Niander
Well-Known Member
Is it possible to Oxy/Gas cut cast iron ?
OMG check those keel bolts!
- Thread starter Niander
- Start date
Tranona
Well-Known Member
If your boat was built according to MG's plans then the keel bolts will go right through the ballast keel and have heads in recessed pockets on the underside. The bolts themselves may have forged heads or like mine have nuts. You need to scrape around at the underside of the keel as the pockets will likely be filled with sealant so appear flush. Would be very surprised if the nuts are in pockets in the side of the keel as this method is unusual in a shallow iron keel - more commonly used in deep lead keels to avoid very long through bolts.
Even if they are studs, which I think unlikely then just remove the nuts, drop the keel and remove the studs and re-assemble with new studs.
lw395
Well-Known Member
Not sure 316 is favourite for keel bolts in a wooden boat these days?
Tranona
Well-Known Member
It is if you bed them well in sealant. The originals in my boat were mild steel and probably galvanised. Water got in along the joint and the oak keel got wet. All the bolts were waisted and the front one snapped in half when I tried to undo the nut. I replaced them with mild steel without dropping the keel and 5 years later when I took the keel off the new bolts were already corroding. New ones are 316 bar threaded at either end and the holes filled with sealant as well as sealing the keel joint. Still appear sound 23 years later. No sign of leaks or movement but admit have not taken any out!
Tiller Girl
Well-Known Member
Personally I wouldn't (didn't) chose 316. Perhaps an interesting experiment. I assume you had a problem with the keel joint which caused early corroding. How can you test whether crevice corrosion is taking place?
My bilge keels (mild steel) are fastened by 316. There is no crevice corrosion but there is alkalid reaction internally around the bilge keel studs (iroko) (would love to try to sail without the bilge keels!)
My bilge keels (mild steel) are fastened by 316. There is no crevice corrosion but there is alkalid reaction internally around the bilge keel studs (iroko) (would love to try to sail without the bilge keels!)
lw395
Well-Known Member
Please explain more about this Alkalid reaction?
Oak is much more acidic than Iroko, FWIW.
Table I Acidities of woods
Wood Typical pH values
Oak 3.35, 3.45, 3.85, 3.9
Sweet chestnut 3.4, 3.45, 3.65
Steamed European beech 3.85, 4.2
Birch 4.85, 5.05, 5.35
Douglas fir 3.45, 3.55, 4.15, 4.2
Gaboon 4.2, 4.55, 5.05, 5.2
Teak 4.65, 5.45
Western red cedar 3.45
Parana pine 5.2 to 8.8
Spruce 4.0, 4.45
Elm 6.45, 7.15 Moderate
African mahogany 5.1, 5.4, 5.55, 6.65
Walnut 4.4, 4.55, 4,85, 5.2
Iroko 5.4, 6.2, 7.25
Ramin 5.25, 5.35
Obeche 4.75, 6.75
Tiller Girl
Well-Known Member
Oh I can't explain it! But I saw it!! Iroko will react to alkalid reaction, not disastrously it (there is a comment in the 1985 survey regarding the starboard beam shelf - I replaced that in 1998. Fresh water damage had started that, presumably seawater over the deck brought the alkalid action to that) The reaction has stopped, presumably better bedded.
Tranona
Well-Known Member
The concern about 316 for keel bolts in wooden boats dates from the time when leaky joints were just a part of life. Bolted structures as in traditional construction are by nature flexible and even with the type of sealants (read lead etc) that were used on the faying surfaces it was almost impossible to keep water out. This was particularly the case when heavy lead keels were hing on lightly constructed hulls - but then bronze bolts were often used.
So, the vulnerable point (as with modern construction) is along the keel joint. With mild steel bolts this results in straight forward rust and in 316 with crevice corrosion. Both can be avoided by sealing the joint better or sealing the bolt to exclude moisture. With my boat i do not have any flex problems as the wood keel is almost straight and a laminate of oak and douglas fir for the deadwood. The hull is glued ply so stiff. The ballast keel is long, flat cast iron. So the whole structure is very rigid making sealing the join easier.
The OPs Waterwitch should have exactly the same basic structure. MG favoured long flat ballast keels as a stiff base for attaching the wood keel. I strongly believe the correct course of action for the OP is to drop the keel and re-attach it properly rather than trying to bodge it.
fisherman
Well-Known Member
I don't know much (anything) about cast iron keels, but is it worth thinking outside the box a bit? What if you drilled a hole sideways through the keel, I would have to assume it's thin enough to achieve this, inch or so diameter, where the existing bolthole is. Now insert a piece of shaft to use as a nut, drilled and tapped across the diameter. It can be of better material, and a bit easier to inspect and service. Apologies if this is really stupid......
Edit: like, how will you find the hole?
Edit: like, how will you find the hole?
Tiller Girl
Well-Known Member
Totally agree with Tranona's final paragraph. OP has a Waterwich I think he said and I think they have a long straight ballast. Let's hope he won't sister keel bolts and gallery the ballast keel!
On the side issue I understand paras one and two. A sort of monocoque. Now on TG has frames 'heeled' into the keelson so will be strong but not as rigid as Tranona's.
On the side issue I understand paras one and two. A sort of monocoque. Now on TG has frames 'heeled' into the keelson so will be strong but not as rigid as Tranona's.
Niander
Well-Known Member
Well its going well i got 2 17.5mm holes drilled today will be relatively simple to tap them out tomorrow to 20mm
bolts screw in about 1.5 "
so ill have two extra sound new 20mm bolts to add strength
i have a nice big 100mmx60mm steel washer under each bolt head
So you call it a bodge i dont agree and it stops the Paranoia!
