Replace plywood bottom

GP14 Sailing Forums Forum Replace plywood bottom

This topic contains 56 replies, has 5 voices, and was last updated by  Taffymat 1 week, 6 days ago.

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  • #19031

    Taffymat
    Participant

    Hi,

    Has anybody here ever replaced the 2x centre plywood sheets on a GP14? I’m thinking of joining it into the original ply somewhere near the mast area, then working aft, approx 4ft.

    I’m wondering how difficult a task it might be to release and refit the boards at centre hog.

    Regards

    Matt

  • #19032

    steve13003
    Participant

    Hi,

    i have replaced several panels on various GPs.  Is your boat a Series 1 boat with buoyancy bags? Up to hull number about 13200 or a newer Series 2 boat with buoyancy under the floor?  First I would buy a set of the construction plans from the Association office, for which ever type of boat you have, this will let you see how the bottom panels and the keel are constructed.

    The keel piece is fitted after the bottom panels are fitted, so to remove then one would normally remove a section of the keel so that the ply can be removed and the new ply fitted to the hog ( the inner part of the keel).  The ply can be replaced between any of the frames I would normally identify the position of the frame and cut through the ply along the middle of the frame so that the existing ply panel and the new ply are supported on the frame, you could also try a half joint where you taper the old and new ply over a length of about 50 to 75mm over a frame.  All new ply and joints should be made using SP epoxy 106 resin and fillers and all new wood coated with epoxy to ensure no further rotting. After fitting the new bottom panels refit the keel .

    what you are planning is not an easy job but is not impossible providing you have a good work space under cover if possible.

    Good luck and let us know how you go.

  • #19033

    Taffymat
    Participant

    Steve, many thanks for that. I can’t find the construction plans on here anywhere? I’ll try and contact them directly to ask for a copy.

    Yes, you are indeed correct a mk1 “12960”. She’s in a rather sorry state atm.

    Removing the keel sounds like it would be a nightmare? I’m going to take another look later on in that case and see if I can come up with an alternative plan.

    I’ll post some pics later, but I did wonder if the plywood sat tight against the mahogany strip that runs the interior length of the boat? If that piece were indeed chamfered and shaped tightly along its length, then I could cut the plywood short of the keel, and epoxy straight to that instead?

    Regards

    Matt

  • #19035

    steve13003
    Participant

    Matt,

    i have dug out my copy of the plans and on Sheet 3 of 4 the keel to hog bottom ply detail shows the ply under the keel but there should be enough width in the hog, the inner part to clean off the bottom panel and fit it to the hog without removing the keel.  I would check the width of the hog along the part you want to replace to see how much of the hog you will have as the landing for your new ply.  You will also need to remove the bilge keels, these screw through into the frames.  Along the chine the bottom ply is screw glued to the inner chine stringer and the outer chine piece sits in a notch and is planed down to match the bottom ply.  You may need to replace part of the outer chine piece just depends on how cleanly you can remove the old ply, it may be best to cut into the inner chine stringer and refinish the outer chine piece to match the new ply.

    if you get stuck for buying a set of plans I do have a set of my own which I could trace the details for you, email me at [email protected] if that helps

    Steve

  • #19045

    Taffymat
    Participant

    Steve,
    <p style=”text-align: left;”>That’s really helpful thanks. I’ve also today been offered a grp hull only as a quick fix. Is that a feasible swap do you know? i.e. swap mast and all fittings over?</p>
    Cheers

    Matt

  • #19068

    Taffymat
    Participant

    Thank you so far to everybody for your help.

    I have just completed a membership form, as clearly this website, and you guys are going to be massively helpful to me moving forward! I really appreciate your help.

    Can I please run through my repair plan of MK1 (12960) wooden hull, and see if anybody has anything to improve or object to? It’s a bit longwinded sorry!!

    I intend to replace the floor section from frame 2(mast foot), through to frame 7 (8ft in length)

    1- Get boat under-cover, lay 2 car tyres on the floor alongside boat, and using a helper roll boat onto it’s side, then fully over into inverted position. Support the upturned hull in several places on blocks & stands.

    2- Cut old ply bottom out alongside keel strip (keel strip seems to be epoxied into place. I think a lot of damage will occur if I try to remove it?). This should leave approx 25mm of hog exposed in order to attach new ply base to.

    3- Mark position of frames underneath the hull. Remove any screws, use a router to remove the ply thickness and epoxy down to the frame below.

    4- Use the router with edge guide to machine away the ply base, up to the chine edge. Remove the plywood bottom. Strip varnish from sides of chine strip, hog, and frames.

