Forum Replies Created

Viewing 15 posts - 316 through 330 (of 708 total)
  • Author
    Posts
  • in reply to: Update on Spark #19188
    Oliver Shaw
    Moderator

    Very nice.

    Vintage pattern sheet horse.

    Bronze?    Newly manufactured?

     

    Oliver

    in reply to: Replace plywood bottom #19186
    Oliver Shaw
    Moderator

    Well done.

    I would guess that the non-radiused corners of the bailer are for ease of manufacture,  particularly in the twin context of controlling manufacturing cost (and thus keeping down the price that you pay),  and obtaining a reasonably watertight seal.

     

    Oliver

    in reply to: Update on Spark #19183
    Oliver Shaw
    Moderator

    Well done.

    Don’t forget to refit your rubbing beads / gunwales before you start painting and varnishing.   (Unless you intend using rubber or PVC D-fendering,  which is not in class but which would be a legitimate option for your situation.)

     

    Oliver

    in reply to: Replace plywood bottom #19179
    Oliver Shaw
    Moderator

    Agreed.    When I took a section of keel off,  for access to the centreboard case securing screws (as the first step towards removing the case in order to deal with a bad leak),  it was around fifty years ago,  and the boat was not as old as your one.   I had momentarily overlooked the possible state of the glue on your one.

    Yes,  there is a sporting chance that the glue will be so degraded that just gentle encouragement (perhaps with the aid of a chisel flat to the bottom between keel and plywood) may be sufficient,  once the screws have been identified and removed.

     

    Oliver

    in reply to: Replace plywood bottom #19176
    Oliver Shaw
    Moderator

    Yes;  or,  at least,  sections of it.

    I presume that you mean the keel itself,  i.e. wood,  rather than the metal keelband.

    If you feel that you will need to remove a section of the keel,  do it before you fit the new plywood;   also remove the plywood under the keel,  and bring the new plywood right up to the centre line.

    First use either a heat gun or paint stripper,  plus scraper,  to remove the paint;   that will expose where the screws are,  albeit that what you will most probably find is circular patches of filler which will then have to be dug out to reveal where the screws themselves are.

    Remove the screws.   That may be easier said than done;  if they were originally brass they will almost certainly now have lost their zinc content,  ending up as porous (and very weak) copper.  heads may well fall apart under the influence of a screwdriver,  shanks may snap,  …    At worst,  you may have to drill them out,  and then make good the resulting holes later.

    Cut straight across the keel,  coming as close as you can down to the plywood,  but ideally not cutting into the plywood;   normally it is better to stop just a fraction short rather than go too far.    (However this is unimportant if you are replacing the plywood anyway,  and epoxy is a wonderful thing if you do inadvertently end up cutting a fraction too far …).    My preferred tool for that job would be a dovetail saw,  but there are alternatives,  including a hacksaw,  and an electric oscillating saw.     Perhaps the least preferred acceptable option is a tenon saw;   a dovetail saw is like a smaller version of a tenon saw and with finer pitch to the teeth.   My one was picked up second-hand on Fakenham market …

    Then chisel away the section to be removed.    Eventually replace with new wood.    If the length to be removed is substantial,  you might prefer to remove the majority of it with a router,  but I suspect that hand tools may still be needed to finish the job.   

    Routers became relatively commonplace for DIY woodworkers only in the last few decades,  and it was only last year that I finally bought one (second-hand,  from Fakenham market   –   and I have still not yet had occasion to use it);    by contrast,  it must be perhaps 50 years since I last had occasion to remove a section of keel.   Hence I naturally think in terms of hand tools,  but by all means update to whatever technology you have available.

    Hope this helps,

     

    Oliver

    in reply to: Replace plywood bottom #19172
    Oliver Shaw
    Moderator

    I think you are right in saying that you have managed to avoid the worst of the curvature.

    The curvature of the extreme forward end is probably about the maximum that the ply will accept  –  Jack Holt seems to have had an exact appreciation of what he could and could not get away with in this wonder new material  –  and Bell Woodworking’s recommended technique for that forward piece was to pour a kettle of boiling water onto it.    I think that is in their book “Home Boat Building Made Easy”,  and I feel sure it is also in Searson Thompson’s cine film of the build process.

