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Viewing 15 posts - 31 through 45 (of 701 total)
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  • Oliver Shaw
    Moderator

    Michael

    You asked a question, and I posted a reply four days ago, but you don’t seem to have seen it!

    I hope the reply was helpful to you.

     

    Oliver

    Oliver Shaw
    Moderator

    Sorry,  but I am not entirely clear what set-up you have,  beyond that you are asking about genoa sheeting and that you have through-deck sheeting.   Through-deck sheeting has benefits in terms of seating comfort,  but in my experience it does tend to suffer more friction than the older on-deck system.

    Photos would be helpful,  please;  and specifically showing all the relevant blocks,  fairleads,  cleat,  etc..

    I have once seen (on Ian Sinclair’s boat) an impressive three-block system beneath the decks,  and that looks to be a good arrangement for minimising friction,  but I have never sailed with that arrangement.   I did at one point buy the fittings to rig that up on A Capella,  but then never got round to fitting it,  because my modified tacking technique (see below) proved to be a satisfactory solution to the friction problem.

    However at a simpler level there are two easy things to try first.   First is to possibly use a thinner rope for the sheet,  and choose the rope for its flexibility and ease of handling rather than for ultimate strength,  as whatever you choose the strength is likely to still be ample.   The thinking here is that thinner and more flexible rope will render through the blocks (etc.) more readily;   but the downside is that thin rope becomes uncomfortable to hold and to pull in when there is any strain on it,  so you are likely to end up choosing a compromise.   I would expect that you are most probably currently using 8 mm diameter;   perhaps try going down to 7mm or even perhaps 6 mm diameter for minimising friction,  although you may prefer significantly larger diameter for comfort in stronger winds;    one compromise may be to switch between light-weather and heavy-weather sheets according to conditions on the day.

    The other thing to try is to adapt your sailing technique slightly to compensate for the friction.  On A Capella I have through-deck sheeting,  and I deliberately chose 10 mm rope for comfort,  which is significantly fatter than most owners choose,  and especially so for use with through-deck sheeting.   This large size is comfortable,  but does result in modest friction,  which is not normally a problem,  except that it becomes acute in the old (lazy) sheet immediately after tacking  –  and I have a solution to that problem.

    The lazy sheet,  i.e. the one on the new windward side,  leaves the fairlead  –  where it experiences slight friction  –  and then has to bend slightly as it goes round the shroud.   Although that bend is very slight it nonetheless exists,  and it causes further friction,  which multiplies the tension in the sheet by a function of the angle through which the sheet turns at that point.   Then the sheet,  now under slightly increased tension,  has to bend around the mast;   which introduces yet more friction,  and especially so as the sheet is already being “tailed” as it rounds the mast by the pull arising from the shroud,  and that in turn is “tailed” by the rope coming from the fairlead.   Then,  when the genoa is moderately hard in (so that its clew is abaft the lee shroud),  the sheet  –  by now under significant tension  –  has to bend around the lee shroud,  multiplying the tension yet further.   Think of how sheet winches on yachts work,  or ships’ mooring bollards on a quayside.    Because the friction is multiplied rather than just added,  it increases exponentially with angle.

    The end result,  in a GP14,  is that this slight friction at the fairlead,  multiplied when the sheet bends round the weather shroud,  and further multiplied when it bends round the mast,  and multiplied yet further when it bends round the lee shroud,  can result in so much tension in the lazy sheet by the time it reaches the clew that it can make it difficult (and sometimes impossible) to pull the genoa fully home.

    My solution to this problem is easy,  once your crew gets used to it,  but it does require a slightly modified tacking technique.    As the boat tacks through the wind the crew physically “overhauls” the old sheet,   i.e. he/she pulls some of the sheet out from the fairlead so as to give plenty of slack,  so that there is no question of the lazy sheet being still under tension.   This is done as a matter of routine,  every time the boat tacks,  and one soon gets into the way of always doing it.    And even when sailing single-handed,  which for myself is probably nowadays the majority of the time,  I still routinely do it on every tack.

    And with that slight modification to tacking technique,  A Capella sails very happily with 10 mm diameter genoa sheets,  sized for comfort.

    Hope this helps.

     

    Oliver

    in reply to: Boat Repairs – MK1 #26383
    Oliver Shaw
    Moderator

    Will try to measure up for the keel sometime;   but it is moderately unlikely to be convenient tomorrow,  and if not done tomorrow I am then away for a week.

    If no-one else comes up with dimensions feel free to remind me in about a week’s time.

     

     

    Oliver

     

    in reply to: Boat Repairs – MK1 #26380
    Oliver Shaw
    Moderator

    That is a good technique that Chris describes,  always provided that you can avoid voids between the two layers of ply,  and I am sure that he paid due attention to that point.

