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Viewing 15 posts - 676 through 690 (of 708 total)
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  • in reply to: Technical Section ? #4473
    Oliver Shaw
    Moderator

    I agree that wood dust does go very dark in colour.  Microgranules tend to be very white,  so perhaps a mixture of the two.   I confess I have not tried colloidal silica.

    There does indeed seem to be a problem with the link,  although I have not debugged quite why.   <span style=”line-height: 1.5em;”>I suggest that you try  </span>http://gp14building.wordpress.com,  then click on Photos,  then <span style=”font-size: 9.5pt; line-height: 115%; font-family: Georgia, serif; color: #743399; border: 1pt none windowtext; padding: 0cm; background-image: initial; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;”>GP14 Rigging Systems</span>

    This is our archive site (“we” in this context being the GP14 Owners Online Community),  and I am not sure whether it is open to non-members of that forum,  but try it and see.  If you can’t get in,  get back to me off-list at acapella13934(no spam)@talktalk.net (omit the “(no spam)” of course) and we can sort something out for you.

     

    Oliver

    in reply to: setting up a spinnaker on mk1 GRP gp14 #4471
    Oliver Shaw
    Moderator

    I am fairly sure that my paper reviewing (early) spinnaker rigging systems is in the Members’ Library,  and it is certainly also on the GP14 Owners Online Community site.

    I hasten to add that in this case to a very large extent I merely collated the work of others,  much of it from “The Basic Boating Book” which used to be published by the Association but which I suspect is now out of print  –  although it would be worth an enquiry to the Office to see whether we have any copies left.

     

    Oliver

    in reply to: Technical Section ? #4470
    Oliver Shaw
    Moderator

    You may also find this photographic record useful;  most of the various different ways in which the boat has been rigged over the years,  up to but not including the latest race rigs.

    <span style=”line-height: 1.5em;”>http://gp14building.wordpress.com/about/photos/gp14-rigging-systems/</span&gt;

    This is from the archive site of the GP14 Owners Online Community.

     

    Oliver

    in reply to: Mast Step Rot – Help! #4469
    Oliver Shaw
    Moderator

    I am picking up this thread somewhat late,   not least because I have been off the forum altogether for perhaps a couple of months while initially away sailing and then caravanning,  and on top of that I have also had a major upgrade to the computer  –  and by my oversight this forum was one tab that I failed to reload when I got the machine back.

    <span style=”line-height: 1.5em;”>Steve has already answered most of your queries,  but I pick up one point in which you specifically referred to myself;  cutting the keel,  and scarf jointing it.    Although the hog (the very substantial timber inside the boat,  along the centre line) is very definitely structural,  indeed it is the backbone of the boat,  the keel (the corresponding piece on the outside) is of very much lighter section.   Since the whole boat is massively strong,  some might even claim her to be over-engineered,  you can afford not to  worry too much about preserving the strength in the keel itself,  provided the hog is sound.</span>

    So,  yes,  if the hog is in good condition you can regard the keel as little more than a non-structural exterior capping piece.   So if you want the easy route,   take off the keel band first,  then a straight cut is a sufficient means of cutting at either end of the section that you need to remove.   Extract the screws (you may well need to strip the paint off the keel in order to locate them),  and if you are VERY lucky you may then find that the glue is on the point of failure anyway and you can simply insert a sharp chisel underneath it (as flat as possible to the plywood) and force it off in one piece.   Then when you later re-assemble,  you can indeed just refit this piece.

    However it is much more likely that the glue won’t fail,  and you will have to cut away the wood from the top,  paring it down with the chisel (or other method/s of your choice).   In that case,  when you come to reassemble you won’t have the piece you removed,  just a pile of shavings,  and you will need to let in the appropriate length of new wood.   In that situation you might as well go all the way,  cut the new timber longer than the gap,  and do scarf <span style=”line-height: 1.5em;”>(a.k.a. scarph)</span><span style=”line-height: 1.5em;”> </span><span style=”line-height: 1.5em;”>joints at either end;  it will be neater,  and even though strength here is not a major issue you might as well have the extra strength.    </span>

    A plain scarf joint is perfectly adequate if you use a good epoxy glue,  but I would also use screws to hold it while the glue sets,  and I would leave the screws in when the job is finished:     http://en.wikipedia.org/wiki/Scarf_joint

    Ideally,  if you do that,  use a gradient of about 1 in 12,  i.e.  for every one inch thickness of the keel use twelve inches length for the taper (at each end).     I think you will in fact find that the keel is only about half an inch thick,  in which case the length of the taper should be about six inches at each end,  but I haven’t measured.    If you are absolutely confident that you are getting your mating surfaces perfectly true then you can use neat (unthickened) epoxy,   but if you have any significant gap to fill then thicken the epoxy with the appropriate microgranules.

