Keel Bolts - Inspection and Potential Remediation


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Dan Coate
Dan Coate
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Hi, I sail a 1990 Pacific Seacraft, Crealock 31. She’s in great shape and the only thing about her that gives me pause are the keel bolts. While I haven’t noticed any problems, the mystery of their condition after 30 years bothers me.

On visual inspection from the bilge there appears to be some superficial rust around the nuts but nothing major. When I pull her out of the water, there is an 8-inch “smile” on the leading edge of the keel where the fiberglass hull and lead keel meet. That area dries fairly quickly after she’s blocked.

Any thoughts on how much I should be thinking about some kind of inspection? I’m thinking of a transatlantic sail with her next year and want to make sure she’s sound.

Hailing port is Pompano Beach, FL, just north of Ft. Lauderdale. Thanks so much.
Dick
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Dan Coate - 4/9/2020
Hi, I sail a 1990 Pacific Seacraft, Crealock 31. She’s in great shape and the only thing about her that gives me pause are the keel bolts. While I haven’t noticed any problems, the mystery of their condition after 30 years bothers me.On visual inspection from the bilge there appears to be some superficial rust around the nuts but nothing major. When I pull her out of the water, there is an 8-inch “smile” on the leading edge of the keel where the fiberglass hull and lead keel meet. That area dries fairly quickly after she’s blocked.Any thoughts on how much I should be thinking about some kind of inspection? I’m thinking of a transatlantic sail with her next year and want to make sure she’s sound.Hailing port is Pompano Beach, FL, just north of Ft. Lauderdale. Thanks so much.

Hi Dan,
Good to worry on a 30-year-old boat. Not to add to your worries, but the rudder is also due for an inspection, a major inspection if rusty water is leaking out the bottom upon hauling. A rudder loss on passage usually means a boat loss or worse.
I would first collect data. Is there a PS web site where there are owners and hx of the boats? How long have you owned her? What are the keel bolts made of and how many are there? Are you clear about groundings: either yours or the PO? Is there evidence of groundings/repairs on the leading edge of the keel. Or in the interior in the bilge area where a hard grounding (or going “a-rock”) would have stressed the tabbing of the sump? Have the keel bolts ever been re-torqued? When on the hard with weight on the keel, have you removed a keel bolt nut and washer and looked at the bedding (not sure this is a good idea with every sailboat, you might consult)? Any weeping around the keel bolts in the bilge?
It sounds like a good sign that there is no water/rust weeping along the keel/hull joint and only a few inches of smile and the water dries quickly in that area.
What do others think?
My quick thoughts, Dick Stevenson, s/v Alchemy

Dan Coate
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Dick: Thanks so much and very helpful! I’m in lockdown/curfew in the BVI at the moment (precautionary, I’m fine). I will use your suggestions when I’m back home in Ft. Lauderdale doing a refit. Thanks again.
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Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"
Dick
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Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy

martintsmith@aol.com
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Dick - 4/20/2020
Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy



martintsmith@aol.com
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Dick - 4/20/2020
Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy

Hi Dick,
Yes sorry, I should have said that the boat was built in 1959. I bought it in 1997 and had the keel bolts ultra sound tested in 1998 or 1999.  The keel /hull seam always looked pretty good so I guess the salt water may have got in from the top or the bottom or both. The keel was cast iron and I suspect the bolts were mild steel
There was a concrete floor in the boatyard so I couldnt dig a hole underneath to take a knocked out bolt, but that winter I had the boat chocked up a bit higher than normal. I chiselled out all the filler which exposed the recessed bolt head underneath the boat. I unscrewed the nut a few threads inside the boat (so I wouldn't mushroom the threaded part) and used a bar and lump hammer to hit it. Once it started moving it came out more easily. Once it hit the ground I hacksawed the end off by the keel so I could knock more out. I should have mentioned that the wasting was only in one place.
For the replacement bolt I sought out a specialist blacksmith who made a wrought iron bolt. I painted it with coal tar and got lifted up in the travel hoist to put it in.
Compared with the number of bolts used on modern boats that 36ft Cheverton designed Danegeld had 14bolts I seem to remember and they were 'galleried' ie not all on the centreline.
My current boat has an encapsulated keel so no bolts which is good in one way but can cause major problems if you hit something hard and puncture the keel.
I hope that answers your questions and good luck to anyone who tackles a keel bolt job!
Martin



