Loading ...
Sorry, an error occurred while loading the content.
 

Brass running strip....

Expand Messages
  • rrob437
    Oliver just a quick query, but did you ever get round to fitting that brass strip to the base of your keel? I sit on an oyster bed when she dries and have
    Message 1 of 15 , Feb 6, 2016
      Oliver just a quick query, but did you ever get round to fitting that brass strip to the base of your keel? I sit on an oyster bed when she dries and have found it to be taking a small toll on this area with the gell coat chipping etc.
      My only issue with fitting one is compromising the keel itself (may have to find another mooring). Happy new year by the way.
    • olivershaw4229
      ... Yes, apart from a very short length at extreme aft end, and another very short length forward of the drop keel slot. Both of those are on the To Do
      Message 2 of 15 , Feb 6, 2016
        >  Oliver just a quick query, but did you ever get round to fitting that brass strip to the base of your keel? I sit on an oyster bed when she dries and have found it to be taking a small toll on this area with the gel coat chipping etc.


        Yes,  apart from a very short length at extreme aft end,  and another very short length forward of the drop keel slot.   Both of those are on the "To Do" list.

        The impetus in my case was drying out on a stony bottom at Ravenglass in 2013.

        I obtained the brass keelband and the bronze screws from Classic Marine,  who keep a good stock of both (and much else besides) in a very comprehensive range of sizes.



        >  My only issue with fitting one is compromising the keel itself

        Indeed so.   

        The drill holes,  and quite possibly the fastenings,  may penetrate right through the GRP.   For some of the fastenings I bedded them in with silicone sealant,  and some with neat epoxy,  but I really cannot be certain which worked better;   nor can I now remember which I used where?

        In just two or three cases,  I think exclusively at the after end,   I found trapped bilge water poured out as soon as I drilled the hole.   Of course one needs to then allow the hole to dry out thoroughly before trying to bed in the fastening,  whether using silicon sealant or epoxy.   

        However a good polysulphide sealant,  such as Boatlife's "Life-Calk",  can be applied to damp surfaces;  indeed the manufacturer says that in emergency it can even be applied underwater!   Unfortunately this is an American product,  and it seems that it is no longer marketed in the UK,  so obtaining it is difficult.    There may however by a UK equivalent.

        On my boat,  being an early one (before they started bonding in ballast beneath the cabin sole),  some of the fastenings protrude through into the keel "gulley" beneath the cabin sole.  I have coated over the protruding points of these with epoxy.

        There were a few small leaks which I quickly identified and sorted out.   There now still remains a very slight leak,  which I have not yet been able to identify.   This is small enough not to worry me while the boat is in use;   typically when cruising I pump the bilges at least once a day,  a little more frequently when on passage,  and I normally find that a very few strokes clears the bilge.  (Gusher 10 pump,  or a near clone.)   Since there is no sump,  when the pump sucks dry it does not in fact mean that the bilge is absolutely empty,  so I am not perturbed if later in the day I get another few strokes-worth out..

        On the rare occasions when there has been noticeably more I have been satisfied that the excess was rainwater.

        However I cannot ignore the leak if leaving her unattended afloat for long periods.    I am happy to leave her afloat unattended for a day or two,  but if I were doing so for longer I would probably fit an automatic bilge pump.   Not least because this will also cope with rain water.    They are cheap enough,  and readily available;  the bigger issue is maintaining battery charge,  but a modest sized solar panel should look after that.
         



        >  Happy new year by the way

        Thanks,  and the same to yourself.




        Oliver
         
      • rrob437
        Many thanks Oliver naturally you give a lot to think about. I ll have a look at the site you mentioned and may well consider doing this at the very least to
        Message 3 of 15 , Feb 6, 2016
          Many thanks Oliver naturally you give a lot to think about. I'll have a look at the site you mentioned and may well consider doing this at the very least to protect her keel from shoals it would make sense. Otherwise it's a more expensive mooring I fear!
        • olivershaw4229
          Most boats, in my experience, have protection in one form or another. From dinghies upwards. The only reason my two previous yachts, and thousands like
          Message 4 of 15 , Feb 6, 2016
            Most boats,  in my experience,  have protection in one form or another.    From dinghies upwards.

