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Mast step subsidence Nauticat 33

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    I recently purchased a Nauticat 33 with a known problem (which was reflected in the price). Boat age = 1979). The problem is that the mast step has subsidence – the coach roof has depressed about 25 mm in and around the mast base. This causes rainwater to pool around the mast base. Internally it looks like the king post (Heads corner timber) has descended about 10 mm. This has been made possible as the king post is not completely keel stepped. Does anyone have experience of this problem at all. I would be grateful for any information you may have on the subject. Peripheral problems include sticking cabin door, rain water ingress and less secure mast. Many thanks. Andy – Poole


    Hi Andy, I have a 1981 Mk2 N33. I had her re-rigged in 2014. The riggers reported a similar problem to yours. I discussed this with ‘Navigators’ based at Chichester Marina. They advised that there was not an immediate risk. The door to the heads is fine the sliding door is a bit stiff, but no other problems. Navigators advised vigilance without action. It does not appear to have developed since. I have not noticed and pools of water at the base of the mast as you describe. When I go down to the boat again in a few weeks I will have a look for what is being compressed and check the pooling.

    I do not seem to have any leaks.

    Best Wishes Pete (Miss Rosie)

    Keith Lewin


    I had a similar problem that was resolved last winter by Ardfern Boatyard in Scotland. The easiest way is to copy their subsequent findings.
    We have been looking further into how to go about repairs to Lady of Hartys coachroof. It isn’t a straightforward fix I’m afraid. We took a core sample and there is no delamination of the deck. We rigged up a lift to the coachroof to make sure that we could reinstate the shape. That was ok. Down below we were investigating the possibility of fitting in an additional fore and aft beam to stiffen and support the deck. We took off the trim on the bulkhead just forward of the mast step and found the bulkhead timber to be soft. Photograph attached. This position would explain why the coachroof area immediately forward of the mast step was depressed. The way the interior has been put together complicates the repair as to access requires removal of the sliding door which requires removal of a panel in the heads etc etc. It is impossible to estimate the cost at the moment as we are finding out what needs opened up as we go along. Only once we have done this and seen what is required to reinforce and repair could we supply a price. I would suspect however that the joinery work will be a large part of the cost. If you could get back to me and let me know how you wish us to proceed and if you have any questions, please get in touch.

    I will send you a couple of pictures to your email and can send some of the completed work after they scarfed in a new piece of beam. Let me know if you require them or if I can be of further help.

    Kind Regards,
    Keith Lewin, Lady of Harty (1978, Hull 570).



    Many thanks for your reply – it is much appreciated. I hope I have not taken up to much of your time today.

    Your experience sounds very familiar to my MK2.

    I just suspect that my boat may be a little more ‘far gone’ than you describe and having discussed it with ‘Navigators’ at Chichester marina.

    Hence I think I may have to take action pretty soon.

    I am more than prepared to go fully ‘professional’ so to speak. This goes against the grain as I usually put my hand to most things on a boat.

    However besides this, I feel its important to try to fully understand what has gone wrong here so I am better able to guide the professionals with repairs.

    So the questions that pop up are typically -Why the depression? Is the coach roof a balsa sandwich which has rotted inside? Is the King post base support a weakness on these otherwise very strong boats?

    All-in-all I think I am heading for a ‘learning ‘ experience, and I will for sure pass on my knowledge back to the forum.





    Many thanks for your reply. I hope I have not taken too much of your time today.

    Your description sounds very familiar indeed. I read your mail with great interest.

    I think I have 2 problems. The first is that I must clearly act fairly quickly to get stuck into the necessary repairs to resolve this depression. I am more than prepared to go’professional’ boat repair on this one, even though its going to be £££s. I normally go about the whole range of repairs on boats myself, but on this occasion I feel I will need to go to the professionals.

    But the second problem is that I need to try to understand why this has happened and what has caused it. Is it the weakness of the king post base? Is it the weakness of the coach roof ? e.g. internal rotting.
    etc. Is it a weakness of the King post assembly? I am still puzzled about large amount of rainwater that is permeating through the upper/outer corners of both sides of the cabin i.e. above galley and above dining area. Its very coincidental, is this related to the depression?

    I have been tipped off that the coach roof is not a balsa sandwich and hence its inners could not have rotted.

