Re: Stus-List Replacing Chainplates
The pins are SS so I expect the galvanic reaction between the aluminum and SS wouldn't be any worse. The aluminum in around the holes in the picture look fine. After reading the posts, I guess I got hosed and bullied by my marina manager into replacing my chainplates. Oh well. I'd like to think he was being protective and afraid of liabilty. I'm sure he profitted from the work but he did get it done for me during the busy season which is rare for most boatyards. I now have better than new chainplates now, I helped the local economy a little, but I got hosed. Chuck S > On August 14, 2019 at 11:26 AM Richard Bush via CnC-List > wrote: > > great discussion; regarding the "SS cover" option, would there be any > issue with galvanic reaction between the aluminum and the SS? > > Richard > s/v Bushmark4: 1985 C 37 CB: Ohio River, Mile 584.4 > Richard N. Bush Offices > 2950 Breckenridge Lane, Suite Nine > Louisville, Kentucky 40220-1462 > 502-584-7255 > > > -Original Message- > From: Neil Gallagher via CnC-List > To: Josh Muckley via CnC-List > Cc: Neil Gallagher > Sent: Wed, Aug 14, 2019 11:12 am > Subject: Re: Stus-List Replacing Chainplates > > Josh, > > Stress corrosion cracking is caused by chlorides (salt) and high tensile > stress, and while it is always a possibility with 304 and 316 SS, keeping > stress levels low enough with normal safety margins should minimize it. Not > that common in most marine fittings, even in salt water. > > Neil Gallagher > Weatherly, 35-1 > Glen Cove, NY > > > ___ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > > ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
FWIW. On my LF39 I have 3 stainless 7/16x2 inch 4 ft long chain plates in each side. These drop down into the hull and are bolted with 1/2in bolts to frame members. I'm not sure they are original, as the boat was upgraded many years ago for extended blue water cruising, or maybe racing. I'm not an engineer but I wouldn't go any thinner whether you use stainless or aluminum. There alloys of aluminum that is just as strong as stainless. Doug Mountjoy Sv Rebecca Leah C LF39253-208-1412Port Orchard YC wa. Original message From: Dan via CnC-List Date: 8/14/19 06:42 (GMT-08:00) To: Cc: Dan , "CNC boat owners, cnc-list" Subject: Re: Stus-List Replacing Chainplates Fortunately our yard doesn't get involved with stepping and unstepping masts so it's 100% my discretion.I know a guy who does stainless. I was thinking about getting him to check out the plates and quote me on new ones made to spec, except instead of 1/2" thickness throughout, I would ask for the below deck portion to be 1/4" or 3/8" thickness. I'm under the impression that stainless is much stronger and can be thinner to achieve the equivalent strength to the aluminum plates. I'm not an engineer, but I'd sail with that setup.If these aluminum plates are fine as is for another 5 years or so I can put this job off. I've seen much worse corrosion.On Wed, Aug 14, 2019 at 10:23 AM CHARLES SCHEAFFER wrote: FWIW. My boat has similar chainplates. Half inch thick aluminum about four feet long. I paid $3000 to have replacements made of the chainplates and mast step in anodized aluminum. I didn't feel qualified to change the original design. The metal shop copied mine exactly, matching the angle of the deck flanges and positioning all the fastener holes and the anodizing is better than new. They are shiny.The long story if you're interested:I pulled the chainplates to replace some wet core in the side decks. They had only minor erosion under the deck in a very small area the size of a dime. The parts above and below were fine. I made the mistake of asking the boat yard manager if he thought I could repair them using epoxy. He got upset and said they needed to be replaced and said if I didn't, he would not restep my mast. He said he would relaunch me with the mast on deck and I could try and get some other marina to step the mast. A 35 foot Ericson had lost it's rig two weeks prior when a headstay fitting parted. I think he overreacted but I agreed to use his recommended shop and they did a wonderful job, delivering all in three weeks. I probably could have gotten a better price somewhere else, but I was in a hurry then. Chuck, Resolute 1990 C 34R, Pasadena Md ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
great discussion; regarding the "SS cover" option, would there be any issue with galvanic reaction between the aluminum and the SS? Richard s/v Bushmark4: 1985 C 37 CB: Ohio River, Mile 584.4 Richard N. Bush Offices 2950 Breckenridge Lane, Suite Nine Louisville, Kentucky 40220-1462 502-584-7255 -Original Message- From: Neil Gallagher via CnC-List To: Josh Muckley via CnC-List Cc: Neil Gallagher Sent: Wed, Aug 14, 2019 11:12 am Subject: Re: Stus-List Replacing Chainplates Josh, Stress corrosion cracking is caused by chlorides (salt) and high tensile stress, and while it is always a possibility with 304 and 316 SS, keeping stress levels low enough with normal safety margins should minimize it. Not that common in most marine fittings, even in salt water. Neil Gallagher Weatherly, 35-1 Glen