May 19, 2001
I seem to remember someone saying that there's a better material for the chainplates than stainless. Please let us know what it is.
Date: Wed Aug 15, 2001 11:31 am
If and when you change the chainplates themselves (eg, if cracked, or when upgrading the mizzen stays to 1/4" and beefing up the extant chainplates) to 316, consider having the new chainplates electropolished, for better passivation and resistance to crevice or contact corrosion in low oxygen, confined areas.
Date: Wed Aug 15, 2001 11:38 am
When I ran the machine shop on Tortola, for a while, the elctro-polishing process was unheard of. So the laborious task was accomplished by sanding three grades, finishing with 360 and the polishing with two grades of rouge on a 1 HP polishing wheel and waxed with hard paste. I inspect them regularly and it seems to work. If I had to do the again, now your method is so much more available and affordable.
Sep 28, 2001
I am going to need to replace a couple of my chain plates and was wondering which would be the most recommended stainless steel, 316 or 304. I have heard that 304 is stronger, but needs to be electropolished to make it look nice. Any suggestions would be greatly appreciated.
Sep 28, 2001
You can expect longer life from 316. I do suggest that any stainless exposed to sunlight, frequent seawater or encapsulation be polished with several grades of abrasive and finished with two grades of rouge.
Stainless survives best when not sealed from the air so any mating surfaces should be as non-porous as possible.
Sep 28, 2001
Electropolishing, which creates a more solid anti-corrosive film on stainless steel than from natural air oxidation, is advised whenever you have surfaces exposed contiguous to unexposed surfaces. I electropolished all my chainplates when I changed the mizzen ones to upgrade back to 1/4" stays. There is one good firm doing that in the Bronx, headed by a wonderful smart black lady.
Sep 28, 2001
Frankly you could use either SS 304 or 316 and they would look the same in appearance. The density of each is the same at 0.29 lbs./cu. in., where as the yield is different. 316 is 18 tons per sq. in. and 304 is 15 tons per sq. in. I doubt that would make any difference in the long run.
Rates of corrosion is essentially the same in salt or fresh water. As to pitting corrosion, type 304 has more of a tendency to pit than 316 and 316 can successfully be used with cathodic or galvanic protection.
I would personally go for the 316 if available but use 304 as second choice without any concern as long as I pulled the chain plates ever 5 years or so for inspection.
Oct 22, 2001
I have removed some of my chain plates for inspection and have found that so far, the only ones that needed to be replaced were the mizzen plates. However, all of the backing plates, which are aluminum, need to be replaced. Are they supposed to be aluminum? Some of them were badly corroded.
Oct 22, 2001
With aluminum back up plates I suspect you had better check if the bonding wires to the chain plates have also had their terminals corroded off (your boat may not have a bonding or grounding system). In the absence of stainless backing plates, doubled stainless fender washers will suffice for a short while but replacements will require each one drilled to its unique bolt pattern...
When reinstalling the plates try to check the condition of the wood encapsulated under the glass in knees. Be sure to isolate the bolts from the wood with, a the very least, a thin coat of silicone or Boat-Life to prevent rot spores from getting into the wooden knees.
Oct 29, 2001
Ours was, we simply wire brushed them and re-installed them after examining the various components.
Nov 8, 2001
I am in the process of changing out chain plates, and am stuck on my forward mizzen plates. When I got the new ones I found that the bolts would only go through the top two holes of the backing plates after putting them through the chain plate spacer block and knee. The bolts are skewed to one side to the point that the bottom bolt will not go through. The chain plate and
backing plate holes line up by themselves, however. At this point I am either going to have to redrill the knee or have a wider backing plate made that can allow for the bottom hole to be offset in order to make it fit.
Nov 8, 2001
If you are sure that you have correctly identified each matched pair and location, and the problem still exists, it appears that you had the new backing plates drilled to match the new chain plates rather than the old backing plates. almost certainly if you are working with the factory holes the original bore was skewed.
If you are certain that there is no rot in the encapsulated knees I suggest you fill all of the holes with a thickened epoxy paste and sand as flush as you can. Then clamp the plate in place and re-drill through the epoxy plugs, then set up the backing plate once again. If you re-drill the knees without protecting the core wood you most certainly will encourage them to rot. The down & dirty alternative is to seat the bolts in GE 5200 after you re-drill the original holes but remember that the inevitable and minor movement of the plates under load will ultimately wear the 5200 thin and probably un-seal the knees.
Try to set up a ground bonding wire of at least 8 gauge USWG to each chain plate and lead the wires to a common ground, preferably to a Dynaplate but the engine block will suffice, as you install each new plate. It will help with your electrolysis and add some lightening protection overall. If it were a cheap or easy job I would suggest a two-inch minimum width, flat, copper bonding strap for better lightening protection led throughout the hull and locker voids. In the event you decide to go to SSB radio in the future it also offers a marginally better ground plane for radio performance.
Nov 13, 2001
If it is just the backing plate thats not lining up, obtain a new piece of aluminum and cut it to fit and drill new holes in it slightly larger than the original bolts and install it. Likely the backing plates are corroded some anyway.
