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Oliver ShawModerator
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
Oliver ShawModeratorWell 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
Oliver ShawModeratorDon’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
Oliver ShawModeratorAgreed 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
Oliver ShawModeratorI 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
Oliver ShawModeratorI 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
Oliver ShawModeratorIt 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
Oliver ShawModeratorI presume that the boat concerned is a GRP one.
Irrespective of the original method of securing them, I would be inclined to try taking advantage of modern materials, in the form of flexible sealant-adhesives. Silicone sealant is fairly ubiquitous, and I am sure would do the job; I have known other owners strongly recommend polysulphide sealant-adhesives; and I myself currently tend to favour CT1, a hybrid polymer sealant-adhesive https://www.ct1.com/our-products/ct1/. An internet search on the name CT1 will reveal plenty of retail stockists, or you could find their local distributor through their website.
Another very well-known brand is Sikaflex, and if I remember correctly they offer a variety of products, to suit different applications; so have a look at their website to choose the most appropriate product https://www.sika.com/en/brands/sikaflex.html.
As I see it, use of an adhesive of any of these types will enable you to bond the timber in place without needing to pierce the top of the buoyancy tank with screws, and hopefully the bond will be sufficiently secure for all normal use while at the same time being weak enough to allow you to remove the timber again in the future if you ever need to do so.
Hope this helps,
Oliver
Oliver ShawModeratorThe short answer to your first question is that transom sheeting tends to be the preferred system for cruising, and the twin tail system led ultimately to the centre tends to be preferred for racing. See the second post in this string for the reasons. There are some owners who regularly do both who have arranged their boats to be readily interchangeable between the two systems for that reason.
The second question is an engineering question, and if you consider the existing structure in standard format I very much suspect that the answer is no, but I am sure that it should be reasonably possible to beef it up sufficiently to take the load. There are two separate issues here; the first is making the top of the case strong enough to take the load – including transmitting it to the sides of the case, and that may perhaps be most easily achieved by spreading the load, while the second is giving sufficient grip for the screws or bolts. The latter is actually a separate question. Bear in mind that your centreboard case was never designed to take a sheet load, because that was not permitted in the Class Rules at the time your boat was built.
Cue now for someone with intimate knowledge of this part of the construction of Mk I and II GRP boats to step in, please. … …
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Failing that, I would assume that it is not currently strong enough, so you need to beef it up. It is a straightforward laminating task to add some more fibreglass, and personally I would use woven glass tape in preference to chopped strand mat, for both strength and appearance. Use epoxy resin, of a type specified for laminating, not polyester; the headline brand is WEST System, but there are others, and supplies are readily obtainable from most yacht and boat chandlers. Please be aware that the stuff sold by car accessory shops tends to be poyester resin, not epoxy, and this is NOT SUITABLE!
Although epoxy resin is significantly more expensive than polyester it is vastly stronger, so you don’t need as much of it, which goes some way to offsetting the higher cost. But much more importantly, polyester resin does not adhere well to most substrates, including not adhering well to cured substrates of the self-same resin, which is one reason why in manufacture it is laid up wet on wet; it adheres well to itself provided the substrate is not yet cured when it is applied. By contrast, epoxy resin is an excellent adhesive that adheres well to most materials, including to cured polyester resin. Your boat was built with polyester resin, but it is epoxy which you need for any repairs or modifications to it.
Build up the thickness of the top surface and also continue the overlay for a short distance vertically down each side of the case; before applying new resin and laying up the laminate prepare the surface first by abrading, and then thoroughly cleaning off the sanding dust (by first dusting it off mechanically and then use a cloth dampened in a suitable solvent/cleaner). That should give adequate structural strength, and for the sake of cosmetic appearance you can then if you wish overcoat it with either thickened epoxy or a suitable filler, and then sand it smooth, and finally paint it. Alternatively you could cap it by bonding on a hardwood capping piece.
Of course, do your “due diligence” before laminating – in this case by abrading the substrate. I suggest a power sander, preferably an orbital one, followed by thorough cleaning to remove all traces of sanding dust,
The problem of obtaining sufficient grip for screws is more complex. You will still have only limited thickness of GRP, and ordinary screws do not cut into this material at all easily, so you end up drilling out almost the full diameter of the screw – which means you have even less grip. Options include the following:
- Screw into pre-drilled holes almost the full diameter which are first coated with epoxy which has not yet cured; screw lightly without fully tensioning the screws, wait for the epoxy to cure, then heat the end of the screw with a soldering iron to soften the epoxy and screw it in tight.
- Create drilled and tapped holes, and use bolts. See the Gougeon Bros technical manual (available as a free download on their site) for details of how to do this.
- Bond in fixed upstanding bolts; again see the above technical manual.
- Bond in fixed upstanding bolts passing through a stainless steel plate bonded into the new laminate, with the laminate continuing over this plate.
- Anything else that the above technical manual may suggest.
As you may gather, the job should be doable, but it seems (to me) likely to entail a modest amount of fibreglass engineering.