Dick
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Dick - 4/20/2020
Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy

Hi Dick,
Yes sorry, I should have said that the boat was built in 1959. I bought it in 1997 and had the keel bolts ultra sound tested in 1998 or 1999.  The keel /hull seam always looked pretty good so I guess the salt water may have got in from the top or the bottom or both. The keel was cast iron and I suspect the bolts were mild steel
There was a concrete floor in the boatyard so I couldnt dig a hole underneath to take a knocked out bolt, but that winter I had the boat chocked up a bit higher than normal. I chiselled out all the filler which exposed the recessed bolt head underneath the boat. I unscrewed the nut a few threads inside the boat (so I wouldn't mushroom the threaded part) and used a bar and lump hammer to hit it. Once it started moving it came out more easily. Once it hit the ground I hacksawed the end off by the keel so I could knock more out. I should have mentioned that the wasting was only in one place.
For the replacement bolt I sought out a specialist blacksmith who made a wrought iron bolt. I painted it with coal tar and got lifted up in the travel hoist to put it in.
Compared with the number of bolts used on modern boats that 36ft Cheverton designed Danegeld had 14bolts I seem to remember and they were 'galleried' ie not all on the centreline.
My current boat has an encapsulated keel so no bolts which is good in one way but can cause major problems if you hit something hard and puncture the keel.
I hope that answers your questions and good luck to anyone who tackles a keel bolt job!
Martin



Hi Martin,
Yours was an unusual situation because of the design of having the keel bolts go right through the keel. This made accessibility far easier.
Mild steel is certainly not the best material and I suspect going through iron was more problematic that through lead. That said, they did their job for 40 years and since there was only one failure out of the 14 bolts, the keel was not going to be a problem anytime soon.
And someone knew a bit about engineering strength by having the bolts “galleried” as you report.
I am no engineer, but I am surprised that you were able to knock out mild steel bolts that lived in an iron keel for 40 years. I would have thought they would have seized together and be virtually impossible to separate. Any engineers reading and can weigh in?
My best, Dick Stevenson, s/v Alchemy

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Dick - 4/21/2020
Dick - 4/20/2020
Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy

Hi Dick,
Yes sorry, I should have said that the boat was built in 1959. I bought it in 1997 and had the keel bolts ultra sound tested in 1998 or 1999.  The keel /hull seam always looked pretty good so I guess the salt water may have got in from the top or the bottom or both. The keel was cast iron and I suspect the bolts were mild steel
There was a concrete floor in the boatyard so I couldnt dig a hole underneath to take a knocked out bolt, but that winter I had the boat chocked up a bit higher than normal. I chiselled out all the filler which exposed the recessed bolt head underneath the boat. I unscrewed the nut a few threads inside the boat (so I wouldn't mushroom the threaded part) and used a bar and lump hammer to hit it. Once it started moving it came out more easily. Once it hit the ground I hacksawed the end off by the keel so I could knock more out. I should have mentioned that the wasting was only in one place.
For the replacement bolt I sought out a specialist blacksmith who made a wrought iron bolt. I painted it with coal tar and got lifted up in the travel hoist to put it in.
Compared with the number of bolts used on modern boats that 36ft Cheverton designed Danegeld had 14bolts I seem to remember and they were 'galleried' ie not all on the centreline.
My current boat has an encapsulated keel so no bolts which is good in one way but can cause major problems if you hit something hard and puncture the keel.
I hope that answers your questions and good luck to anyone who tackles a keel bolt job!
Martin



Hi Martin,
Yours was an unusual situation because of the design of having the keel bolts go right through the keel. This made accessibility far easier.
Mild steel is certainly not the best material and I suspect going through iron was more problematic that through lead. That said, they did their job for 40 years and since there was only one failure out of the 14 bolts, the keel was not going to be a problem anytime soon.
And someone knew a bit about engineering strength by having the bolts “galleried” as you report.
I am no engineer, but I am surprised that you were able to knock out mild steel bolts that lived in an iron keel for 40 years. I would have thought they would have seized together and be virtually impossible to separate. Any engineers reading and can weigh in?
My best, Dick Stevenson, s/v Alchemy



