Boat Diagnostics

Boat Problems? Start Here.

Common boat problems and what to check first — written by ABYC-certified marine technicians.

My Boat Won't Start — What to Check First

Nothing ruins a Saturday faster than a boat that won't crank or fire. Most no-start problems on the Bay come down to one of five t…

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Boat Engine Overheating — Diagnosis & Fix

Overheating is the #1 cause of catastrophic engine damage on the Bay. Shut the engine down within 30 seconds of seeing high temp —…

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Boat Taking on Water — What to Do

Some bilge water is normal. A lot is an emergency. Here's how to tell the difference and what to do.…

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Outboard Losing Power Under Load

If your outboard runs fine at idle but won't reach full RPM under load, you're losing power somewhere. Here's how to find it.…

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Marine Battery Won't Hold Charge

If your battery dies between weekend trips, the problem is almost always one of three things.…

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Gelcoat Cracks & Crazing — Cosmetic or Structural?

Spider cracks in gelcoat are common on Bay boats. Most are cosmetic. Some signal serious structural problems. Here's how to tell.…

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Soft Spot in Boat Deck — Now What?

Walking on a deck that gives under your feet means the core has rotted. The good news: it's fixable. The bad news: don't ignore it…

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Smoke From Marine Engine — What It Means

Different colors mean different things. Don't ignore it.…

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My Boat Smells Like Sewage — How to Fix It

If your boat smells, it's almost always permeated sanitation hose. Cheap hose lets odor through the wall after 3–5 years.…

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Shore Power Not Working at the Slip

Shore power problems usually trace to one of three places: the dock, the cord, or the boat.…

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Bilge Pump Running Constantly

A bilge pump that runs all the time means water is coming in faster than the pump can keep up at the float-switch level — or the f…

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Boat Steering Stiff or Hard to Turn

Stiff steering is dangerous and almost always fixable.…

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Prop Vibration at Speed — Causes & Fixes

A new vibration that gets worse with throttle is almost always the propeller, the shaft, or the cutless bearing. Ignoring it leads…

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Engine Hard to Start When Cold

If your boat fires right up warm but cranks forever cold, the issue is fuel delivery, glow plugs, or compression — and it almost a…

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Engine Compartment Blower Not Working

On a gas-powered boat, the blower is a safety device — fuel vapors in the bilge plus a spark equals an explosion. If yours doesn't…

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Trim Tabs Stuck or Not Responding

Trim tabs that stop working ruin fuel economy and ride quality. The fix is usually electric or hydraulic — and almost always corro…

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VHF Radio Has No Signal or Heavy Static

A VHF that doesn't reach the Coast Guard is a safety problem. Bad reception or transmission is almost always the antenna, the conn…

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GPS / Chartplotter Frozen or Glitching

When your Garmin, Raymarine, Furuno, or Simrad starts glitching, it's almost always firmware, network, or power — not a dead unit.…

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Fuel Gauge Reading Wrong

A fuel gauge that lies is dangerous — running out of fuel offshore is no joke. The fix is almost always the sender in the tank, no…

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Fresh Water Pump Cycling On and Off

A water pump that clicks on and off when no faucet is open means there's a leak in the pressure system somewhere. Find it before t…

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Anchor Windlass Not Working

A dead windlass at 6 a.m. in Drake's Bay is a bad day. Most windlass failures are electrical, not mechanical.…

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Engine Running Rough at Idle

A rough idle that smooths out at speed almost always points to fouled injectors, a failed sensor, or a vacuum leak. Don't ignore i…

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Boat Hard to Shift Into Gear

A stiff shifter is usually a cable problem, not a transmission problem. Don't replace the transmission until you've exhausted the …

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Stern or Navigation Lights Not Working

Running without working nav lights is a USCG violation and a collision risk. Most nav-light failures are corrosion at the fixture,…

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Marine Refrigerator Not Cooling

A warm fridge on a hot Bay weekend is misery. Most marine fridge failures are airflow, voltage, or a low refrigerant charge.…

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Marine Water Heater Not Heating

Marine water heaters fail in predictable ways. The fix is almost always one of three things — and you don't always need to replace…

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Engine Alarm Buzzer Won't Stop

An engine alarm is your first warning before catastrophic damage. Don't silence it without finding the cause — the buzzer just bou…

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Stuffing Box Leaking Excessively

Traditional packing should drip slowly while the shaft turns and stop drips at rest. A constant or fast drip means the packing is …

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Loose Rudder or Steering Play

Excessive steering play is dangerous and gets worse fast. The fix is usually a worn bearing or hydraulic air — both totally fixabl…

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Headsail Furler Stuck or Hard to Roll

A furler that binds is usually a halyard wrap, a seized swivel, or a worn bearing — and the fix gets cheaper if you catch it befor…

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Diesel Engine Won't Shut Off

A diesel that keeps running with the key off is a failed fuel cutoff — and it won't fix itself. Don't run the boat until it's repa…

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Blisters on the Bottom (Osmotic Blistering)

Bottom blisters under the antifouling are osmotic — water has wicked into the laminate. Caught early it's a manageable repair. Ign…

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Winch Frozen or Hard to Crank

A winch that grinds, slips, or won't turn is overdue for service. Sailboat winches need annual cleaning and re-greasing — most hav…

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Oily Sheen in the Bilge

Oily bilge water is illegal to discharge and signals an engine, transmission, or fuel-system leak. Find the source before the EPA,…

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Engine Loses RPM Mid-Run

An engine that pulls fine for 15 minutes then loses RPM is almost always fuel starvation or overheating — and it's predictable eno…

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Through-Hull or Seacock Corrosion

Corroded through-hulls and seacocks are the #1 sinking cause for boats at the dock. Pink discoloration on bronze means dezincifica…

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Can't Solve It Yourself?

Call (415) 524-5194 — most diagnostics we can finish in 15 minutes at the slip.

Call (415) 524-5194