    On which topic,  I saw the film some years ago (converted to video),  probably at Dovey Yacht Club,  Abderdyfi;   and also film of the launching of the prototype at Aberdyfi.    I cannot now be sure whether this was all in the same film,  or whether it was two separate films.    Does anyone know whether the Association has a copy?    It is something which we ought to have,  and it would be great to have it available on the website.    There may of course be be only one copy,  in the possession of Searson’s estate,  unless they have already passed it on.

     

    Oliver

    in reply to: Floorboards #19166
    Oliver Shaw
    Moderator

    Yes,  the early GRP boats were built in the comparative infancy of GRP technology,  and at a time when we were still learning about the properties of the material (including learning about its strength and its weaknesses).   Added to which,  GRP is strongest when used to make curved surfaces,  but the GP14 was designed to be built from an intrinsically flat material,  i.e. plywood.

    The result of that combination of factors was that the early GRP boats had issues of structural strength,  including weak bottom panels.    It was far from unknown for road trailers,  and even launching trolleys,  to push through the bottom of the boat;   indeed I myself experienced such an incident in the very early seventies,  in a virtually brand new boat,  and all we were doing was pulling her up the slipway at Bassenthwaite after the day’s racing.

    More modern plastic boats,  and especially the modern epoxy boats,  are very much stronger;   the engineering has come a long way since those early days.

    That apart,  I agree with all that has been said thus far in the explanations.

     

    Oliver

    in reply to: Replace plywood bottom #19146
    Oliver Shaw
    Moderator

    She is looking good.

    Well done.

     

    Oliver

    in reply to: Replace plywood bottom #19142
    Oliver Shaw
    Moderator

    Yes,  you can safely use paint stripper.

    Some are better than others.   My own favourite is one of the oldest,  and probably the most aggressive,  Nitromors Original.   Be aware that it is pretty ferocious stuff,  so use with all proper care.    Apply it to only a small initial area;   Ian Proctor recommended just one square foot if I remember correctly (in his 1950s book Racing Dinghy Maintenance),  allow it perhaps 5-10 minutes to soak in (Proctor recommends using this time to re-sharpen your scraper),  then paint a different small area,  and then scrape the first area.     Keep going in a sequence like this.

    Allow about 5 minutes to soak in,  perhaps 10 minutes at maximum;    certainly not the 20 minutes sometimes recommended;   the stripper will evaporate if left that long!

    Your scraper needs to be seriously sharp at all times.   If you use a conventional scraper you will need to re-sharpen it every few minutes,  and there is a technique to getting it sharp enough.    However that need has been overtaken by modern technology;    use instead a scraper with a modern tungsten carbide blade,  and then you won’t need to re-sharpen it after every few minutes’ use,  (and with that material for the blade you won’t be able to sharpen it anyway),   so you could now work a sequence of three or even four areas all on the go at the same time,  each at a different stage of the sequence  –  always provided you can keep track of where each patch is up to.

    Nitromors nowadays offer several different formulations,  designed for different substrates,  so that they can be sure not to damage more delicate substrates.   However the gentler ones are correspondingly less effective at removing paint.    Personally I always use the toughest of the lot,   their Original,   and work on the principle that if there is a substantial thickness of paint it won’t penetrate right through with the first application;     and once you get down to the level where it will penetrate right through it will have been fairly weakened by attacking the paint,  and it won’t remain in contact with the epoxy long enough to do it any serious damage.   However you are welcome to take a more cautious approach,  using a gentler paint stripper;   but the job will take significantly longer,  and will be significantly more work.

    -o0o-                    -o0o-                    -o0o-

    Adding pictures;   I think you have already found the mechanism,  but you need to re-size your photos first.  A box between the typing pane and the “Choose file” button states that the maximum file size allowed is 512 kB.    That is quite small if your photos are originally taken at high resolution intended for printing,  or for projection onto a large screen;   but it is in fact amply good enough for the size that will be displayed on this forum.   Use any photo-editing program of your choice to re-size your photos;   you probably have one (or more) already on your computer.