While you are doing it you may wish to fit a central pillar to mount the swivelling sheet block (plus jammer if you decide to fit one).
Hope this is of some help.
Oliver
- This reply was modified 1 year, 2 months ago by Oliver Shaw.
Oliver ShawModeratorApologies that I am in the middle of an intensive spell of examining work, so I hope others will pick up on the repair issues. If no response I will attempt to pick it up when I am less pressed for time.
A brief explanation of your formatting problems. These seem special to this site; if you type up in Word, or any other programme, and then copy and paste you get all the formatting commands appearing as text; result is gibberish to the layman! Sorry, that is just a characteristic of the site.
Yes, I know, the Webmaster is keen to sort out this and several other issues, but the cost of doing a proper job is very considerable.
Oliver
Oliver ShawModeratorThe information you want is already on this site, in the Members’ Area; see Members’ Library, and then GP14 History.
Sail numbers 13440 to 13507 were issued in 1996, so if your boat was new when first registered – which is usually the case, but not always – that will be the year of build.
Exceptions occasionally arise if the first owner was a club or sailing school, and did not register the boat; and very exceptionally also if the first owner was a private individual but one who had no interest in the Association, or in racing.
You can obtain digital copies of such history as we have on your boat on request from our Archivist, via the Association office.
Hope this helps,
Oliver
Oliver ShawModeratorA rope horse may or may not be very similar to a split tail mainsheet, depending entirely on how it is configured.
There are two key characteristics of the modern split mainsheet, one of which is that it is ultimately led to the centre of the boat, which many see as a benefit when racing, and which you see as a benefit for your purposes (because your students are already familiar with that arrangement). The rope horse can be ultimately led forward in exactly the same way, but it is more usually led to the helmsman direct from the transom; and that decision is a matter of your own choice, for your purposes.
However the other key characteristic of a split tail mainsheet, which is a benefit when sailing on a course, particularly to windward, (but can be a minor disadvantage during a gybe), is that – provided it is set up so that the joint is close to the boom when close-hauled – it always automatically transfers the load to the windward quarter. Effectively the leeward tail will be carrying little or no load, and may even be slack; but it takes up the load as soon as the boat comes onto the opposite tack. Whichever tack the boat is on, the boom is always sheeted to the windward quarter; and that makes for a system which is particularly effective for controlling the lateral position of the boom. The converse of this is that it exerts much less downward pull on the boom, and so does little to help flatten the sail; but with modern powerful kickers there is no longer a requirement for the mainsheet to control sail shape, as that is adequately controlled by the kicker.
As a result, the split tail mainsheet does not (on a GP14, and other boats of similar size) require any “purchase” (mechanical advantage, gained by block and tackle) in the mainsheet.
How closely, if at all, your rope horse comes to this configuration depends entirely on how it is configured. At one end of the scale, if there is little slack in the horse when it is not under load, and the mainsheet block is free to run the full length of the rope horse, always remaining close to the deck, and with no control lines, it is a radically different system. In that arrangement, the boom will always be sheeted to a point somewhere between the centre and the leeward quarter, not the windward quarter; the sheet will exert a significant downward pull on the boom when hard on the wind (which may help flatten the sail if you have a kicker of only small purchase, but this will be irrelevant if you have a modern powerful kicker); and it will not be particularly effective at controlling the boom laterally, so you will need a purchase of at least 2:1. A few helmsmen prefer 3:2, which offers greater mechanical advantage but also (of course) greater velocity ratio, so there is that much more rope to pull in or pay out when needed. However most helmsmen find 2:1 sufficient, and prefer that ratio because there is less rope to pull in or pay out.
However if your mainsheet is secured to the centre of your rope horse, instead of being free to run along the horse, then it starts to become closer to the split tail arrangement. It is now in effect one version of the split tail arrangement, but only if the horse is long enough for the junction of the two ropes to rise well above the deck, indeed fairly close to the boom when hard on the wind. In that arrangement the windward side of the horse will (perhaps approximately) line up with the actual sheet, while the lee side of the horse will be slack; and in that mode, but only in that mode, it will perform just like the split tail mainsheet – but the latter is simpler and neater.
In between those two very different modes you might conjecturally have the sheet permanently secured to the middle of the horse, but the length of the horse permitting that joint to rise only modestly above the transom. In that scenario it would be a half-way house, and the characteristics would be somewhere between those of the two different modes.
Hope this helps,
Oliver
Oliver ShawModeratorI think the short answer has to be “Your choice; either would be reasonable”.
However some additional points may be helpful.
