woiron 8" Galvanized Swivel Top Bunk Bracket Kit — 4pcs, adjustable height & anti-rotation U-bolts

woiron 4 Pcs 8" Galvanized Swivel Top Bunk Bracket Kit secures bunk boards to trailer crossmembers with adjustable swivel tops so your boat hull sits supported and aligned.

This heavy-duty kit includes four 8" uprights and four swivel tops, plus all necessary U-bolts and fasteners to attach bunk supports to a variety of trailer crossmembers. The galvanized finish resists rust and corrosion for long-term outdoor use, while the swivel-topped design lets you set bunk angle and height to match the hull profile of ski boats, fishing boats, or sailboats.

How does the swivel top help fit different hull shapes?

The swivel top lets the bunk bracket pivot so the bunk board can match the contour of the boat hull — whether you need a flat lay or a tilted support. This short travel adjustment reduces pressure points and spreads load across the bunk surface for safer launching and retrieval.

• Swivel top pivots to align with angled or flat hull sections
• Slotted bunk support holes enable precise height positioning
• Adjustable thread length accommodates varied mounting heights

Will these brackets fit my trailer crossmembers?

The kit is designed for common square and rectangular crossmembers and includes extended-thread U-bolts to wrap and clamp around the beam. It works with several beam sizes, making it compatible with many aftermarket and factory trailers.

• 3.1" extended thread U-bolts fit 3"x3", 2"x3", and 1.5"x3" crossmembers
• U-bolts measure 1/2" diameter, 3" wide, 4.5" long for secure clamping
• Slotted mounting holes allow minor lateral and height adjustments

How durable and weather-resistant are these bunk brackets?

Constructed from heavy metal with a galvanized surface, the brackets resist bending, rust, and corrosion better than plain steel hardware. Concave features and design details reduce unwanted rotation and maintain bracket alignment under load and vibration.

• Galvanized finish protects against water, salt, and road exposure
• Robust metal construction resists deformation under load
• Concave anti-rotation design stabilizes swivel top and U-bolt clamp

How simple is installation and what’s included?

Installation is straightforward: position the uprights on the crossmember, wrap the included U-bolts, and secure with washers and nuts. The slotted bunk plates make final height and angle adjustments quick so you can fine-tune fitment without disassembling the bracket.

• Kit includes 4 uprights, 4 swivel tops, U-bolts, bolts, washers, and lag screws
• Works on front and rear crossmembers or C-channel shapes
• Slotted holes permit on-the-trailer adjustment after initial mounting

Who is this for: boat owners, trailer technicians, and DIYers who need a reliable, adjustable bunk mounting solution for small to medium boats. If you haul a ski boat, bass boat, or sailboat and want improved hull support with corrosion-resistant hardware that adapts to different crossmember sizes, this woiron swivel top bunk bracket kit offers a practical upgrade to standard fixed bunk supports.