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What every boat owner should know about their exhaust

Did you know engine damage caused by boat exhaust can be extremely costly?

This can happen unexpectedly if a boat is moored in a pen and can’t move with the tide or current. As a result water washes into the exhaust and causes damage to the engine.

We spoke with Complete Marine Consulting Managing Director John Gray, an expert with plenty of information about what happens when things go wrong on the water. As a marine assessor, John travels all over Australia to inspect damaged marine vessels.

John has some great stories about cases he has worked on, which may just help other people in the boating community avoid similar situations.

Here’s one he shared with us earlier in the week.

(Names and identifying details have been removed for confidentiality reasons.)

Trident Marine: Tell us what happened!

John Gray: A 52-foot Flybridge cruiser was moored at Rowley Shoals, which is 200 nautical miles from Broome. The cruiser had spent several days on a swing mooring, and when the engine was started, they discovered it was full of water and inoperable.

TM: So they were stuck in a remote location with one engine?

JG: Yes, so they returned to Broome on one engine, which was later also found to be damaged. Both engines were removed from the boat, which in itself was tedious, as it was a production boat, so they were not easily accessible in this instance. The entire galley was removed along with the aft saloon bulkhead, which was all done onsite in Broome.

TM: What did you discover?

JG: We determined that the main engines had taken on water via both port and starboard exhausts, which are standard design by a mainstream Aussie manufacturer. This in itself is unusual. Once the engine exhaust design was confirmed as being within OEM guidelines, it was determined that an opposing, strong tide and wind essentially pushed water up the exhausts over a period of time.

TM: So water got in the exhaust, which got in the engine?

JG: This is an unusual situation and 99% of the time it would not be an issue, however, this shows that even good trusted vessel design is not necessarily infallible. There are times when engineering is pushed beyond its limits and massive amounts of damage can result.

TM: Is there anything that could have helped these boat owners?

JG: While manufacturers do their best to design boats well, it’s best to remember that there are no standards for pleasure boats. Marine exhausts are worth checking to make sure they have sufficient rise, or as much as the hull itself allows. They should be designed to keep water well away from the engines by any and all means. Exhausts may need to be upgraded if the design skirts too close to minimum OEM requirements, just to be safe.

TM: Was it expensive to repair?

JG: Unfortunately I’ve never seen a marine engine that is cheap to repair, especially when damaged by seawater. This was a very expensive claim, which was in the order of $350,000. This cost was to repair onsite in Broome and later in Perth to return the boat to its pre-loss condition.

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