    5- Repair any damaged frames with sapele scarfed & epoxied into place. Replace the stringer along the 8ft length each side with new “obeche” timber to same dimensions, scarfed & epoxied into place. Replace external rubbing strakes “bilge keels?” with new timber “ash or obeche?”

    6- Prepare an 8:1 scarf joint midway across the frames no2 & no7.

    7- Coat plywood in Epoxy internally & externally. Epoxy and stainless screw the new 6mm “Robbins elite” plywood hull bottom into place using scarfed & epoxied joints at frame no2 & no7, these scarfed joints are then screwed into centre of frames.

    8- Epoxy tape any joints onto frames, keel, hog, and the exterior of the chine.

    9- Paint it, re-assemble it and enjoy it?

     

    Any suggestions, or critique are gratefully received! 🙂

    Many thanks again

    Matt

     

     

    • This reply was modified 2 months, 3 weeks ago by  Taffymat.
    • #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

  • #19070

    Chris
    Participant

    1) Use something hard for your bilge keels. Obeche is too soft.

    2) You’ll want to fillet your joints, glass tape can trap moisture which then cant escape. fillets are stronger.

    3) it might be worth drilling some holes into the keel to see what the core sample is like. If its dry and doesn’t want to come off leave well alone. if its wet then its worth encouraging it to come off. Wet and rotten are not the same thing, the front 3ft of keel on mine was absolutely saturated with water. I took it off, dried it, and replaced the same wood. I then plugged the holes with some mahogany. Its. better safe than sorry here as water can bleed down the ply and degrade the glue joints to the structural frames. Epoxy is better, but it still happens and you’d be surprised at how much cascamite is used in boats that you’d automatically assume are epoxy throughout.

  • #19072

    Taffymat
    Participant

    Thanks Chris, I’ll get ash laths made for the bilge keeps then?

    Does Obeche look similar to ash? The interior stringers look like ash to me? But they could well be obeche if it looks similar?

    Fillets only, great stuff. Less work for me!😁

    I’ll definitely check everywhere for moisture..

     

    How do I know if I have mast step conversion already?

     

    Cheers, Matt.

  • #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

  • #19074

    Chris
    Participant

    ash and obeche are not dissimilar in colour once aged a bit, both are a paleish yellow. Ash has a more obvious grain pattern. The stringers *might* I suppose be ash, its not especially heavy and a GP is a heavy boat but I’ve yet to see a 12xxx numbered hull with anything other than obeche stringers.

    Obeche is also significantly more prone to rot, so I’d say if they’re rotten they’re almost certainly obeche. We had a similar quandary with the stem on my boat which was very rotten and we couldn’t decide between the two – Alistair confirmed it was obeche.

  • #19092

    Taffymat
    Participant

    Oliver,

    Thank you yet again. Your suggestion of a simpler joint is greatly welcomed. I was concerned about the feasibility of a uniform scarf joint in situ.

    My initial thoughts of making the scarf joint midway on a frame, was in order to screw through the joint, and into the frame as a means of clamping it together and forming the correct shape.

    I could actually move slightly farther towards the stern, and make a lap joint with a backing piece. The hull has less shape here, so it would be a simpler task. A 75mm x 6mm ply backing strip would be ok, I think?

    Can I ask, is there somewhere I am able to find some guidelines as to what an acceptable minimum bonding surface width would be? Say X times material thickness?

    Thanks again

  • #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

  • #19141

    Taffymat
    Participant

    A little update for you guys…. I’ve stripped the top deck, and applied epoxy. Shes looking better already.

    I’m going to turn her upside down this week, and start on the bottom.

    Anybody know if it’s ok to use to paint stripper to remove the paint on the underside? The underside has already been deposited, and I’d rather not remove the epoxy that with the heat gun. The paint is failing with solvent pop. That’s why I want to remove it. I assume the stripper wont damage the epoxy?

    I’m trying to figure out how to add pics!

  • #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

  • #19143

    Taffymat
    Participant

    Thanks Oliver..

    Hopefully the pics worked this time. Hopefully you approve of works so far.

    I know of a commercial paint company, i use through work, so I may give them a call about stripper tomorrow. Ill revert back to Nitromors tho if needed. Glad to hear it’ll not likely harm the epoxy. Seems a waste to strip it all off.

    I’ve also got one of the tungsten pull-scrapers. Fantastic bit of kit.

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  • #19146

    Oliver Shaw
    Moderator

    She is looking good.

    Well done.

     

    Oliver

  • #19167

    Taffymat
    Participant

    Ok… so I took the plunge today!!!

    Scary stuff!!