Cove, NY ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Josh, Stress corrosion cracking is caused by chlorides (salt) and high tensile stress, and while it is always a possibility with 304 and 316 SS, keeping stress levels low enough with normal safety margins should minimize it. Not that common in most marine fittings, even in salt water. Neil Gallagher Weatherly, 35-1 Glen Cove, NY On 8/14/2019 10:27 AM, Josh Muckley via CnC-List wrote: Neil, you mentioned fatigue cracking in aluminum. What about stress corrosion cracking in SS? Dan, my thought is that the plates are safe for use of the boat. I believe it is more likely that the standing rigging will fail before the chainplates do. I don't know about you but I have plenty of other boat projects that are more worthy of my money. Josh Muckley S/V Sea Hawk 1989 C 37+ Solomons, MD On Wed, Aug 14, 2019, 10:15 AM Neil Gallagher via CnC-List mailto:cnc-list@cnc-list.com>> wrote: Dan, Grade 316 stainless is about two to three times as strong as aluminum, it varies a lot depending on what grade Al you're using. (Some numbers: utlimate tensile strength of 316 SS is about 84,000 psi, aluminum 6061-T6, a common marine alloy, is 42,000 psi) SS is also less prone to cracking under fatigue loading. IMHO those chainplates aren't all that bad, the holes are not elongated, just a little rough. It'd be nice to see the top of the holes where the load is transferred, but what's visible is decent. There's no significant wastage in thickness, appears to be mostly the surface coating that has worn off. If you're really concerned you can have them dye penetrant tested for cracks, could be done in place. Of course free advice is worth what you pay for it Neil Gallagher Weatherly, 35-1 Glen Cove, NY On 8/14/2019 9:42 AM, Dan via CnC-List wrote: > Fortunately our yard doesn't get involved with stepping and unstepping > masts so it's 100% my discretion. > > I know a guy who does stainless. I was thinking about getting him to > check out the plates and quote me on new ones made to spec, except > instead of 1/2" thickness throughout, I would ask for the below deck > portion to be 1/4" or 3/8" thickness. I'm under the impression that > stainless is much stronger and can be thinner to achieve the > equivalent strength to the aluminum plates. I'm not an engineer, but > I'd sail with that setup. > > If these aluminum plates are fine as is for another 5 years or so I > can put this job off. I've seen much worse corrosion. > ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Thanks Josh, Neil, Yes, I had people help me remove the mast and when the corrosion was evident, both sailors working on the connections told me the plates had plenty of metal and I should just clean them up - which I will definitely do. I'm still curious about replacement cost so while the plates are removed I'm going to get some estimates. From the numbers Neil just mentioned It sounds like 1/4" stainless would have the equivalent strength, so I'll see what that costs - but I agree with Rob Ball in that the tops could be serviceable or re-inforced but I'll see what the pros say when I take it in for costing - at least I'll know. Chees, Dan I'll report back to the list afterwards. Cheers, Dan On Wed, Aug 14, 2019 at 11:28 AM Josh Muckley via CnC-List < cnc-list@cnc-list.com> wrote: > Neil, you mentioned fatigue cracking in aluminum. What about stress > corrosion cracking in SS? > > Dan, my thought is that the plates are safe for use of the boat. I > believe it is more likely that the standing rigging will fail before the > chainplates do. I don't know about you but I have plenty of other boat > projects that are more worthy of my money. > > Josh Muckley > S/V Sea Hawk > 1989 C 37+ > Solomons, MD > > > > > On Wed, Aug 14, 2019, 10:15 AM Neil Gallagher via CnC-List < > cnc-list@cnc-list.com> wrote: > >> Dan, >> >> Grade 316 stainless is about two to three times as strong as aluminum, >> it varies a lot depending on what grade Al you're using. (Some numbers: >> utlimate tensile strength of 316 SS is about 84,000 psi, aluminum >> 6061-T6, a common marine alloy, is 42,000 psi) SS is also less prone to >> cracking under fatigue loading. >> >> IMHO those chainplates aren't all that bad, the holes are not elongated, >> just a little rough. It'd be nice to see the top of the holes where the >> load is transferred, but what's visible is decent. There's no >> significant wastage in thickness, appears to be mostly the surface >> coating that has worn off. If you're really concerned you can have them >> dye penetrant tested for cracks, could be done in place. >> >> Of course free advice is worth what you pay for it >> >> Neil Gallagher >> Weatherly, 35-1 >> Glen Cove, NY >> >> >> On 8/14/2019 9:42 AM, Dan via CnC-List wrote: >> > Fortunately our yard doesn't get involved with stepping and unstepping >> > masts so it's 100% my discretion. >> > >> > I know a guy who does stainless. I was thinking about getting him to >> > check out the plates and quote me on new ones made to spec, except >> > instead of 1/2" thickness throughout, I would ask for the below deck >> > portion to be 1/4" or 