Keel problems on Outrageous S&S Swan 47/039

A diary of dark discovery
While getting Outrageous inspected for coding, cracks were noted at the forward and aft end of the keel/hull joint. Forward looked worse with a gap of 4-5mm while at the back the crack remained closed.  This was not dissimilar to pictures on this forum on other S&S Swans so, perhaps no reason to worry? The Surveyor also noted some signs of separation of the hull from the crossframes up to the first stringer from the main bulkhead back to the engine bay as well as a crack at the base of the main bulkhead forward of the mast and some flaking of antifoul just above the keel joint. Initially he put this down to an old collision which had only slowly manifested itself over time.  This was strange as Outrageous has been sailed hard in the last 6 years  while I have owned her but was in this time certainly never involved in a collision or grounding and the bulkhead and hull separation were not present during the survey upon purchase.

In order to be safe the surveyor recommended removal of the keel which one reputable boatyard associated with Swan scoffed at.  Nonetheles I went with the recommendation of the surveyor - fortunately as, on further Investigation the stub of the hull above the keel joint had cracked along almost the whole length of the keel; on one side right through the glassfibre -where the long steel plate had, over time, worked against the hull as the mast pumped  it! It seems the problem is  one of long years of hard use rather than a particular incident.  Part of the problem may be that these beautiful yachts can continue to carry large amounts of sail in high winds without complaint, something that has led us on more than one ocasion to push her pretty hard indeed!
The outcome is a visit by a naval architect to decide how best to effect the repair. A massive repair bill to be sure - how much is still being negotiated but nothing compared to what would have happened had the crack opened up at sea.
Thus a word of warning to those of you with Swan 47's or other S&S Swans with similar cracks at the front and rear of the keel joint. All may be fine. It may just be a "typical well-known" S&S Swan weakness. I truly hope so.  But please please look carefully. You may also have Outrageous cracks.  These might be evidenced by cracking or flaking antifoul. Also sounding along the hull with a small hammer will be a good sign of any related bonding failure.  Please do look carefully, Swan yachts surely look a lot better on the water than under it!
If you do have any concerns please feel free to contact me and i can tell you about the solution and outcome of the Outrageous repair!
Happy sailing
Mark Stevenson        mark.stevenson@bluewin.ch

I am sorry to learn of you problems - have you photographs of the damaged section so we can all learn?

Regards
David

Photos will be uploaded in a week or two. Whole hull base currently being ground out before being relaid. Water ingress into the cracks has severely weakened whole of area under mast step which all has to be replaced. Ouch!

I bought my 47 Grampus #17 in 1995. I observed a crack in the aft area of the joint of the lead keel. I am pretty sure that there was a position of Nautor on this topic, as I saw in a letter of the shipyard in reply to the previous owner. The reason of the unconvenient looked to me rather strange: if I remember well it was stated that the crack was due to different coefficients of thermal expansion of lead and fiberglass and suggested to fill the gap with silicone.
I have a different opinion, not so easygoing as from Nautor but, too, not so dramatic.

It would be good to know from the professor his opinion and, too, a search in
the Nautor archives.
It is important to see the pictures, too

Oops, Grampus is hull # 16....

Oops, Grampus is hull # 16....

The keel is now off and it is not a Pretty picture. Water ingress between the keel and hull, apparently over many years as well as the working of the whole hull stub area has led to severe delamination and weakening of the whole area. A sacrificial opaque glass fibre shell has been applied. All of the bad glass ground out and a new stub laid tapering up to the first stringer. The keel goes back on next week at which point all (except my bank balance) will be heading towards relaunch mid July. Pictures will be uploaded once received from the surveyor.

Dear Mark and dear Mateo,

Rumtrader (47,059) also show these cracks between the keel and the hull.  Following the recommendation of the different post on this forum I have just sealed the crack every year.  They seem to appear more and more quickly during the season.  Can you send me picture of the cracks and the way you solved the problem. 

Kind Regards,

Ludovic

Dear Mark and dear Mateo,

Sorry to hear about rumtrader. Am still trying to get pictures from surveyor. If you have a problem of the same severity you will probably observe stringers detaching from hull above stub. Tapping along the hull above the stringers when rumtrader out of the water will show very easily whether the separation has occurred or not. Am happy to talk further if necessary. You can contact me on mark.stevenson@bluewin.ch or on + 41793415037

Regards

Mark

I bought my 47 Grampus #17 in 1995. I observed a crack in the aft area of the joint of the lead keel. I am pretty sure that there was a position of Nautor on this topic, as I saw in a letter of the shipyard in reply to the previous owner. The reason of the unconvenient looked to me rather strange: if I remember well it was stated that the crack was due to different coefficients of thermal expansion of lead and fiberglass and suggested to fill the gap with silicone. I have a different opinion, not so easygoing as from Nautor but, too, not so dramatic. It would be good to know from the professor his opinion and, too, a search in the Nautor archives. It is important to see the pictures, too