First, the general consensus seems to be that the almost ubiquitous split-tail mainsheet led up to the boom from the quarters and then along the boom and down to the centre – which is very far from true centre sheeting – is probably the optimum system for racing, while traditional transom sheeting is probably (undoubtedly in my personal opinion) be fay the better option for cruising. Several reasons for those choices:
For racing, it is helpful to be facing forward when tacking or gybing, because these will often be in very close proximity to other boats, and gybes will often (and tacks sometimes) be close to fixed geographical locations (i,e, the windward mark and the gybe mark). Added to that, with a modern rig with a kicker powerful enough to control the shape of the sail without needing the mainsheet to help flatten it in stronger winds, the split-tail sheet effectively always sheets the boom to the windward quarter; this gives by far the most effective sheeting line, and thus for a given wind load and desired boom position it minimises the load on the sheet needed to hold the boom there. That is why there is no need for a multiple purchase with this arrangement.
For cruising, all except the last of these considerations are irrelevant, and conflicting considerations become much more important. Close proximity to other boats will rarely if ever arise, and you normally have almost unlimited choice in the location of where you tack or (more importantly) gybe. So there is no requirement to face forwards, but it is very helpful to be able to face aft during a gybe, in order to choose your wave (or your “smooth”), and gybe at the optimum point for the following seas. Add to that the much greater space in the cockpit, which becomes important if you have more than two persons aboard, and the balance swings heavily in favour of transom sheeting for cruising.
A third consideration is that there is a benefit in trainees having had experience of both sheeting systems; so if they have initially learned on centre sheeting it could well now be time to give them valuable experience on transom sheeting.
Hope this helps,
Oliver
- This reply was modified 1 year, 3 months ago by Oliver Shaw. Reason: typo
Oliver ShawModeratorIt is not entirely clear from your sail number which model of boat you have; the masterly history of the GP14 hull by Roy Nettleship seems to place her later than the Fibredon Mk IV but earlier than the Mk IVa, (probably) later than the Paul Amos boats (although 3 boats were later produced by Storrar & Relph from the moulds), and earlier than the Speed Sails ones! All except the first of this list have underfloor buoyancy. So your boat appears to date from around the time that underfloor buoyancy was being introduced, but it is not clear to me whether you do or do not have it.
Agreed that the floor is higher on the (wooden) Series 2 boat (but only the floor, and specifically not the deck or the thwart); but my impression (without actually measuring) is that this is a matter of only a very few inches.
I noticed this in only two ways; if trying to camp aboard there is insufficient room to sleep beneath the thwart in Series 2 although it is possible in Series 1, and following a capsize although there may look to be a boatful of water aboard the depth is nothing like what appearances suggest – and it is remarkable just how quickly that can be shed through the transom scuppers.
It is conceivable that if you do have underfloor buoyancy, and if you are used to the Series 1 boat, the higher floor may just be sufficient to require “a bigger duck” when tacking or gybing; but my experience in Fireflies in my youth suggests that you will very quickly adapt to this. Indeed when I had a Series 2 boat built for me in 2006 while I was still regularly also sailing a Series 1 boat I didn’t even notice the reduction in headroom. If this is the explanation in your case I suspect that you will very soon get used to it, to the extent that you no longer notice it.
Oliver
- This reply was modified 1 year, 5 months ago by Oliver Shaw. Reason: Correction of typo
Oliver ShawModeratorLooking at the photo, your boom appears to be on a fixed gooseneck, which is normal for boats built in the last few decades, so its height is fixed. I really do think you will soon get used to this height, which is a lot more generous than on some other dinghy classes; and my experience is that most dinghy sailors fairly rapidly get used to the very precise heights of their booms (in whatever classes they sail), to prodigious accuracy. When I sailed Fireflies as a student 60 years ago (with a much lower boom than the GP14) it was fairly usual in those days to wear knitted “bobble hats”, and my one happened to have lost its bobble; no problem, until my mother presented me with a new one, complete with bobble – and for the first few sails I was forever catching the bobble (but never my head itself) on the boom; one intuitively learned the height of the boom to within a very few inches.
However it appears that the head of the mainsail is several inches below the black band at the head of the mast, which accounts for the slightly slack luff, and may also result in slight droop of the boom towards the transom.
The usual reason for this is what is known in the trade as “Operator Error” – the (entirely understandable) practice of putting the boom on the gooseneck before hoisting the sail. This works on the older style of sliding gooseneck, provided you set this at the top of the track and then pull it down to the lower black band once the sail has been fully hoisted and the halliard cleated off; back in the fifties and sixties most of us grew up with this system.
But this won’t work with a modern fixed gooseneck. Here you need to fully hoist the sail (so far as it will go, which should be to the upper black band) before putting the boom on the gooseneck, then cleat off the halliard, and only when that has been done do you then pull the boom downwards and fit it onto the gooseneck.
If you are used to the older system this takes a little getting used to, but I think you will find that this cures the problem.
If despite trying this you still have problems, ask at your club; WKSC have a very strong GP14 fleet, and I am sure that other members will very willingly assist. Failing that, contact me directly, since I am only just over the water from you; cruising@gp14.org.
I will leave our GRP experts to advise on covers, as my own background is primarily in the wooden boats.
Hope this helps,
Oliver
- This reply was modified 1 year, 5 months ago by Oliver Shaw.
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