Stray marina electric currents?

[Lake-Effect]

Originally Posted by SecondBase

So to take the ABYC to task - AFAIK they bear maybe 5% responsibility for US builder corrosion sinkings due to a missing standard sending industry off in the wrong direction?

Does ABYC have a (real world) standard such that a thruhull must resist X amount of stray current for Y months?

...

p.s. “proper grounding system” doesn’t cut it as an excuse to me unless that vulnerable grounding system can also resist the identical sideload.

The American Boat & Yacht Council (ABYC) is a non-profit, member organization that develops voluntary global safety standards for the design, construction, maintenance, and repair of recreational boats.

... repeat, voluntary.

Yes, sure it would be nice if there was a tried and true standard for corrosion resistance. And side load.

Then you need suppliers the world over to follow this voluntary standard, and boatmakers to always use the more expensive parts built to that standard. Voluntarily.

Seriously though, there's tons of factors behind corrosion: proper naval bronze vs brass, valve type and construction, dissimilar metals, bonded or not, and all the potential sources of stray current. I suspect even the stoutest naval bronze through-hull can be destroyed in short order by a stray current or improper bondiing. So, such a corrosion standard could only be depended upon when all the other factors have been optimized.

[boatpoker]

Originally Posted by SecondBase

Probably - for example I can simplify the galvanic load for a new ABYC Standard.

So why don't you ?

Anyone can join ABYC and get on one of their technical committee's if they have knowledge and credentials in the subject area. You apparently know more than them so we'd all benefit.

[SecondBase]

Originally Posted by Lake-Effect

I suspect even the stoutest naval bronze through-hull can be destroyed in short order by a stray current or improper bondiing.

Great points Lake Effect including the voluntary comments and the sentence above.

I’m not the expert but if the numbers show more boats sink from corrosion than from side load, my concern is we may be solving the smaller issue not the bigger issue. Happy to be proven wrong by stats from the number of sinkings.

Anyone on the forum here had their boat or a boat they directly know of sink from side load? Same question for corrosion - your boat or direct knowledge?

[boatpoker]

Originally Posted by Lake-Effect

I suspect even the stoutest naval bronze through-hull can be destroyed in short order by a stray current or improper bondiing.

Naval bronze , most often called "naval brass" falls squarely in the "brass" camp due to it's having 35 - 40% zinc content. This is the type of ball valve you can get at Home Depot and is not suitable for use below the waterline due to it's potential (almost certain) for de-zincification as the copper and zinc are too far apart on the galvanic scale.

A top quality "seacock" will be made of a real "bronze" such as silicon with anywhere from zero to a maximun of 5% zinc.

[Lake-Effect]

Originally Posted by boatpoker

Naval bronze , most often called "naval brass" falls squarely in the "brass" camp due to it's having 35 - 40% zinc content. This is the type of ball valve you can get at Home Depot and is not suitable for use below the waterline due to it's potential (almost certain) for de-zincification as the copper and zinc are too far apart on the galvanic scale.

A top quality "seacock" will be made of a real "bronze" such as silicon with anywhere from zero to a maximun of 5% zinc.

My error, sorry; I thought the "good stuff" most suitable for marine fittings was called naval bronze.

What are the various types of brass/bronze used in marine fittings, ranked by suitability for use on a boat? Thanks.

[boatpoker]

Originally Posted by Lake-Effect

My error, sorry; I thought the "good stuff" most suitable for marine fittings was called naval bronze.

What are the various types of brass/bronze used in marine fittings, ranked by suitability for use on a boat? Thanks.

You ask a complex question.... Naval Brass can and is used safely in marine applications, not however for constant immersion in salt water.

Brass, bronze, stainless steel etc. are not specific metals but rather groups of metals. i.e. Stainless steel is of five different types .... PH, Duplex, Ferritic, Austenitic and Martensitic within these five groups there are dozens of sub-types such as 304, 318, 316, 316L etc. This same scenario applies to bronze, brass, aluminum and any other group of metals. Some applications on a boat require 304, some 316 or 316L or one of the many dozens of others.

