PDA

View Full Version : Dyarchy topmast



ACB
12-03-2002, 05:12 AM
I have been havering round this one for ages. I either fit a fidded topmast or I go for a Marconi mast, ideally with the topmast socketed in for ease of storage (40ft masts are easy, 50ft masts are difficult) in which case I might as well have a luff groove a la Dyarchy.

Anyone got any views?

Ian G Wright
12-03-2002, 06:19 AM
What problems have you had with a yard topsail Andrew?
My suspicion is that the Dyarchy system is teetering on the border between an ingenious solution and too clever by half. Then again Jack Giles designed it, and who do I think I am disputing with the master?
I doubt that there is a perfect tops'l system anywhere. Everything must have it's cost, and the 'cost' of a tops'l is constant irritation,,,,,,,,,,,

IanW.

ACB
12-03-2002, 06:34 AM
Ian, here is a little list....

1. Stowing the yard. It takes up a lot of room and creates windage, even when stowed, as I have it, up a shroud. It is too long to go on deck. It we had points reefing, it could go along the boom in lazyjacks, but we have roller.

I suppose the windage of a topmast would be worse....

2. Handling the brute. The C of G of yard and sail, when on end, is above my head!

3. The fiddle factor - getting the halyard on the right place on the yard.

4. I have never had much luck with leaders - suppose I should keep trying.

Basically, the contraption is such a lot of work to set, (whilst handing it can be downright terrifying!) that I rarely use it, whereas a really simple topsail would be used all the time.

John B
12-03-2002, 03:08 PM
I'm not sure exactly how Sorceress ( the Dyarchy )works but I'm sure they gave up on the groove idea.I think they have a jackstay. I agree with Ian. At least, I've heard the groove idea wasn't successful. Why not make a taller mast and run a shorter yard. A compromise rig. Do away with the jackyard.( or not) A yardless jackyarder!! whooeee.
That's pretty serious though, Andrew, build a new mast?
another idea( without really having an accurate picture of your Rig... it's different from your sailplan if I recall?) is to just get a smaller topsail made. short yard, no jackyard ( nice for stowing).. and make it your everyday sail. Put your big jackyard sail away for special regattas.

What are leaders?

[ 12-03-2002, 03:09 PM: Message edited by: John B ]

ishmael
12-03-2002, 03:14 PM
Can anyone post some drawings? or photogs?

John B
12-03-2002, 03:40 PM
your wish.. etc
http://www.imagestation.com/picture/sraid15/p682f7391c2f04df80965a13cefcf720a/fde6594f.jpg

ACB
12-03-2002, 04:34 PM
Thanks, everyone.

Yes, I fancy that the drawing John has just posted, a modification, drawn by her designer in 1938, which endured until 1956, when the topmast was done away with, will be the answer, once more!

What she has now is what she was launched with; the rig is the same except that the mast is a pole mast, some 6ft taller than the one in the drawing, with an 18ft yard which carries the topsail.

This is because the original mast rotted through at the deck some time in the 1960's and a new mast was made to the original drawings, not the modified ones.

This was modified because the topsail yard was unmanageable. So, indeed, it is!

Thanks, everyone. I am convinced; no Dyarchy topmast! I will go for a conventional fidded topmast, do away with the yard, but retain the 8ft jackyard, which is very little trouble (at least, compared to its 18ft big brother!)

A side benefit of this is that a fidded topmast goes better with deadeyes, channels and lanyards!

A leader is a length of rope with a small soft eye spliced into one end. The rope goes round the mast, above the hounds and sometimes above the peak halyard bolts, back through the soft eye and thus down to the deck. The luff of the topsail, and sometimes the heel of the topsail yard if carried, has a piston hank seized on and this goes round the leader. After the topsail is mastheaded, but before the sheet is hardened in, the leader is set up hard and this draws the luff of the topsail (or the heel of the yard, as the case may be) hard up to the topmast.

At least, that's the theory.

[ 12-03-2002, 05:51 PM: Message edited by: ACB ]

Ian G Wright
12-03-2002, 06:50 PM
Andrew,
Can you find an ex-windsurfer mast of the right length? Mine is 14ft and makes for MUCH better handling,,,,,,
I have a spare, perhaps you could socket a 4ft (wooden)extension into the wide end? That would lower the CG right enough, perhaps just enough to avoid a re-rig.

IanW.

[ 12-03-2002, 06:51 PM: Message edited by: Ian G Wright ]

ACB
12-03-2002, 07:07 PM
Thanks, Ian; that seems to be the place to start!

John B
12-03-2002, 08:40 PM
leader... like the fairlead idea the Carrs used on Curlew( and I copied). sets up the yard beautifully.
http://www.imagestation.com/picture/sraid41/pc79337548f6746a153631d6cb0bc3282/fcf96d7e.jpg

[ 12-03-2002, 08:48 PM: Message edited by: John B ]

ACB
12-04-2002, 01:11 PM
Ah, rather better than a leader. Allow me to copy that!

