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| Keel Bolts and General Topics on Keel - Swan 57 - large vertical keel crack at trailing edge |
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Join Date: 20 July 2017
Posts: 148 |
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Swan 57 - large vertical keel crack at trailing edge Good evening!
Some worrying news for Kairos today, I'm afraid ... out boatyard was taking Kairos out of Winter storage today and noticed a large crack at the top end of the keel's trailing edge when lifting - photos below.
The crack is very deep - around 100mm straight into amidships, you can see a steel ruler being used on one of the photos. Nothing noteable from the inside but the crack is possibly to low for the bilge level, and also there would be tanks etc. in the way.
Almost looks like the keel is delaminating into two halfs ...?
This crack was reportably not visible while Kairos was in storage as the view was obscured by the storage supports.
It's early days and we've got a surveyor coming later in the week but as the hull was cleaned when Kairos got winterised I would think this crack would have been noticed if it would have been already there then. It therefore looks like the crack may have developed over Winter.
We had no groundings last season so are a little bit at a loss what happened, hopefully the surveyor will have some ideas.
If anyone has seen something like this before or has an idea we would very much love to hear from you - thank you!
Fair winds,
Stefan
SY Kairos (57/043)
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Join Date: 29 January 2007
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Dear Stefan,  |
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Join Date: 20 July 2017
Posts: 148 |
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Dear Matteo Thank you so much for your lightning fast response and the drawing! Will definitely keep you posted! Fair winds, Stefan SY Kairos (57/043) |
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Join Date: 20 July 2017
Posts: 148 |
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Dear all, by way of an update - the surveyor had a look at Kairos yesterday. The full written report will take a little longer but the verbal feedback is that the area in question - the kind of 'triangle' between the after part of the keel and the hull - was apparently manufatured in two halfs. These appear to then have been glued/epoxied together but the trailing edge where both halfs meet was apparently not laminated over. They checked the position of the keel and keel bolts, and also for any movement between the keel and the hull when sitting on the keel vs. in the travel lift/keel hanging. There was no movement observed, and nothing hints that there ever was any movement between the keel and the hull, which is of course great news. So the verdict for now is that the crack/delamination that appeared between the two halfs of the 'triangle' is solely due to aging of the material/epoxy. Certainly excusable as it did last 43 years... The repair approach will be to mechanically open up one side of the 'triangle' to find out how far the delamination goes, and then rebuilt the removed side to again have a solid structure. In a nutshell - while the repair will take some time due to the current workload of our boat yard, as far as we know the 'triangle' area is not structural and the damage therefore appears to be nowhere near as bad as we initially feared. Panic over! Thanks again to Matteo, the drawing was extremely helpful indeed! I will try to see if we can obtain some photos of the repair and post them here; in the meantime, if anyone would have any comments or similar experience we would love to hear those! Fair winds, Stefan |
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Join Date: 20 July 2017
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Good evening! We now have had the initial report from the surveyor, and I have managed to visit Kairos for two days last week. A little sad to see her on the dry with all the other boats floating but we will get there... The surveyor did a very through job by the looks of it and also inspected the inside of hull. As mentioned before, there is no movement of the keel relative to the hull but on one of the support beams below the main bulkhead in the salon a hairline crack was found. This hairline crack opens to approximately 1mm width when Kairos is in the cradle/resting on the keel and opens to when in the travel lift. So exactly the oposite behaviour what the crack in the keel does, which opens when being lifted and is closed when resting on the keel. I have posted some pictures of the support beam below - you can see that the area arouns the crack has been painted with different shade of bilge paint so this may have been 'repaired' before. Also, there seem to be another support beam rught forward of the bulkhead; only the after one has a crack. The two beams seem to have been bolted together - only at the top and not at the bottom of the bilge. Judging how this was done, the way too small washers used, and there are boilts only where it was easy to install, we believe this is not original and might have been part of the 'repair attempt'. We are currently not sure if these two cracks are related, and how they were caused. Both cracks are at the same position along the hull, though, and roughly where the rear support straps of the travel lift would be. Next steps is to take the after fuel tank out and investigate the crack in the support beam by opening it up as required ... then rebuild the beam ... Hopefully this should all be done within the next 5 weeks or so, fingers crossed. As always, any ideas are most welcome - thank you! Will keep you posted, fair winds Stefan SY Kairos (57/043)
 Location of support beam near main bulkhead  Close-up with crack closed  Close-up with crack opened |
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Join Date: 20 July 2017
Posts: 148 |
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Post to show the bolts that we think are not original. Sorry, not the best photo. There are around 5 ot 6 of these bolts.
Fair winds Stefan SY Kairos (57/043)  Bolts marked in red; crack in the centre; no damage to beam forward of the bulkhead |
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Join Date: 29 January 2007
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Dear Stefan, |
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Join Date: 27 October 2013
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To me (with the limited information I have) the crack in the center of the beam could be a result of a heavy grounding. A yacht, at high speed, hit a rock on the front of the keel would result in a very large vertical load on the aft cross members. This theory is supported by the observation that the crack opens when the yacht is on land and stands on the keel. However, I don’t know if the damaged beam is on the aft of the keel, where this effect would be largest.