Stops an incredibly massive yard bill also!...btw i havent seen any water leaking up so the joint at least in these areas is sealed.
bolts screw in about 1.5 "
so ill have two extra sound new 20mm bolts to add strength
i have a nice big 100mmx60mm steel washer under each bolt head
So you call it a bodge i dont agree and it stops the Paranoia!
Stops an incredibly massive yard bill also!...btw i havent seen any water leaking up so the joint at least in these areas is sealed.
fisherman
Well-Known Member
The surveyor suggested next time I was lifted I should change the skeg bolts. Galv cup square 10mm, 1976 vintage, probably, certainly no newer than 1991, through mild steel and the GRP keel. I removed one, it was as new, it rusted more in the car glove box over the next year.
OTOH a wood boat built in 1980 had to have new keel bolts in 1998, needle thin in the middle. Iroko keel.
OTOH a wood boat built in 1980 had to have new keel bolts in 1998, needle thin in the middle. Iroko keel.
Fimacca
Well-Known Member
Well if the keels fall off, just think of the speeds you can gain !
Like being in a laser again !!
Like being in a laser again !!
Tranona
Well-Known Member
So, why are you bothering with all this work if there are no leaks and the keel is still firmly attached?
nemodreams
Well-Known Member
I would have been tempted to contact someone like Drill Cut. It would have been done in an hour easy. They have all the gear and special metal boring core-type bits.
You could have had four done - and deeper. 1 1/2" seems a bit lean for stressed casting carrying a lot of weight - but i am no engineer !
You could have had four done - and deeper. 1 1/2" seems a bit lean for stressed casting carrying a lot of weight - but i am no engineer !
Norman_E
Well-Known Member
You could actually do it with a drill press. You just need a small one with a half inch chuck but you need to modify it a bit. Firstly small cheap drill presses dont have a low enough speed, but you can make them slower of you fit a different longer belt and a bigger pulley on the driven shaft. Don't tell Health & Safety because you need to discard the belt guard to do this. Secondly discard the drill table and undo the screws holding the head to the column, so that you can lower the head down the column. Now remove the baseplate at the bottom of the column and bolt the column flange to a flat piece of steel with a slot cut in big enough to fit over the existing keel studs. Bolt the modified drill down to an existing stud and line it up to drill where you need. Use blacksmiths drills which have half inch shank but sizes up to one inch to open out the existing bolt holes one by one to tap them out the next largest size and replace the studs one by one.
I once modified a drilling machine to drill holes below the level of its own baseplate, by turning the baseplate round to face backwards, removing the drill table and dropping the head down the column. That machine had three pulleys so that low speeds were possible, but with the head lowered down the column the whole belt guard had to come off, and longer belts were needed with the middle pulley fitted to an extended arm so that the belts missed the projecting part of the column.
When drilling deep holes in cast iron it is best to withdraw the drill regularly, and clear out the cuttings that are left in the hole. A magnetised steel rod will do that.
Niander
Well-Known Member
Well yes still attached but when i checked a bolt... like this bolt actually is a stud with a nut on top so i tried to unscrew a nut...they were extremely tight[as had not been touched in how many years?[Only God knows how long]
previous owner didnt know and he hardly sailed it as hes Very OLD and passedIt.
so back to the nut i found one that actually moved slightly so moved it back n forth as ya do then it would undo but thats not getting the stud out to inspect is it so screwed it back down to tighten it up but the thing just started drawing out the stud.... not tightening at all!....so whats happening?.....stud is dead,waisted away over the years
or maybe there was so little of it left it snapped hence im adding new bolts and its working but a slow difficult job
but i know how to sharpen drill bits...and weld etc so happy days and no Large yard bill!
Thanks for all the ideas btw !
Tranona
Well-Known Member
Still doubt they are studs. As I said MGs designs always had through bolts. studs are a relatively recent method and mostly used in GRP boats where the bolt on keel is deep and narrow so through bolts are impractical.
What you are describing suggests the bolts are waisted where they go through the wooden keel into the cast iron - as I described earlier. drilling and tapping to put screws in is a bodge, however you try to justify it. The only solution is to drop the keel and do the job properly. nowhere near as difficult as you might imagine provided you have a crane or hoist to lift the boat off the keel. As the keel is long and flat you do not have to build any supports to hold it. Just rest it on wooden blocks clear of the pockets in the bottom of the keel, take the nuts off the bolts inside the boat, hammer them down if you can then lift the boat up.
What you are describing suggests the bolts are waisted where they go through the wooden keel into the cast iron - as I described earlier. drilling and tapping to put screws in is a bodge, however you try to justify it. The only solution is to drop the keel and do the job properly. nowhere near as difficult as you might imagine provided you have a crane or hoist to lift the boat off the keel. As the keel is long and flat you do not have to build any supports to hold it. Just rest it on wooden blocks clear of the pockets in the bottom of the keel, take the nuts off the bolts inside the boat, hammer them down if you can then lift the boat up.
fisherman
Well-Known Member
To find out if they are through bolts get a hollow nosed punch and see if you can knock the lower part of the bolt out. If so it's just a lift out and insert new bolts, no need to drop the keel (although you might want to remake the joint)
Tranona
Well-Known Member
Yes, you can remove the bolts and replace that way, although if they are seriously waisted it can be difficult to remove the lower part. I did this on a similar boat, but the replacement bolts went the same way very quickly as that does not solve the problem of getting water in the joint.