Ed Burnett
12-05-2002, 11:18 AM
Andrew,

I am not sure that using the halyard as a leader would work too well on a jib headed topsail. I agree with John that it works very well indeed with a yard, but I think it would tend to pull a sail without yard too close into the mast when hoisting and lowering - the upshot of this being a half shredded sail jambed up in the main halyard blocks.

The nice thing about the leader is that providing it is left slack when hoisting, the sail can fly out a little way aft of the mast away from trouble. You can also hank the whole lower half of the luff onto the leader to help keep it all under control.

I am just about to email you an image of a combined leader / downhaul tensioning scheme that I worked out a few years ago. There is nothing new about using one tackle for both these jobs, but the sketch shows a variation which stows neatly and avoids a tangled puddle of tackle on the deck just when things are getting fun. I would post the image here, but it would take me some time to figure out how and I ought really to be doing something else. Please feel free to pop it up here (with the notes) if you want.

Good luck, ED.

ACB
12-05-2002, 11:53 AM
OK, folks, I've got Ed's drawing safely saved - now how do I post it?

Stephen
12-05-2002, 12:05 PM
I'd like a copy too - if you can't post it, can you email the pic to me as well?
Thanks
Stephen

Ian G Wright
12-05-2002, 12:40 PM
Originally posted by Stephen:
I'd like a copy too Me too as well also thank you,,,,,,,,,
up to now I limit my cleverness to using the tail of the tops'l halyard as a downhaul/tackline.
Sailing solo I find that I need both hands to haul the halyard, one hand to ease the sheet, one to tension the tackline and keep the yard upright and stop it threading through the peak blocks, and teeth and feet as needed.
I'll take all the help I can get. Or a Crew.

IanW

ACB
12-12-2002, 12:53 PM
Right, folks, thanks for all your advice so far, may I change the subject in mid-thread and ask a staysail question? The reason for carrying on in the same thread is that John very kindly posted the sailplan here.

I find, somewhat to my shock, that we have three staysails, and I am considering investing in a fourth!

In order of size, these are:

1. Tow foresail (balloon staysail). Rather a striking shade of blue, polyester, copied from the old one. This can be set on a reach, through to a run, in F 2, and comes down at the top of F4.

2. Ghoster foresail. Spinnaker cloth with a tape luff - carried from F 0 to the top of F1. Was originally my sister's ketch's mizzen staysail. I would not have bought a sail like this, but it is
very nice to have one - it will set, and provide a slot over the mainsail, when otherwise we would be flopping about.

3. The working staysail. Made in a heavy weight of polyester cotton, no longer gettable, oil and ochre dressed, with two rows of reef points, carried from F2 to F9, so far. This is a jolly fine sail, but it has two minor drawbacks - it is set on a boom, which means that it is decidedly small for the foretriangle.

Given the importance of the staysail to a gaff cutter, I thought it might be worth having a sheet staysail made - it will be about 30sq.ft larger.

So I consulted a sailmaker of repute, recommended by Ian The Right, who came and measured, said nice things about the boat, and then said that he has a weight of Clipper cloth (soft type polyester, much like Oceanus) that is just the right weight, or some polyester cotton which is on the light side.

I am very fond of the polyester cotton sails that we have, and would like to stick with this material. However, that would mean retaining the existing small staysail (which is in good nick!)and changing staysails in case of severe weather.

The aforesaid sailmaker of repute said that he would put a single reef in the lighter poly cotton cloth, but not two, as the sail would rip if it flogged if it had two reefs tied up.

The purpose of this sail is getting to windward in ordinary weather - F3-5.

Now, would you go for:

a. Clipper, rope luff, with two rows of reef points

b. Clipper, no reefs, on a Wykeham Martin gear, i.e. wire luff

c. Poly cotton, rope luff, with one row of reef points?

John B
12-12-2002, 03:27 PM
We have an interesting terminology variance coming up here or I'm misunderstanding. A staysail to me is one that sets at or near the stem..... the inner of the jib/ staysail pairing. These light sails sound as if they might go out on the bowsprit? or not.. do they set on the stem?
I agree about the importance of the staysail. I've even been daydreaming about shifting the tack out along the bowsprit a wee bit to get a bigger one. The boat goes to windward so well when the jib is off.( pet theory= gaff rig windward performance is bad because of forestay sag not 4 sides on the mainsail) It's just the horsepower drop unless there's plenty of wind that's the problem.

Ian G Wright
12-12-2002, 03:37 PM
Originally posted by ACB:

a. Clipper, rope luff, with two rows of reef points

b. Clipper, no reefs, on a Wykeham Martin gear, i.e. wire luff

c. Poly cotton, rope luff, with one row of reef points?Or d, Clipper, rope luff(Hanks?) mitre cut as large Tow Fores'l but flat enough to get to windward if sheeted inside the shrouds. No reefs, I don't like reefs in heads'ls. Others do,,,,,,,

IanW

ACB
12-12-2002, 05:59 PM
They call that a Genoa jib, Ian!

John, I am indeed talking about the sail that is set with its tack at the stemhead, hanked on to the lower or inner or main forestay.

As you certainly know, some small straight stemmers such as Itchen ferry boats, winkle brigs and Falmouth working boats do carry the staysail on a short bumkin alongside the bowsprit. Not what I call seamanlike, because the forestay holds the whole rig up, but there we are....