    And staggered butt joints remind me that I have twice in my younger days repaired rot in Firefly dinghies by laminating up thin narrow hardwood strips in crossing diagonal layers,  I think three layers.    If the first layer is thin enough,  and the strips narrow enough,  it is reasonably easy to get them into a fair curve.    Once they are bonded in and the glue cured they provide a reasonably stable surface for laying up the second (diagonally crossing) layer on top of them;   and once that layer is cured you have a good firm surface to lay up the third and final layer.   That method would seem to be adaptable for the forefoot on a GP14,  and it is effectively laminating up plywood in situ.

    I fully concur with reinstating the bulkhead “even for cruising”;   particularly if taken to full height it achieves far more buoyancy than is normally achievable with bags,  and in the event of capsize that additional buoyancy is highly desirable!   The minimum buoyancy required for class rues is just that  –  a bare minimum;   it will enable the boat to be righted,  and bailed out by means of a large bucket,  but it will not make life easy!   Certainly if one wants the transom scuppers to do their job properly it is desirable to maximise the buoyancy in the boat,  and particularly that in the bows.

    Even with a full bulkhead you can still use the enclosed space for stowage;    just fit nice large waterproof access hatches.    Mine on A Capella are nearly a foot in diameter.

    Again I concur with coating everything with epoxy before painting or varnishing.    It might be worth considering Smith’s CPES,  a wood-based epoxy originally designed for treating rotted wood but also increasingly used as a varnish primer.    I have been using it for about the last 12 months,  and am pleased with the results,   although a longer period will be needed to fully evaluate how effective it is in the durability stakes.

    Incidentally if the bow region is to be totally enclosed by a bulkhead it won’t normally be seen,  so you might wish to consider using paint rather than varnish;   it is probably more durable.

    Hope this helps,

     

    Oliver

    in reply to: Boat Repairs – MK1 #26371
    Oliver Shaw
    Moderator

    UPDATE re plywood thicknesses:     you may actually be in luck.

    On checking,  I see that your sail number dates from 1986,  so it seems likely that your boat may be just young enough to have been built with metric plywood.    One website states that plywood has been made in metric sizes since 1978.

    So that may be one problem solved.

    You appear to be on a roll!

     

    Oliver

    in reply to: Boat Repairs – MK1 #26370
    Oliver Shaw
    Moderator

    As a final P.S.;   on a matter of nomenclature,  your boat is a Series 1,  not a Mk 1.     Mark 1 (and II,  III,  IV and IVa) were designators for successive models of early glassfibre boats,  and I am sure you wouldn’t want her to be confused with her GRP sisters  –  especially as you appear to be sufficient of a craftsman and enthusiast to specifically enjoy the wood.

    This is something that many owners are not aware of!

     

    Oliver

    in reply to: Boat Repairs – MK1 #26369
    Oliver Shaw
    Moderator

    It appears from the second set of photos that the damage extends right to the forefoot.

    Although I have never had the misfortune to need to work on this area,  I understand from my reading of the Bell Woodworking book and also seeing Searson Thompson’s film around 15 years ago that this one area is the most difficult part of the entire boat to fit,  because the plywood is forced into a curvature that is just about on the very limit of what it will accept.   According to Bell’s,  their technique was to first secure the ply abaft this region,  and then pour a kettle of boiling water over the ply where it is required to bend so severely,  in order to soften it.

    Link to the copy of the book on this site here,   see page 9.    This page also gives some potentially useful ideas on marking and cutting this area to shape,  and also on the change of bevel at the chine in this area.

    An adaptation of that technique might be a way forward for this apparently very difficult part of the job.

    Hope this helps.

     

    Oliver

    • This reply was modified 6 months, 1 week ago by Oliver Shaw. Reason: Inclusion of link to relevant page in the Bell Woodworking book
    in reply to: Boat Repairs – MK1 #26368
    Oliver Shaw
    Moderator

    If you decide on butt joints it is worth considering whether you can use the existing framing to back up at least some of those joints,  at least in part;  and then consider taking the joint a little further outwards from the hole in order to use those structures.    An obvious example is of course the hog,  which is amply wide enough.    At the other extreme,  the (lateral) frames are almost certainly not wide enough,  unless you bond in additional pieces as “sisters” to the faces of the frames in order to provide a greater thickness (fore-and-aft).   Between these two extremes,  the (longitudinal) stringer is narrower than I would wish for use as a backing piece,  but it might make the basis of a backing pad if then further beefed up with judicious use (two or three layers) of woven glass cloth and epoxy over the stringer and extending onto the plywood for at least an inch (and I suggest two inches would be better) either side of the stringer.

