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Keel Bolts and General Topics on Keel - Mast step protection from corrosion
16 July 2023 - 21:39
Join Date: 01 December 2019
Posts: 27

Mast step protection from corrosion


I am noticing some corrosion (rust) on the bottom part of the mast step on my Swan 47. The glassed protective layer has cracked at places.

I've read through the previous threads and there is a lot of info on refurbishing it.

Short of taking it out and rebuilding. Can I protect it by paining it? 

Is the original galvanized steel? If so, can I use epoxy based paint, oil based anti rust (Rust-Oleum 7769) and enamel or something else? 

Any guidance on how to treat and protect rusty parts would be great!


Typon , S&S Swan 47

17 July 2023 - 09:06
Join Date: 29 January 2007
Posts: 1031

Hi Peter,

could you please post or send me via private message some photos? Originally there is no glass protection.

There is a complete document on how to rebuilt it on classicswan (technical papers).

Looking forward to seein the photos.

All best,

matteo (47/069 Vanessa)

14 August 2023 - 04:14
Join Date: 01 December 2019
Posts: 27

Hi all,

Just a quick update.

I removed as much rust as I could and painted the mast step with cold galvanizing paint. 

Looks much better. Hope it stops or at least slows down rusting.



27 October 2023 - 15:40
Join Date: 25 July 2008
Posts: 30

Dear Peter,

I am happy you started a new post, Rumtrader is a S&S 47 MKII and I have looked at this maststep corrosion for the last 14 years with scare.  From above it always looked OK but below and behind there was big coroded metal pieces (see picture 1).

So this year I decided to take this issue while RUMTRADER was in Belgium close to my home.  I removed the mast for the third time and decided to restaure the mast step. 

The good new is that on my 47 the mast step was easy to remove.  The metal thickness was so reduced that some keel bold could be unscrewed by hand. We have now sent the piece to make a perfect copy in steel and it will be galvanized.  The man doing this has done the exact same work for Seastar a S&S 41.  The experience showed that before galvanizing the steel you need to see if it fits, nothing being totally strait.  Keel bold must fit perfectly in the holes.

Looking at this picture I am so relieved to have started this worlk.

I will keep you poste of the different stage of this work and on the mast corrosion issues too.

Question: what would be the correct name for this steel beam, for me the mast step is only the piece above.  This steel beam realy hold the boat together making the junction between keel bolts and the hull.  Could we call it the boat steel frame?


Your advise most welcome.

Ludovic from RUMTRADER (S&S 47 - 59)

Coroded steel in the bottom of the mast step

Once the mast step is removed you can see what is below

Corosion has eaten all the original steel

27 October 2023 - 15:54
Join Date: 25 July 2008
Posts: 30

Folowing my first message we have also remove the steel hook that is at the rear of the steel boat frame in our bilge. 

I will not remake the hook but only the plate to hold the keel bolts.

Ounce all this corrosion is removed we can admire the quality of the hull and the beauty of the bolts.

More picture in the future.


Bilge hook and plate

after removing the frame and before cleaning

after cleaning and removing both the frame and the hook, picture specially for Matteo

27 October 2023 - 17:09
Join Date: 29 January 2007
Posts: 1031

Cher Ludovic,

me and Lars exchanged maybe hundreds of messages on this matter over the last 20 years, and he has always referred to it as "mast step", but "steel beam" of course is correct too.

Would love to receive a photographic documentation, in high definition, of the magnificent job you did on Rumtrader!



Fair winds!

matteo (47/069 Vanessa)

29 October 2023 - 16:45
Join Date: 31 January 2007
Posts: 52

Dear Ludovic,

Lars used to call the piece above the mast step "mast shoe".

Best regards,

Jyrki (38/014 Infant)

05 November 2023 - 04:47
Join Date: 27 October 2013
Posts: 60

Hi Ludovic,

Thank you for sharing some photos of the mast step operation.

We are many that would love to see more pictures if possible.

I will have to do the same operation on Mallemuk (47/045) at some point.

And pictures would help a lot to explain to the yard what the works imply.

If not posting them here you could maybe send them directly to me?

Thank you very much

Niels Bjorn : S/Y Mallemuk 47/045

13 November 2023 - 17:55
Join Date: 01 December 2019
Posts: 27

Thank you for sharing all this info!

