Keel Bolts

tane

Anarchist
914
245
"... one end lag..." - if I understand that correctly: that's a "wood-screw", right? Would that make for a quiet sleep off-watch, closehauled in >25kn?
 

WindnCs

Member
One is talking about using a lag for this Tane, that’s was just a discussion about a similar process used for installing newel posts on a staircase.
 

accnick

Super Anarchist
3,227
2,244
I've had keel bolts that run the gamut. On my old wooden yawl, the were bronze bolts through the floor timbers all the way through the 10,500 pound lead keel casting, socketed on the bottom with nuts and washers. The longest bolts were about 5' long.

The cruising boat I built had an external iron keel casting weighing a bit over 11,000 pounds. The top of the keel was drilled and tapped--about eight bolt diameters deep--and the bolts themselves were coarse-thread mild steel studs. These were threaded into the keel casting using heavy grease as a lubricant. The keel was then conventionally bedded onto the hull molding, with the nuts re-torqued during and after the bedding compound cure

I never removed one f those bolts for inspection, and would not as long as there is no evidence of rust coming out of the keel/hull interface or the bolts and backing plates in the bilge. In the bilge, these were heavily coated with gelcoat to protect them.

That boat was designed for an iron keel. I considered casting a lead keel, but the smaller volume of the lead keel required designing and making structural glass spacers between the hull molding and the new keel casting, as well as a new keel plug, and was cost-prohibitive on my budget at that time.

In practice, the iron keel worked out just fine, and survived grounding on a reef in the Red Sea with nothing more than a few scratches. (The rest of the boat was totally unharmed.)
 

lawdog

New member
3
2
Although the bolts may look good(the part you can see) they are usually corroded just below the sole. I took my keel to Mars Keel and had them install new bolts, and my keel was not moving like yours, but simply letting water in when heeled hard over. The water never came above the bilge boards or cabin sole, but the boat is 35 years old. Mars Keel is located in Canada and one of the best keel manufacturers in the world, and was very reasonable in charges. before and after pictures.
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Bill Way

New member
"I'd take the opportunity to make some backing plates much bigger than those nuts too."

That's what they did on the Oyster(?) yacht that sank in the med when it lost its keel. The owner replaced the backing plate with a larger one. When the inspected the boat after raising it, the designers determined that the larger plate actually concentrated the forces in a smaller area. So if you're going to change the design, have someone on your team who can analyze the forces at work.
 

Rasputin22

Rasputin22
13,911
3,470
I was pretty impressed with Mars Keels when I modeled this keel for a big Bob Perry 63' ketch. They were very helpful in providing me with very specific details on bolt material, placement and the armature which held the big threaded rods in place when the keel was poured.

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My keel bolt experience is limited with a 33' 1957 wooden schooner. The keel is lead with bronze bolts- either 1" or 1.25". During the the restoration 2015-2018 we did not have to touch existing keel boats but did tap 1/2" SIBR rods into the lead to hold the 3" oak floor timbers. We brought in a machinist to make the drills and tap. After drilling, clean out the hole with a 20 gage shot gun cleaning rod with grease. When you tap, practice on a piece of lead first. When the tap jams-DO NOT BACK OUT THE TAP. Go deeper a 1/4 turn. ( this defies logic-that is why you need to practice. ). If the boat is wood, suggest you seal the with Tar. Hot tar on the top and cold roofing tar at the bottom
 

SockeyeUS119

Super Anarchist
Thanks for that idea Latad! So that's how I would install a newel post for staircase, but using a double ended bolt, one end lag, one end machine. Laying that out on a 37 foot boat, hoping for perfect plumb on the boat, and perfectly plumb drilling, sounds very difficult to achieve. I like the idea though. Drilling all the way through the keel sounds equally as hard, so I'm hoping the torquing works. Thanks for that idea!
Look back up at Pricilla’s reply. It’s not a joke about “outboard keel bolts” That horizontal rod with a threaded hole is how knockdown furniture is connected. The advantage is 1) wider distribution of the load in the soft material 2) easy to form the space for that rod, just drill 3) easy to get the keel bolt threading into the nut/rod- a slot in one end lines up the hole. Beauty- bury the ends in lead or bog. Paint and go sailing.
 

