Antenna Mounts On Board: 3D-Printed Brackets for VHF, AIS and Starlink
Every boat ends up with more antennas than it was built for. A VHF whip, a GPS puck, an AIS splitter that wants its own aerial, a 4G dome for the marina Wi-Fi, and now a flat white Starlink panel that nobody designed a mounting point for. The commercial brackets that exist are either expensive stainless fabrications or generic plastic clamps that fit everything badly. This is one of the areas where a printed bracket, sized to your rail and your device, genuinely beats what you can buy off the shelf.
It is also an area where people get it wrong, because an antenna mount looks like a simple part and behaves like a structural one. Here is how to think about it before you slice anything.
Know what load you are actually designing for
The antenna itself weighs almost nothing. A 1 m VHF whip is a few hundred grams; a GPS puck is lighter than your phone. The load that breaks brackets is not weight, it is the combination of wind drag on a long lever arm and the boat's own motion.
Three loads matter:
- Wind drag. A flat Starlink panel is roughly 0.15 m² of frontal area. At 40 knots apparent that is on the order of 30–40 N of push — not huge, but applied at the end of a 200 mm arm it becomes 6–8 Nm of bending at the bracket root. Multiply if you mount it high and the boat heels.
- Motion loading. A masthead or radar-arch mount sees accelerations of several g when the boat slams. A 1.5 kg dome at 5 g is momentarily pulling 75 N, repeatedly, in both directions.
- Vibration fatigue. This is the quiet killer. Engine and rig vibration cycles a bracket millions of times. Parts fail at layer lines long before they yield.
The practical conclusion: design for stiffness and fatigue, not for ultimate strength. A bracket that flexes visibly in a gust will eventually crack, even if it never feels close to breaking when you push it by hand.
Material: this one is not a free choice
An antenna bracket lives in full sun, permanently. PLA is out — it will sag on a hot deck and go brittle within a season. PETG is acceptable for shaded or below-deck mounts and for anything you are happy to replace annually. For anything that lives on a rail, arch or mast, ASA is the right answer: it holds up to UV far better and keeps its stiffness at deck temperatures that routinely hit 60 °C on a dark surface.
We covered the trade-offs in detail in Best Materials for 3D Printing Boat Parts, and the UV question specifically in Make Your 3D Prints UV-Resistant for the Deck. Short version for antenna mounts: ASA, or PETG plus paint if ASA is not an option.
One material note specific to antennas: keep metal-filled and carbon-filled filaments away from the antenna's radiating element and ground plane. Carbon-fibre-filled nylon is conductive enough to detune a VHF whip or attenuate a GPS signal. Plain ASA, PETG and glass-filled nylon are all radio-transparent and fine.
Where to attach it
The mounting interface decides most of the design. Four common cases:
| Location | Interface | Watch out for |
|---|---|---|
| Stanchion or pushpit rail | Split clamp, 25 mm or 1 in tube | Rail is structural — do not over-torque or crush it |
| Radar arch / pole | Clamp or through-bolted plate | Highest vibration; use metal fasteners, not printed threads |
| Mast or spreader | Strap or riveted plate | Halyard chafe; nothing that can catch a sail |
| Coachroof / flat deck | Bonded or bolted base plate | Deck core integrity — seal any new hole properly |
Rail clamps are the easiest win because they need no holes. If you are building one, the geometry and torque advice in Rail Mounts: 3D-Printed Clamps for Stanchions, Pulpits and Handrails applies directly — measure the tube with a caliper rather than trusting the nominal size, and use a rubber or TPU liner so the clamp grips without marking the stainless.
For heavier devices, browse the brackets and clamp bodies in Navigation & Electronics and Deck & Rigging as starting points — most are parametric, so you set the tube diameter and the device footprint rather than hoping a fixed model fits.
Six design rules that keep brackets alive
- Print the bracket so the load runs along layers, not across them. A vertical arm printed standing up will snap at a layer line. Lay it flat, or split it and bolt two flat parts together.
- Keep the lever arm short. Halving the standoff quarters the stress at the root. Mount close to the rail and accept a slightly worse antenna position.
- Fillet every internal corner. A 3 mm radius where the arm meets the base is the single cheapest improvement you can make.
- Use metal fasteners with heat-set inserts. Never rely on a printed thread for a bracket that lives outside. See Heat-Set Inserts and Marine Hardware.
- Go solid, not infill. For a part this small, 5–6 walls and 40–60 % infill costs a few grams and buys a lot of fatigue life.
- Leave a drip loop and a cable strain relief. The coax should never hang on its connector. Build a cable clip into the bracket.
Starlink and other flat panels: the special case
Flat panels are the hardest thing on this list because they are pure sail area. Two things help. First, mount the panel so it can be removed in under a minute — a printed quick-release cradle with a metal pin beats a permanent bracket you will curse in a blow. Second, design the failure: make the printed part the sacrificial element, so if something has to let go it is a €2 bracket and not the panel or the rail.
If your boat sees genuine offshore conditions, treat a printed panel mount as a fair-weather convenience and stow the panel below when it pipes up.
Testing before you trust it
Before the bracket goes to sea, do three things. Hang roughly five times the device's weight off it for an hour and check for creep. Grab the antenna and wobble it hard — if you can feel the bracket flex rather than the rail, it is too soft. Then re-check every fastener after the first weekend out, because printed parts relax slightly under initial load and clamps almost always need a second nip up.
Plenty of useful starting geometry is free: have a look through For Free before you buy anything.
A word on safety
3D-printed parts are not certified marine equipment. An antenna bracket is not a life-safety item in itself, but a VHF aerial is part of your ability to call for help, and anything mounted high can become a projectile if it detaches. Verify the material and the mount are suitable for the job before relying on them, inspect brackets at the start of each season, and never use printed parts for standing rigging, steering, or anything below the waterline. If in doubt, over-build it or buy the stainless one.
Questions about a specific antenna or rail size? Write to info@marinelab3d.com — we size files to fit.