LM 30 / LM 28 BILGE Keel Bolt Replacement ; Help

[Chris Wood]

I have a Bilge Keel LM 30, Suffered damage to a keel and requires Keel Bolts to be replaced. The Yard is struggling to extract the bent ones. Can anyone advise whether the bolts are threaded in or cast in situ? I believe the Keels are Cast Iron, the bolts are stainless. Can they be extracted? Has anyone replaced bolts before or had to Sister them in? I would guess that LM 30 Bilge and LM 28 Bilge Keelers are constructed in the same way. Many thanks for any guidance, Regards Chris

[nauticalnick]

Hi Chris,

Sorry to hear of the damage.

Normally the keel bolts are mild steel and are screwed into the keel. In fact the term bolt is somewhat misleading as it is usually a stud screwed into the keel with a large nut on top. l've extracted these studs on a previous boat ( not LM ) by locking two nuts on top of the stud and then winding away, although this method will depend on how much stud is exposed and the access.

Stainless steel is not normally used for keel bolts as stainless requires oxygen to remain corrosion free. You don't say whether the yard have dropped the keel or are trying to extract them in situ.

l have yet see any keels where the fixing bolts/studs are cast as part of the keel so my humble opinion they should be able to be extracted. But if they are bent then this could of course be more of an issue.

Keep us posted as to what happens.

Good luck.

NIck

[Chris Wood]

Hi nick,
thanks for your reply. The keel is off and the yard have tried the usual tricks you mentioned including application of heat. There is a suspicion that the bolts are in someway bonded in - I understand this is unusual. The thread does not go all the way to the keel but stops some 10mm off. This is why I am particularly keen to know what method LM used for their keel bolts. The bend is not the problem it may be more force is required, more heat, could be a reverse thread (unlikely). 
So it would be good to hear from anyone who had experience of LM keel bolts so we know what we are trying to tackle .

thanks again,

Chris

[nauticalnick]

Hi Chris,

Well the yard have tried everything l would have done !

The only other method l can think off would be to cut off the the offending bolt at keel level, then drill it out and then re-tap it or use a helicoil insert if possible but this is drastic stuff and a bit specialist in view of the size of the keelbolt.

Hopefully somebody will come along with more information but either way the bolt has to be extracted.

If you know of a friendly surveyor it be worth asking him if they can help or have a look at the Danish LM owners club site. Google will translate it for you.

Regards,

Nick

[Chris Wood]

Hi Nick,

thanks for for your continued interest. I have a surveyor involved (this is one element of an expensive insurance claim!) and I am hoping to hear from him this week. Drill and re tap is the ultimate sanction but trying to keep the ever escalating cost down.!
i will advise the outcome in due course and would welcome any other ideas in the meantime from any one on the forum.
thanks again,
Chris

[Chris Wood]

No further developments - continued to try and free the bolts with more efforts but the next stage is to transfer the keels to a heavy engineering company to drill and re-tap!

[jandane]

Hi chrisww
I may still have a contact to some of the persons who actually made the LMs in Lunderskov. I have tried to send a mail around and askink about the bolts etc. The moment I get a reply, it will be posted

[jandane]

I had a reply from one of the former LM builders in Denmark. He writes: "The keel bolts are moulded into the keels so the work of changing them is very difficult."
and here one more from one of the other shipbuilders on the factory: "The keels of the LM32 and the bilge keels of the LM30 are boltet onto the hull. As far as I remember, is it 6 or 8 bolts in each keel. They are made of steel and are moulded into the keel. The joinling of the keel and the hull is sealed with a 3M product, called 5200. The moulded-in bolts are laid into the cast iron of the keel in a U-shape with grooves on top of the "U"
The LM30 with the standard keel had the keel mouæded onto the hull, and the LM32 had the keel bolted onto the hull.
Hope this can be of any help....
best wishes
Jan

[Chris Wood]

Hi Jandane,

That is fantastic help - although I believe we had already come to that conclusion and replacements will have to be re-drilled into the cast iron and threaded in the conventional way.

I will keep the Forum posted on progress but I believe this is very useful knowledge for all LM owners with bolted keels - bonding into cast Iron I understand is very unusual.

Best Regards,

Chris

[Chris Wood]

Jan,
in my haste to get this information to my surveyor and engineer I omitted to thank you for your efforts in obtaining this information. It is very useful to us and I believe, very valuable for those owners who like me (and an experienced surveyor ) had not come across this method of bonding keel studs into a cast iron keel.

Thank you so much, I will keep the forum advised of progress.

Best regards,

Chris

[jandane]

most welcome
jan

[nauticalnick]

Well, you live and learn as they say ! That is most surprising to hear.

It just goes to show that the 'LM' is something very special and l'm sorry to have led you up the garden path on this one Chris but at least you have now got the correct information even though it doesn't change what has to be done.

I think Jan with his access to such information when the need arises will be a much valued contributor to this board.

Good luck,

Nick

[Charles]

It's not just his access to information that makes Jan such a valued contributor, it's the extraordinary depth of his own experience and his helpfulness in sharing it in excellent English that has made him a key player in this association since the day it was set up. Long may he continue!

Many thanks Jan

Charles

[Charlie]

Pic from the LM brochure may help as it shows the bolts.

Charlie

[Chris Wood]

Hi - Thanks Charlie - Your picture shows a Fin keel I believe and is formed differently to the LM Bilge Keels, the subject of this thread. Attached please see some pics from my personal experience, which will now require further history!

The full keel picture shows bolts with GRP still attached where it pulled away from the hull. The single bolt has extra square washers just added to aid lifting in the yard. The final picture shows a forward bolt in the foreground and the bent paired bolt / Studs aft. (we now know the two Studs are formed by casting in a threaded U bolt, which is why they are impossible to remove in the conventional way).

To put this disaster into context, she sank (unattended) on a shallow, tidal, swinging mooring on a stormy night following a faulty heads siphoning water in. The tide went out & lowered from 5 + metres to 1 metre. She should have settled happily onto her bilges but the weight of water in the hull, (now largely unsupported) caused the port keel to sink into softer ground and fracture. Subsequent tide cycles covered the boat and then emptied through the fractured hull. She was recovered after 4 days. She is now the subject of a full and very expensive (but largely insured) rebuild. - We (ie specialist yard) will overcome the bent bolt issue by trimming the existing studs flush, and having new conventional threaded bar drilled and tapped adjacent to the old positions. The Port Keel stub has been rebuilt and the Starboard side strengthened. New holes will be cut to accomodate the new bolt positions. I am personally doing much of the revarnishing and I have a garage, shed and spare room scattered with 'boat bits'. I hope that the summer will see her back in commission, with new electrics, engine and upholstery together with newly fitted keels!

I have learned a lot in this process so I hope that some of my experience will be of use to future LM forum members!

Regards & Thanks,

Chris