Drilling out keel bolt advice.

[BAD ORCA]

I need to start prepping for my big haulout this spring. One of the jobs being done is dropping my keel and inspecting my keel bolts.

I have one keel bolt that is a big concern for corrosion. Because its the keel bolt at the leading edge of the keel (which is lead), its location and shallow depth in the keel, sistering in a new keel bolt (if it is in fact badly corroded) is not an option.

Quotes for sending the keel off to have it professionally replaced by Mars Metals are cost prohibitive, over 25K to replace when yard time and shipping are added into the equation.

There is a DIY fix that is very simple in theory and has been done succesfully by DIY'rs already which is to cut perpendicular into the lead keel, through the bolt at about 12" depth then drill out the old keel bolt, epoxy in a new one with a very large nut/washer onto the bottom then fair in the keel where the lead was cut out with epoxy and fiberglass, reassemble and attach internally with nut and backing plate as normal.

The problem would be drilling out the old keel bolt. I could either drill right through it, which seems like a nightmare considering its stainless steel or i thought possibly drilling around it with a very long hole saw. Theoretically a 6" holesaw thats just slightly larger than the diameter of the keel bolt without the pilot bit would be able to be drilled from the top and bottom for an overall depth of 12".

Here is a blog from someone who did this exact thing for a visual explanation of what i am intending to do. It sounds like they drilled through the bolt.

https://sailboatrefit.com/how-to-replace-keel-bolts/

I want to try a test before i haul out in the spring and be prepped and ready to go if in fact this repair needs to be done. The problem im having is finding a 7/8 or 1" hole saw thats at least 6" in length. If i could find one i can easily get a piece of lead from a metal supplier near me to test out my theory with the hole saw.

First question would be if anyone has a source for such a hole saw? My google searches are not turning up anything that length. I swear iv'e seen them before in previous searches but am having no luck this time. I have come across very long coring bits for stone that mgith be an option but seems like they require a special coring drill.

I guess my next question would be opinions on how to drill directly down the center of a stainless bolt. Is this something that can be done with a special drill bit by a DIY'r and a hand drill or is this something that requires special equipment. Any other opinions are welcome.

Hopefully this wont be necessary to do and the bolt is in good condition, but i need to be ready to go with a solution before i haul out because every 'lay day' at the local yards is about $300 per day. I dont want to sit there for two weeks trying to figure this out.

Thank you if you read this far. Welcome any advice.

[stormalong]

Well, first of all dropping a keel is not a very common thing, I do a lot of work on my boat but dropping a keel is probably best left to a yard experienced in such things. Keep in mind that without a keel the boat balance is dramatically changed, Are you planning to remove the mast first?

You say nothing about the boat model, builder or age. All relevant for a discussion of this type.

[BAD ORCA]

Originally Posted by stormalong

Well, first of all dropping a keel is not a very common thing, I do a lot of work on my boat but dropping a keel is probably best left to a yard experienced in such things. Keep in mind that without a keel the boat balance is dramatically changed, Are you planning to remove the mast first?

You say nothing about the boat model, builder or age. All relevant for a discussion of this type.

Yes the yard will help with dropping the keel. That part is not a problem. Yes mast will be un-stepped first. It has to be on my boat (keel stepped). I have all those details worked out. This is something thats been worked out and planned with the yard already. They dont replace keel bolts so that part is up to me. I have a guy that can sister in new bolts if any others are bad. He has been to my boat and we have discussed this. The problem is/could be the very front bolt. All thats left to figure out is how to get it out if necessary.

Its a 40 Y/O boat that i intend to take offshore in the future. Dropping the keel just to be absolutely sure i think is a prudent thing to do. It needs to be re-bedded anyways so a bolt inspection/repair will be on the table no matter what. The mast step will be replaced as well so Its a perfect time to get them both done.

[deblen]

Very clever repair by the boatyard in the link!
Would you have to drop the keel to use similar method.


As for the hole saw:
Find a carbide toothed hole saw that will slide over old keel bolt.
Cut the "back end" off it with disk grinder
Find a pipe that will just fit & weld them
Weld the cut off "back end",or a piece of 1/2" rod to other end of pipe
You now have a deep hole saw.
Remove nuts & washers & drill right down thru bottom of boat.
When you get to desired depth,use another carbide holesaw to drill crossways thru the keel & old keel bolt.
Remove upper part of old keel bolt.