3/8" thickness. I'm under the impression that >> > stainless is much stronger and can be thinner to achieve the >> > equivalent strength to the aluminum plates. I'm not an engineer, but >> > I'd sail with that setup. >> > >> > If these aluminum plates are fine as is for another 5 years or so I >> > can put this job off. I've seen much worse corrosion. >> > >> >> >> ___ >> >> Thanks everyone for supporting this list with your contributions. Each >> and every one is greatly appreciated. If you want to support the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> >> ___ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Neil, you mentioned fatigue cracking in aluminum. What about stress corrosion cracking in SS? Dan, my thought is that the plates are safe for use of the boat. I believe it is more likely that the standing rigging will fail before the chainplates do. I don't know about you but I have plenty of other boat projects that are more worthy of my money. Josh Muckley S/V Sea Hawk 1989 C 37+ Solomons, MD On Wed, Aug 14, 2019, 10:15 AM Neil Gallagher via CnC-List < cnc-list@cnc-list.com> wrote: > Dan, > > Grade 316 stainless is about two to three times as strong as aluminum, > it varies a lot depending on what grade Al you're using. (Some numbers: > utlimate tensile strength of 316 SS is about 84,000 psi, aluminum > 6061-T6, a common marine alloy, is 42,000 psi) SS is also less prone to > cracking under fatigue loading. > > IMHO those chainplates aren't all that bad, the holes are not elongated, > just a little rough. It'd be nice to see the top of the holes where the > load is transferred, but what's visible is decent. There's no > significant wastage in thickness, appears to be mostly the surface > coating that has worn off. If you're really concerned you can have them > dye penetrant tested for cracks, could be done in place. > > Of course free advice is worth what you pay for it > > Neil Gallagher > Weatherly, 35-1 > Glen Cove, NY > > > On 8/14/2019 9:42 AM, Dan via CnC-List wrote: > > Fortunately our yard doesn't get involved with stepping and unstepping > > masts so it's 100% my discretion. > > > > I know a guy who does stainless. I was thinking about getting him to > > check out the plates and quote me on new ones made to spec, except > > instead of 1/2" thickness throughout, I would ask for the below deck > > portion to be 1/4" or 3/8" thickness. I'm under the impression that > > stainless is much stronger and can be thinner to achieve the > > equivalent strength to the aluminum plates. I'm not an engineer, but > > I'd sail with that setup. > > > > If these aluminum plates are fine as is for another 5 years or so I > > can put this job off. I've seen much worse corrosion. > > > > > ___ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Dan, Grade 316 stainless is about two to three times as strong as aluminum, it varies a lot depending on what grade Al you're using. (Some numbers: utlimate tensile strength of 316 SS is about 84,000 psi, aluminum 6061-T6, a common marine alloy, is 42,000 psi) SS is also less prone to cracking under fatigue loading. IMHO those chainplates aren't all that bad, the holes are not elongated, just a little rough. It'd be nice to see the top of the holes where the load is transferred, but what's visible is decent. There's no significant wastage in thickness, appears to be mostly the surface coating that has worn off. If you're really concerned you can have them dye penetrant tested for cracks, could be done in place. Of course free advice is worth what you pay for it Neil Gallagher Weatherly, 35-1 Glen Cove, NY On 8/14/2019 9:42 AM, Dan via CnC-List wrote: Fortunately our yard doesn't get involved with stepping and unstepping masts so it's 100% my discretion. I know a guy who does stainless. I was thinking about getting him to check out the plates and quote me on new ones made to spec, except instead of 1/2" thickness throughout, I would ask for the below deck portion to be 1/4" or 3/8" thickness. I'm under the impression that stainless is much stronger and can be thinner to achieve the equivalent strength to the aluminum plates. I'm not an engineer, but I'd sail with that setup. If these aluminum plates are fine as is for another 5 years or so I can put this job off. I've seen much worse corrosion. ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Your friend should be able to figure out the needed thickness based on relative strengths. I’m sure there are books with tables containing such information. I would not simply go with something thinner without having someone knowledgeable with metals weigh in. My two cents. From: Dan via CnC-List Sent: Wednesday, August 14, 2019 9:42 AM Cc: Dan ; CNC boat owners, cnc-list Subject: Re: Stus-List Replacing Chainplates Fortunately our yard doesn't get involved with stepping and unstepping masts so it's 100% my discretion. I know a guy who does stainless. I was thinking about getting him to check out the plates and quote me on new ones made to spec, except instead of 1/2" thickness throughout, I would ask for the below deck portion to be 1/4" or 3/8" thickness. I'm under the impression