    Bottom panels removed. 😬

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  • #19170

    Chris
    Participant

    Looks good – and not an especially bad job on one of these. I think making the patch bigger makes it easier to be honest.

    Keep it up – the boat looks well worth saving.

  • #19171

    Taffymat
    Participant

    Thanks Chris.

    I agree its far easier to do these two large patches than several smaller repairs.

    My only concern at the minute is how to curve the ply down onto the chine towards the bow. I thought I’d managed to avoid the worst of the curvature.

    I’m rather enjoying the project more than I thought too.

  • #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

  • #19173

    Taffymat
    Participant

    Chris,

    Any tips for removing a section of the keel? I’ve been back to the boat tonight and scraped away a little. Theres a suspicious looking repair that I’d like to take a look at.

    Would a simple straight but joint be ok, as it will be backed up on the hog? I’m thinking of cutting it at the centreboard slot, and working 400mm forward. I cant see any screws from inside because of the mast step etc.

    Thanks, Matt.

     

  • #19174

    Taffymat
    Participant

    Thanks Oliver,

    I had no idea the GP was launched at Aberdyfi. That was actually going to be one of my first destinations with it!

    I’ve got a week off next week, so hopefully I’ll make some good progress.

    Matt

  • #19175

    Taffymat
    Participant

    Oliver,

    Sorry, I meant to ask you also if you’d had any experience or suggestions for removing a section of keel strip?
    <p style=”text-align: left;”>Cheers,  Matt</p>

  • #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

  • #19177

    Chris
    Participant

    Basically with the bands off if it falls off its got to come off! Beyond that the glue join will be degraded so gentle encouragement should see the borderline wood come away. If you are towards the ends of the boat I’d go all the way.

    Mine was at the bow and wasn’t actually rotten, just extremely wet. I drilled holes in it to establish the extent of the wet timber, cut at an angle (Not especially steep) and used a wide chisel to remove the section which was just over a foot. The only things holding it on were paint and nails, the glue had gone completely.

    Re assembly was the reverse of removal and I used the same wood – once dry it was fine. I filled the core sample holes with plugs from an old GP side bench (Rotten mk1 GPs are an excellent source of good quality hardwood).

  • #19178

    Chris
    Participant

    What I should also say is that you’re not just removing the keel to dry and replace the keel. What is underneath is actually far more important and fiddly to repair if it goes wrong. That was why I took the keel off mine, it was wet, not rotten and would have dried on its own in a week or three. What was underneath the keel however was also sodden and would have taken many months to dry. Also I was unaware of it until the keel was off and by now it would probably have rotted the play out again and we’d have been back to square one.

    I’m a big believer in only doing this sort of work once!

  • #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

  • #19180

    Taffymat
    Participant

    Thanks both….

    I’m thinking that I’m going to regret it! But I’ll have a crack at removing it as my first job next week.😫.. I was hoping all my disassembly was complete.

    Cheers, Matt

     

  • #19185

    Taffymat
    Participant

    Ok, keel removed! Forgot my phone though, so no pics yet.

    It did come away easier than I feared. All was good underneath, and I will replace the section that was removed. There was a dodgy looking repair made of 6 pieces over an 8 inch section!

    I’ve also decided to cut another 2ft out from the smaller repair side. One of the Andersen bailers has caused the bottom of the boat to crack at the corner of the cutout. It rests on the trolley at that point. Seems strange to me that a marine component is designed without radiused corners!

    Lots pics next week. I’ve booked the week off work for re-assembly.

  • #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

  • #19223

    Taffymat
    Participant

    A little update for anybody that may be interested?

    I had the week off work last week, so have made some real progress.

    Ended up making the smaller panel the same size because of a few issues I discovered once the paint was removed.

    Final gloss coat goes on Wednesday. Then flip her over, sand and varnish the interior and deck.

    • This reply was modified 1 month, 2 weeks ago by  Taffymat.
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  • #19240

    Oliver Shaw
    Moderator

    Port self-bailer looks further forward than starboard one;   that imbalance is bound to slow you down at least 3%  …

    (Only kidding.)

    Very well done so far.

     

    Oliver

  • #19243

    Taffymat
    Participant

    Ha, thanks Oliver.. I think it’s to do with not maintaining the aspect ratio when I’ve reduced the image.

    They’re definitely parallel. Thanks for all your help so far Oliver. I’d have probably wimped out of this without words of encouragement from you guys.

  • #19244

    Chris
    Participant

    Ive just picked up a Duffin Mk1 13063 thats destined for the bonfire. Case, hog and floor rotten. The rest of it looks very good, it looked great until the floorboards came out! Its been left with the water pooled around closed bailers which I suspect is what happened to yours too.