    Certainly I would by most grateful is you could send any related photos …

    regards and many thanks indeed


    Poole Yacht Club, Dorset


    I have just had this problem sorted on my 1979 Nauticat 33 Mk11. Over a number of years water had been leaking through the deck glands for all the mainmast electrics, radio gps etc. the water ran down the cables and through the main thwartships beam just above the sliding door. The beam was rotten and so the mast step and surrounding deck area had subsided. Head lining removed along with adjacent panels and bulkhead to get access to replace main beam. Not noticed earlier through various surveys as the headlining hid the destruction that was taking place. Costly repair but only solution £2.5 K. King post not damaged but main beam was almost non existant.

    Hope that helps
    Kind regards
    George Crowe



    Many thanks for that. This sounds ‘near identical’ to my current 1979 Mk 11 problem. This certainly does help me !! I will refer to your experience closely when I further dig into the affected area to find the root cause.

    Its a pretty nasty problem and looks a bit costly too. However I am over whelmed by the helpful and generous feedback I am getting from the association. As a result I no longer feel so worried about tackling it.



    Poole Yacht Club


    I bought my 1976 NC34 mk1 ZARZUELA some 21 years ago. On taking delivery I noticed that the stays were slack, fore cabin door hard to shut and an obvious sag in the lintel. None of these problems had been mentioned by the surveyor who had passed the rigging as sound.

    On lifting the deck around the mast step we were horrified to find that the cross beams were spongy due to being soaked for years because the deck air vents had never been opened to allow any moisture to dry out. Subsequently I only shut the vents when going to sea and re-open them whenever in a berth.


    I have a 1981 NC33 which appears to have been supplied part complete from stilata to a yard in Holland. Boat was completed in 1995 to Nauticat Drawings which are still on board. Previous owner bought boat in Holland and survey showed deck sag at mast step 8mm as measured by surveyor. Boat bought subject to reduction negotiated by surveyor and sailed to UK. New owner took boat to FOX’s Ipswich and asked for quote for this problem together with other issues. They (Fox’s) de rigged boat and cut exploratory hole in mast step to assess whether any de lamination had occurred. The grp was fine but the toilet bulkhead together with associated timberwork was inadequate for the job.As you will be aware when sailing hard particularly on the wind the forces are predominately compression. Fox’s said they had encountered this problem before and they re glassed the timber work and fitted a mast support against the bulkhead from the mast base to the Keel. I t is fabricated from 80mm dia St. St. tube with a plate welded each end in 10mm thick St. St. ( all 316 Polished etc.) I am on holiday in Florida at present and all details are at home in Dublin as is the boat. I return in early Feb and if u wish I can dig out costs and take photos etc. then. From memory the job cost in the region of £2500 inc removal and re firtting mast .My email The total repairs inclusive of osmosis and fitting of in boom feefing together with new booms and 2 speed self tailing winckes,new rigging etc was approx 16K. The original mast support as shown on the Nauticat drawings is inadequate for a boat of the nauticat weight.Particularly if it is sailed hard over a long no. of years. Its OK for motor sailing .Fox’s conclusion not mine.
    cheers, David Hopkins.


    HEADLINING – Nauticat 33′ MK2 (1979) “DULCIA”
    One of the first jobs in the repair of mast step depression is to remove the internal headlining beneath the mast. It’s removal will allow full eye sight of the inner problems and allow access to conduct your repair strategy. This has started this week. On examination, to my surprise the vinyl headlining is backed with 10mm ply. Its thickness has made it difficult to remove and has resulted in some damage. As I am planning to replace / reuse the headlining to maintain authenticity I will inevitably require some additional material to replace the damaged sections. So my question is to ask if any one knows if this type of headlining is still available? and if so the details of the supplier. I would be grateful of any advice on this.
    I hope to produce a description of the whole repair operation in due course.
    many thanks



    Hi everyone, I have discovered I have a similar problem but with the mizzen mast. I think all the comments so far relate to the main? Has anyone any experience of the mizzen problem/solution? I haven’t investigated yet but obviously the mizzen sits on the cable/hydraulic conduit. My aft head door won’t shut against the companionway opening but shuts fine on the head itself. The door was a bit tight last season but much worse recently so I checked and the mast step is definitely depressed – as am I!

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