that stainless is much stronger and can be thinner to achieve the equivalent strength to the aluminum plates. I'm not an engineer, but I'd sail with that setup. If these aluminum plates are fine as is for another 5 years or so I can put this job off. I've seen much worse corrosion. On Wed, Aug 14, 2019 at 10:23 AM CHARLES SCHEAFFER wrote: FWIW. My boat has similar chainplates. Half inch thick aluminum about four feet long. I paid $3000 to have replacements made of the chainplates and mast step in anodized aluminum. I didn't feel qualified to change the original design. The metal shop copied mine exactly, matching the angle of the deck flanges and positioning all the fastener holes and the anodizing is better than new. They are shiny. The long story if you're interested: I pulled the chainplates to replace some wet core in the side decks. They had only minor erosion under the deck in a very small area the size of a dime. The parts above and below were fine. I made the mistake of asking the boat yard manager if he thought I could repair them using epoxy. He got upset and said they needed to be replaced and said if I didn't, he would not restep my mast. He said he would relaunch me with the mast on deck and I could try and get some other marina to step the mast. A 35 foot Ericson had lost it's rig two weeks prior when a headstay fitting parted. I think he overreacted but I agreed to use his recommended shop and they did a wonderful job, delivering all in three weeks. I probably could have gotten a better price somewhere else, but I was in a hurry then. Chuck, Resolute 1990 C 34R, Pasadena Md ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Re: Stus-List Replacing Chainplates
Fortunately our yard doesn't get involved with stepping and unstepping masts so it's 100% my discretion. I know a guy who does stainless. I was thinking about getting him to check out the plates and quote me on new ones made to spec, except instead of 1/2" thickness throughout, I would ask for the below deck portion to be 1/4" or 3/8" thickness. I'm under the impression that stainless is much stronger and can be thinner to achieve the equivalent strength to the aluminum plates. I'm not an engineer, but I'd sail with that setup. If these aluminum plates are fine as is for another 5 years or so I can put this job off. I've seen much worse corrosion. On Wed, Aug 14, 2019 at 10:23 AM CHARLES SCHEAFFER wrote: > FWIW. My boat has similar chainplates. Half inch thick aluminum about four > feet long. I paid $3000 to have replacements made of the chainplates and > mast step in anodized aluminum. I didn't feel qualified to change the > original design. The metal shop copied mine exactly, matching the angle of > the deck flanges and positioning all the fastener holes and the anodizing > is better than new. They are shiny. > > > > The long story if you're interested: > I pulled the chainplates to replace some wet core in the side decks. They > had only minor erosion under the deck in a very small area the size of a > dime. The parts above and below were fine. I made the mistake of asking the > boat yard manager if he thought I could repair them using epoxy. He got > upset and said they needed to be replaced and said if I didn't, he would > not restep my mast. He said he would relaunch me with the mast on deck and > I could try and get some other marina to step the mast. A 35 foot Ericson > had lost it's rig two weeks prior when a headstay fitting parted. I think > he overreacted but I agreed to use his recommended shop and they did a > wonderful job, delivering all in three weeks. I probably could have > gotten a better price somewhere else, but I was in a hurry then. > > > Chuck, Resolute 1990 C 34R, Pasadena Md > ___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
Stus-List Replacing Chainplates
FWIW. My boat has similar chainplates. Half inch thick aluminum about four feet long. I paid $3000 to have replacements made of the chainplates and mast step in anodized aluminum. I didn't feel qualified to change the original design. The metal shop copied mine exactly, matching the angle of the deck flanges and positioning all the fastener holes and the anodizing is better than new. They are shiny. The long story if you're interested: I pulled the chainplates to replace some wet core in the side decks. They had only minor erosion under the deck in a very small area the size of a dime. The parts above and below were fine. I made the mistake of asking the boat yard manager if he thought I could repair them using epoxy. He got upset and said they needed to be replaced and said if I didn't, he would not restep my mast. He said he would relaunch me with the mast on deck and I could try and get some other marina to step the mast. A 35 foot Ericson had lost it's rig two weeks prior when a headstay fitting parted. I think he overreacted but I agreed to use his recommended shop and they did a wonderful job, delivering all in three weeks. I probably could have gotten a better price somewhere else, but I was in a hurry then. Chuck, Resolute 1990 C 34R, Pasadena Md___ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
