OMG check those keel bolts!

Niander

Niander

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Ok i have a major project at the mo that is adding[sistering] keel bolts to my 30'ketch
the cast iron is bloody hard and im having a hell of a job drilling into it.
ive extended drill bits to 20" lg by welding steel rod to the drill bits ...
This is a very difficult job but had to be done as i tested a keel bolt by tightening it and it was just coming out of the hole...im other words had rusted right through! ,,,,boat not leaving drying mooring until ive strengthend it up!
Plan is drill and tap for 20mm bolts .
Any advice?...just got some 8mm cobalt drill bits to start the hole....out with the trusty stick welder again to extend one!
 
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FWIW

You might find it easier to drill out the remains of the existing threads in the keel to a tapping size for larger bolts.

Unless the mating face of the cast iron has been machined (unlikely) there will still be a very hard skin on the surface 'as cast' and drilling through the sand-contaminated surface will be quite a task to do in-situ with hand-held power tools, as you seem to have found out.
 
Drilling cast iron is usually a doddle, grey iron as used for keels is not hard and the graphite acts as a lubricant for the bit. There may be a layer of chilled white iron near the surface that will only be quite thin, once through this it should be much easier.

It sounds like a good job for Helicoils but if the old bolts/holes have rusted so badly I suggest you need to drop the keels and rebed to keep the water out.
 
Nicholas123 said:
Please tell us about the make of boat you have so that we can avoid buying one........scaremongering about keel bolts in general as if all boats are the same is not helpful.
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Checking on of the most important structural attachments on your boat I would suggest is fairly prudent. Especially given the age of the boats a lot of us own.

As for the OP assuming the keel isn't encapsulated, its going to be easier to do a proper job as suggested above if you drop the keel off, allows you to rebed as well.
 
Ceirwan said:
Checking on of the most important structural attachments on your boat I would suggest is fairly prudent. Especially given the age of the boats a lot of us own.
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Maybe if it were a five minute job yes,as it is I have many much more important things to worry about.

All boats are different.It might be helpful to know about the ones that are renowned for dodgy keel bolts :encouragement:

By the way,I believe Snapdragons have encapsulated keels so if you want to worry I suggest you go round looking for cracks & anyway of water ingress.I've heard of some where the entire contents have dropped out :eek:

:D
 
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vyv_cox said:
Drilling cast iron is usually a doddle
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well, it's fine in a drill press but I wouldn't want to drill 20mm holes in CI using a hand drill. Does anyone know of a portable equivalent to a drill press for this kind of job ?

Boo2
 
Nicholas123 said:
Please tell us about the make of boat you have so that we can avoid buying one........scaremongering about keel bolts in general as if all boats are the same is not helpful.
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Spose you have a plastic boat those dont seem to have the keel bolt problems that ALL wooden boats have to watch out for....
MY boat was professionally built in 1963 make.... Maurice Griffiths Waterwitch 30
so far i have 3 extra bolts in they are 16" lg 20mm starting with an 8mm and working up in 1.5 mm sizes up to 17.5mm tapping size its scary as if a drill snaps i cannot get it out 14" down!...mettle comes out as a kind of grey powder.
i would much prefer drilling mild steel!
 
Presumably you are drilling through a thick wooden keel before the iron keel which acts as a guide - you dont say what drilling machine you have available -an old fashioned heavy duty slow speed with a piece of pipe opposite the handle would be ideal - eye nut on an existing keel bolt with a loop of rope & piece of wood to apply pressure on the bigger drills , very much a two man job ,best of luck

Jim
 
Nicholas123 said:
Maybe if it were a five minute job yes,as it is I have many much more important things to worry about.
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The suggestion being that if a job takes more than 5 minutes it isn't worth doing?

To be fair on most GRP boats it doesn't take long at all, two nuts onto the stud and wind it out. If its an old boat it maybe rusted on anyway so you could just turn it out.
Here's a keel bolt from my Eygthene 24 when I had her:
DSC00512.jpg


Over a 1/3 of the diameter of the bolt had been lost. It didn't leak on the inside of the boat at all though.

As you say it depends on the boat, but unless they get inspected periodically you'll never know.
 
It seems some holes are drilling easier than others must be hard spots...very annoying!
think ill have to drop the keel next year but add as much strength as possible so i can sail this year
must be quite a few around with wasted bolts but you dont hear of many keels dropping off!
 
I confess being mystified as to why the keel bolts are being sistered. Surely remove the defective/all old bolts and replace in the same hole. I did it a complete set about 20 years ago and have looked at a couple at random twice since then. Keel bolts for timber boats are really service items - long intervals but necessity.
 