    As one tip for re-sizing;   you may find that your photo-editing program allows you to set the image size in pixels,  rather than the file size in bytes.    Try 1000 pixels for the longest size,   save to a different filename (so that you don’t spoil your high resolution original),  and then either try to upload that or  –  if you wish  –  right-click on the file icon first and select Properties to check the filesize.

    Hope this helps,

     

    Oliver

    in reply to: Update on Spark #19132
    Oliver Shaw
    Moderator

    The proposed timescale is a monumentally ambitious target;     good luck !!

     

    Oliver

    in reply to: Replace plywood bottom #19095
    Oliver Shaw
    Moderator

    I think the simplest joint,  and perfectly acceptable,  would be a butt joint with a ply backing piece.

    A good reference source,  indeed the standard reference book (so far as there is such a thing),  for all epoxy work is the Gougeon Bros. manual;   https://www.westsystem.com/the-gougeon-brothers-on-boat-construction/

     

    Oliver

    in reply to: Replace plywood bottom #19083
    Oliver Shaw
    Moderator

    Second attempt,  now that I am back home and can use a desktop PC rather than only a tablet;   the latter is something of a nightmare!

    Delighted that you have decided to join the Association!

    I confess that this is one repair which I have never had occasion to do myself,   but I have seen photos and write-ups of several other projects of this nature,  and have done a fair amount of other boat repair myself.    So my observations are based on a general awareness rather than first-hand experience of this particular job.

     

    Your step 2;   I provisionally concur,  subject to checking the keel for water saturation (as Chris has suggested),  subject also to sufficient bonding width on the hog being exposed,  and further subject to the old ply between hog and keel being in sound condition.    This last condition must be regarded as fairly doubtful until you have actually removed the damaged ply and positively verified that what is left there trapped between keel and hog is sound.

    Note that if you terminate the new ply at the edge of the keel,  rather than underneath the keel,  the edge of the ply will be potentially exposed,  so it will be vital that this is well epoxied.

    If in any doubt about any of these conditions,  remove the keel;   except inside the centreboard slot the edge of the ply will then be protected by the keel.

     

    Your step 6:   I presume that the frame itself is either sound or will have already been repaired,  and the scarf joint you refer to is between old and new ply.    I would expect (without measuring up),  that the scarf will actually be significantly wider than the width of the frames.

    That being so,  locating the scarf joint (in the ply) exactly on the frames is irrelevant;   it could be anywhere convenient,   but actually making the scarf joint while the (old) ply is on the boat (and therefore curved,  in two planes) may be difficult.   There are alternatives.

    A butt joint is perfectly acceptable,  provided there is adequate width of backing piece.    The frame itself will not be wide enough to serve adequately as a backing piece for a butt joint,  but its width can be doubled by use of a sister piece epoxied to the frame,   or the butt joint may be made away from the frame using a ply backing piece.    In either case there will inevitably be a weight penalty,  but this should be very modest,  indeed probably trivial;   and if the boat is already down to minimum racing weight and carrying corrector weights you could compensate by reducing the corrector weights accordingly.    (I think you would then need to get the new hull weight checked,  and your certificate endorsed,  if you were to adjust the corrector weights.)

    A refinement,  after making such a butt joint,  would be to then rout out the top layer of ply for a short distance either side of the joint,  and insert an inlay piece,  so that the main part of the joint in the ply is not on the surface.

    Another alternative is a lap splice joint,  cutting away (by router or otherwise) multiple faces parallel to the surface rather than the single angled surface of a scarf joint.    Depending on your available tools,   this might perhaps be easier than a scarf,   because of the curvature of the panels.    https://en.wikipedia.org/wiki/Splice_joint#Half_lap_splice_joint.