Have a half round "nut" made from a 1/2 section of SS rod that fits the cross hole roughly.
Insert new keel bolt down hole & thread it into "cross nut"

Personally,I would leave the cross hole open for future crevice corrosion prevention/inspection,but it's your boat.
Seal the hole in the fiberglass with a non permanent sealant such as butyl,under the k-bolt flat washer,to allow future inspection.
Cheers/Len

[BAD ORCA]

Originally Posted by deblen

Very clever repair by the boatyard in the link!
Would you have to drop the keel to use similar method.


As for the hole saw:
Find a carbide toothed hole saw that will slide over old keel bolt.
Cut the "back end" off it with disk grinder
Find a pipe that will just fit & weld them
Weld the cut off "back end",or a piece of 1/2" rod to other end of pipe
You now have a deep hole saw.
Remove nuts & washers & drill right down thru bottom of boat.
When you get to desired depth,use another carbide holesaw to drill crossways thru the keel & old keel bolt.
Remove upper part of old keel bolt.

Have a half round "nut" made from a 1/2 section of SS rod that fits the cross hole roughly.
Insert new keel bolt down hole & thread it into "cross nut"

Personally,I would leave the cross hole open for future crevice corrosion prevention/inspection,but it's your boat.
Seal the hole in the fiberglass with a non permanent sealant such as butyl,under the k-bolt flat washer,to allow future inspection.
Cheers/Len

Well the front of my keel has the catalina smile and has light rust stain at the leading edge last time i hauled out so thats why keel is being dropped. It did not weep for very long though so im hoping water did not intrude to bolts, but it definately needs re-bedding.

Thanks, thats a great idea for the holesaw. It made me think, i could also probably do the same to a couple hole saws to get at least 6" cut depth if i had to if i cant find pipe with a similar wall thickness. Cut the end off of one and the teeth off of the other. McMaster looks like they have thin wall steel tube though, so this may be what i end up doing.

Iv'e read of similar technique for the bolts in the middle sections of the keel. I have a feeling my other bolts are ok. Someone once said somewhere, it may have been this forum that if you ping the end of the keel bolts with a ballpeen hammer and they ring slightly like a tuning fork, there is no severe corrosion in them. Alll of mine ring when tapped so if this method has merrit they are still good. The front bolt sort of rings when tapped, slightly less but it still does so fingers crossed.

[Marathon1150]

"I guess my next question would be opinions on how to drill directly down the center of a stainless bolt. Is this something that can be done with a special drill bit by a DIY'r and a hand drill or is this something that requires special equipment. Any other opinions are welcome."

We had to drill four iron bolts out of our iron keel. We learned that the bolts were fine but the heads were very badly corroded and broke off. We did this with the boat in the water and the drilling process was very hard despite being iron. A very large industrial drill and several drill bits later, led to success. We were able to unscrew one of the bolts using a chisel and hammer and tapping it counterclockwise.

We oversized the holes, tapped them and inserted threaded stainless rod along with epoxy to reduce the probability of electrolysis. Oversize SS backing plates and nuts were then used to secure everything to the hull. That was nearly 10 years ago and all continues to be fine.

[deblen]

Centering the drill bit tips.

https://www.youtube.com/watch?v=dJfkCj3FWBs

Annular cutters,rebar cutters vs holesaws


https://www.carbideanddiamondtooling...bors.Mag.Drill

[BAD ORCA]

Originally Posted by Marathon1150

"I guess my next question would be opinions on how to drill directly down the center of a stainless bolt. Is this something that can be done with a special drill bit by a DIY'r and a hand drill or is this something that requires special equipment. Any other opinions are welcome."

We had to drill four iron bolts out of our iron keel. We learned that the bolts were fine but the heads were very badly corroded and broke off. We did this with the boat in the water and the drilling process was very hard despite being iron. A very large industrial drill and several drill bits later, led to success. We were able to unscrew one of the bolts using a chisel and hammer and tapping it counterclockwise.

We oversized the holes, tapped them and inserted threaded stainless rod along with epoxy to reduce the probability of electrolysis. Oversize SS backing plates and nuts were then used to secure everything to the hull. That was nearly 10 years ago and all continues to be fine.

