How to tell if a boat has taken on water

Outboard engines opened up for service

The first one I found, I was standing in the cabin of a Formula 430 SSC on survey day. This was before I was even a broker. I was there as the buyer’s guy.

The surveyor pulled the sole hatch. I put a light down into the cabin bilge. There were salt crystals sitting on the stringer like frost.

Not damp. Not a stain. Crystals, dry and white, in a compartment that should never see salt water at all.

That boat had gone down to the cabin at its own dock. Nobody had told the buyer.

How to tell if a boat has been sunk, and why the tells last

Stop looking at the shiny parts. Instead, look in the places nobody cleans.

Salt leaves a signature. Water leaves a level. Repairs leave a mismatch. A boat that went down and came back up will show you at least two of those three. Usually it shows all three, as long as you know where to put the light.

The seller is not always hiding it, by the way. Plenty of owners bought a boat that had been under and were never told either. Even so, the burden is on you to find it before your money moves.

Engine room bilge of an express cruiser, the first place I put a light when working out how to tell if a boat has been sunk
The bilge under the engines. Nobody details this, which is exactly why it tells the truth.

Salt crystals are the tell nobody scrubs

Salt water evaporates and leaves the salt behind. That salt sits in whatever low corner it dried in. Then it stays there for years, unless somebody goes after it with fresh water and a rag.

People clean what they can see. In practice, nobody cleans the underside of a fuel tank. Nor the back corner of a lazarette, the inside of a chain locker, or the void behind a battery box.

So that is where I go first. I want a bright light and a phone camera on a stick. Then I look at:

  • Cabin bilges and any compartment forward of the engine room
  • The underside of tanks, and the hull skin beneath them
  • Wire looms where they pass through a bulkhead, especially the top of the loom
  • The inside faces of lockers, above where water normally sits
  • Under the helm, behind the dash, at the back of the breaker panel

White crusting on a stringer in a dry compartment is not condensation. Instead, it is a boat telling you it was once full of ocean.

Water leaves a level, and a level is hard to fake

Water finds one height and holds it. As a result, a boat that sat submerged for a few hours carries a line. That line will be dead level across every surface it touched.

Look for staining or a change in texture at a consistent height. Check the bulkhead, the stringer, and the back of a locker. Then ask whether that elevation makes any sense.

Bilge water sloshing at sea makes a messy, uneven mark low down. By contrast, a boat that sat full of water makes a ruled line. Furthermore, it makes that line somewhere water has no business reaching.

In practice, the giveaway is when the line sits above something expensive. For example, if it runs across the top of the starter motor, you are not looking at a wet bilge.

If you are under contract right now and this is starting to sound familiar, send me the listing before your survey date. I would rather look at it early than read the report afterward.

A new engine room on an old boat

This is the one that gave the Formula away, once I knew what I was seeing.

When a boat goes under, the insurer replaces what got wet. Generators, gyro stabilizers, wiring looms, pumps and electronics all get swapped. Main engines often do not, because rebuilding a pair costs more than the settlement.

So you end up with an engine room where everything is new except the two most important things in it.

On that Formula, the Seakeeper was new. The generator was new. The wiring was new. Meanwhile the motors were original, and they had been underwater.

I worked my contacts at Formula until I reached the top and confirmed what had happened. My buyer walked. Even today I would give him the same advice, because you cannot un-soak a wiring harness.

Twin diesel engines under an open hatch, original motors sitting alongside replaced components
New generator, new wiring, original motors. That combination is a question, not a coincidence.

Corrosion lives on the underside and the back

Air gets everywhere, but salt water settles. Consequently the damage shows up on surfaces facing down and facing away.

Take the cover off the main breaker panel. Then look at the back of the breakers, not the front. Pull an inspection plate and check the underside of a bus bar.

Also look at the bottom of the engine mounts. Check the lower bolts on the transmission, the underside of the alternator, and the back face of the starter.

Green powder on the low side of a terminal, on a boat with a clean deck, is worth more than any answer a seller gives you.

Meanwhile, silt is the other one. Sand or fine grey mud in a place gravity never carried it means that compartment was full of standing water.

