Best Material for Chainplates ?

[delmarrey]

Originally Posted by Stillraining

Can you expound on that Daddle...Would SS toggle pins be one of those?...Delmary is a Machinist and seems to think it would be a good idea.

This seems like it would be a huge job though...Im thinking the attachment area for the main spreaders would have to incorporate a fair sized area of the hull like 9 square feet or so....That would be a huge are of internal deconstruction to access on my and most other boats.

I think the electrolysis would occur if the CF/SS were immersed in saltwater. Occasional exposure shouldn't be a problem. I know that aluminum w/CF is a no no. The bicycle industry has had some failures.

Graphite and SS are both high on the galvanic list. Galvanic series - Wikipedia, the free encyclopedia

You might want to contact cat man do Cruisers & Sailing Forums - View Profile: cat man do He's building a Cat using some CF tabs for an anchor bridle and other stuff.
It would be nice to talk to some Boeing people.

[sildene]

I have read about SS chainplates suffering crevice corrosion where they pass trough the deck - presumably a small gap (crevice) between the chainplate surface and surrounding structure allows the crevice corrosion to start. Not good - who wants their chainplates to suddenly snap?

Now, if you're handy (and lucky) maybe you can use a flexible sealant like silicone (although I hate the stuff) to make sure no water gets down from the deck onto the chainplate, and seal it from below such that no water gets up from the cabin side either. Now, if you manage to keep the chainplate dry in the through-deck region, do you thereby eliminate the crevice corrosion threat (in that area) entirely?

Secondly, does anybody's practical experience indicate that you just cannot keep that chainplate region dry by using sealants?

Martin

[estarzinger]

Originally Posted by sildene

Secondly, does anybody's practical experience indicate that you just cannot keep that chainplate region dry by using sealants?

Martin

Yes, it is very hard to absolutely and permanently seal SS chainplates that way with sealant . . . and there is really no way to inspect it to know if it is sealed or not. The deck is flexing, the ss chainplate is building up surface rust . . . and the sealant bond will break in some small gap and let water in to sit there.

It is slightly more possible to seal the chainplates with a rubber compression gasket.

[mikereed100]

Originally Posted by Stillraining

Regarding carbon fiber for chain plates....what is the standard means of adhering them as a retrofit to the hull?

And what size would be required to replace a 1/2" x 3" SS one.

The answer will depend on your configuration. If you have a bulkhead to attach to then you can simply epoxy the CF to the bulkhead. If you have a flat-sided hull that has been reinforced to take a chainplate then you can epoxy to this. Use narrow strips of uni applied at a small angle and fan them out.

Originally Posted by Stillraining

This seems like it would be a huge job though...Im thinking the attachment area for the main spreaders would have to incorporate a fair sized area of the hull like 9 square feet or so....That would be a huge are of internal deconstruction to access on my and most other boats.

Most epoxies will give you roughly 1000lbs/square inch adhesion in shear so your attatchment area need not be that large. You can avoid corrosion (and cost) issues by using S-glass which has a similar tensile strength to carbon although none of the bragging rights. Paint them black and you're good to go.

Mike

[sneuman]

if I used silicon bronze, assume I should also use 655 (silicon bronze) fasteners. Assume 655/316 stainless combo would be a no no ...? Likewise, what about the passivity (is that the correct term) between the 655 chainplates and the ss clevis pin/rigging screw?

[estarzinger]

Originally Posted by sneuman

if I used silicon bronze, assume I should also use 655 (silicon bronze) fasteners. Assume 655/316 stainless combo would be a no no ...? Likewise, what about the passivity (is that the correct term) between the 655 chainplates and the ss clevis pin/rigging screw?

Take a look at the galvanic series table. 316L and 655 are quite close. You will not have any problem mixing these two on deck. You can put some tufgel on the pins, which would absolutely minimize even the small potential of problem (its used to isolate aluminum from stainless fastners which is a much worse potential problem) . . . . and its useful stuff to lubricate the turnbuckle screws anyway.

[S&S]

Originally Posted by estarzinger

Take a look at the galvanic series table. 316L and 655 are quite close. You will not have any problem mixing these two on deck. You can put some tufgel on the pins, which would absolutely minimize even the small potential of problem (its used to isolate aluminum from stainless fastners which is a much worse potential problem) . . . . and its useful stuff to lubricate the turnbuckle screws anyway.

Yep.
We have bronze plates and stainless pins- no problems.

[Stillraining]

Originally Posted by mikereed100

The answer will depend on your configuration. If you have a bulkhead to attach to then you can simply epoxy the CF to the bulkhead. If you have a flat-sided hull that has been reinforced to take a chainplate then you can epoxy to this. Use narrow strips of uni applied at a small angle and fan them out.



Most epoxies will give you roughly 1000lbs/square inch adhesion in shear so your attatchment area need not be that large. You can avoid corrosion (and cost) issues by using S-glass which has a similar tensile strength to carbon although none of the bragging rights. Paint them black and you're good to go.

Mike

Very informative Mike...thanks.

One question: I see you used what appears to be a galvanized thimble in one application..possible SS.... and I'm assuming glass fibers bent around it..Although not the way I envisioned the process at all..what is the benefit or risk in this method...my pee brain tell me we have a corrosion issue right off the bat here...and chaffing issues on the glass fibers..no?