Priscilla

Super Anarchist
4,285
2,898
One thing to be aware of is the risk of winding down the hull or deforming it to eliminate the gap which may well stress other areas like floors or cabinets etc.
May well pay to fit some temporary wedges if the hull deflects and reach for some 5200 or similar let it set then torque the keel bolts.
 

ExOmo

Best Anarchist Ever
2,067
229
The Great Void
"I'd take the opportunity to make some backing plates much bigger than those nuts too."

That's what they did on the Oyster(?) yacht that sank in the med when it lost its keel. The owner replaced the backing plate with a larger one. When the inspected the boat after raising it, the designers determined that the larger plate actually concentrated the forces in a smaller area. So if you're going to change the design, have someone on your team who can analyze the forces at work.
If you are talking about Polina Star III, then I think there was an issue with the laminate/ply tapers/drop offs/laminate thicknesses in the keel area that were not in spec with original layup spec. Said backing plates may have contributed but I understand there was a more fundamental issue. If someone actually knows or does more google-fu, then please chime in but I think it's important to be accurate.
 

toddster

Super Anarchist
4,265
999
The Gorge
Although the bolts may look good(the part you can see) they are usually corroded just below the sole. I took my keel to Mars Keel and had them install new bolts, and my keel was not moving like yours, but simply letting water in when heeled hard over. The water never came above the bilge boards or cabin sole, but the boat is 35 years old. Mars Keel is located in Canada and one of the best keel manufacturers in the world, and was very reasonable in charges. before and after pictures.
View attachment 529442 View attachment 529443
Gee thanks. So my nightmares for tonight have been established…
 

SloopJonB

Super Anarchist
68,746
12,385
Great Wet North
"I'd take the opportunity to make some backing plates much bigger than those nuts too."

That's what they did on the Oyster(?) yacht that sank in the med when it lost its keel. The owner replaced the backing plate with a larger one. When the inspected the boat after raising it, the designers determined that the larger plate actually concentrated the forces in a smaller area. So if you're going to change the design, have someone on your team who can analyze the forces at work.
That makes no sense on the face of it.

Can you provide some specifics?
 

tane

Anarchist
914
245
"I'd take the opportunity to make some backing plates much bigger than those nuts too."

... that the larger plate actually concentrated the forces in a smaller area. ...
would like to know the physics behind that...!
 

accnick

Super Anarchist
3,227
2,244
One thing to be aware of is the risk of winding down the hull or deforming it to eliminate the gap which may well stress other areas like floors or cabinets etc.
May well pay to fit some temporary wedges if the hull deflects and reach for some 5200 or similar let it set then torque the keel bolts.
This is one reason you do this with the boat resting on the keel. If the gap closes with the weight of the hull on the keel, that is probably the “natural” state of the keel and hull.

It’s hard to generalize on this one, but you usually want a firm interface between the top of the keel casting and the hull to distribute load properly.

If there is cracking soft compound along the keel/hull interface, you may want to clean this out and start over. At some point, dropping the keel and starting over may be called for.

This can be a harder process on a cruising boat than a racing boat, as the bolts may be spread out over a larger area of the bilge, and less accessible.

This is also the time to inspect all the structure in the bilge area to look for fractures and/or separations.

This may be an iterative process.

Or, it may be as simple as re-torquing the keel bolts. As has been stated, you have to be sure the nuts are free to move on the bolts, and the threads are clean all the way to the hull structure they pass through. Otherwise, you may get a false picture of how tight the keel/hull connection really is.

I am not a huge fan of structural adhesives like 5200 in this application. I’ve seen people trying to remove keel castings when all the keelbolt nuts are removed, and the adhesive is still holding the keel on.

Then again, that may be a good thing, provided everything stays where it is supposed to be.

If water is getting in that joint via a gap, this is working hard to destroy your keelbolts, like the photo posted earlier in this thread.
 

WindnCs

Member
Although the bolts may look good(the part you can see) they are usually corroded just below the sole. I took my keel to Mars Keel and had them install new bolts, and my keel was not moving like yours, but simply letting water in when heeled hard over. The water never came above the bilge boards or cabin sole, but the boat is 35 years old. Mars Keel is located in Canada and one of the best keel manufacturers in the world, and was very reasonable in charges. before and after pictures.
View attachment 529442 View attachment 529443
Hey Lawdog! Yes that’s is a concern! Unfortunately, at this time, I can’t drop the keel to look. Nor could I make it to Maine. They did a beautiful job on yours, must be a great and safe feeling to have that under you now, man those looked scary! Fortunately, my boat has spent the last 30yrs in fresh water, so hopefully that has saved it. Thanks for that reply!
 