            The only reason my two previous yachts,  and thousands like them,  had no keelband was their massive lumps of iron forming their ballast keels ...   ...

            The Privateer is unusual in not having protection as standard,  and personally I think it an important omission.    You are discovering why.    And it is not only the question of your home mooring,  but where you may dry out in the course of cruising,  or other normal use.

            Even if you use your boat only for day sailing,  you may still on occasion want to dry her out on a beach,   Or,  heaven forbid,  ground her unintentionally on a shoal.    I have twice done the latter,  in water which I knew was seriously shallow,  while the depth sounder was insisting that I still had several feet beneath the keel ...    ...




            Oliver

          • Jonathan Knight
            I wonder if you used a 50mm wide strip it could just be epoxied on, saving drilling into the hull. It would need the hull sanding to clean and roughen the
            Message 5 of 15 , Feb 7, 2016

              I wonder if you used a 50mm wide strip it could just be epoxied on, saving drilling into the hull. It would need the hull sanding to clean and roughen the surface slightly. After all many boats are just glued together.
              Regards Jonathan

              On 6 Feb 2016 23:32, "acapella13934@... [privateer20]" <privateer20@...> wrote:
               

              Most boats,  in my experience,  have protection in one form or another.    From dinghies upwards.


              The only reason my two previous yachts,  and thousands like them,  had no keelband was their massive lumps of iron forming their ballast keels ...   ...

              The Privateer is unusual in not having protection as standard,  and personally I think it an important omission.    You are discovering why.    And it is not only the question of your home mooring,  but where you may dry out in the course of cruising,  or other normal use.

              Even if you use your boat only for day sailing,  you may still on occasion want to dry her out on a beach,   Or,  heaven forbid,  ground her unintentionally on a shoal.    I have twice done the latter,  in water which I knew was seriously shallow,  while the depth sounder was insisting that I still had several feet beneath the keel ...    ...




              Oliver

            • olivershaw4229
              ... It probably could. But in the longer term, the keelband is sacrificial. How would you then get it off in order to fit a replacement? Not impossible,
              Message 6 of 15 , Feb 7, 2016
                >  I wonder if you used a 50mm wide strip it could just be epoxied on, saving drilling into the hull.



                It probably could.

                But in the longer term,  the keelband is sacrificial.   How would you then get it off in order to fit a replacement?

                Not impossible,  but an added complication. 

                That would add to the more obvious complication of maintaining adequate contact between a fairly bendy metal strip and a rigid and probably not perfectly true bottom GRP surface while the epoxy cures.




                Oliver
              • Jonathan Knight
                True Oliver. Brass rubbing strip is expensive. As and when I do the job I think I ll go for an occasional screw but rely on a good rubber type solution. I have
                Message 7 of 15 , Feb 7, 2016

                  True Oliver. Brass rubbing strip is expensive. As and when I do the job I think I'll go for an occasional screw but rely on a good rubber type solution. I have had excellent results with Sticks Like Sht. Not a nice name though.
                  Jonathan

                  On 7 Feb 2016 18:48, "acapella13934@... [privateer20]" <privateer20@...> wrote:
                   

                  >  I wonder if you used a 50mm wide strip it could just be epoxied on, saving drilling into the hull.




                  It probably could.

                  But in the longer term,  the keelband is sacrificial.   How would you then get it off in order to fit a replacement?

                  Not impossible,  but an added complication. 

                  That would add to the more obvious complication of maintaining adequate contact between a fairly bendy metal strip and a rigid and probably not perfectly true bottom GRP surface while the epoxy cures.




                  Oliver
                • olivershaw4229
                  ... For what it is worth, I went for the traditional half round, I think probably either half inch or five eighths (it is sold in imperial sections, but
                  Message 8 of 15 , Feb 7, 2016
                    >  Brass rubbing strip is expensive.