     

    Oliver

    in reply to: Stopper or putty to hide wood screws #4468
    Oliver Shaw
    Moderator

    Brummer stopper was certainly the standard material for the job when the boat was built,  but as Steve rightly says it does tend to crumble in time,  although I confess that I sometimes still use it for very small areas.

    Another option,  an alternative to the colloidal silica,  for the epoxy route is sanding dust from the same type of wood.    My orbital sander has a dust collection facility,  and whenever I find myself doing a lot of sanding on bare wood I empty the contents of the dust bag afterwards into one of two screw top jam jars,  one for mahogany and similarly coloured woods,  and one for spruce or pine or similar.    Then on later jobs,  when I find that I need a matching filler,  I have the material ready to hand.

    You won’t get a perfect match,  but for small areas it is not bad.

    For situations where the screws are deeply recessed down parallel-bored doles (not V-shaped countersunk holes) wood plugs are superb;  you can use matching wood,  and can line up the grain parallel with the surrounding wood,  bond them in with epoxy,  and by the time they have been faired off and sanded and varnished even you yourself will sometimes have a hard job to locate exactly where they are.  The casual observer will normally never see them at all.    But for the particular situation you are describing I think you are right;  the holes won’t be deep enough to use this method.

     

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #4012
    Oliver Shaw
    Moderator

    I am pleased that your investigations thus far have refined your understanding of where the problem lies,  and that we seem to now have a firm diagnosis.     And I am pleased,  but not surprised,  to hear that you find yourself still busy in retirement;   so do I,  but at least we can be busy about out own chosen activities,  and to some extent we can control the pace …

     

    I think it very likely that you will now need to turn the boat over and remove the relevant section of the keel.    Not only will this allow you access to the underside of the ply,  and to the fastenings;   it will also then allow more scope for the ply to be temporarily sprung away from the hog while you attempt to dribble epoxy into the gap.    Incidentally I would expect that you will find it easiest to dribble the epoxy in if you put the boat on her side for this part of the operation;    she will remain semi-stable on her side,  but for safety and security you will need to arrange for an assistant to help you set her up in that position,  and arrange props to support her there.

     

    We both hope that you will find that you are dealing with nothing worse than a glue failure,  and that all the wood is still sound,  but that will of course need checking once you have the structure opened up.    Even with just a glue failure,  you are likely to find that the inside surfaces of the joint are now contaminated with gunge,  which will need to be cleaned out.   A hacksaw blade may be helpful here.

     

    I have not yet used the product,  but if you go for epoxy you may find that the WEST product SIX-10 is helpful for this job;    it  is a thickened epoxy which comes in a cartridge which fits a standard cartridge gun.      It comprises the separate components within the cartridge and they are mixed in the nozzle as it is extruded.    The benefit is that it can be injected into the crack.    At least one GP14 restorer in the eastern USA speaks very highly of it.   It is available in this country from the usual WEST suppliers.

     

    If you decide that you are unable to clean out the inside of the joint sufficiently for epoxy to have a fair chance of sticking,  but can make a secure mechanical joint with screws,  you might consider injecting Life-Calk polysuphide sealant as previously discussed instead of epoxy.   It will have zero structural strength,  which is why you will need a secure mechanical joint by means of screws,  but it is a superb sealant and will stick to almost everything,  even if you cannot get the surfaces properly clean and dry.   “Preferably apply to clean dry surfaces.   If necessary,  apply to reasonably clean damp surfaces.   In emergency,  can even be applied underwater.”

     

    If you find yourself faced with rotted ply in the region of the joint,  unless the rot is extremely localised the simplest solution may then be to cut out the damaged ply and let in a replacement piece;   cut out a piece of sufficient width to take the outer edge well clear of the hog,  so that you have easy access to the edge,  and then use a backing pad (bonded with epoxy) to make a good strong joint to the surrounding ply.

