Thru Hull Replacements

[MR nova @#25]

Is it common practice to replace all the the thru hulls fittings on a 35 yr old boat just because?

 

[Alumarine]

Is it common practice to replace all the the thru hulls fittings on a 35 yr old boat just because?

Do you mean above or below the water line?
Above I've never heard of it and below I only have limited experience so can't comment.

 

[dingbat]

Depends on the material and their usage.

Plastic thru hulls are long over due.

Metal thru hulls should be thoroughly inspected, possibly dye tested for cracks in critical (below water line) applications.

 

[crazy charlie]

Not a common practice however if anything looks suspect just replace it and go from there.I just replaced one on a boat same age and this particular one was quite easy as far as access and getting exact size replacement.Not all thru hulls are easy access.Charlie

 

[Scott Danforth]

if you have plastic and they lasted 35 years, the boat was not kept outside. usually the plastic thru-hulls fail after 5 years

if you have stainless, inspect for crevice corrosion

if you have brass, they will be green, however may outlive your grandchildren

 

[shrew]

Is it done frequently?? NO

Should it be? It depends.

There are 4 typical materials for Nylon, Marelon, Stainless Steel, Bronze.

Bronze are expensive but will last decades and decades and decades. Suited for above and below waterline use.

Stainless Steel: Pretty, can have hidden corrosion when water is introduced without oxygen. When these conditions occur failure occurs with no obvious deterioration or warning. Suited for above waterline use only.

Nylon: Plastic, and no UV resistant. Will degrade to a brittle chalky state and have a high potential for failure after roughly 10-15 years. Suited for above waterline use only.

Marelon: Plastic. UV resistant. Suited for above and below waterline use. Can last for decades.

For me....
Below waterline = Bronze
Above waterline = Bronze or Marelon

Any Nylon will get replaced when they become chalky. SS will get replaced if I start to see rust weeping. Bronze and Marelon can be trusted.

 

[dingbat]

The problem with these types of threads is it gives a false sense of security.

Nothing is infallible......never assume anything when it comes to safety. Thru hulls, Seacocks and all related plumbing (pumps, etc.) should be thoroughly inspected annually. Anything even remotely suspect should be replaced

Bronze is susceptible to dissimilar metals corrosion and stress cracking (vibration)

Nylon thru-hulls typically fail where the body of the fitting joins the outer flange.
When I swapped out the 5 year old OE Nylon fitting for SS, all but one broke off in my hand. All cracked on the back side of the flange.

Note crack on inside of opening


Personally:
Above WL -316 Stainless (bling)
Below WL - C83600 bronze

 

[mr 88]

Is it a salt water boat kept year round in the water ? Is it a northern fresh water stored under tarp / shed for 8 months of the year boat ? There is a difference between the two. No doubt it may be overdue, especially if you don't know if or when they were swapped out by previous owners.

 

[MR nova @#25]

Do you mean above or below the water line?
Above I've never heard of it and below I only have limited experience so can't comment.

My bad, they are all below the waterline and they are metal.

 

[Scott Danforth]

My bad, they are all below the waterline and they are metal.

Stainless or Bronze?