The application determines the type and sub-type to be used and the choice is huge. No one can specify any metal without knowing exactly how and where it will be used.

This is what makes any kind of corrosion standard a fantasy unless one has the budget of the US Navy.

[SecondBase]

Originally Posted by boatpoker

The application determines the type and sub-type to be used and the choice is huge. No one can specify any metal without knowing exactly how and where it will be used.

This is what makes any kind of corrosion standard a fantasy unless one has the budget of the US Navy.

Do fittings need to perform in a hot marina - yes or no?

Which composite or metal fittings offer a guarantee against corrosion in a hot marina?

[smac999]

Originally Posted by Lake-Effect

Yes, sure it would be nice if there was a tried and true standard for corrosion resistance..

all of the ABYC bonding and grounding rules are for safety, and preventing electrocution on the boat or in the water around the boat. and have nothing to do with preventing corrosion. most of the things induce or make corrosion worse, not better.

[Lake-Effect]

Originally Posted by smac999

...the ABYC bonding and grounding rules ... have nothing to do with preventing corrosion. most of the things induce or make corrosion worse, not better.

That's not true. There might be situations where not being bonded would reduce the potential corrosion of a metal thruhull in the presence of some other abnormal or incorrect situation, but I don't know of any ABYC recommendation that causes or increases corrosion in a normal (not faulty) situation.

[SecondBase]

Originally Posted by Lake-Effect

That's not true. There might be situations where not being bonded would reduce the potential corrosion of a metal thruhull in the presence of some other abnormal or incorrect situation, but I don't know of any ABYC recommendation that causes or increases corrosion in a normal (not faulty) situation.

Ok good point. So let me say it another way. I suspect there were no valid composite solutions at the time ABYC set the standard. For that reason I’m guessing the tradeoff between side load and corrosion was not considered?

A composite airbus holding together surprised some pilots when CPT Sully stuck his “miracle” landing. Miracle being how us mere mortals describe his 30+ years of experience.

Back to ABYC I don’t like to see a standard flouted over common sense.

Standard: double clamp all thru hulls
Common sense: close all thru hulls before you leave the boat.
If you could only choose one of the above which would it be?

Standard: resist side load
Common sense: understand and then weigh the tradeoff between side load and corrosion. Mitigate appropriately for your boat & situation.

I believe Mads called it best on his warrior 38 Athena. However, if your boat doesn’t travel (to different marinas) I can see you prioritizing side load instead.

[Lake-Effect]

Originally Posted by SecondBase

Ok good point. So let me say it another way. I suspect there were no valid composite solutions at the time ABYC set the standard. For that reason I’m guessing the tradeoff between side load and corrosion was not considered?

A composite airbus holding together surprised some pilots when CPT Sully stuck his “miracle” landing. Miracle being how us mere mortals describe his 30+ years of experience.

I must confess that I haven't been paying complete attention to the 'side load' issue. I am interested in the electrical stuff mostly; that's what I went to school for, and I got ABYC certified in Electrical so that I could win arguments.

Back to ABYC I don’t like to see a standard flouted over common sense.

Standard: double clamp all thru hulls
Common sense: close all thru hulls before you leave the boat.
If you could only choose one of the above which would it be?

What kind of question is that? They're both good things to do and doing one shouldn't preclude doing the other.

Maybe all thruhulls should be protected by an enclosure or shroud to guard against side impacts?

[added notes]
Seacocks, thruhulls, drain plugs are covered in ABYC H-27.
There's a handoff to another standard:
ANSI/UL 1121, Marine Through-Hull Fittings and Sea-Valves.

Mainesail has an article on some sideload testing he's done.

[Lake-Effect]

More links:
Thru hulls and seacocks | Sailingmates
http://www.michel-christen.com/2T-H.pdf
https://www.passagemaker.com/technical/seacocks

[GordMay]

Originally Posted by Lake-Effect

... Yes, sure it would be nice if there was a tried and true standard for corrosion resistance. And side load ...

I believe that the ABYC standard is for the assembly (thru-hull/seacock), as installed, to withstand a 500-pound lateral (side) load for thirty seconds.