serious corrosion in a narrow boat bow thruster tube.

[@mwhitcombe]

Hello, you say 5mm is too thin, what wall thickness would you recommend for a new build. Thank you for the informative video.

[@TheMarineSurveyorNotebookBenSu]

Personally try around 8mm if possible but make sure it is properly protected

[@finlaybichan1275]

would cavitation be having an effect here in speeding up corrosion?

[@TheMarineSurveyorNotebookBenSu]

Always a possibility but more likely from the lack of protection.

[@msinclair8261]

How much would it cost to replace a tube. My boat has just been surveyed prior to sale and and this problem has cropped up. I'm being told £4-£7k. This sounds way too much.

[@TheMarineSurveyorNotebookBenSu]

Depending on length of tube plus access that doesn't sound far off. Some have to have the whole well deck out to Weld inside and outside plus all the removal and refit of motor etc.

[@msinclair9633]

@@TheMarineSurveyorNotebookBenSu Thanks. Access should be easy as the bow thruster tube and all its parts are between two bulkheads with a lift off lid exposing everything. Hopefully will be requoted a smaller price.

[@MartynDuerden]

I agree 4-7k is crazy. A replacement 6” tube 1/2” thick 4ft long is around £350 A good welder should have this swapped out in a 8-12 hours Plus your dry dock. £1500 tops.