Keel Bolt nut diameter

I wish to replace the nuts and backing plates on the keel bolt of my 1090.

Does anyone know the diameter of the thread, I am guessing it is M16 ... but I am not certain.

I plan to replace all the backing plates and pads with 316 Stainless, as there is some rust. I think the bolts are OK, but the backing pads need replacement.

Bonjour,

here below message in French version.

Je voudrais remplacer les écrous et contre plaques des boulons de quille de mon 1090

Quelqun connaitrait-il le diamètre du filet ? je pense que c'est du M16... mais je n'en suis pas certain.

Je prévois de remplacer toutes les contre plaques et rondelles en inox 316 car il y a de la rouille.
Je pense que les boulons sont OK mais plaques et rondelles doivent être remplacées.

Hello,
part of the answer is in this drawing:
clubfeeling1090.fr/images/Doctech/bateau...goujonslestplomb.pdf
However, be careful: I suspect the keel bolts being different according to the building year.
Let us know when you measure them. Thanks.

OK, I will have to make another visit to the boat in 2 weeks and measure them.

I fact is certain: they are not INOX, it is a 1987 boat, so maybe it is before they started to use INOX?

I will measure them and report back.

So, they are M22, with a 70mm x 6mm backing plate.

The nuts on Encyte are really bad ... I am replacing with 316 Stainless.

And finally, the diagram shows the bolts are stainless (Inox) 22mm ... on our boat (Number 8 in the series!) the bolts are not inox, they are normal steel for the deep keel (iron keel).

Infact, one could not use Inox in the cast iron, it would be galvanic. I did more research, and using a stainless nut and washer on the carbon steel bolt would be very bad, the corrosion would be on the bolt, which is a bad reaction.

The correct nut and washer to use on the steel bolt is galvanised. M22 square plate is very hard to find galvanised, we found M24 only ... so we will use that, with an additional washer on top.

And the work continues ... the plates are very bad, but the M22 rod is in good condition.

The rods in good condition

thanks alot for all pictures.
But (there is always a but ) I have a question, can you describe us how you remove nuts?
Have a nice day!

I used a "torque muliplier" ... you turn the handle 65 revolution, the nut turn 1 revolution.

They are cheap on eBay : www.ebay.co.uk/itm/2pc-Heavy-Duty-Torque...wUKxYjGu7:rk:14:pf:0

Be careful when putting back the nuts ... the device is very powerful!

And of course, you should not remove all the nuts at the same time, 2 or 3 at the same time, maximum!

Hello Robin,
you make a very good point, about the dangerous mix Stainless / Carbon steel.
I believe I will replace the stainless bolts with galvanized on my boat.
Many thanks !

And, it is done!

I noticed some rust protruding from the paint on the aft keelbolt, so I decided to remove the paint and inspect it.
It looks like the backing plate is 70x70 and the bolt is M22. The bolt and the nut is galvanized, the backing plate is not magnetic so it has to be A2/A4. The other keelbolts on the boat looks fine and on the other ones the backing plate is galvanized…

I guess sometime in history someone has changed the nut and the backing plate and used a stainless backing plate. The paint is the original one, so I am not quite sure.

So for the question:

Do you think it is possible to split the nut with a Dremel and install a new galvanized backing plate and nut while the boat is at sea?

How much torque is recommended for the nut?

 

I read in the article “dequillage” that the studs on the 1090 are cast into the keel (neither threaded nor bolt pockets). Can someone confirm that it is not possible to withdraw the studs?

ps! On my 1090 the keel is made of iron, not lead. Maybe the boat in the article has a lead keel?

clubfeeling1090.fr/coque/dequillage