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.