Hey Y'all! So this is a few part question. First, I'm inspecting the keel bolts on my 1977 Crealock 37, lead keel. Bolts look good after inspection. Only light corrosion on the bolts most aft, which scrubbed right off, and no rust. She's on the hard, and the bolts are still tight even with the weight on the keel. Not sure one would be able to tell anyway?

However, when she's lifted, the forward part of the keel separates, I'd say about 1/4", maybe 3/8", for maybe 18" moving aft, getting tighter, as it moves aft. Hard to say, I wasn't measuring it last time we lifted to splash, and when we hauled this last time, of course the bottom was wet, and dirty, so it was too hard to see. The rest of the keel/stub joint looks tight. And as I mentioned the keel bolts look, I would say good. The bottom of the bilge is also in great shape all around, super solid with a tap test from a 16oz Hart trimmer, my fave hammer of all time :) Also, there was no sensation or sound of movement when sailing, and I never noticed an increase in the water in the bilge. Of course I wasn't really looking for that, but the boat's pretty dry.

So I'd like some opinions on whether I should torque the bolts,... I'm sure I'll get an opinion or two here. And I'd also like to know how the keel bolts are "connected" to the keel. Are they anchor bolts? Are they fastened into a threaded insert, that is cast into the lead? I've always wondered how that is done.

I saw a thread on here, that Ishmael, commented on, saying to loosen them a bit first to do a better inspection, then torque them. that sounded like good advice....

Anyways, thanks ya'll for the info, opinions, ideas, and your time!

Best ~ Wind and Cs
View attachment 529139
Hi, here is what I can share from my experience with a J80.
To properly inspect the bolts you need to remove the nut and inspect the thread integrity. Especially if the bolt/nut couple has been submerged in salt water and the stainless alloy used is not the same there can be quite a bit of corrosion hidden under the nut. It was my case! Best way (if you can) if to haul the boat out and to have it rest on its keel while you remove the nuts one at the time. Once inspected, replace, tighten to torque with a torque wrench. There is a special protective grease you can buy and in that case you should look at a correction in the torque value because "dry" or "greased" coupling need different torque values (you can find online resourced for that, just take the right alloy and the right bolt size and you get the appropriate torque value. If you do not know your alloy for sure, assume it is SS304).
One of my bolts was beyond safe, so I did exacltly what the guys in NC suggested. I drilled a ~ 6 inches hole through the keel and purchased from McMasterCarr a special stainless steel anchor and its epoxy resin (I took the concrete kit because after some research I found that lead and concrete have similar mechanical traction and shear characteristics). I had the hole drilled by a professional, I did not have a long enough drill bit and it has to be damn straight and square to the bottom of your sump. It costed me something like 90$ as part of a general haul out. I did the rest myself. For best adhesion, the surface of the hole should be slightly rough so I brushed the hole with a hard stainless steel round brush (no brass! residues will create galvanic corrosion) until I got a decent roughness on inner surface of the bore. Let it cure and seal the bottom of the sump (cleaned and sanded) with a layer or two of epoxy to make sure that anchor never gets water. Use the biggest washers you can find to distribute the effort on a wider surface. You're good to go.
The whole process I described was perfomed with the boat dry docked and resting on its keel which is what is strongly recommend, especially if your keel is loose and I would definetly not sail until this is fixed.
Good luck!
 

WindnCs

Member
"I'd take the opportunity to make some backing plates much bigger than those nuts too."

That's what they did on the Oyster(?) yacht that sank in the med when it lost its keel. The owner replaced the backing plate with a larger one. When the inspected the boat after raising it, the designers determined that the larger plate actually concentrated the forces in a smaller area. So if you're going to change the design, have someone on your team who can analyze the forces at work.
That’s very interesting Bill! The physics of that are curious. Pacific Seacraft now uses a 3” square x1/4” thick backing plate for each bolt. I’m considering that myself. One at a time while she’s balanced well on her keel on the hard. Thanks for that info!
 