Stll it would require mass interior removal on my boat to do..

[Stillraining]

Originally Posted by delmarrey

I think the electrolysis would occur if the CF/SS were immersed in saltwater. Occasional exposure shouldn't be a problem. I know that aluminum w/CF is a no no. The bicycle industry has had some failures.

Graphite and SS are both high on the galvanic list. Galvanic series - Wikipedia, the free encyclopedia

You might want to contact cat man do Cruisers & Sailing Forums - View Profile: cat man do He's building a Cat using some CF tabs for an anchor bridle and other stuff.
It would be nice to talk to some Boeing people.

Thanks Del....it seems there is no perfect answer is there ...

[barnakiel]

Well, do not think there is such a thing as overall "best" but definitely in some applications bronze will beat SS (and SS will beat bronze in others).

I would love to have our chainplates made in bronze one day - I have seen bronze toggles deformed long before they snapped (they did not) - while SS seems to have a much more dramatic mode of failure.

Good luck in your search, and PLS post the results once the stuff gets manufactured.

barnie

[delmarrey]

Originally Posted by barnakiel

Well, do not think there is such a thing as overall "best" but definitely in some applications bronze will beat SS (and SS will beat bronze in others).

I would love to have our chainplates made in bronze one day - I have seen bronze toggles deformed long before they snapped (they did not) - while SS seems to have a much more dramatic mode of failure.

Good luck in your search, and PLS post the results once the stuff gets manufactured.

barnie

I would agree!
With SS once it starts to crack the erosion factor seems to follow. Where as with bronze it doesn't really crack until it has mushroomed out quite a bit and erosion isn't really a problem unless it is immersed. Also bronze will take a shock many times more then SS.

The problem with bronze is once it's welded it changes it's properties dramatically which limits its fabrication abilities.

BTW Most rigging turnbuckles are cast bronze (plated). No galvanic problems there.

[delmarrey]

Originally Posted by mikereed100

The answer will depend on your configuration. If you have a bulkhead to attach to then you can simply epoxy the CF to the bulkhead. If you have a flat-sided hull that has been reinforced to take a chainplate then you can epoxy to this. Use narrow strips of uni applied at a small angle and fan them out.



Most epoxies will give you roughly 1000lbs/square inch adhesion in shear so your attatchment area need not be that large. You can avoid corrosion (and cost) issues by using S-glass which has a similar tensile strength to carbon although none of the bragging rights. Paint them black and you're good to go.

Mike

That does look like a pretty strong system for a straight pull BUT what would happen if that eye were to get hit or bent over a bit. Personally, I think I would build a structure around the eye to protect it from movement.

And wouldn't it be beneficial (stronger) to add some glass filler and fair in the outer hull (green area)?

[IceMan]

I have read about SS chainplates suffering crevice corrosion where they pass trough the deck - presumably a small gap (crevice) between the chainplate surface and surrounding structure allows the crevice corrosion to start. Not good - who wants their chainplates to suddenly snap?

Sildene,
This type of failure is common on chainplates that are welded 2 or more pieces. Water gets inside the weld and then over time it fails. If yours is like mine, have an NDI lab come out and perform an eddie current inspection. They will be able to tell you if it's a bad weld or not.

Now, if you're handy (and lucky) maybe you can use a flexible sealant like silicone (although I hate the stuff) to make sure no water gets down from the deck onto the chainplate, and seal it from below such that no water gets up from the cabin side either

I don't know how others feel but I think there is no place on a boat for silicone rubber or RTV except for sealing a bathroom fixture like the sink. Other than that it's a no no for me. What I do to seal the chainplate tangs on my boat is to clean out the area around the chain plate and down as far as feasable. Then get 210T primer from sikiflex and coat the chainplate and the surround area, wood and all. After that has sit for a half an hour, take sikiflex 292 and fill the void throughly!!!! Then if your chainplate has a covering plate with small screws, install butyl tape around the tang under the cover plate. Then attach the plate with the screws and let the tape squeeze out between the tang and the cover top, bottom and sides, then remove the excess. The 292 will stay flexible for dozens of years and the primer assures that the 292 holds to whatever it comes in contace with. And of course, the buytl tape will never harden. Also, 292 can be just as messy as 5200. Take all taping and clean up precautions. Sorry for being long winded but I've tried several ways and this one seems to be the best if anyone is interested.
WD

P.S. Can't remember where it is at but there is an excellent article by one of the posters here about buytl tape. Best I've ever seen.

[delmarrey]

Butyl tape is good stuff but on a deck fitting in the hot climates it would get real messy. In Alaska it would make sense due to the extreme cold, one would need something that would stay pliable. Rather then the butyl (down south) one could continue on with the 292.

And yeah! Residential silicone doesn't stick to moving parts.

[GordMay]

Originally Posted by IceMan

... What I do to seal the chainplate tangs on my boat is to clean out the area around the chain plate and down as far as feasable. Then get 210T primer from sikiflex and coat the chainplate and the surround area, wood and all. After that has sit for a half an hour, take sikiflex 292 and fill the void throughly!!!!
... Also, 292 can be just as messy as 5200 ...

Like 5200, 292 is Sika's polyurethane product. They're virtually interchangable.