Nov 14, 2001
I was able to file out one of the holes in each of the port and starboard backing plates to get the third bolt through. By the way, I opted to have 316l stainless backing plates made to avoid galvanic corrosion. The original plates were quite corroded. Thank you for your response.
Nov 14, 2001
During my chain plate replacement process, I found that the core surrounding the openings in the deck was not protected and wet in places. I opened the first four with a drill and a rotary rasp, but would recommend using a bastard file for the straight edges and a rat-tailed file for the ends since one may take off too more material than is needed with a drill. I would also recommend taking out enough material for the width of two chain plates--this allows leeway for your epoxy/filler mix with room for caulk to fill in the seams. You should also remove some material from the ends, I estimate that I remove about a quarter of an inch on each end. !!SUGGESTION!! Mark the original positions of the chain plates before you remove them!!! This will guide you when drilling out the space for the epoxy after it has set up.
I am using the west system 205 and 105 mixtures with 303 filler mixed to a consistency slightly thicker than pancake batter. This allows for it to flow into the voids while providing more support than straight epoxy. I have been pouring it in stages of about 1/2 in. thick and allowing to cure before adding another batch in order to avoid excessive heat from the exothermic reaction of the two parts. My favorite rotten core digging tool came with the boat. It is a combination right angle screwdriver with a right angle awl on the other end instead of a phillips.
Another suggestion is to buy your both your 205 and 105 in the gallon size containers if you plan on doing more than occasional small jobs. You can buy the C size pumps. You can get an extension for the hardener pump. With the large capacity, you don't have to worry about your hardener running out for a long time. Recently I had problems with my small size hardener when I got near the end. Although I was able to pump the proper amount of epoxy, the hardener would not come out of its spout at the proper ratio since it was low. The proper amount was there, but spread across the bottom of the can. I had to throw the mixture away because I could not insure that I had the proper ratio with several half-full squirts. The gallon size hardener will prevent this if you keep a reserve can. You just switch cans when it starts getting low and add the remainder to the new can after it gets used down a little. If anyone has suggestions or comments, I would be happy to hear them.
Nov 15, 2001
My first batch of chain plate replacement is in progress with the four lower mainmast plates out and the two forward mizzen plates out. After I replace these, can I disconnect the upper sidestays and the split backstay on the mainmast simultaneously without putting outside support?
Nov 20, 2001
Yesterday I began installing my new chain plates. Starboard and forward main chain fine. Port forward chain plate not so great. What happened is that when I drilled an opening through the epoxy as per my markings of the old chain plate location protruding through the deck, the new chain plate would not fit flush against the support knee in the hanging closet. I inspected the old chain plate and found that it was bent. Whoever installed it at the factory had bolted it and forced the lower part up against the knee, bending the plate. Shame on them!! I had to pour two more batches of epoxy, waiting for quite some time on my knees to shape the second batch
during that very short amount of time in the curing phase when it has begun to thicken, but not gotten so hard that you can scrape away any overflow. Tomorrow I will drill it out and bolt the plate.
Please pardon my lament. Perhaps someone else may benefit from my experience.
Nov 26, 2001
Watertight security forces were thoroughly-routed early today during an attempt to secure forward chain plate openings. A new attempt will be made using top secret weapons thoroughly unfamiliar to most yacht manufacturers: West system epoxy and phillips head screws.
It was a frustrating time. I found that I had to redrill the holes for the cover plate and another screw broke off in the hole. I will overdrill all of the holes, fill them with 105 and redrill them in case some of them go into the core. I will also need to rasp out the screw holes in the cover plate to accomodate the next screw size larger. To battle again in the name of watertight integrity!!!>
1388 Jan 24, 2002
I have been waiting for quite some time to epoxy and seal the core around my port aft spreader chain plate opening. It was nearly dry back in October, but it has rained on an average of once every two weeks since then. I rasped it out and dug out the punky material and taped it over with heavy-duty duct tape. What confounds me is that the core is always wet after a heavy rain. I can only surmise that the moisture may be coming from a leaky stanchion bed nearby or the chain plate for the port upper shroud which is just forward. Three weeks of dry weather would do the trick, but lately Gulf Coast Texas weather has been uncooperative. Any comments or suggestions?
James, Niko (91)
1389 Jan 24, 2002
Iíve been going thru the same process with my SWII k113. I found that the stanchion beds were solid laminate (not cored from the factory). I removed the bow pulpit, both mooring cleats, both hawse pipes, and the holding tank pumpout fitting (port side) and found that ALL of them were leaking! I routed out the mushy core material and taped up the holes as you did. So far all is still dry after many rains. I havenít yet epoxied to seal the core. I have already sealed the core around the chain plates (after letting it dry out). I suggest that you inspect ALL thru deck fittings upstream from your chainplate in question.
Bill S. "City Bird"
1400 Jan 24, 2002
Wet pulp around shroud
Suspect that the forward shroud also is leaking, why not use tape and plastic on the deck preventing the water from entering any area around that region. Tape one at a time to locate the leaking one.