WindnCs

Member
This is one reason you do this with the boat resting on the keel. If the gap closes with the weight of the hull on the keel, that is probably the “natural” state of the keel and hull.

It’s hard to generalize on this one, but you usually want a firm interface between the top of the keel casting and the hull to distribute load properly.

If there is cracking soft compound along the keel/hull interface, you may want to clean this out and start over. At some point, dropping the keel and starting over may be called for.

This can be a harder process on a cruising boat than a racing boat, as the bolts may be spread out over a larger area of the bilge, and less accessible.

This is also the time to inspect all the structure in the bilge area to look for fractures and/or separations.

This may be an iterative process.

Or, it may be as simple as re-torquing the keel bolts. As has been stated, you have to be sure the nuts are free to move on the bolts, and the threads are clean all the way to the hull structure they pass through. Otherwise, you may get a false picture of how tight the keel/hull connection really is.

I am not a huge fan of structural adhesives like 5200 in this application. I’ve seen people trying to remove keel castings when all the keelbolt nuts are removed, and the adhesive is still holding the keel on.

Then again, that may be a good thing, provided everything stays where it is supposed to be.

If water is getting in that joint via a gap, this is working hard to destroy your keelbolts, like the photo posted earlier in this thread.
Thanks Accnick! Yes, she is on the hard and this will be done there. The sole of the bilge looks good upon first inspection but I need to take a closer look at everything! Removing the bolts one at a time, inspecting each one, and torquing them down was/is my planned procedure, but we’ll see what comes when we start pulling the nuts. As always, I’m aware of the can of worms I’m opening, and frankly not too stoked about it. I was hoping for a simple “torque the bolts” fix.
 

WindnCs

Member
Hi, here is what I can share from my experience with a J80.
To properly inspect the bolts you need to remove the nut and inspect the thread integrity. Especially if the bolt/nut couple has been submerged in salt water and the stainless alloy used is not the same there can be quite a bit of corrosion hidden under the nut. It was my case! Best way (if you can) if to haul the boat out and to have it rest on its keel while you remove the nuts one at the time. Once inspected, replace, tighten to torque with a torque wrench. There is a special protective grease you can buy and in that case you should look at a correction in the torque value because "dry" or "greased" coupling need different torque values (you can find online resourced for that, just take the right alloy and the right bolt size and you get the appropriate torque value. If you do not know your alloy for sure, assume it is SS304).
One of my bolts was beyond safe, so I did exacltly what the guys in NC suggested. I drilled a ~ 6 inches hole through the keel and purchased from McMasterCarr a special stainless steel anchor and its epoxy resin (I took the concrete kit because after some research I found that lead and concrete have similar mechanical traction and shear characteristics). I had the hole drilled by a professional, I did not have a long enough drill bit and it has to be damn straight and square to the bottom of your sump. It costed me something like 90$ as part of a general haul out. I did the rest myself. For best adhesion, the surface of the hole should be slightly rough so I brushed the hole with a hard stainless steel round brush (no brass! residues will create galvanic corrosion) until I got a decent roughness on inner surface of the bore. Let it cure and seal the bottom of the sump (cleaned and sanded) with a layer or two of epoxy to make sure that anchor never gets water. Use the biggest washers you can find to distribute the effort on a wider surface. You're good to go.
The whole process I described was perfomed with the boat dry docked and resting on its keel which is what is strongly recommend, especially if your keel is loose and I would definetly not sail until this is fixed.
Good luck!
Hey Monda! Lots of great info in there! My planned procedure was as you mentioned. Remove one nut at a time, inspect, clean, replace nut and torque. I’m curious what the “special “ grease you used was. I was going to use tefgel. If I do need to replace a bolt, I think drilling through the keel is the way to go too. Having a pro do it is also a great idea! I can’t imagine having to drill that whole so perfectly straight, especially through those substrates. I’m a 30yr woodworker, having built some intense pieces of furniture in my career, and I still get nervous just drilling through wood sometimes.
All in all, this could be a huge job if there’s a problem with a bolt, and if so, may necessitate the selling of the boat. I need to have her ready for an “easier” Ocean passage from San Diego to La Paz, and don’t have much time for the work. We’ll see what things look like and go from there. Dropping the keel is, I think, the best idea, a thorough inspection is called for, but I’m afraid that’s not in the cards. Thanks!
 




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