Buying an 81 cp23/1 questions. *update, bought it!*

[millsy]

When I removed my chainplates, on one I found a very fine transverse hairline crack across the top bolt hole, from crevice/stress corrosion.  I think I have a photo of it somewhere (I used the serviceable portion of it for another project).  The backside of this particular chainplate was rusty because the sealant had failed years before. 

It is my experience that SS chainplates break where they pass through a deck or other locations where the sealant has broken down.  This happens most often in an area of stress concentration, bend, or weld.  The SS mounting bolts can have the same condition, so it is a good idea to remove, clean, and re-bed chainplates as a matter of preventative maintenance.  Bronze, on the other hand, is great- I would love to go with bronze chainplates someday...

Regarding bent/twisted chainplates, this has happened to me before when raising the mast when the lower end of the turnbuckles bound on the chainplates as they rotated around.  I just straighted these with two crescent wrenches- similar to using the claw of the hammer I suppose.  If this happens too many times I could see this weakening the metal so you will want to have a good look at any bent ones.

Chris
C-23 Dolce

[Billy]

Seems like Bronze, although corrosion resistant, would not have enough strength in tension. SS is MUCH stronger although it does corrode over time.

[Frantic]

Lots of good information here. Thanks everyone! Looks like we are going to go pick it up tomorrow

[Salty19]

Congrats to your Dad!! Boat looks real nice!

I'm with Wes and in favor of replacement if in doubt. You do not want them to fail--granted the 23 has 3 shrouds on each side so a failure may only mean dropping sail and motoring home.
Bolts too.

Billy, I'm a little dumfounded that Matt would just bend them back into shape. Surely he knows a thing or two about it, so who knows?  Could be a waste of money. Could be a judgment call once he looks at it.  Could be Wes and I are suffering from paranoia.  Nah...I'll go with judgement call.

[Allure2sail]

Hi:
Each time a metal plate is bent it loses some of it's original strength properties, sorry but straighting it out does not restore it to it's original strength. I know it is hard to believe but a stainless steel bolt or plate is not as strong as a regular steel plate or bolt (look it up on the internet). It is used heavily in the marine industry because it is resistant to corrosion, not for it's strength. I know the stresses put on a chain plate are well below it's failure level but I myself would not straighten and reuse a bent chainplate. The price of a chainplate is very small compared to the damage that could result if it did fail. I find it hard to believe (no, I'm actually surprised) any engineer would tell you to put a hammer to it and straighten it out then reinstall it. I've been doing mechanical design work for 25 years and I'm familiar with 303, 304, & 316, stainless steel  material properties......simply stated, I'd toss it. That's my two cents worth.
Best of luck with you new boat......
Bruce

[crazycarl]

just read a story in sail magazine about a couple circumnavigating when a chain plate broke and they lost the top half of the mast while hundreds of miles out at sea. 

i have a bent chain plate on my 19 that will be replaced this winter.  i didn't even try to bend it back for fear of weakening it more.

[millsy]

I think that we are talking about two different types of bends:  I was referring to the twisting- above the slot level- that can occur when the TB's bind on the chainplates while raising the mast.  I believe that this is what Matt referrs to when he talks about straightening with the claw of a hammer.

Looking back at Frantic's photos it appears the chainplate is bent/reoriented in a new forward direction.  This would put an unusual strain on the chainplate particularly in the area of the upper bolt hole.  I am not even sure how one would go about straightening a chainplate like this.  Maybe someone tied a spring line to it at some point?

Chris
Dolce C-23

[Tim Gardner]

One last word to add to Bruce's.  Nearly all stainless steels work harden, meaning as they bend, they lose malleability.  This is accompanied by increasing brittleness, leading to "stress or fretting corrosion failure".

BTW,  Almost all of the stainless steel used in boat and shipbuilding is used above the waterline.  Stainless needs to oxidize to create the corrosion resistant layer exposed to whatever environment it's in.  Immerse it in water (no oxygen) and it will fail much sooner than in air.
This corrosion resistant layer is broken when the steel is bent beyond it's yield point (the point where it remains bent). It then forms a new layer from the newly exposed surface, gets bent again, etc.  This action is sometimes known as "Crevice corrosion cracking".  Happens in all metals that oxidize.

Enough forensic metallurgy for today.  Replace the chain plates!

TG

[Frantic]

Ok so. The boat is now at the marina sitting on the trailer. We are going to change a few shrouds and chainplates. Aside from that everything is ok..except I really must know, do some of your really trailer these around? How do you get the mast up? Wow was that hard to do! Coming from a 16, where raising the mast is cake, this seemed almost impossible! Hell, we even tore off the mast step the first time we attempted to raise it(no real damage thankfully, just needed new screws) and we had three people? I'm sure we must have been doing something wrong... Finally on the third try we got it up but it took us about an hour. Thank goodness we can keep the mast up at the marina! FYI.. When we raised it we had all the shrouds attached except the forestay. We walked the mast back, put in the pin and had one person pulling the forestay while 2 people lifted the mast. So what did we do wrong here?

[Bob23]

   You could not and should not have the forward lower shrouds attached. The aft lowers and upper shrouds do not even need loosening upon lowering the mast. I back off on my backstay and the forestay.
   I raise my mast easily with 2 people. First I tie an extension line on the jib halyard, usually a piece of 3/4" line so I can get a good grip. Make sure the loose end of the halyard is cleated off well to the mast. Before raising, make sure all lines are led correctly and nothing is gonna get tangled. My helper is in the rear part of the cockpit and starts the raising. At the same time, I'm pulling hard on the line I mentioned and as soon as the mast has some angle to it, I can take all the weight. He is making sure the mast doesn't go sideways while I pull and up she goes. It's important to do this fast so the more vertical the mast gets, the shrouds are keeping it from going sideways.
   It's really not too hard. The trick is making sure all lines, shrouds and stay are correctly placed, not tangled and the mast is pulled up quick before it can start to sway.
   You should rebed that mast step. Just a few screws are not enough. Rebed in 4200 caulk or something similiar to prevent water intrusion into the raised deck area which supports the weight of the mast.
Bob23

[Frantic]

Thanks, ya, we actually bolted down the mast step all thenway through into the cabin with a piece of starboard as support. Worked well.

I'm not clear on which shrouds tom leave disconnected. We eventually disconnect the forward side stays and left the rear stay connected. Where we supposed to remove the rear side stays?

Also, I've never dealt with a rear stay. Our is a bit slack... Is that normal or should it be tight? Also, we have a roller furling system. It appears a bit loose to me. How do I get to the turnbuckle that's in side the furled?

Thanks again for all the help everyone! This boat is making me crazy lol... I really appreciate the simplicity of my 16 these days

[LConrad]

I find it easier to remove the forward and the main side stays. The back side stays can remain attached with no problem.

Not sure about the forward stay under the furler, but the foreward and aft should be tight. A baggy furler makes the jib too full for heavier air. Weather helm improved after I tightened mine.