Chain plates - replace or not?

[Pilot Rob]

We are relatively new boat owners who are refitting a 1987 46' Jack Savage built Oceanic, located in a marina in the tropics in North Queensland Australia. Our next project is to replace all standing SS rigging. We had not considered changing the SS chain plates, but now we are getting feedback (and this forum seems to confirm) that we should do that as well. We have owned the boat for two years and there is no record of the age of the current rigging, hence the replacement. The mast is coming out as well. There is a lot of experience and knowledge on this forum so putting out a call for opinions on the value and approach of replacing, or not, the chain plates.

Looking forward to your advice!

Rob & Kim
SY Mimas
Townsville Australia

[John A]

It's currently 10pm on the west coast of the US and 1am on the east coast so I doubt that you'll get a high number of answers from the US at this time..

I would suggest that the chainplates should be replaced as part pf the rigging replacement on a boat this old.

[DeepFrz]

25 years is a long time. Are they stainless or bronze? Whatever they should certainly be removed and carefully checked to see if there are any stress cracks or pitting.

Also take a look at this current thread if you haven't already seen it.

http://www.cruisersforum.com/forums/...ml#post1058572

[hugosalt]

Changing out chain plates at this time would make a lot of sense.
Take old plates to a machine shop to use as a template.
Seems to be a growing consensus against replacing with SS.

[rebel heart]

Well, check out this bolt that came out of my less than 25 year old standing rigging:

http://www.cruisersforum.com/forums/...olt-90926.html

About 50% of the chainplates and fasteners I've pulled have varying degrees of corrosion, some that make me really happy I'm changing them out. It's a pain in the ass job replacing them, but it's really not *that* bad, and it's cheap insurance.

[Stumble]

I am absolutely prejudice since I sell titanium chainplates.

On a 25 year old boat at a minimum the chainplates should be pulled and inspected either by someone who has experience with dye testing, or by x-ray. Assuming they pass then their fine. On the other hand by the time you pull them out, pay for the inspection, then put them back in, the cost of new isn't really that much more.

As far as material...

If you can identify what alloy you have (304, 316, 316L) then replace them with the same. If not, you need to assume they are made from the strongest of the options (304) which is also the least corrosion resistant. And replace like for like.

The other option is to switch to titanium. Which will be more expensive, but are immune to corrosion in the marine environment (at least in tempratures below 215F, or 102C).

[noelex 77]

The oceanic is great cruising boat, but they have had some problems with chainplates.
There was a report of chainplates failure in the magazine Cruising Helmsmen a few years ago. (I think it was a 42 from memory, but assume the chainplates are identical, or at least similar)
I also had a friend with a 46 that had chainplate failure, but fortunately managed to save the rig.
Two is not a big number, but significant given only a small number were built.

At least remove the chainplates and inspect them very carefully, but as Greg says the replacement cost is not usually high for the peace of mind.

[Blue Stocking]

Greg, can you give us some of the specifics about the best fastenings to use with titanium chainplates.
Do they need to be insulated from Ti, how about elec bonding for lightning ,etc.
Reaction with chemicals in caulking, sealers?
Thanks.

[Stumble]

Originally Posted by Blue Stocking

Greg, can you give us some of the specifics about the best fastenings to use with titanium chainplates.
Do they need to be insulated from Ti, how about elec bonding for lightning ,etc.
Reaction with chemicals in caulking, sealers?
Thanks.

Blue, I would recommend titanium fasteners with titanium chainplates. The issue is that because titanium is the most noble of the structual metals, a bolt made from anything else may be subject to galvanic attack. Frankly when you compare our prices to many chandleries price for stainless there isn't much of a price difference.

At least for the forseable future titanium will be more than stainless, but not nearly as much more as many think. For instance our lifeline stantions are $62. Lewmar wants $99 for theirs, and Gurhauer wants $35. So the price difference is close enough that premium stainless parts may actually be more than titanium... Weird world.

As for corrosion, or attack by chemicals:

There are only a very small number of things that attack titanium. Generally none of them are present in the marine world. While I am not a chemist, I have looked into this a good bit. Strong concentrations of sulphuric acid can attack titanium, but we are talking orders of magnitude stronger concentrations than battery acid. Chemically pure dry chlorine gass (but not wet) can attack it

Frankly titanium in the normal marine environment is just immune to corrosion. The only place on a boat where it suffers from corrosion is when used in wet exhausts, where the tempratures exceed 215 degrees F. But even there it is still orders of magnitude better than any other option.

Just a few examples of where the corrosion resistance of titanium is currently in widespread use...

100,000 year rating against corrosion for nuclear waste storage containers.
Nuclear reactors
Lifetime warranty on chlorine pool hear exchangers
Lifetime warranty on high concentration desalination plants parts

One of the more common uses of titanium is in an environment significantly more harsh than the marine world. When it is used as surgical implants (screws, legs, ect). Where the parts are always close to 100F, wet, live in a salty brine, and never get exposed to air or free oxygen. And titanium implants still outlive even the best marine stainless on a boat.

[barnakiel]

I would replace.

If you pull them out and they are in great shape, you can just re-bed them. But if they show any signs of their age, replace.

I watch boats coming in without their sticks two-three times a year here. Most of the failures ARE at chainplates.

b.

[Pilot Rob]

Hi all - thanks for the educated feedback. We are removing and inspecting first. They seem to be of superior condition considering the state of the external rigging. We are also contacting the previous owners to see if they can shed any light on possible work they may have done.

Rob

[Stumble]

Rob,

I would highly recommend having them at least dye tested, if not x-ray inspected. A visual inspection alone (except under a microscope) is only acceptable if the part can be rejected visually. For instance if there is visual degradation or significant problems then obviously there is no need to go further. But to be sure they are ok, you really do need to go further.

[GaryMayo]

Also pay close attention to where the chainplate fastens to the hull. On my boat, when I replace mine, going a little longer and adding an additional attachment point.

[DeepFrz]

I would highly recommend having them at least dye tested, if not x-ray inspected. A visual inspection alone (except under a microscope) is only acceptable if the part can be rejected visually.

+1