In short, learning how to tell if a boat has been sunk is mostly learning to look at the surfaces nobody photographs.

What the paperwork will and will not tell you

A total loss usually leaves a trail. However, a boat that was raised, repaired and never claimed often leaves nothing at all.

Ask for the full service history. Then read the invoices instead of counting them. A cluster of electrical and machinery work inside one three month window, with nothing before or after, is a repair rather than maintenance.

I will tell you plainly that records get edited. For example, I once took a listing where the seller handed me a four inch stack of them. I had the stack scanned and sorted.

The history showed major fiberglass and engine work, consistent with the boat having delaminated and taken on water. The owner confirmed it privately. Then he told me to pull those invoices out and say nothing.

I refused. He yelled at me and fired me on the spot, and the listing agreement was cancelled.

For the record, that boat was sellable. Disclosed, documented, and signed off by a surveyor, somebody buys it at the right number. Hidden, it is a lawsuit waiting for whoever signs.

Before the deposit clears

Send me the listing and the hull number. I will tell you what I would want opened up, and what I would ask the seller in writing, before anyone spends money on a haul out.

Call or text 954 504 8367

Disclosed is a completely different conversation

None of this puts a wet boat off the table. Rather, it means you have to price it as what it is.

I used to look after a VanDutch 40 whose owner bought it as a project. He knew it had taken a lot of salt water in the engine room. He went in with his eyes open.

Even so, the submerged wiring left him with constant electrical faults. There was a repair bill most months for as long as I was involved with that boat.

He is fine with that because he chose it. Had the same boat been sold to him as clean, he would have been furious, and rightly so.

That is the real lesson. Salt in the wiring does not get fixed, it gets managed. Therefore the only version of this deal that works is the one where you knew going in and paid accordingly.

What I ask for, in writing

Verbal answers are worth nothing later. So these go in an email, and I want the reply in an email too.

  • Has the vessel ever been submerged, grounded, or taken on water above the bilge, under any owner?
  • Has an insurance claim ever been filed, and was the vessel ever declared a total loss?
  • Have the main engines ever been submerged, opened, rebuilt or replaced?
  • Please provide the complete service history, unredacted, including work done under a claim.

A seller with a clean boat answers those in one line. By contrast, anyone who gets cute with the wording has just told you something.

Once the answers are in hand, the rest of the buying process is a lot simpler. I walk through the running side of it in my sea trial checklist, and the condition side in how I read a wash job.

Common questions

Can a marine survey find a boat that has taken on water?

A good surveyor will catch it, and that is exactly what you hire one for. Even so, the surveyor is aboard for a few hours on a single day. Knowing the tells yourself means you can flag a compartment and ask them to look harder while they are there. The Society of Accredited Marine Surveyors lists accredited surveyors by area.

Does a boat that has taken on water always show up on a title search?

No. A search may surface a documented total loss. However, a boat that was raised, repaired and never claimed will often show nothing. Absence of a record is not evidence the boat is clean.

Are salt crystals in the bilge always a sign of sinking?

Not always. Salt in the engine room bilge can come from a leaking raw water hose or a shaft seal. What matters is location. For example, salt in a dry forward compartment, well above the waterline, is a different problem entirely.

Is a boat that has taken on water ever worth buying?

Sometimes. The sinking has to be disclosed, the repair documented, and a surveyor has to sign off on the work. In other words, you are buying a boat with a permanent electrical question mark, so it needs to be priced like one.

Back to that Formula

My buyer got a deal on the price. He wanted the boat badly. Then he asked me what I would do.

I told him I would walk. You cannot un-soak a wiring harness, and he would spend five years chasing faults he could not find.

He walked. Ten minutes with a flashlight, in a compartment nobody cleans, saved him from a decade of it.

That is what how to tell if a boat has been sunk really comes down to. Not a trick, just a light and the willingness to open the panels nobody opens.

If something about a boat is not sitting right with you, that instinct is usually worth listening to. Send me the listing and tell me what is bothering you. I will give you a straight read on whether it is worth a haul out.

Frank Christopher, 954 504 8367. Text me the link and I will come back to you the same day.

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