBought as 12 × 20′. Framing follows the lumber you pick.
- 10′ joists · 0% wasteBest of six stock lengths
A demo L-dock with a composite rim picked, not this plan.
Sources
- 1.Barr Plastics — Dock floats. Float sizes and buoyancy ratings (accessed Oct 2026)
- 2.Cellofoam (hosted by Overton’s) — Permafloat size and buoyancy chart. Ratings assume complete submersion (accessed Oct 2026)
- 3.Dock Edge — Floating dock hardware — how-to guide. 25 lb per sq ft flotation rule; freeboard can be raised with 2x8 or 2x10 framing (accessed Oct 2026)
- 4.dockbuilders.com — Flotation calculation — dock floats. Lumber docks weigh 10–15 lb per sq ft; design for about 40% submergence under dead load (accessed Oct 2026)
- 5.North Carolina Office of State Fire Marshal — Building Code Structural Ad-Hoc Committee minutes, October 14, 2020. Proposed code text: floating dock live loads and 3 in of freeboard under dead + live load (accessed Oct 2026)
- 6.Prince William County, Virginia — Guidelines for permitting residential docks (version 2022-03-02). 20 psf live load for floating docks; engineer-sealed plans for floating docks (accessed Oct 2026)
- 7.Decks & Docks Lumber — Building a floating dock. 2x8 outer frame with a 2x6 subframe; sections up to 20 ft long and at least 5 ft wide (accessed Oct 2026)
- 8.Multinautic — How to build a wooden dock. 25 lb per sq ft rule, low vs high freeboard floats, lag screws per float, anchoring weights (accessed Oct 2026)