     

    Please be aware that I shall be away and incommunicado for most of April.

     

    Good luck.

     

     

    Oliver

    in reply to: Rudder Blade Dimensions #3983
    Oliver Shaw
    Moderator

    See the Class Rules (on this site,  in the Members’ Library);  the note at the end of Rule 5 gives the dimensions.

     

     

    Oliver

    in reply to: Barn Find – Vintage GP14 No. 1514 #3967
    Oliver Shaw
    Moderator

    And now for the visuals:

     

    Steve White has hosted the photos of the vessel on his sailing club site,  Cody SC;   they have no association with the sale of the vessel apart from wanting to help find a good home for her.

    http://www.codysailingclub.co.uk/a/?page_id=672

     

     

    Oliver

    in reply to: Barn Find – Vintage GP14 No. 1514 #3966
    Oliver Shaw
    Moderator

    FURTHER UPDATE:

     

    We are now certain that she has been in the ownership of just one family from new:   very probably one single owner from new,  although we cannot completely exclude the possibility that she may have been passed from father to son.

     

    I am also told that they were not the sort of people to compromise on quality,   so that tallies with both our deduction that she was built in-house by Bells and with the fact that she has been kept in apparently first class order.

     

    Oliver

    in reply to: Barn Find – Vintage GP14 No. 1514 #3964
    Oliver Shaw
    Moderator

    UPDATE:     A remarkably rapid response from Hugh Brazier,  our Archivist,  with the digitised archive file attached,  shows that the builder is listed as Bell Woodworking.   So we both think that I am probably right in thinking that she was built by Bells themselves,  rather than supplied as a kit for home building.

     

    More information to follow as it comes in.

     

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #3953
    Oliver Shaw
    Moderator

    ” You can afford to regard the keel as largely non-structural, so a straight cut at right-angles is fine; there is no need to do a scarf joint”

     

    Even better,  simple vertical cuts to remove the section of the old keel,  but if your woodwork skills are up to it then when you are ready to fit a length of new timber bevel down the exposed ends at that stage (about 1 in 12 gradient) and scarf in the new wood.    That will provide the added strength of a scarf joint,  while avoiding the unnecessary awkward attempt to saw an accurate very shallow bevel when removing the old timber.

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #3951
    Oliver Shaw
    Moderator

    Thinking further about this,  once you are absolutely certain that the leak is between ply and hog,  and not between hog and case,  I think that you are probably going to have to turn the boat upside down,  remove the keelband (or at least that section of it.  and remove the relevant portion of the keel.

     

    Saw through the keel both ahead of the case and abaft it,  taking care to avoid (so far as possible) touching the surface of the plywood with the saw;     since there is a slight V to the bottom avoiding that will be a lot easier than if the bottom were flat.    You can afford to regard the keel as largely non-structural,  so a straight cut at right-angles is fine;  there is no need to do a scarf joint;    the internal framing together with the case will provide all the structural strength needed.    Strip off the paint on that part of the keel in order to expose the heads of the screws,  and remove the screws.   If you are lucky they will unscrew;   however you may well have to drill the heads off,  then cut off the shanks flush (and file them truly flush) once the keel is removed,  and use fresh screws in fresh holes when you reassemble.

     

    Again if you are very lucky you may now find that section of the keel lifts off;   much more likely,  however,   you may have to chisel it off,  and replace it with new wood when you have finished.   But the total amount of wood involved is not large.   Use a decent marine hardwood for any replacement.

     

    Once that section of the keel is off you have access to the ply,  and the joint between ply and hog,  and you can then get to work with epoxy and fresh screws.

     

    The original screws are likely to have (once) been brass;    with dezincification over the last several decades they are probably porous copper by now,  and structurally very weak,  and thus liable to either snap or break up altogether.   The choice for replacements is bronze (expensive,  and not always easy to obtain,  but Classic Marine can usually supply them) or stainless steel.   Stainless is the mainstream choice,  and they are readily available (and I think cheaper than bronze).    Reading between the lines of your post I suspect that preserving historical authenticity of a vintage boat is not one of your priorities,  so I would go for stainless.