    Given the extent of the work involved,  it is worth considering the question whether it might be both easier and more satisfactory to replace the full width of the panel from hog to chine piece,  for the requisite length.    It is difficult to judge from the photos,  but it is worth seriously asking the question.

    One further point to follow.

     

    Oliver

    in reply to: Boat Repairs – MK1 #26367
    Oliver Shaw
    Moderator

    I don’t know whether to be concerned,  or to stand in awe and admiration,  at your intention to use scarf joints.

    A single scarf joint is reasonably easy,   and with reasonable care a good job can be made.   Of course the two gradients need to be a perfect match,  but the precise location of the join is immaterial.

    A pair of matching scarf joints is significantly more difficult,   because (on a typically 12:1 gradient) a slight difference in the amount of wood you shave off the bevel shifts the joint laterally by 12 times that amount;   and if you are trying to slot a graving piece into a gap in such a way that the base of it sits flush and the length is an exact match to the gap this requires some very delicate fitting.     It is easier if both faces are accessible to the plane,  so that you can use slightly thicker wood for the infill,  and then plane both surfaces to get them flush;   but all too often the “inside” surface is inaccessible because part of the structure of the boat is in the way.     I have successfully done a few of these,  on a variety of boats,  when replacing damaged sections of rubbing strake,  and I have been pleased and satisfied with the results;   but I regard them as a demanding test of my skills,  and about the limit of what I can successfully achieve.

    Trying to do four matching scarf joints around the edges of a rectangle is a whole new challenge.   The requirement is,  of course,  to get all four joints neat,  and with the infill piece sitting at exactly the right height,  and with no visible gap around any of the edges;  and moreover to achieve this on a curved surface.    I am sure that the professionals can achieve it,   but when I tried it for two deck infills on my vintage boat I eventually gave up and settled instead for neat butt joints with a backing pad underneath.

    If you are up for the challenge,  and confident that you can make a success of it,  I stand in awe;   but if in doubt you might consider butt joints suitably backed on the inside.

    More to follow.

     

    Oliver

    in reply to: Boat Repairs – MK1 #26366
    Oliver Shaw
    Moderator

    Well done thus far!

    One problem that you will very probably find is matching the thickness of the plywood.    It is likely that your boat would have been built with plywood to an imperial thickness,   somewhere around 1/4-inch (equivalent to 6.35 mm,  but that is not of course a standard modern thickness);   3/16-inch (equivalent to 4.76 mm) seems perhaps a little too light  –  and certainly slightly less than the current class minimum,  and I don’t remember whether 7/32-inch was ever offered.   Your replacement will almost certainly have to be metric thickness,  either 5 mm or 6 mm.

    You suggest 4 mm,  but that is definitely too thin,  with 5 mm being the class minimum,  and since you say that you intend to use the boat for cruising and make no mention of racing I would prioritise strength over weight-saving.  So although I think on balance that 5 mm is probably the one to go for,  I recommend that you at least consider 6 mm,  but be guided by the thickness of the original.

    Whichever thickness you choose will probably not be an exact match.    For your use of the boat I recommend fairing in the change in thickness along the edges of the join;   this can be done by a combination of planing and sanding what stands slightly proud,  plus filling (use a 2-part epoxy filler) what is slightly recessed.    The alternative  –  of choosing a thickness slightly more than the original and then thinning it to a precise match before fitting  –  is not worth the enormous effort involved,  unless perhaps you have access to an industrial thicknessing machine;   and even with such a machine,  this approach might result in unsuitable cross-grain on the inside surface.

    More to follow in a separate response.

     

    Oliver

    in reply to: Boat Repairs – MK1 #26365
    Oliver Shaw
    Moderator

    Don’t you just love it when you type a detailed response and then inadvertently lose the lot before submitting it!!!

    I have seen your query,  and have a response in mind;    I will try to get back to you later today with a second attempt!

     

     

    Oliver

    in reply to: Launch trolley cradle repair #26338
    Oliver Shaw
    Moderator

    Agreed the problem of the corroded support would seem to be a matter for your local welding engineer,  or possibly your local garage.    Be aware that the original is likely to have been galvanised,  and it will probably be impracticable to reinstate that galvanising;   the best you can do in that department is paint,  using a zinc-rich primer,  and then take the trouble to keep that paint in acceptable condition long term.

    But the initial enquiry was asking about the fibreglass cradle,   rather than the support.

    I suspect that you may need to deal with both issues.

     

    Oliver

    in reply to: Launch trolley cradle repair #26336
    Oliver Shaw
    Moderator

    I would expect that a new replacement cradle would be the easiest and probably the most satisfactory solution.

