SeaRay 290 | Sinking - Mercruiser Stern Drive Investigation | # 00726

SeaRay 290 Sinking 

Mercruiser Stern Drive Investigation.                           

This is important information for all Mercruiser Sterndrive installations / owners.

P1300939        P1300955

Being appointed by a well known Insurance Company to investigate this unfortunate incident, and without going into too much detail surrounding the circumstances of this incident we detail the causes and lessons to be learnt

Through a combination of high tides, highest rainfall recorded for the month, damaged rear cover, bilge pump failure and a strong current the twin petrol engine sterndrive 32′ offshore express cruiser sank.


There was no evidence of any hull impact damage or no skin fitting failure

We were aware that both Mercruiser Stern Drive units had been totally submerged

There was no visual evidence of the transom bellows having split being the usual problem in such circumstances.

However from a previous (similar) investigation we were aware that the Mercruiser stern drive alloy casing – enclosing the steering arm / head – BEHIND THE MERCRUISER BADGES is subject to electrical / galvanic / electrolysis activity

Consequently the alloy casing wall behind the Mercruiser Badges is destroyed with a resultant hole and the inevitable sinking

P1300947         P1310173

View of resultant damage & water ingress through hole (electrolysis) in outdrive casing

Due to the stick-on badges this damage (hole) cannot or may not be seen or realised by a conscienous owner

Lessons to be learnt ……….

1.  Pre-requisite to have an operational / automatic bilge pump – failure may result in an insurance claim refusal

2.  Protect exposed areas, cockpits etc with a serviceable cover

3.  Investigate and monitor the alloy casing enclosing the steering head, remove the Mercruiser labels if necessary to inspect

This boat was an insurance write off

This is the second (similar cause) sinking incident / cause that we have investigated – You have been warned

For more information contact European Marine Services Ltd.  Marine Surveyors & Consultants 
EMS also undertake Boat Safety Inspections & Engine Inspections
Tel: 01603 327 123