Sea-Dog 316 stainless rail base fittings hold round marine tubing against a mounting surface. The six models compared here have different socket angles, tubing sizes and mounting footprints. Match the actual rail outside diameter and mounting area before selecting a round or rectangular base for a compatible rail assembly.
Round base or rectangular base?
Three flat-head mounting points. The 7/8-inch versions in this guide use a 2-5/8-inch diameter base; the 1-inch version uses 2-3/4 inches.
Four flat-head mounting points. Dimensions vary with the angle and tubing size; compare the complete footprint rather than the number of holes alone.
Shape symbols illustrate the two mounting-flange styles only. They are not scale drawings or drilling templates.
Sea-Dog stainless rail-base angles and mounting dimensions
Sea-Dog lists these fittings as investment-cast 316 stainless steel with set screws where appropriate. The manufacturer supplies no mounting fasteners with these rail bases.
| MPN | Base shape | Socket angle | Tube O.D. | Base footprint | Mounting fasteners |
|---|---|---|---|---|---|
| 280600-1 | Round | 60° | 7/8 in | 2-5/8 in diameter | 3 × #10 flat-head screws |
| 280601-1 | Round | 60° | 1 in | 2-3/4 in diameter | 3 × 1/4-in flat-head screws |
| 280900-1 | Round | 90° | 7/8 in | 2-5/8 in diameter | 3 × #10 flat-head screws |
| 281600-1 | Rectangular | 60° | 7/8 in | 1-3/4 × 3-1/16 in | 4 × #10 flat-head screws |
| 281900-1 | Rectangular | 90° | 7/8 in | 1-11/16 × 3 in | 4 × #10 flat-head screws |
| 281901-1 | Rectangular | 90° | 1 in | 1-7/8 × 3-3/16 in | 4 × 1/4-in flat-head screws |
Dimensions are manufacturer nominal measurements in inches. FH means flat-head. The screw sizes listed are fastener specifications, not hardware included in the package.
Tubing, fasteners and mounting checks
Measure the rail's outside diameter and check its tubing wall, planned socket angle, mounting surface and backing support. Three-hole round bases and four-hole rectangular bases use different fastener patterns; follow Sea-Dog's installation specifications and the boat builder's support requirements.
For example, 280600-1 and 280601-1 are both 60° round bases, but take different tubing diameters and screw sizes. Likewise, 280900-1 and 281900-1 both accept 7/8-inch tube at 90° but have different base shapes and mounting patterns.
The manufacturer's guidance specifies a 1/8-inch Allen wrench for set screws. Inspect any reused tubing and use appropriate corrosion-resistant mounting hardware; do not assume existing screws are reusable.
Sea-Dog 316 stainless marine rail bases
Select the fitting with the correct base, angle and tube outside diameter to review product details.
Sea-Dog 280600-1
A 60-degree round-base socket for 7/8-inch rail tubing.
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Sea-Dog 280601-1
The one-inch-tube version of the 60-degree round-base fitting.
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Sea-Dog 280900-1
An upright 90-degree round rail socket for 7/8-inch tube.
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Sea-Dog 281600-1
A sloped rail socket on a rectangular, four-fastener base.
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Sea-Dog 281900-1
An upright 7/8-inch socket on a rectangular mounting flange.
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Sea-Dog 281901-1
A wider 90-degree rectangular base designed for one-inch tubing.
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