Dodged a Bullet?

[Thistle]

Both the engine and heads intake seacocks in Thistle Dubh were a bit suspect so I decided to replace them. After a lot of hesitation I've started to replace the skin fittings as well which, although they looked fine and had no leaks, have been on the boat for a long time. Here's what happened ...



The flanged nut didn't move but the fitting sheared at the base of the thread and the next thread started to tear off. No problem while the boat is ashore but would have caused some difficulty when afloat, even with appropriate softwood plugs taped to the adjacent pipework.

So bullet dodged and hopefully others can learn from the experience.

PS The replacements will be TruDesign so no metal to corrode/fail.

 

[cpedw]

How old are those fittings?

 

[Thistle]

How old are those fittings?

I bought the boat in 2001 and it wasn't new then.

 

[Refueler]

Well caught ...

But there is another factor ... and I only mention this - NOT as information to not replace etc.....

I would suggest that many boats are going around with skin fittings that would do similar .. I hazard a guess that my boats may have similar result if I went to remove a fitting. But they continue to be OK because no-ones attacking the fitting to replace.

Looking at the photos - the fittings have obviously suffered as they are now showing more 'copper' colour ... such fittings would be weak and likely unable to withstand the sort of force needed to remove the seacock mounted on it ... a completely different force that being afloat would exert.
I am aware of the age of my skin fittings and is why I make sure the seacocks can operate without straining such fittings ....

BUT as I say - it is no excuse to ignore and its good that its been caught before catastrophe.

 

[Thistle]

Well caught ...

But there is another factor ... and I only mention this - NOT as information to not replace etc.....

I would suggest that many boats are going around with skin fittings that would do similar .. I hazard a guess that my boats may have similar result if I went to remove a fitting. But they continue to be OK because no-ones attacking the fitting to replace.

Looking at the photos - the fittings have obviously suffered as they are now showing more 'copper' colour ... such fittings would be weak and likely unable to withstand the sort of force needed to remove the seacock mounted on it ... a completely different force that being afloat would exert.
I am aware of the age of my skin fittings and is why I make sure the seacocks can operate without straining such fittings ....

BUT as I say - it is no excuse to ignore and its good that its been caught before catastrophe.

Thank you and I agree entirely ... that's probably why I've got away with this for so long. The eventual failure was caused by an intentional rotational force but I'd worry that an accidental lateral knock could have the same net effect.

 

[rotrax]

I dont think they were Bronze, they have the look of de-zincified Brass.

Truedesign are great, always easy to rotate.

 

[Tranona]

Yes, classic dezincification of plain 60/40 brass commonly used on new boats in the period - and still widely used. Since then DZR has become available for both fittings and valves at significantly lower cost than bronze, and also cheaper than non metallic. These will not corrode and last indefinitely.

 

[Sea Change]

Both the engine and heads intake seacocks in Thistle Dubh were a bit suspect so I decided to replace them. After a lot of hesitation I've started to replace the skin fittings as well which, although they looked fine and had no leaks, have been on the boat for a long time. Here's what happened ...

View attachment 171396

The flanged nut didn't move but the fitting sheared at the base of the thread and the next thread started to tear off. No problem while the boat is ashore but would have caused some difficulty when afloat, even with appropriate softwood plugs taped to the adjacent pipework.

So bullet dodged and hopefully others can learn from the experience.

PS The replacements will be TruDesign so no metal to corrode/fail.

Similar happened to me, but I was doing the job between tides with the boat leaning against a wall. It did wonders for my motivation to get the job finished.

 

[rogerthebodger]

I fitted a new skin fitting and seacock to the underside of my boat between tines on a scrubbing post

One of out inspection authorities require to violently shake the seacocks BEFORE lifting the boat out of the water.

Utterly stupid but they are authorized to confirm my boat is seaworthy

 

[RunAgroundHard]

If you feel inclined, send the images and brief explanation to Cox Engineering who curate stuff like this as a resource centre for sailors. I think this is noteworthy because it is easy to assume that this style of fitting and failure mode was yesterdays problem.

Cox Engineering

Glad you caught the weakened skin fittings onshore. It would have been a bit of a hassle on the water.