                    For what it is worth,  I went for the traditional half round,  I think probably either half inch or five eighths (it is sold in imperial sections,  but priced by the metre ....!!),  and put one strip down each side of the keel.

                    That will be not quite as much protection as covering the full width,  but it is probably sufficient protection,  and is a great deal cheaper.

                    Bronze screws are also expensive!





                    Oliver

                  • olivershaw4229
                    ... I now see from my records that I used 5/8 inch. Oliver
                    Message 9 of 15 , Feb 7, 2016
                      > I went for the traditional half round,  I think probably either half inch or five eighths 


                      I now see from my records that I used 5/8 inch.




                      Oliver
                    • g8jmb
                      good polysulphide sealant, such as Boatlife s Life-Calk , can be applied to damp surfaces; indeed the manufacturer says that in emergency it can even be
                      Message 10 of 15 , Feb 9, 2016


                        " good polysulphide sealant,  such as Boatlife's "Life-Calk",  can be applied to damp surfaces;  indeed the manufacturer says that in emergency it can even be applied underwater!   Unfortunately this is an American product,  and it seems that it is no longer marketed in the UK,  so obtaining it is difficult.    There may however by a UK equivalent.


                         Siroflex - SX Polyurethane/Polysulphide Sealants

                         

                        Polysulphide Sealant The last time I got any, it came from toolstation - but they don't stock it any more.


                        So I rang siroflex, who said 'polysulphide is being discontinued,'   -so the jury is out.


                        Brass is not recommended for marine use - it dezincifies - maybe ok for dinghies that live on dry land, but not on boats that live on moorings.  Ever tried removing old brass screws from a boat? They crumble before your very eyes.  I would not use brass for a keel strip, especially when fitted with screws that penetrate the hull.. A Better to lay  up several thicknesses of GRP along the keel. Or 316 grade stainless, through bolted.

                        JohnB

                      • g8jmb
                        perhaps? Evo-stik Polysulphide High Quality Ready Mixed Sealant C21 | Wickes.co.uk
                        Message 11 of 15 , Feb 9, 2016

                          perhaps?

                          Evo-stik Polysulphide High Quality Ready Mixed Sealant C21 | Wickes.co.uk


                           johnb

                        • olivershaw4229
                          ... Agreed in general principle, although it depends very much on both the type of brass and the size and nature of the fitting. I am not a metallurgist, but
                          Message 12 of 15 , Feb 9, 2016
                            Brass is not recommended for marine use - it dezincifies - maybe ok for dinghies that live on dry land, but not on boats that live on moorings.  Ever tried removing old brass screws from a boat? They crumble before your very eyes.  I would not use brass for a keel strip, especially when fitted with screws that penetrate the hull.



                            Agreed in general principle,  although it depends very much on both the type of brass and the size and nature of the fitting.

                            I am not a metallurgist,  but this is my educated layman's understanding.

                            There are various different grades of brass,  including Admiralty brass and naval brass  -  which I understand are actually bronzes  -  and aluminium brasses.   To add to the confusion,  a technical article which I read a few years ago but cannot now trace also informs us that certain alloys named as bronzes are actually brasses ....

                            To quote Encyclopedia Brittannica,  "A third group of brasses includes those with other elements besides copper and zinc, added to improve physical and mechanical properties, corrosion resistance, or machinability or to modify colour.  Among these are the lead brasses, which are more easily machined; the naval and admiralty brasses, in which a small amount of tin improves resistance to corrosion by seawater;  and the aluminum brasses, which provide strength and corrosion resistance where the naval brasses may fail."

                            The preferred metals for use on boats are either a suitable bronze (gunmetal being the most usual choice,  or phosphor bronze for propeller shafts and bearings) or the correct grade of stainless steel;  note that not all grades are of marine quality.    Galvanised steel is a popular low cost option,  but ugly and heavy,  and once the galvanising wears off - which it tends to do in any situation exposed to moving friction (and even with some applications which aren't)  - it can quickly become a rusty mess.

