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Keel Bolts and General Topics on Keel - Keel has a separate section at the bottom? Swan 48, Hull #02
21 April 2023 - 17:16
Join Date: 18 April 2023
Posts: 3

Keel has a separate section at the bottom? Swan 48, Hull #02

The leading edge of the keel of my 1972 Swan 48 made contact with the sea floor, and it revealed a surprising structure at the bottom of the keel that I’m quite curious about. It looks like there is a separate bottom section to the keel, possibly made from a different metal? Is this original? Has the keel been extended somehow? Extra weight added? Or is this an old repair from a previous grounding? There is a wound on the very bottom of the bottom piece that has rust in it. Could this piece have been attached with some internal iron structures or something, that’s been exposed due to the grounding, and is now rusting away? If anyone knows anything about what this might be, I would be very happy to hear about it.

Thank you very much!

Side view. You can see the extent of the damage at the leading, bottom edge of the keel

Starboard side, close up

Extreme close up of underside, looking straight into wound. Rusty water dripping. bottom

22 April 2023 - 05:32
Join Date: 29 January 2007
Posts: 1024

Dear August,

happy nothing serious happened after touching ground. Trailing and leading edges have a stainless fairing when built, is that you are talking about? Is draft correct (7' 6") or extended?

matteo (47/069 Vanessa)

22 April 2023 - 15:21
Join Date: 05 August 2010
Posts: 162

Dear August,

nice to hear you're still on Isbjorn!

I'll attach a picture of the keel after we took our grounding and opened the covering laminate to check the keel joint. You can see that all three edges of the keel have a (stainless) steel protection around the relatively soft lead. I believe what you see is part of that protection; if it does not go further up the front edge, the yard may have changed the design -- the pic has been taken on hull #039.

There shouldn't be any significant amount of rust on stainless steel, but if I correctly interpret the marine growth on the damaged part, water has had some time to gain entry into crevices where it is relatively stagnant -- and that can cause strange behavior in something called "stainless", as many owners of stainless steel anchor chains will confirm.
Anyway, the steel shoe is only there to protect the lead -- so my strategy would be to clean, cover, and relax.

Best regards,
Martin (Vellamo, 48/039)

Keel, port side, laid open

01 June 2023 - 08:55
Join Date: 18 April 2023
Posts: 3

Dear Matteo!

Thank you so much for your answer. I was not aware of this stainless steel fairing, and I belive that is what it must be, yes. Quite relieved! The draft does not seem to be extended, so 7'10'' should be correct, I think? 

Thanks again!

- August

01 June 2023 - 08:58
Join Date: 29 January 2007
Posts: 1024

That's OK dear August!


matteo (47/069 Vanessa)

01 June 2023 - 09:01
Join Date: 18 April 2023
Posts: 3

Dear Martin!

Thanks you so much for your in-depth and detailed answer! Very interesting. I was not aware of this construction, and I am now convinced that this is indeed what must be visible on my keel. That excellent photo makes it very easy to see. I will take your advice to clean, cover and relax ;)

I have seen my fair share of rust on stainless steel on the boat where metal has been glassed in or covered up -  so that might very well be what is going on here. I will probably get the hull sand blasted this winter, and that will make for an excellent opportunity to do some more reasarch into it.

Thanks again! :)

All the best

- August

01 June 2023 - 09:07
Join Date: 29 January 2007
Posts: 1024

Dear August,

after sandblasting I would not glass over the keel (not original).


04 June 2023 - 13:39
Join Date: 19 December 2019
Posts: 26

Hi August,

Nothing significant to add following Matteo and Martins' posts

S&S / Nautor referred to it as a 'docking keel'. It's function is as stated in previous posts - to protect the soft lead, but also served to support the lower bearing of the trim tab.

See attached detail on the keel for the Swan 48.  

If you tap-test the keel, you will notice a change in tone where the trim tab was originally designed. This is a fairing piece. If you had a trim tab or not, the piece is not lead.  Because of this, I would be careful of chocks or wedges on the aft end of the keel when ashore. Last pic of another 48 - visible outline of fairing piece.

Also a pic of our 43, trim tab lower bearing and stainless 'docking keel'.

Thank you,



#2079 - Swan 48 Detail on keel

#1973 - Swan 43 - Docking keel

Swan 48 - rough outline of fairing piece

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