    I did wonder if there’d be any takers for it as a Mk2 conversion but I doubt it. Shame.

  • #19330

    Taffymat
    Participant

    <p style=”text-align: left;”>Ok… progress is still being made.</p>
    I’ll post more pics soon. Most of my work is after work, by headtorch at the minute.  So difficult to get worthwhile pics.

    Hoping to finish varnishing this weekend, and re-assembly later on next week.

    Being new to sailing, and only ever sailed double skinned, plastic boats. Something that’s been bugging me is how to effect an acceptable water tightness on the transom flaps? and how much of a nightmare is it to get back under way following a capsize in a boat relying on buoyancy bags? Albeit, I do have the watertight bulkhead at the bow. I’m imaging that there will be a massive amount of water within the cockpit once righted?

    Many thanks again for your help.

    Regards

    Matt

  • #19331

    Chris
    Participant

    the best stuff to use is 1mm Lexan. You’ll get it off eBay, just watch the size and make sure it’s big enough. No hinges are required with this stuff and the best way is to use one piece to cover both holes I think. You can cut it with good scissors or a band saw.

    Generally if these are leaking its because you’re sitting too far back in the boat.

  • #19335

    Taffymat
    Participant

    Chris,

     

    That sounds like a good way forward with those. Are they screwed on the side if the holes as before? Do you have any pics of this setup please?

    If I dont use a hinge do i still need a bungee cord to keep them shut, or would I rely on its natural tendency to flex.

    Cheers

    Matt

  • #19336

    Oliver Shaw
    Moderator

    My limited experience of capsizing series 1 boats back in the sixties is that after a capsize you can expect them to come up half full of water.   Transom scuppers were introduced to deal with this problem.   Most of my personal experience was with a boat with buoyancy bags throughout,  including the bow,  and one thing that I learned from a deliberate experiment in flooding the boat is that you need the maximum possible bow bouyancy to enable the transom scuppers to do their job.   If you have just the minimum bow buoyancy permitted,  as I had when I tried this experiment,  when you come to sheet in to attempt to sail her dry there is a real rik that she will instead simply submarine.

    However if you have the maximum possible reserve bouyancy,  including a bult-in bow tank and the largest possible side and quarters buoyancy bags,   that is a very different situation,  and I am prepared to accept that the transom scuppers may well then work well.   You have the benefit of at least the built-in bow tank,  and I would recommend that you fit the largest buoyancy bags that will physically fit under the side benches and in the quarters.

    In my case,  in the sixties,  having cut the transom scuppers I never then used them for real.   In the light of my experiment I did fit the largest bow bag that I could get into the space,  and I carried a plastic bucket;   following a capsize I would then use the bucket to bail about half the water out before using the self-bailers to sail her dry.     When I later had another series 1 boat early in the Millenium,  which did have a bow tank plus seriously large buoyancy bags,  the opportunity to see how well the transom scuppers worked never arose.

     

    Oliver

  • #19341

    Chris
    Participant

    I’d probably make the flaps out of one piece and secure in the middle – the rudder retraining clip would be an adequate fixing point. They’d look like a figure on 8 on its side.

    As for in use the last time I capsized a mk 1 GP was many years ago in a boat with a bow bag. I dont recall the flaps being much use. A bow tank is not only more buoyant, it keeps the water from sloshing all round the boat and this is vital to getting the flaps to work. I think in a bow tank boat they’ll work pretty well.

    I think 2x 36×12 bags in the back and 2x 34×9 under the benches was standard. But its been a while!

  • #19358

    Taffymat
    Participant

    Thanks both… I’m pretty sure it has plenty of capacity in the buoyancy bags too. The sizes of them I’ll check next week. They are tucked away in works attic currently.

    I had a feeling that the bow bulkhead would make make life easier.

    At the rear, I’m going to take a look at the 1mm Lexan option for sure.

     

    Thanks again

    Matt

  • #19359

    Oliver Shaw
    Moderator

    Once you are ready,  you don’t need to necessarily capsize in order to test the system.

    Choose a day when there is a decent wind,  around force 4.   (Anything less,  and you have no right to be inadvertently capsized anyway).

    Choose favourable conditions,  and/or ask your club safety boat to stand by.

    Then sit stationary in the water,  open the transom flaps,  and allow her to flood.

    Then sheet in on a beam or broad reach,  and attempt to sail her dry.

    Either it will work,  or it won’t.   But at least you will know.  And if you choose suitable conditions and/or have a safety boat standing by you will not be at any risk.

    With generous reserve buoyancy I would hope,  and cautiously expect,  that it would work;   but it would be good to know for sure.