I noticed last summer in case of relatively rough sea that the bilge pump was working too often.
I could exclude all other reasons of water intake with the exception of the two creeks at the level of the lead to hull junction fore and abaft, to which I was accustomed, helas.
Now the boat is ashore sustained on the hull and the keel hanging.
We deepened the two cracks until evidence of the lead and the Grp of the hull. The fore crack is no problem, dry,no leak. Abaft there was a lot of humidity. I filled with water the bilge, above the top level of the central bilge cage, until the fuel filters. There was evidence of water dripping. I eliminated everything of the sikalikely rotten mastic and it was evidenced that the is a gap of 5 two 8 mm in the aft area of the keel until around 10 cm of the last bolt aft.
When I bought the boat almost 20 years ago there was already a craze, but I did not suspect that there is such a big gap from hull to keel in that area.
We have not been able to screw the nuts of the last bolt and we will try again when the boat will stand on her keel.
Anyway we doubt of the result, because the crack stops before the bilge cage.
Shall I fill with a polyurethane or with a stripe of grp and mastic only on the exterior area?
Might it be possible that the lead keel, when cast, had not been faired horizontally and the gap was originally filled with sika?I doubt that the grp bottom went up. The craze is not continuing afore.
I am enclosing some pictures, sorry for the bad quality, anyway this will give an idea
thank you, Matteo, Grampus 47/016

Dear Matteo
It should be possible to close the crack permanently by tightening the aft keelbolts, but there must also be sound laminate, big enough washers, and proper floors in the area in order to make a permanent repair. I would be glad to assist but good photos from the inside are required, and it is suggested that you sound the area by tapping.
Very skilled repair worker available if you require help.
It is advisable to put beads of mastic around the bolts before putting the hull to rest on the keel, and then fill the slots around the bolts from the inside as described in the thread dated 04 Feb 2013. It also contains other useful information.
When the keel was installed originally wet mats were put between hull and keel, this fills out the voids in the connection and makes a tight fit, as the cured mats become part of the hull.
Kind regards
Lars

Dear Lars,
I am grateful to you for your competent advise, unfortunately I have not been able to follow completely your suggestions.
We have observed some things that are probably relevant:
1) It looks out as there is a bead of mastic between the hull and the keel only in an area from abaft until 10 cm afore the last bolt. In your post you describe properly the process of joining the keel to the hull as laying a fresh mat of fiberglass before lowering the hull to the keel. From this point it looks like there has already been an intervention from another shipyard.
2) observing the afterside keel of Sarabande there is a straight stainless steel angle relief which goes up until the junction of the keel. In my case there is another strip of rounded steel plate covering the fiberglass. This fact strengthens my opinion of a special manteinance made in the past. Unfortunately it might be difficult to trace in these days the previous owner.

We have emptied the crack until it was feasable, cleaning all the previous mastic and filled in the creek and around the bolt (in the area between hull and keel)until there was only fiberglass and lead.In the area afore of the picture there is no sign af crack, not even a light crazing on the antifouling. The adhesion in these areas, including the crazed fore edge of keel to hull looks perfect.
With the crack filled again with sika adhesive not yet cured the yard has tried to lift the keel by help of a jack. The jack was positioned just under the place of the bolt in question. Unfortunately the boat moved too much forward, so they had to stop. I believe that the force applied might have been roughly 10 tons.
With this pressure there was no sign of outspill of adhesive, nor any crack continuing afore of the worked area. Again, it was not possible to screw or unscrew the nut by a levered spanner, it was sticked. Unfortunately I did not check personally inside for small creeks, anyway the laminate sounds very compact. We will try again when in the water.

My opinion is that to do the complete job,it should be made as in the case of Sarabande, with the keel down with all the bolts. But, then we need to dismount at least the central tank and, probably, the mast.
I fear that this intervention might not be definitive, and I will have again to do a more radical work in future. I hope not, we will see.

. The pictures uploaded show a detail of the edge back with the steel plate, the area of the crack which has been filled with epoxy filler after 36 hours curing of the sikaflex. The third picture shows the area covered with a mat of fiberglass. We will continue with another larger fiberglass mat then epoxy resin and finally primer and antifouling.

I thank you very much for your advice, it is possible that in this shipyard the workers are not very skilled. I will refer in future, hoping this might help the other owners facing with similar problems.
Best regards,
Matteo, Grampus 47/016

Dear Matteo
Thank you for the observations and photos.
Two comments:
-The stainless pieces along the trailing edge of the keel originally ended at the top of lead level. It is likely that there has been extensive repair work in this area.
-If the keel bolt nut can not be moved the threads have galled (frozen). It is suggested to first try thread penetrant like WD-40, and force the nut alternatingly in both directions close/open. If this does not help, heating the nut may be tried, but the laminate should not exceed 60 deg C. The last remedy is to split the nut.
The threads need to be cleaned with the correct size thread die before a new nut is put on. As far as I know the thread is 1 inch, but it may be either UNC or UNF. It is recommended to use nuts of another stainless material, for example AISI 329 if you can find those, this reduces the risk of galling.
Kind regards
Lars

Dear Lars,
tank you as always for your wise suggestions and indications.
I agree that the rounded plate on the reverse elbow at the exit of the keel must have been added to reduce the stress in that area on the laminate

Best regards,
Matteo, Grampus 47/016