This topic contains 13 replies, has 6 voices, and was last updated by  Stephen and George Taylor 1 week, 2 days ago.

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  • #10278

    Simon Garratt
    Participant

    Hi,

     

    The pintle on Gambol is showing it’s age. The last time it was removed it appears to have been re- bedded on bath sealant. The result of both is a hole (enlarged on the underside) which is clearly going to reduce the strength of the fitting.

    I will probably re-bed on Sikaflex 292i which will add strength with a firm bond. What I can’t really decide is should I have the fitting remade – if I did in what material? As can be seen the skeg has been clad in ply to presumably add some additional strength.

    Stainless doesn’t like being buried in this way, not sure about aluminium and especially grade & where to get it done or will I get away with having it welded? The weld option throws up the same questions of grade & who to approach.

    Does anyone have any ideas or a pintle in good condition that I could purchase (he asks hopefully)?

    Many thanks, Simon.

     

     

     

  • #10279

    murray reid
    Participant

    Hi Simon

    I will check my spares later today.  I dont know if it will make a difference but is your rudder stock a type 1 or type 2 ? From your photo the pintle appears to be fairly corroded. Were the fastenings stainless steel? It should be possible to patch repair it by welding it up  – that would keep you going for another season or two. I would look at having a new aluminium one made with an aluminium pin as well to reduce the amount of dissimilar metals below the waterline. See the attached PDF for recommended grades of aluminium for each purpose.

    I will get back to you once I have checked my spare rudder.

    Murray A87

    discussions/211-T01aluminiumstandards.pdf

  • #10280

    We recovered a Type 1 rudder pintle when we broke up A12 three years ago, still attached to a chunk of the skeg. I believe it was sold to A5 Diaphony but I don’t know if he used it or still has it.

    Best wishes,

    John

  • #10281

    Trevor Thompson
    Moderator

    Simon

    All of the second hand pintles I have come across are at least as bad as the one in your photo. We still have A12’s here – but I would not use it on my boat – and therefor can not recomend that you use it!

    We have the drawing for that component – which is at least something you can go along to a manufacturer with. The dificulty will be finding some company who will do it properly from suitable materials and for a sensible price.

    As far as corrosion – that is always the potential problem. The original was stainless and I am sure a replacement would last as long – it is over 50 years old after all. The key is to exclude oxygen using sikaflex and epoxy materials from those areas which are covered – and then to electrically insulate the stainless from the alloy with nylon bearings.

     

    Trevor

  • #10282

    Simon Garratt
    Participant

    Many thanks for the replies.

    I have already come to the conclusion that I will look into getting a new one made in Aluminium – Trevor my cheque for the drawing is already on it’s way.

    The only problem still is which grade to use. If I have this right the original made from Hiduminium? had an ultimate tensile strength of 61k to 72.5k psi. 5086 or 6061 marine grades are around 45k psi. How much of the original specification was down to the material being available and was it over engineered? I really don’t want to find out the hard way.

    7075 (used in aircraft industry) has the strength but, from what I can find out, is not so happy in a marine environment. Though as Trevor says, the key is to prevent salt water reaching the aluminium in the first place and the original has managed 50 years with inferior sealants to those available now.

    I will go and see what the engineering firm, I used to have the prop shaft reworked, in the New Year have to say – though Crewe engineering firms are more used to working with bits for trains than boats.

    Simon

  • #10283

    Pete Crane
    Participant

    Hi Simon

    I more or less did what Trevor has suggested. I reused the pin of the pintle, which is stainless, cutting off the aluminum housing. Stainless bar was then bent round, welded and then drilled, then countersunk or tapped to take SS countersunk headed bolts. On the original set up one of the aluminum rivets/bolts had failed due to corrosion in the wood and the others were in very poor condition.

    No problems with lining up the bolt holes as I re-built the skeg. Note that the stainless long bolt that went through my skeg was still in near perfect condition (over 50 years old) and has been re-used. Also stainless steal bolts on the P bracket were also in fine condition. These bolts were re-bedded in sikaflex over 20 years ago and re-done 2 years ago when I replaced the P bracket.

    I would go for a stainless steel.

    Pete

    Simon Garratt said:

    Many thanks for the replies.