Thanks for that. I think stainless would absolutely drive be insane. I would probably end up selling the boat and getting an RV.

[Matt Johnson]

Where are you hauling out? We did this in 2012 in St Augustine Florida.

The owner of Oasis Marine melted the old "J" bolt out - leaving a bolt shaped pocket in the keel - then magically welded the lead back into place over the new bolt. It was amazing to watch his skill with a torch, keeping the keel side at just the right temperature, while poring the molten lead back into position. I think he charged $750 a bolt in 2012.

[BAD ORCA]

Originally Posted by Matt Johnson

Where are you hauling out? We did this in 2012 in St Augustine Florida.

The owner of Oasis Marine melted the old "J" bolt out - leaving a bolt shaped pocket in the keel - then magically welded the lead back into place over the new bolt. It was amazing to watch his skill with a torch, keeping the keel side at just the right temperature, while poring the molten lead back into position. I think he charged $750 a bolt in 2012.

Southern California. I couldnt find anyone in California that would do that. There was a guy that used to but no longer does. The guy he sold his company to only sisters in new bolts now by drilling new bolt holes alongside the old ones. He can get access to all the bolts if need be except the first one. Mars Metals would melt them out but i would have to ship them the keel and the turnaround is weeks.

Unfortunately we have no low cost haul out options in my area. All the yards charge for every lay day that is between $200-300 per day. Its what it is though and just means having to be prepared before hauling out.

[TeddyDiver]

Hole saw will get stuck in lead. I've drilled lead with wood drils, to be specific with 20 and 24mm wood drils. They lift the lead chips up thou your must lift and clean the chips very often. Drill around the keel bolt as many holes as you can and you should be able to get it of. Remember there's a nut and a washer or the keel bolt is J-type so leave some space around and prepare to on or two destroyed drills. Take a new keel bolt, have a premade jig (made with the old bolt in place) to hold new bolt in place and pour melted lead in the hole. Then fair the surface..

[misssherry]

Have you taken the nut off of the suspect bolt? It is not uncommon for crevice corrosion to occur under the nut and not affect the lower part of the keel bolt. This scenario would be caused by stagnate bilge water instead of water coming up from the keel/hull joint. If the corrosion is limited to the top of the bolt, that section can be cut off and connected to a short threaded rod with a 316 ss coupler.

[BAD ORCA]

Originally Posted by misssherry

Have you taken the nut off of the suspect bolt? It is not uncommon for crevice corrosion to occur under the nut and not affect the lower part of the keel bolt. This scenario would be caused by stagnate bilge water instead of water coming up from the keel/hull joint. If the corrosion is limited to the top of the bolt, that section can be cut off and connected to a short threaded rod with a 316 ss coupler.

No not yet. I did clean it up from the top with a wire wheel brush but only have seen the top of the bolt/nut. Unfortunately that keel bolt sits in a little bilge compartment and was sitting in salt water that leaked in from a seacock in the bow for god knows how many years. The nut and top of the bolt are moderately corroded. The nut will likely have to be cut off.

Luckily i have room around the bolt in the bilge area to cut into to get a nut on deeper on the bolt if thats the case. On my boat they filled the bilge in with a special mixture like a thick gelcoat that was supposed to absorb impact loads in case of a grounding. At least thats how it was explained to me. I can easily cut into this material with a router if i have to remove some to get deeper access to better threads.

Fingers crossed this is all that will be required.

[misssherry]

Get a large socket on the nut and use a socket wrench extension that is long enough to clear the bilge obstructions. Use a breaker bar to remove the nut and inspect the bolt. Don't be surprised if the nut turns easily or the bolt breaks. I did this with several suspect bolts with the boat in the water. One nut at a time, of course!

[b.needalman]

Use a set of high quality metal bits. The drills have to be harder than what it is cutting. For stainless, use low drill speed and not too much pressure. Use cutting oil on the drill bit. Clear the hole frequently by pulling the drill partially our. Keep the hole wet with cutting oil. IF it smokes, it's getting too hot. Start with a small diameter and work up to larger sizes. Slow and careful does it. If stainless gets hot it will harden and then you will have more trouble.

Hone your skill on hardware from the junk box for practice.

PS This is the kind of thing that might be best done by a professional. The boat will turn upside down if the keel takes leave of the boat, with dangerous consequences to you and your crew.