The only wooden boat keel olts I've been involved with were not tapped into the keel, but the holes went right through.
So if an old keel bolt fails completely, the boat will leak rather a lot.
The bolts had some sort of tapered head.
I'm told the old boys would dry the boat on a grid, bash out the old bolts and put new ones in. A few per tide.
No travelhoists in them days.

I suspect wooden boats vary a lot in these details.

I think there is a lot of metal in most wooden boat's keels as an allowance for rusting. The keel is fairly shallow not a damn great fin?
So there is not much leverage, mostly just the weight of the keel. So if the bolt does not break when you look at it with a decent spanner, it probably still has strength.
One case I know, 60 year old boat, not very big, 1/2in (or maybe more?) bolts rusted down to under 3mm, still winning races...
Now has bronze bolts that will outlast boat and owner I think.
 
Niander said:
It seems some holes are drilling easier than others must be hard spots...very annoying!
think ill have to drop the keel next year but add as much strength as possible so i can sail this year
must be quite a few around with wasted bolts but you dont hear of many keels dropping off!
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Almost certainly be wasted. I have an Eventide (also professionally built) from the same year. I made the mistake of replacing the bolts without removing the keel in 1988 because one snapped while testing the nut. In 1992 I removed the keel because I increased the draft and the "new" bolts were already on their way out.

Astonished you are wasting time and energy trying to drill new holes to add bolts. Drop the keel, clean the surfaces, get new bolts made in 316, threaded at both ends so the bottom nut fits in the pocket, bed the keel in Sikaflex and coat the new bolts as well. You can then forget about it. Mine are still sound 23 years on.
 
Nicholas123 said:
Maybe if it were a five minute job yes,as it is I have many much more important things to worry about.

All boats are different.It might be helpful to know about the ones that are renowned for dodgy keel bolts :encouragement:

By the way,I believe Snapdragons have encapsulated keels so if you want to worry I suggest you go round looking for cracks & anyway of water ingress.I've heard of some where the entire contents have dropped out :eek:

:D
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There was quite a range of Snappies, KC - bilge, fin, lift, several builders and some home finished to individual specifications. Certainly not all encapsulated even if the most common...
 
Ceirwan said:
To be fair on most GRP boats it doesn't take long at all, two nuts onto the stud and wind it out. If its an old boat it maybe rusted on anyway so you could just turn it out.....
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You were lucky it was a quick and easy job. It is not always so. Ask a boatyard for an fixed quote for removing a single keelbolt and they'll tell you it they can't give a definite answer. Anything between an hour (done in situ, came out easily, found sound and put back, with much of that time spent finding the right tools) to a week at least (taking down the mast, propping the boat, making a stand for the keel and lifting the hull off the entire keel etc. etc. )

Not all keelbolts CAN be drawn: a few are J-shaped with the bottom cast into the keel when made. Some have hollow pockets in the side of the keel with nuts at the bottom. Some older long-keelers have nuts on the underside of the keel base, sealed in with unknown-to-science tarry gloop. Some newer composite steel/lead keels are back to nuts at the underside holding a lead bulb up onto a steel fin stem, though it's probably epoxy rather than tar that seals the hole.
 
If you can get hold of a drill press rotate the base or head 180 degrees so it allows the bit to past through & then bolt the base to another keel bolt that has not rusted right through. - must be one to start with otherwise keel will have dropped off !!!. Once you have one bolt in then it is easier to use that for clamping for the next hole & so on. Cast iron is easier than steel to drill once through the outer hardened surface ( about 6mm thick on a large casting). I would not keep drilling bigger diameter holes at first. Try drilling a small hole then drilling with the tapping size straight off. You only need to drill a pilot the width of the flat on the main drill. If you drill successively larger holes you can get snagging of the drill bit. I do not know the size of the keel but can you put more bolts in at, say 150mm They can be smaller diameter & in most cases the existing bolt will be well over designed to allow for surface corrosion so new SS ones will be better
 
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Ceirwan said:
Here's a keel bolt from my Eygthene 24 when I had her:
http://s28.postimg.org/l134r7w5p/DSC00512.jpg

Over a 1/3 of the diameter of the bolt had been lost. It didn't leak on the inside of the boat at all though.
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I hope you don't mind, when I saw that green tint I couldn't help myself:

gQgAIa3.jpg

I also tried to pull out some more detail from the corroded section, so I repost in case some viewers find it clearer.

Please let me know if you'd rather I delete this image.
 
MY keel doesent have pockets unfortunately this method is the easiest to rectify.
but ive looked on the sides of the keel and no sign of any so they must just be tapped in
interesting idea to add some pockets by cutting holes in side of the keel where the would bolts go...
But how easy to cut?
 
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