Was the metal on the bottom exposed when you started - or was that brown (epoxy?) material still covering the flatt bottom parts?

For me the bottom of the metal is covered by that brown material - so I am hoping that it is protected from water - but not 100% sure.

How will you protect this in the future, will you put en epoxy layer on top of the keel bolts once completed?


27 January 2024 - 19:16
Join Date: 29 July 2012
Posts: 4

Hello fellows of suffering in love with swans!

I haven´t participated in the very interesting posts on the major issues of swan ageing. I confess innate reluctance about disclosing any plastic surgery having to be done on those I love, whether my wife or my boat. However, I feel indebted to this community, having so far only consumed your valuable experiences on such sensitive subjects as hidden cracks, loose screws and rust on your beauties and will share some of my problems.

The mast step or back bone of swans lasts amazingly long for them having been built of galvanized steel and being subjected to constant salty moisture in the bilge, which will always "eat" the galvanic coating with time. Therefore, on one hand we might not consider the original drains out of the mast and from the anchor bin past this steel frame to be the perfect construction we like to expect from our Swans. On the other hand, it has proven to last 50 year plus. Now however many more of us will be addressing this problem. 

As far as I oversee the posts these mast step beams have been repaired by cutting out decay and bolting in reinforcements, they have been completely remade again in galvanized steel and there is some discussion about reconstruction in composite or stainless. Our cherished professor suggested not 316 stainless, but 2205 duplex, without however reasoning why. One can suppose due to the higher risk of fatigue and crevice corrosion of 316 and stagnant salt water corrosion. I haven´t found titanium discussed as an option. One might want to consider expenses, but in view of the small share of costs generated from material against workmanship, the choice of material would seem negligible and would there not be an argument for choosing the most long-lasting material?

Personally, I am in the decision process of remaking a new mast step beam in stainless. Overengineering 316 stainless has been suggested to me. So far, no metal workshop has warmed to produce the piece in 2205 duplex or titanium, but I have just started my search. I would very much appreciate opinions and comments from the community.

Good luck for the new year!

Alberto (Sirona S&S 48 #3 1972)

original stat of mast foot after 50years

bed after removal of mast foot and lifting steel eye, blank keel bolts in good condition

27 January 2024 - 19:22
Join Date: 29 July 2012
Posts: 4

corroded mast step beam and lift ring

28 January 2024 - 18:51
Join Date: 29 January 2007
Posts: 1031

Dear Alberto,

thank you very much for sharing info and photographs of you Mast Step refitting project!

Actually Lars did not like stainless steel because he thought welding steel, which requires much more temperature than welding 2205, could not keep the perfect drafted/cutted measurments after welding.

I have to say that over the years we helped many S&S Swan owners who did a new mast step in stainless steel, and all mast steps have been perfectly drafted/cutted/welded/installed.

You are right, we never discussed titanium, and that could be a good option!

Hope to receive more info and images during the refitting job!

All best,

matteo (47/069 Vanessa)

22 March 2024 - 19:59
Join Date: 25 July 2008
Posts: 30

Dear Peter,

Hello Swan friends,

The picture of Rumtrader mast step shows that corrosion had eaten the whole steel. This was much worse that what I expected.  As this mast step is compressed by the mast and hold the keel we could have been in deep trouble in hard conditions.

A new piece was made in steel following Lars recommendation (see picture).  This new  mast step must be adjusted in-situ before being galvanized.  Nothing is perfectly straight on the hull and we wanted to have the most adjusted mast step.  Any modification after galvanisation would have weaken the corrosion resistance.

We then installed the mast step (a second time) on epoxy to avoid any water being trapped between the mast step and the hull.  

The good news is that on RUMTRADER it was pure mecanical work, the mast step can be removed by just removing bolts.

Plate were also replaced in the bilge and below the fresh water tank.

I feel a very big relief and think this has saved the hull for the next 50 years.  My advise: do not hesitate this is just to important.

The work was performed in Belgium and the yard had already changed the mast step of Seastar (Swan 41)

Ludovic for RUMTRADER S&S 47


Old mast step completely corroded

New mast step

New mast step

22 March 2024 - 20:03
Join Date: 25 July 2008
Posts: 30

This is other photos

29 April 2024 - 06:05
Join Date: 01 December 2019
Posts: 27



Thank you for sharing all this valuable information!

Solid result. I am keeping an eye on my mast step to evaluate it.



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