Bjorn, Mallemuk 47/045 |
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Join Date: 20 July 2017
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Hi Bjorn, thank you - this may well have been the case. It's interesting that only the after beam of the 'double beam arrangement' was affected, not both, though. Either way, the crack must have already been there when we bought Kairos as evidenced by the existing 'repair attempts' (new bilge paint and through bolts). Our boatyard has now managed to empty and dismantle the after diesel tank, which provides more access and better visibility to the affected beam. Please see photos below - it appears that the crack has not propagated all the way through the beam but only the top 15-20 cm; it looks like it has also not extended past the patch with the new bilge paint over the years. I take this is as a good sign. The bolts that apparently were added afterwards to tie the forward and after beams toghether can also be seen better in the first picture below. Question is, should we retain the bolts after the repair, or remove them. I guess they won't do any harm since there are in but we will definitely swap the washers for much larger ones were possible. Next steps will be to grind open the crack back to sound material and rebuilt the beam back to original conditions. Same with the crack in the keel. I will update you as the news come in, we are currently still on schedule in terms of completion prior to the first trip for this season - fingers crossed it stays like this. Fair winds, Stefan SY Kairos (57/043)  Aft diesel tank removed - through-bolts in beam visible  Crack appears to have not extended past the patch where bilge paint was reapplied  Close-up of crack |
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Join Date: 20 July 2017
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Good evening! By way of an update, our boatyard has been busy over the last week and freed up the damaged sections. Some pictures below. They have also done some trial laminating and found that polyester resin provided better adhesion results than epoxy resin. So they will use polyester resin to laminate and top this up with a layer of epoxy resin at the end to give better protection against osmosis. Below here are some more pictures. Fair winds. Stefan SY Kairos (57/043)  Close-up crack in beam  Initial investigation - inside  Initial investigation - keel |
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Join Date: 20 July 2017
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Some more pictures below - no duplicates this time, I hope! It feels like a long week already! Stefan SY Kairos (57/043)    |
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Unfortunately, it appears that there is some water seeping out of the section on the keel that the boatyard is looking to laminate. They are trying to dry it with heaters etc but so far it has not stopped seeping. Obviously, they cannont laminate and rebuild the section properly when it is wet. The screws in the metal plates are also lose/rotate.
The boatyard don't know where the water is coming from; from what I can understand from the drawing Matteo posted is that this section appears to only be a tryangular 'fill-in section' between the after part of keel and the hull. No structural function, only hydrodynamics, I suppose. And it does not seem to be connected directly to the bilge nor the area where the keel bolts are (further forward) so I don't think the water is coming from these areas. It might have just entered in the crack if that was already present last season, maybe as a hairline crack, and is now slowly seeping out ...
Very frustrating as we were hoping to finally start the season at the end of the months but this is looking less likely by the day, with Kairos still on the dry, mast unstepped and some final engine maintenance still outstanding ... and it could be weeks if not months until this seeping stops.
It also seems that the section was repaired previously, but rather badly using filler rather than laminating, which may be part of the problem we have now.
We will discuss with our boatyard and surveyor if it is feasable to do a temprary repair now to rescue the remaining sailing season, and then repair/laminate this properly in the Winter. Plenty of time to dry out then ... Obviously only a potential option if the section is indeed not structural.
Well, onwards and upwards! All ideas/suggestions very welcome, as always!
Fair winds,
Stefan SY Kairos (57/043)
 Resin trials 1  Resin trials 2  Filler |
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Join Date: 20 July 2017
Posts: 148 |
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 More filler :-(  Water seepage  Close-up metal plate |
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Join Date: 29 January 2007
Posts: 1145 |
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Dear Stefan, |
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Join Date: 20 July 2017
Posts: 148 |
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Good morning, A quick update and to hopefully close the post ... Our boatyard managed to complete all the repairs in June woth virtually days left to get Kairos back in the water and step the mast before the next sailing trip was scheduled to start. Stress levels were high and the crew on tender hooks as flights etc were booked but it worked out in the end ... so we 'only'had to cancel tow trips this seasons. Just hope we can skip such issues in 2026 ... I will ask for some photos but in the end, the repair was relatively straigth forward, just rebuilding the layers of GRP to the same specs. Our boatyard found some older repairs witha lot of filler at the trailing edge, which probably contributed to the crack. This has now repaired properly with fibre matt laminated around the edge, which should prevent this in the future. The crack on the inside beam was re-laminated similarly, again this wasn't done properly in the past. Overall not a great start on the season, luckily we didn't have too big of a plan for 2025, but at least it's now fixed. Also gave us some time to install a new generator. Our insurer Pantaenius was very helpful indeed, too. While the repair itself was not covered by insurelance (as the exact root cause could not be established/was likely caused by an event prior to us owning Kairos) they appointed and paid for the surveyor as well as the work required to establish this.
Fair winds and thanks again for your support,
Stefan SY Kairos (57/043) |
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Join Date: 17 July 2020
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Happy to read that this was not structural like on Algol... Fair winds Kairos ! Yves (Algol 57-007) |
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