    A good starting point would be to ask all the trailer manufacturers who offer specific GP14 trailers whether they can offer a replacement front cradle.   A look at the photos on their websites will be an excellent guide as to whether they are your type of trolley.

    Manufacturers/retailers to try include Chris Brown (cbcoverstore),  Trident,  Sovereign,  Mersea Trailers,  West Mersea;   but please also do your own research online.   Many manufacturers’ specific GP14 trailers are near clones of the original (West Mersea?) design.

    However the design of the front cradle is much less critical than that of the main (aft/midships) cradle;   so you could also consider generic front cradles from any of the boat trailer manufacturers and/or retailers.   Again please do your own research online,  searching initially for “boat trailer manufacturers”;   but such names as Indespension,  SBS,  Mersea Trailers,  Extreme Trailers,  Snipe,  all come to mind.   Many trailer parts retailers,  and at least some manufacturers,  will offer parts.

    Hope this helps,

     

    Oliver

    in reply to: Adding reefs to a GP14 main sail. #26307
    Oliver Shaw
    Moderator

    I broadly concur with Steve’s response,  with the added comment that I personally would prefer to have the job done professionally,  and I would not expect it to cost the earth;    but you could ask your chosen sailmaker for a quote before you commit yourself.

    If you are supremely confident of your abilities and you have access to a heavy duty suitable sewing machine with zig-zag stitch,  then fine;   but unless you tick all the boxes in that department don’t take the risk of spoiling a good sail.

    And if you were thinking of doing the work on a clapped out sail it is probably never going to be satisfactory.

    I can warmly recommend Edge Sails,  who seem to be the preferred sailmaker for cruising sails in the class.

    Another option is to look for a good secondhand sail with reef points already fitted.   If you find one in good condition,  at the right price,  and especially if it is by Edge Sails,  snap it up.

    If you are having the work done on an existing sail,  or doing it yourself,  it would pay you to have a look at my paper on reefing systems,  in the Members’ Library,  which amongst other things suggests suitable depths for reef points.    I came upon these depths more or less by chance,  when I bought a cruising GP14 and thought that the depths of reefs were surprisingly deep,  but I very soon learned the wisdom of that arrangement,  and I replicated it when I ordered new sails for A Capella.   In effect they are a traditional second reef and third reef,  with no traditional first reef.

    When cruising,  you never need to optimise the amount of reef that you take in;   if you need to reef at all,  then make it plenty,  in the hopes that you won’t soon afterwards need to take in yet more.

    And even with these unusually deep reefs the boat still goes very well indeed.   There have been occasions when I have led the cruising fleet on a course to windward while sailing reefed,  with at least some other boats in the fleet sailing on full sail.   And I have occasionally had the boat planing hard under deep reefs,  equivalent to a traditional third reef,  on one occasion off Anglesey even having a close escort of a school of dolphins;   I think it likely that they were attracted to us because we were moving fast enough to interest them.

    Hope this helps,

     

    Oliver

    in reply to: Centre mainsheet? #26290
    Oliver Shaw
    Moderator

    It is also popular with some traditional classes;   “traditional” as in the traditions (albeit borrowed in some cases) from before the explosion of light dinghy classes in the fifties and sixties,  even though some of the classes using the system are actually much more recent.

    I met the inboard half of this system (although the attachment to the transom was block and tackle,  not twin tails) when I hired a Rebel class traditional 22-ft Broads racing dayboat for a day in the summer of last year.    I very much enjoyed the boat,  and as a dinghy-sailor-turned-yachtsman 22 ft is right in my comfort zone,  but was less enamoured of the sheeting system;   but I nonetheless found that within minutes I had got used to it.

    The biggest limitation in my eyes was that there was no means of cleating the mainsheet.   Alright,  in a dinghy the traditional dictum is that one never does that anyway,  although over the last twenty years or so centre sheeting with jammers seems to have come into the class,  and I confess that I nowadays like having the option.    But that option is based upon sufficient experience to be able to decide when  –  and when not  –  to cleat it.   And in the 20 years since I returned to GP14s (after several decades sailing almost exclusively yachts),  I have capsized a total of three times;  and two of those were when I couldn’t get the mainsheet out of the cleat quickly enough!

    (The other occasion was when I failed to allow for the inexperience of my trainee crew;   when we got a vicious header,  well offshore,  in about force 4 or 5,  I instinctively ordered “Tack”,  and expected him to release the genoa sheet as he moved across the boat.   He didn’t,  and over we went when the full genoa backed.   Had I allowed for his inexperience,  as I undoubtedly should have done,  I would have released it myself as I put the boat about.)

    But in larger sizes the ability to cleat the main is sometimes immensely useful.

     

     

    Oliver

Viewing 15 posts - 31 through 45 (of 701 total)