    I have already come to the conclusion that I will look into getting a new one made in Aluminium – Trevor my cheque for the drawing is already on it’s way.

    The only problem still is which grade to use. If I have this right the original made from Hiduminium? had an ultimate tensile strength of 61k to 72.5k psi. 5086 or 6061 marine grades are around 45k psi. How much of the original specification was down to the material being available and was it over engineered? I really don’t want to find out the hard way.

    7075 (used in aircraft industry) has the strength but, from what I can find out, is not so happy in a marine environment. Though as Trevor says, the key is to prevent salt water reaching the aluminium in the first place and the original has managed 50 years with inferior sealants to those available now.

    I will go and see what the engineering firm, I used to have the prop shaft reworked, in the New Year have to say – though Crewe engineering firms are more used to working with bits for trains than boats.

    Simon

  • #10284

    murray reid
    Participant

    Checked my spares and I only have the gudgeon fittings off the rudder stock – no pintle’s. The aluminium stock and gudgeon’s are all fairly corroded. A87 had stainless pintles when I bought her but they are for a rudder ‘box’ for a vertical lift rudder – so not much help I am afraid. If you are reusing the stainless steel pin check it for crevice corrosion in the area where it passed through the aluminium pintle body. If you do have an all stainless fitting made ensure (as Trevor mentioned) that the aluminium rudder stock is isolated from any stainless by using an appropriate insulating bush such as a nylon one. I suggest you read through the aluminium standards paper, attached to my previous reply, it lists the various grades and applications.

    Cheers

    Murray

  • #10285

    Simon Garratt
    Participant

    Murray,

    Many thanks for having a look – it’s really appreciated. I have since found a spare, in a box of bits I didn’t know I had! Unfortunately as you might expect it’s only in a little better shape than the one I removed.

    I have the drawing for it now so I will go and see what the engineering firm makes of it sometime in the next few weeks.

    Regards,

    Simon

  • #10286

    Simon Garratt
    Participant

    I finally got my new pintle back today. Milled from a chunk of 7075-T6511 aluminium (rather than the original welded version in 3/8″ plate – I think that later boats were milled from solid bar?) with 316 stainless pins by Congleton Engineering (I think that they have done a Stella job – though it did cost £215). I have isolated the stainless pins from the aluminium with Duralac. I would have liked to have got it anodised but balked at the £132 min charge I was quoted (from another company) and I was also concerned about getting it back quickly! The old one did 50 years – so it will see me out & some!

  • #10287

    murray reid
    Participant

    Beautiful!!

    A87

  • #10288

    Simon Garratt
    Participant

    Murray,

    You are so right!

    The guy who ended up finishing the job is a real craftsman the main pin & though holding pin fit perfectly. When the measurements from the plan are cross checked they are all spot on. The main pin was put in upside down (I didn’t leave the old fitting as I wanted to scarf in some new wood – probably a mistake (in the end) not to) but because he had put the retaining pin in dead centre (main pin has a shoulder) it wasn’t a problem.

    Forget fine art, sculptures & the like I could look at this for a long time – almost a shame it’s not going to be seen.

     

    Regards,

     

    Simon

  • #10289

    Trevor Thompson
    Moderator

    Simon

    I need to get new rudder fittings made for Calista. The rudder stock was bent like a banana in a road accident. Can you provide me with contact details for congleton engineering please?

     

    Thanks Trevor

  • #10290

    Simon Garratt
    Participant

    Trevor,

    I did think about sending the details. They have done a good job but it has taken a long time – they seem busy and it was a small job and certain machines were set up and in constant use. To balance and in fairness sorting the exact grade of aluminium & supplier was the biggest issue time wise.

    If you do use them I would recommend sending them the old rudder & drawings.

    http://congleton-engineering.co.uk/

     

    I dealt with Rory but I think he will still be on holiday next week – 01260 279647.

     

    All the best with it & keep us updated.

     

    Regards,

     

    Simon

     

     

  • #14200

    I am going though the same process with T12. The old aluminium part was corroded so off the machine shop for a new one. Photos to follow. Unfortunately the long vertical timber has been effected by the corrosion of the pintle so I have made a new one in Iroko. Again pics to follow.

     

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