     

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #3950
    Oliver Shaw
    Moderator

    You seem to have eliminated one of “the usual suspects”,  and the next step would appear to be for you to now investigate further,  and perhaps try things out.

     

    I will very willingly give what help I can,  but in that context please be aware that I plan to be at sea from the beginning of April until Easter,  and then away again from immediately after Easter for the following 10 days or.    So I will not be able to respond to queries during that period.

     

    You may also find a lot of help on the GP14 Owners Online Community site;   link should be this site,  or go direct to https://groups.yahoo.com/neo/groups/GP14_Community/info

     

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #3947
    Oliver Shaw
    Moderator

    Yet another option,  by no means a proper cure but “first aid” which has sometimes effected at least a significant improvement.  is to clean up and dry off the entire area and then press a suitable grade of Sylglas tape along the full length of the outside of the join,  pressing it down firmly onto the wood.

     

    This was a popular “first aid” approach in the sixties,  and on many boats it effected a significant improvement that lasted for several years.

     

    I see that the range of Sylglas tapes has substantially expanded since I first knew it,  when there was at first only the one,   so check out the range and use your judgement if you decide to try this.

     

    http://www.sylglas.com/

     

     

     

    Oliver

    in reply to: Leak in Mk 1 wood GP #3946
    Oliver Shaw
    Moderator

    Apologies if I was a bit crotchety!

     

    I am still not clear from your reply,  and I suspect that neither are you (yet),  whether the water is coming in between the case and the hog,  or between the hog and the plywood.   I think further investigation is needed to determine this.   I would suggest,  if convenient,  that this is best done by getting the boat absolutely dry inside and then floating her.    Then absolutely as soon as she goes in the water look to see where the water comes in;   is it above or below the hog?    If necessary,  mop out the first bit of water than comes in and observe again.   But you will need to observe the very start of the flow;  once you have enough water in the bottom to cover the hog it is too late to see where it is coming in.

     

     

    <span style=”text-decoration: underline;”>If leak is between case and hog:</span>

    The detail of construction varies slightly between different boats,  and you won’t know what the detail is on yours without taking her apart!    But for a boat of this age <span style=”text-decoration: underline;”>expect</span> to find the case bedded down onto Prestik tape or similar soft flexible bedding material,  pulled down onto it by a number of large woodscrews driven upwards through the ply and the hog (the longitudinal structural timber  –  the “plank”  –  on the inside,  between case and plywood).   Whether those screws also pass through the keel (the hardwood on the outside of the plywood),  or whether they lie underneath it and at least a section of the keel has to be taken off before you can gain access,  seems to have varied between builders.

     

    Given that the original construction relied on screws for mechanical strength,  and a soft semi-sticky bedding compound for sealing,  and given also that you now have a failure of that seal and that the wood is wet,  I do not think that epoxy has any fair chance of making a secure bond if you do the repair in situ.   That is why I recommended a polysulphide sealant for an attempt at an in  situ repair;   this may or may not work,  but it is worth a try.

     

    If of course you do decide to take the case out,  then (and only then) epoxy becomes an excellent choice for refitting it,  with everything cleaned up first,  and any rotten wood cut out and replaced.    But at this present stage I understand that you are hoping to effect at least a good temporary repair (good for a few years) without  the need to take the case out.

     

     

    <span style=”text-decoration: underline;”>If leakage is between plywood and hog:</span>

     

    I have never personally met this problem,  although it is a known problem around the mast step as a result of either rot or excessive strain arising from too much rig tension.   When the boat was designed,  in 1949,  today’s ultra-high rig tensions were unknown,  so the boat was never designed to accommodate them.    The static load alone,  before the wind loading even starts,  results in a downward force of somewhere around half a tonne force (from memory;   I am not re-doing the calculation at this point) on the mast step at the maximum rig tensions in common use.

     

    If that is the problem,  then a different solution will be needed,  and it will almost certainly include doing the approved mast step conversion.   This is designed to strengthen the area around the mast step,  by spreading the load,  in order to allow modern rig tensions to be used,  but it is also a recommended structural upgrade whenever one is doing a repair to structural damage or rot in this area.

     

    I realise that this is not yet a definitive answer,  because we still need to establish the diagnosis more firmly,  but I hope it helps.

     

     

    Oliver

     

Viewing 15 posts - 676 through 690 (of 708 total)