26/08/2018 at 9:33 am #16445
Another request for GP14 wisdom…
When I rig my new jib, am I going to need a new pair of cleats?
After reading everything I can find, I get the impression that I won’t be using the existing genoa cleats. In which case, where should I position the new ones? And will the sheets still run through the existing genoa fairleads?
26/08/2018 at 9:57 am #16446
I thought at first you were using the word “cleats” in the American sense, to mean what we call fairleads; but I then spotted that you also ask whether the sheets should run through the genoa fairleads, so you are making a distinction between the two. So far as the set of the sail is concerned, what matters is the position of the fairleads, not the jam cleats, and it is perfectly possible to sail without jam cleats – particularly if you are using only a jib, rather than a genoa.
So position the fairleads for correct setting of the sail (see below).
Then position the jam cleats so that they are convenient and reliable in use; you can easily get the sheet into the jammer, while sitting out, and (absolutely vital) you can instantly release it from the jammer on demand.
That apart, your question depends on what precisely you mean by a jib; i.e. it depends on the dimensions and the cut of your sail.
The original design sailplan was mainsail and jib, and the jib (in that sense) is still specified in the Class Rules and therefore has very specific (maximum) dimensions. It is almost unheard of for a sailmaker to make the jib significantly smaller than the maximum permitted dimensions, so a sail would normally be made as close as reasonably possible to the maximum dimensions, but just very slightly below the maximum in order to allow a working tolerance.
However your previous post refers to “some jibs being longer or shorter than others”, i.e. what you have may or may not be an official GP14 jib. Unless you intend racing in CVDRA events that will be entirely academic so far as Class Rules are concerned, since it will not exceed the permitted size of the genoa, but it may affect where you require your fairleads to be.
A further complication is the emergence in recent years of the unofficial midi sail; this is not specified in the Class Rules, so dimensions and cut are not standardised, but the size falls somewhere between the official jib and the genoa, and my understanding is that for this sail it is usually recommended that it has its own set of fairleads mounted further inboard than the genoa fairleads.
Since there is some uncertainty about your sail the best approach is probably experimentation. Hoist the sail, with the halliard properly taut, with the boat ashore and on her trailer, on an occasion when there is a good sailing wind blowing; anything from force 2 to force 3, possibly even force 4. Align the boat 45 degrees to the wind, as though sailing close-hauled (i.e. on a beat). Now lead the sheet down to the deck by hand and see where it needs to come to in order for the sail to set well.
When you think you have the answer, also hoist the main and sheet it in – and if it is blowing force 4 you may need some assistance, to prevent the boat from tipping over. Now check the jib sheeting position again, to ensure that it does not backwind the main, that you have a good curve, and an open slot.
If it helps, the original design, which you remember set the official jib, had fixed fairleads; these were mounted amidships, more or less in line with the centre of the thwart, and at the outboard edge of the deck. Some limited control of sheeting angle could be achieved by mounting the tack of the jib on a strop if necessary.
Hope this helps,
- This reply was modified 11 months ago by Oliver Shaw.
26/08/2018 at 11:12 am #16448
Thanks for that, Oliver.
Right now, I’m looking at what seems to be pretty much an all original Thames Marine GRP Mk2. I have genoa fairleads and jam cleats in a single unit, mounted on rails on the deck just abaft of the shrouds. Also some lone jam cleats on the deck forward of the shrouds, which I imagine to be something to do with the spinnaker (an unknown quantity for me as yet).
The jib won’t be an official one as per Class Rules. I discussed this with the sailmaker. Since I’m not planning on doing any racing, I asked him to make up the jib with the same luff length as the genoa, to make the foresails easily interchangeable.
Reading your reply, I can see that rigging all this is going to call for some trial and error. But it sounds as if I am probably going to need some separate fairleads (and jam cleats) abaft of the existing rails. Does that sound right?
26/08/2018 at 1:13 pm #16449
In the first instance I would try using your existing genoa fairleads and jam cleats. That will not necessarily be ideal, but it will at least work after a fashion, and the set of the sail will then give you some idea in what direction you want to move. Then you can try the experimentation that I suggested previously.
If you are lucky, and it is by no means an impossibility, you may even find that they work fine. If the luff is the same length as that of a genoa, and the leech and the foot happen to be in the same proportions as those of a genoa, you will probably find that the existing position is indeed about right.
One thing you do not want to do, in the course of experimenting, is to drill holes in the deck until you are very sure that they are in the right place!
- This reply was modified 11 months ago by Oliver Shaw.
26/08/2018 at 1:40 pm #16451
Many thanks for your advice, Oliver. I shall proceed as you suggest.
As you can tell, I’m still getting a feel for this boat. But she’s already proving a real pleasure to sail!
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