    See pages 27 and 28 of “Home Boat Building Made Easy”,  by the Bell Woodworking Company,  for a more general discussion of repair techniques.   My comments above are an adaptation of that advice,   modified for the size of the job on your boat.   That book is long out of print,  but (with the permission of the late Searson Thompson)  I scanned it and uploaded  it to the GP14 Owners Online Community site some years ago.    https://groups.yahoo.com/neo/groups/GP14_Community/photos/albums/1717966512/lightbox/568223741?orderBy=ordinal&sortOrder=asc&photoFilter=ALL#zax/416512707

    Hope this helps,

     

    Oliver

    in reply to: Replace plywood bottom #19073
    Oliver Shaw
    Moderator

    Mast step conversion;   if you  have it,  the mast step will be a metal track,  with pins across it to determine the fore-and-aft location,  and the foot of the mast will be a tenon which fits into the track.   The track sits on a longitudinal member which is raised above the hog,  and which is tenoned into the centreboard case;    the purpose of this redesign is to spread the load over a greater length of the hog.    Although it won’t be obvious without actual measurement,  the mast is also 12 cm shorter,  to take account of the raised position of the step.

    If you don’t have the mast step conversion the step is a square mortise in a wooden block which sits directly on the hog,  and the foot of the mast is square,  rather than having a (rectangular) tenon).

     

    Oliver

    in reply to: Crazy idea? #19065
    Oliver Shaw
    Moderator

    Robbins routinely supply across the country,  using either their own transport or a courier.   You would (presumably) be charged carriage,   but they are nonetheless worth considering.

    Alternatively,  in North Wales you might try Scott Mecalfe at Waterfront Marine,  Port Penrhyn;   he is a nationally known traditional boat builder and restorer,   in a seriously big way,   but he might well stock Robbins’ materials and be prepared to re-sell them.   That is at least worth an enquiry,  although I have never had any dealings with him myself,  so I am not committing him in any way.

     

    Oliver

    in reply to: Crazy idea? #19048
    Oliver Shaw
    Moderator

    Matt It is certainly an idea to consider, but it is not necessarily a panacea. Fundamentally it is a matter of first deciding what it is that you want to achieve.

    In principle, the fittings can be switched across.

    GRP boats are often perceived as being free of maintenance and repair problems. There is some (limited) validity in that, but see the recent string on serious problems in Speed Sails GRP boats. And long before the Speed Sails boats, the first generation of GRP boats had a number of structural weaknesses (with reports of trailers and launching trolleys going through the bottoms of the boats, and shroud plates pulling out, in particular; indeed I myself experienced the first of these problems, in a nearly brand new boat). Nonetheless, an impressive number of them have survived to this day.

    Your wooden boat, if you choose to repair her, has the potential at the end of the repair process for being a thing of beauty, and also of being a boat in which you personally will have invested a considerable amount of TLC and in which you can take a justifiable pride. Those aesthetic considerations may, or may not, be important to you, and they are almost impossible to put either a financial or a time value on; only you can decide that question.

    If your primary concern is simply to get a boat, any boat, into sailable condition as quickly and easily as possible then the GRP option would seem to be a potential way forward, always provided that the hull is reasonably sound.

    If you decide to repair your wooden boat, it is a major undertaking, but it is all do-able – and plenty of others have been there before you and done similar (and even bigger) repairs. There are some inspiring photo albums on the GP14 Owners Online Community site, and even more on our archive site.

    Removing the keel, in the context of the size of the rest of the job, is not the major bogey which you seem to fear. My personal take on it is that the GP14 is somewhat over-engineered, and massively stronger than it needs to be, and that the keel is essentially non-structural in terms of the strength of the hull, although important for taking the rub when beaching the boat. The main backbone of the hull is the hog (the longitudinal timber inside the planking), not the keel, so you can afford to cut away the keel with impunity in order to effect the necessary repairs, and replace it later.

    (For comparison, The Heron – a later design also by Jack Holt, and in some ways a smaller sister ship to the GP14 – is much more lightly constructed. I have heard it suggested that the Heron is the better engineered design for that reason; but I know nothing about their comparative longevity. I am no longer involved with that class, and I have no information on how many of the first 100 boats, say, are still around and in sailable condition!)

    Hope this helps,

     

    Oliver

Viewing 15 posts - 316 through 330 (of 708 total)