     

    Oliver

     

  • #19364

    norman
    Participant

    Take Oliver’s advice and carry a bucket.  Sod’s law states that the force 4 which tips you over could drop to 2 or less when you need to sail it dry.  I would also retain a bungee to keep the flaps closed.

    Norman

  • #19365

    Oliver Shaw
    Moderator

    It has been said that one of the fastest methods of all to remove water from inside a boat involves a frightened man with a bucket …

     

    Oliver

  • #19389

    Taffymat
    Participant

    Great,

    Thanks for that idea of flooding the hull. I had indeed intended to capsize her. But I’ll take your idea for sure!

    Can I ask a few more snippets of advice please?

    I’ve found a little wooden tee-shaped piece of wood. If seems purposely dimensioned, so I assumed it is a tool or gauge. Have you any suggestion?

    Also, any ideas where I can purchase a spring to repair this cam-cleat please? It’s off of a HA/4274 unit.

    I’m hoping for a test run next week on Bala lake.

    Cheers,  Matt.

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  • #19393

    Oliver Shaw
    Moderator

    T-shaped piece of wood:  so idea.   Sorry.

    Cam cleat;  these can usually be stripped and cleaned,  but to the best of my knowledge the individual parts are not normally marketed.    However the cost of replacing the complete fitting with new is not exhorbitant.

    “Back in the day”  –  i.e. c. 1970,  when I had Barton cam cleats for the genoa sheets (rather larger than your ones) the plastic jaws were softer than I hope modern ones are,  and in seriously competitive racing the teeth wore out quite frequently.   But in those days the manufacturer did market replacement jaws,  and I used to get through about two sets per season.  However I am sure that those days are long gone.

     

    Oliver

  • #19395

    Chris
    Participant

    Those are Harken ones. You can get the springs, I think P&B do them. If they don’t give Harken themselves a call and see if they’ll help.

    The whole fitting is actually quite expensive compared to most but they are very, very good and well worth keeping.

  • #19397

    Oliver Shaw
    Moderator

    We live and learn;   I am happy to stand corrected.

     

    Oliver

  • #19399

    Chris
    Participant

    I’ve just checked, they’re part no HSB56 and readily available.

    About £3

    Unusual these days!

  • #19400

    Chris
    Participant

    piece of wood could be a (very) thin mast gate chock.

  • #19401

    Taffymat
    Participant

    Many many thanks to you both!! Chris  that’s fantastic,  I had found that you could buy Harken spares, but I had assumed it was an Allen cleat.

    That’s extremely helpful of.you to find that for me. Looks like I have a 150 cleat then. Glad you found that for me, they’re nearly £50 to replace the unit!!!

    I’m heading over to the boat in the morning,  I’ll see if it fits in the mast slot. I’ve just got to re-fit the floorboards, address the transom flaps, and shes all done!!😁

    Wahoo

  • #19402

    Chris
    Participant

    Looking again at the wood the grain is running in an odd direction for a hardwood chock. This implies that it was once plywood, has been marinading in the bottom of the boat for ages, has delaminated and fallen apart. Most GP chocks are about 8mm I think. I made mine out of tufnol. If you use that as a pattern I would significantly reduce the size of the T as it’ll get caught on the Genoa sheets.

    If for any reason you can’t resurrect the cleat the Harken ones knock spots off all the others and are well worth the extra cost.

    • This reply was modified 3 weeks, 5 days ago by  Chris.
  • #19418

    Taffymat
    Participant

    Good evening!!!

    Well, thanks to the help from you guys, another repaired GP14 took to the water today. Llyn Brenig to be exact. There wasnt much wind about, but that was perfect for me to start trying to figure everything out.

    It was brilliant to test her out today, and I’m still feeling very pleased with all the work that went into it. The advice on here has been invaluable!

    Big thanks yet again.

    Matt

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  • #19422

    Oliver Shaw
    Moderator

    Glad it went so well.

    She looks to have been well worth saving;   and as an added bonus you will have expanded your own skill set and will have more confidence for any future repairs.

     

    Oliver

  • #19425

    Taffymat
    Participant

    Oliver,

     

    Thanks, I’m feeling pretty pleased with myself! 😁

    Is there an easy way for me to determine the builder? I’ve noticed the woodwork is a different style to others in the club.

    Regards

    Matt

  • #19426

    Chris
    Participant

    Its a Duffin hull.

    Well worth saving, well done!

  • #19429

    Taffymat
    Participant

    Wow, thanks Chris. You clearly know your stuff!😁.

    Thanks again everybody for your help.

    Matt

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