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Dick - 4/21/2020
Dick - 4/20/2020
Hi Dan,
When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound. this involved me grinding or filing the top of the bolts flat. The technician doing the job put some type of grease on the bolts put a transducer? on each of the bolts and looked at the results on a screen.
He declared that all the bolts were O K except one bolt on which he didnt get a satisfactory image . I decided to knock this bolt out and the 1 1/4 " dia was wasted to 1/4"!!              
I think the mac hine used is similar to the sort used in hospital on pregnant women.
Martin Smith Yacht "Chardonnay of Solent"

Hi Martin,
A very interesting report, but I remain a bit confused: you report, “When I had a wooden boat built in 1959 I had the keel bolts checked by ultra sound”. Was the boat built in 1959 and the bolts checked in the way described much later?
If so, how much later: how long did it take for the damage to occur? Did you suspect salt water got in from the keel/hull seam or that it migrated down from inadequate caulking around the bolt heads in the bilge?
What metal were the bolts made of?
Were the bolts into a lead or iron keel?
Were the bolts studs or “J” and how did you “knock” it out: I would think that a diameter loss of 1.5 inches to ¼ inch would break off with most “knocking out” techniques.
Thanks for your thoughts, Dick Stevenson, s/v Alchemy

Hi Dick,
Yes sorry, I should have said that the boat was built in 1959. I bought it in 1997 and had the keel bolts ultra sound tested in 1998 or 1999.  The keel /hull seam always looked pretty good so I guess the salt water may have got in from the top or the bottom or both. The keel was cast iron and I suspect the bolts were mild steel
There was a concrete floor in the boatyard so I couldnt dig a hole underneath to take a knocked out bolt, but that winter I had the boat chocked up a bit higher than normal. I chiselled out all the filler which exposed the recessed bolt head underneath the boat. I unscrewed the nut a few threads inside the boat (so I wouldn't mushroom the threaded part) and used a bar and lump hammer to hit it. Once it started moving it came out more easily. Once it hit the ground I hacksawed the end off by the keel so I could knock more out. I should have mentioned that the wasting was only in one place.
For the replacement bolt I sought out a specialist blacksmith who made a wrought iron bolt. I painted it with coal tar and got lifted up in the travel hoist to put it in.
Compared with the number of bolts used on modern boats that 36ft Cheverton designed Danegeld had 14bolts I seem to remember and they were 'galleried' ie not all on the centreline.
My current boat has an encapsulated keel so no bolts which is good in one way but can cause major problems if you hit something hard and puncture the keel.
I hope that answers your questions and good luck to anyone who tackles a keel bolt job!
Martin



Hi Martin,
Yours was an unusual situation because of the design of having the keel bolts go right through the keel. This made accessibility far easier.
Mild steel is certainly not the best material and I suspect going through iron was more problematic that through lead. That said, they did their job for 40 years and since there was only one failure out of the 14 bolts, the keel was not going to be a problem anytime soon.
And someone knew a bit about engineering strength by having the bolts “galleried” as you report.
I am no engineer, but I am surprised that you were able to knock out mild steel bolts that lived in an iron keel for 40 years. I would have thought they would have seized together and be virtually impossible to separate. Any engineers reading and can weigh in?
My best, Dick Stevenson, s/v Alchemy



Hi Dick,
I have seen quite few wooden boats of 1950s and earlier with keel bolts that went right through the keel. if its a lead keel I think bronze bolts are used
One technique to free off bolts is to make a 'coffer dam' out of a short piece of plastic pipe. Use sealant to fix it around the bolt with the nut off and fill it with penetrating oil and leave it to soak through for a few days. I honestly can't remember if I did this or not but |I did read about it at the time.
If the bolt won't move and it is hit repeatedly, the head can mushroom out so its too big to go through the hole so fewer blows with more force is better.
I also removed a bolt from another wooden boat I once owned to check on its condition and for ease of putting it in without digging a hole under the boat or having it lifted up by crane I had it made with a thread and nut on the bottom as well as the top.
I later found out this was a mistake as this won't last as long as having a fixed one piece head on the bottom of the bolt.
Martin

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