Keel movement on 2003 Bavaria 38

[kenwood1957]

Hi all. I have a 2003 38 with deep lead keel. Every lift out I receive report of either a "loose" or "moving" keel.

Have obviously had structure examined and keel bolts etc - all apparently fine. The leading and trailing edges of the keel allow for some flexing of the hull :'fore and aft' but, yet again at recent lift, both fore and aft and lateral (side to side) movement reported "beyond the usual".

Trying to secure a perspective from Bavaria (via Clipper Marine) and will have surveyed again.

Can I ask if anyone has any experience or insight please.

With thanks in anticipation.

[Symphony]

Has the sealant broken between the keel and the hull? If not then the keel is unlikely to be moving relevant to the hull. If it has then the first step is to take the weight off the keel and rake all the old sealant out, clean and reseal - sort of half way house to dropping the keel. When the sealant has ser, lower the boat to compress the sealant and check the nuts on the keel studs are tight. This should prevent water from getting in and possibly causing corrosion of the studs. If there is still movement then it is flexibility of the support  structure that needs investigating.

[kenwood1957]

Thanks for this response.  Will take your advice but my principal question is whether or not movement of the keel is typical and, if so, to what extent. Thanks again

[Symphony]

some flexing of the hull with the deep lead keel is not uncommon. However the real concern is whether the sealant is breaking away to the extent that the keel is moving relevant to the hull and possibly letting water get at the studs which can lead to crevice corrosion. The later type of movement could be caused by the former, so the joint needs to be checked regularly.

[kenwood1957]

Thank you again - very helpful.

[aquapore]

I raised this question recently on the forum when I got a minuscule amount of sea water coming through the keel bolts = about 50 mls a week.
The issue start after hitting a submerged rock.
At the time I had a diver look at the keel and reported nothing to see.
The advice from this forum was to have the boat raised and check it out with a surveyor which I did through the insurance Co.
When the boat was raised and still wet there were bubbles coming between the hull and keel seal showing a detachment.
The insurance Co organised a repair which consisted of:
Dropping the keel
Scraping of old and resealing.

This has be done while the boat is suspended. The keel is  removed (and also the mast as the boat would otherwise turn over).
The new sealant is applied - There is a Bavaria prescribed material for the sealing - its a filled epoxy I believe.
The keel is attached and the bolts torqued to 50% of their final value.
After the epoxy sets the bolts are then torqued up to their full tension.
The work cannot be done while there is weight on the keel.

This is not a small job. The value of the work was $16,000.

It reason why so much attention was given to this apparently  trivial leak is to protect the stainless steel bolts from crevice corrosion.

I hope this help. My boat is a 2003 Bavaria 41

Regards


Aquapore

[kenwood1957]

Thank you for this helpful contribution.

Are you aware of there having been any keel movement and hull flexing before your incident?

Bob

[Imagine]

This can't be normal,I have a 2002 36 and have done nearly 90 thousand miles and have defiantly no movement

[Symphony]

This can't be normal,I have a 2002 36 and have done nearly 90 thousand miles and have defiantly no movement

The boat in the original post is different from yours and has a deep lead keel. It is not unusual for such keels to show some movement and flex in the hull, particularly aft of the keel. This applies to other similar keels on other boats as well as some Bavaria models.

There is no follow up so we don't know whether there were any signs of real damage that might have come from a grounding or collision.

[Sen Mora]

Is your keel bolt attachment similar to the attached picture (B41 late 2003)? The washers under the keel bolt nuts are way too small to spread the load adequately to counterbalance the bending transmitted by keel bolts. I believe that this arrangement was modified by Bavaria in later models.

[Craig]

Fin keels in Bavarias are fitted in a similar way to Beneteaus, Jeanneau and almost all other modern boats. Any boat that has suffered a grounding can have keel problems.

The problem with flexing is that it causes delamination. Keels falling off because of corrosion of keel bolts is very rare. It is more common for the keel and the bolts to pull out of the glass, often ripping large sections of glass out.

I recommend you look at the annex to the Cheeki Rafiti accident report. The big problem is identifying delamination. This can only be done using ultrasound while the boat is suspended in a sling with the keel off the ground. The scary part is that different repairers have totally different views on how to identify damage and how to rectify it.

Any flexing seems to indicate a problem requiring rectification, not just resealing to stop water penetration. Retightening the bolts may mrely compress the delamination and obscure the problem, and definitely won't fix it. The problem with delamination is that the keel may come off suddenly.

Craig
"Shirley Valentine"
Gold Coast
Australia

[Symphony]

The boat in the original post is built in a different way to Cheeki Rafiki and there is little in the report of its loss that is directly relevant apart from the general advice that keels and structures should be checked closely after a grounding.

[Sen Mora]

Here is a link discussing keel attachement issues of B's of similar vintage following the incident of 2005.

https://www.boatdesign.net/threads/bavaria-match-42-lost-its-keel.7362/page-4#post-56145

The 6th comment on page 4(among others) addresses well the problem with small washers under the keel bolt nuts.

[Symphony]

Here is a link discussing keel attachement issues of B's of similar vintage following the incident of 2005.

https://www.boatdesign.net/threads/bavaria-match-42-lost-its-keel.7362/page-4#post-56145

The 6th comment on page 4(among others) addresses well the problem with small washers under the keel bolt nuts.

The design of the Match series is very different from the Cruiser Bavarias and the comments about that incident are not relevant to the J&J design boats of the period.

All the Match series boats were subsequently modified to improve the keel attachment. No modifications were required to the Cruiser series boats.

[Sen Mora]

Symphony, the point I was trying to make is that small washers as shown on the picture I posted before are far from optimal. It does not matter what model or make it is, it may be sailed without a hitch for long time but it may cause gradually worsening local flexing and detachment of the glued inner grid or even worse due to extreme loads. It would take very small angular flexing of fiberglass in the area of the washers to correspond to a visible lateral movement of the bottom of the keel. Much larger washers would be able to spread the load and reduce any flexing and reduce the shear load on the hull bottom.