Bavaria Keel Bolt Torque settings?? Help?!

No, he is not a moron. I don't recall any torque settings for keel bolts in the manual.

I seem to recall from my long ago studies that there is a table for calculating torque settings from the size of the bolt, but in practical terms it is not critical. Normally it would be done in two stages. First tight enough to squirt some sealer out and then hardened up once the sealer has set to compress the seal.

If, off course you have just had one off to check then the keel will still be tight so you only have to harden up as far as it will go.
 
Thanks for that,

You are indeed correct torque settings are based on the material gauge and thread. I too recall some dim and distant tables for calculation.

Over tightening can stretch or fatigue on keel bolts bolts and in some cases cause damage to material between the hull and keel.

The Keel was dropped and re-bedded last October and I have noticed recently that over half of the "locking" nuts are loose and in consequence want to correctly tighten the base nuts.

Is there a manual for this boat? The owners manual is virtually bereft of useful information.

Cheers,

GB
 
Yes, it is the owners manual I was referring to.

I would not worry about stretch - I think they are 22 or 25mm and it is unlikely that you could ever put enough torque manually on them to stretch. My concern would be more about slackening off. I would be tempted to just take off the lock nuts and harden up the main nuts if you can. Last time I did keel nuts they were 20mm and I used a tommy bar and a length of scaffold pole about 2 feet long and leaned on it. Been there for 12 years now!

Worth checking the hull keel joint externally for any signs of movement.
 
I would suggest that the keel bolts on any boat are grossly oversized not so much for strength or resistance to fatigue but rather for long life in the face of corrosion. That means that torque is not so much about the bolt as more about the structure that is being pulled together.
So as suggested provided the keel is close enough to the hull and the bolts are tight enough to stop any movement you really don't have any worries.

By comparison the torque of the bolts on a cylinder head on your diesel engine are critical. Here the bolts are relatively thin for the loads. They are expected to remain corrosion free through their life so fatigue failure is the biggest concern. The bolts are stretched to a degree so that fatigue causing pulses of stress only vary the amount of stretch. This gives great resistance to fatigue. Of course the amount of stretch is critical too much will damage the bolt while too little means it can fail from fatigue. Note in this case it is all about the life of the bolt. It is assumed the cylinder head and block are very strong and simply press together with no concern about how tight the joint is. (assuming it will always be tight enough).

So bolt torque is not always critical. olewill
 
You must log in or register to reply here.

Share this page

Top