How to Install a Marine Compass: Flush Mount vs. Bulkhead Mount

Why a Magnetic Compass Still Matters

GPS chartplotters are indispensable, but a magnetic compass is your fail-safe when electronics go dark — dead battery, blown fuse, or water intrusion. Every serious boater should have a properly installed, compensated compass at the helm. It requires no power, has no software to crash, and will outlast most electronics on your boat.

This guide covers how to choose the right mount style and walk you through a clean installation.

Step 1: Choose Your Mount Style

Marine compasses come in three primary mounting configurations. The right choice depends on your helm layout:

Flush Mount

The compass sits in a cutout in the dash or console, with only the dome visible above the surface. This gives the cleanest look and protects the compass body from impact. Best for: center consoles, cuddy cabins, and any helm with a flat dash panel.

Popular options from our catalog:

Bulkhead Mount

The compass mounts flat against a vertical surface — a bulkhead, side panel, or cabin wall. No cutout required; it attaches with screws through the mounting flange. Best for: sailboats, trawlers, and any installation where a flat dash isn't available.

Ritchie BN-202 Navigator Compass – Bulkhead Mount, Black

Bracket Mount

Mounts on a swivel bracket, allowing you to angle the compass for the best viewing position. Good for retrofits where cutting into the dash isn't an option.

Ritchie B-51 Explorer Compass – Bracket Mount, Black

Step 2: Choose the Right Location

Compass placement is critical. A poorly located compass will give inaccurate readings due to magnetic interference from nearby electronics and metal. Follow these rules:

Keep it at least 18–24 inches away from speakers, radios, depth finders, and large metal objects
Position it at eye level from the helm seat so you can read it without leaning forward
Avoid placing it directly above or below your VHF radio or fishfinder — these generate magnetic fields
Test before cutting: hold the compass in the proposed location and rotate it 360° — if the card swings erratically, find a different spot

Step 3: Cut the Mounting Hole (Flush Mount)

Skip this step for bulkhead or bracket mounts.

What you'll need: hole saw (size specified in your compass manual), drill, masking tape, pencil, jigsaw or rotary tool.

Apply masking tape over the cut area to prevent scratching the dash surface
Mark the center point of your cutout with a pencil
Drill a pilot hole at the center mark
Use the correct hole saw size (check your compass manual — typically 3–4" depending on model) to cut the mounting hole
Smooth any rough edges with sandpaper or a file
Test-fit the compass before applying sealant

Step 4: Seal and Mount

Apply a thin bead of marine-grade sealant (3M 4200 or equivalent) around the mounting flange or cutout rim
Press the compass into position
Secure with the provided mounting screws — do not overtighten, as this can crack the housing
Wipe away any excess sealant immediately with a clean cloth
Allow sealant to cure per manufacturer instructions before exposing to water

Step 5: Connect the Compass Light (If Equipped)

Many compasses include a built-in illumination light for night use. Connect the two wires (positive and negative) to your helm lighting circuit so the compass light dims with your other instruments. Use a properly rated inline fuse on the positive wire.

Step 6: Compensate the Compass

After installation, you must compensate (adjust) the compass to correct for local magnetic deviation caused by your boat's metal and electronics. Most Ritchie compasses include built-in compensating magnets accessible via small screws on the compass body.

Take the boat to open water away from other vessels and structures
Head due North using a known reference (GPS or chart)
Adjust the N-S compensating screw until the compass reads North
Turn to due East and adjust the E-W compensating screw until the compass reads East
Make a deviation table by checking the compass on 8 headings (N, NE, E, SE, S, SW, W, NW) and recording any remaining error

A deviation of ±2° or less on all headings is acceptable for most recreational use.

Pro Tips

Never store a handheld radio or phone directly next to your compass — even temporarily
If you add new electronics after installation, re-check your compass for deviation
Ritchie compasses use a liquid-filled card that dampens movement — avoid exposing them to extreme heat, which can cause bubbles in the fluid
Clean the dome with a soft cloth and mild soap only — solvents will cloud the plastic

Shop Marine Compasses at Egret Marine

Browse our full selection of Marine Navigation & Instruments including the complete Ritchie compass lineup. Whether you need a flush mount for a center console or a bulkhead mount for a sailboat, we have the right compass for your installation.

Questions about compass selection or installation? Contact the Egret Marine team — we're here to help.