Keel bolt hole

[Thedigger]

Hi, I am restoring an insurance write off after the fin keel ran aground. I removed the keel and had to straighten the keel bolts which bent and sistered to new bolts at the front. I filled the keel holes in hull with fibreglass now have to drill new holes for the bolts. What sort of drill bit and drill should I use. The holes will be 22mm and the hull is about 50mm thick?

 

[Rum Run]

You are going to need a big powerfull low geared mains drill, which even then will probably only gave a maximum chuck capacity of 16mm so the drill bit will need to be of the type called a blacksmiths drill, which has a reduced shank

 

[Thedigger]

I have a mains roybi hammer drill will that do?

 

[Akestor]

That's 22x50. I would prefer a whole saw as it would help keep the drilling constantly vertical assuming you did a good pilot hole. It cuts fiberglass like bread, great but you need low revs. Instead of a power drill, i used the battery screwdriver, with bursts of 2-3 seconds because i couldnt lower the revs on the power drill. Costs around 5-10 euros depending on the brand.

 

[knuterikt]

That's 22x50. I would prefer a whole saw as it would help keep the drilling constantly vertical assuming you did a good pilot hole. It cuts fiberglass like bread, great but you need low revs. Instead of a power drill, i used the battery screwdriver, with bursts of 2-3 seconds because i couldnt lower the revs on the power drill. Costs around 5-10 euros depending on the brand.
View attachment 93384

Use a HSS hole saw

 

[vyv_cox]

For interest, how have you repaired the holes in 50 mm thick fibreglass? Sounds like a technical challenge.

 

[Thedigger]

Hi,
I stuffed fibreglass resin matting down the bolt holes. Very difficult to sand on either side. And I have 2 new holes to drill as two of the bolts had to be cut away. It's a pretty tough job and not looking forward to boring the new holes. 22mm holes mean I have little margin of error when I lift the hull into the keel. I replacing the old washers so that should help. I'm having difficulty with the drill bits and what type of drill to use. I have a cable hammer drill but the attachment is not compatible with the bits I have.