                            Classic Marine are one of the top boat suppliers,  within their chosen field of classic boats;   so because of the classic emphasis their stock is overwhelmingly brass or bronze,  supplemented by galvanised,  and a very limited stock in stainless steel.   Their reputation is such that where they stock brass I am sure that it will be a suitable grade,  and fully fit for purpose.   And remember that keelbands are intended from outset to be sacrificial,  and also virtually non-structural;   all they have to do is to protect from rubbing and impacts.
                             
                            Dezincification is a process that works slowly inwards from the surface,  and the keelband has a moderately substantial amount of metal;   however screws are very much smaller,  which is why brass screws have a notorious problem in this regard.   I think it highly unlikely that the keelband will cease to be functional due to dezincification any earlier than one would wish to replace it anyway because of extended batterings from hitting the bottom.   My guess is a lifetime of years,  perhaps many years,  and that with a suitable grade of brass dezincification is not going to be an issue with it.

                            But you are absolutely right that the screws should not be brass;   which is why I used (and mentioned) bronze screws.

                            Adding extra layers of GRP is of course a valid alternative,  but one which is very obviously sacrificial,  and which is likely to wear faster.   The plus point is that although the need for repairs is likely to be much more frequent,  they are likely to be comparatively smaller touch-up repairs on each occasion rather than wholesale replacement.   But if a boat regularly dries out on a harsh bottom the repairs may been to be done at least annually.

                            Whichever route you decide to take,  inspect from time to time while the boat is out of the water,  and be prepared for either periodic replacement or ongoing maintenance.



                            Oliver

                          • olivershaw4229
                            Thanks for that link. Oliver
                            Message 13 of 15 , Feb 9, 2016
                              Thanks for that link.



                              Oliver

                            • olivershaw4229
                              Even if Siroflex polysulphide sealant can still be obtained, their data sheet for it gives the preparation instructions as (effectively) Surfaces must be
                              Message 14 of 15 , Feb 9, 2016
                                Even if Siroflex polysulphide sealant can still be obtained,  their data sheet for it gives the preparation instructions as (effectively) "Surfaces must be clean,  dry,  free from grease or loose material.  Primers may be required on some surfaces."

                                By contrast,  the Life-Calk instructions say,  in effect,  "Preferably apply to clean dry surfaces.  If necessary apply to damp surfaces.  In emergency can  even be applied underwater."

                                I used to use Life-Caulk regularly back in the eighties,  and although the emergency situation never arose I can testify that applying to damp surfaces always worked satisfactorily.    The big problem was ensuring that none of it got onto surfaces where it was not wanted,  because it sticks voraciously to almost anything.

                                It may well be that the two products are based on different polysulphides.   I was clearly under the impression back in the eighties that Life-Calk was a barium formulation,  although I don't now know whether that impression was correct.    But if correct that does suggest a possible explanation for the difference between the two products;   one perhaps based on barium polysulphide and the other on an entirely different polysulphide,  although a quick check online suggests that barium polysulphide is best known as a pesticide.

                                Two-pot industrial polysulphides listed by Master Bond:  Polysulfide Compounds for Bonding, Sealing and Coating Applications | MasterBond.com

                                 





                                Oliver

                              • olivershaw4229
                                Ah!! At last; found a UK supplier of Life-Calk at a sensible price: Boatlife Life Calk http://www.bosuns.co.uk/-1897-Boatlife-Life-Calk
                                Message 15 of 15 , Feb 9, 2016
                                  Ah!!

                                  At last;    found a UK supplier of Life-Calk at a sensible price:

                                   


                                  Amazon UK also offer it,  but at a thoroughly astronomical price.

                                  But the price from this supplier is comparable with the US price,  as indeed it should be.

                                  However don't go out and snap it up just on the offchance of having a use for it later,  as it does have a limited shelf life.

                                  In the course of searching,  I also found some reviews:
                                  BOATLIFE Life-Calk® Sealant | West Marine

                                   

                                  All but one of them were immensely favourable,  and most stated that they found it so much better than the competing products.   One very negative review was from someone who found it difficult to use,  and who also made a telling point about its shelf life.




                                  Oliver

                                Your message has been successfully submitted and will be delivered to recipients shortly.