I do like reefs in staysails. Not in jibs, but in staysails. To sail with just a jib, no staysail, is an abomination in the eyes of all right thinking people unless you are about to pick up a mooring, drop an anchor, have recently dropped a mooring or have recently picked up an anchor.

Changing jibs is one thing; changing the staysail as well is rather unnecessary when the shape of the sail (almost a right angled triangle) and its cut (vertical, traditionally) means you can easily shift the sheet and reef it without even lowering it. There are those who try to reef the sail after lowering it completely; this is a recipe for making a pig's ear of the job. Ease the halyard, shift the lazy sheet or put a handy billy on it pro tem; shift the tack, roll up the foot and tie the points in.

Ian G Wright
12-12-2002, 06:27 PM
Originally posted by ACB:
They call that a Genoa jib, Ian!.Genoa stays'l if you please,,,,,,
Mine, which you know I have had only this year has been a revalation. Good from F2 to F6 inside either the light (big) jib or the smaller working jib seems to pull rather than press. Wish I had bought one years ago.
IanW.

John B
12-12-2002, 06:46 PM
Gotcha.
Mine is on a boom and is working really well but I could get a bit more area by making it sheet normally and go for some overlap. I had one like that... a genoa staysail,It always annoyed me though.... fine for on the wind( sheeted inside the shrouds) but as soon as you eased sheets it would foul up in the leeward lower and distort.
Nope,I don't want to give up on my self tacker and we go quick enough. I just change jib sizes for different conditions. It's good food for thought Andrew. as I said before, we really go well upwind with main and staysail albeit a tad heavy( depending on a reef or not) provided there's enough wind... say at least 20kts. I'll play with this over christmas. We may even tie a slab in and leave it in for the cruise.

ACB
12-12-2002, 07:26 PM
That's it exactly, John. I feel that my small boomed staysail is not creating the correct "slot" between its leech and the luff of the mainsail; as usually sheeted, on the horse, it is too far away and probably the wrong shape, with too much twist. The friction in the system makes it very hard to eliminate this.

Therefore we are losing drive to windward. The change when the tow foresail comes down is like losing two cylinders on a car. She remains docile but slows down rather more than I fancy she should do, and she does not point as I feel she should (mind you, what boat does, but I am sure my little Mytica pointed higher!)

I don't want any overlap, Ian. I want it clear of the forward shroud, otherwise, as John says, it's a pain when you start the sheet. I recognise the genoa staysail that you are describing, but with my rig there is not room for it to sheet inside the shrouds. It is very effective if you can manage it, as you can do an Illingworth type rig with a genoa staysail and Yankee jib.

Incidentally, the Famous Sailmaker agreed with both of you about the topsail. He also told me to put the inside ballast back. Since She Who Must be Obeyed also says this, the missing ton of lead is going back....

John B
12-12-2002, 09:57 PM
When I ordered my staysail I said " I want it flat. flatt. don't forget to make it flat. not like a dish, flat ." Then he put some shape in (because that's what they do)but it's pretty flat. That's why its not much good in the light by itself but the"flat" makes it cooperate very nicely with the jib.
I wish I'd said that about the topsail. in fact I wonder if there is value in any shape at all in it given draft can be got by starting the sheet on a reach and getting it to work when hard on the wind is difficult when it has much draft. I only get the back 1/3 or 1/2 to work on the wind but nevertheless it adds quite a bit of horsepower.
Perhaps you might run those comments past your famous sailmaker if you see him ,as the expertise in topsails in NZ is EXTINCT.

Ed Burnett
12-13-2002, 04:24 AM
Andrew -

It does sound like you have a bit of a gap in your staysail wardrobe, although if you put any more sails on the boat will you still be able to get below?

My own preference would be to get rid of the boom, and have a working staysail with the clew more or less in line with the gooseneck (on paper at least). I would have one smallish reef in this, and certainly a rope luff. Finding the right sheet lead for this sail will be worth a bit of care - you want it far enough inboard so that you can ease the sheet without it immediately bearing on the forward lower. You may find you have to lead the sheet around the outside for reaching.

You then might have a look at the possibility of getting your current working staysail cut down a bit. Keep the luff good and long, but reduce it's area so it is about right for 25knots of breeze and up. You should be able to do this so it sheets to the same point on deck as the larger (new) sail.

I don't like deep reefs in staysails, as it merely compounds the problem with gaff rigs in a breeze, ie. very low aspect ratio. The aim of the small but tall staysail is to give the boat the right tool for the job when faced with a long beat in breezy conditions.

John -

I like flatish sails too, but you have to be careful with stretch in gear etc. The flat sail will be less tolerant of things bending and stretching, and tends to be more fussy of trim.

Forgive me, but it sounds like you may have a bit of a jib luff tension problem. Get that to stand properly and you may find yourself getting to the weather mark noticeably quicker. The problem could be stretchy gear, or might it be that your runner system (3:1 to disadvantage) is not powerful enough?

ACB
12-13-2002, 06:36 AM
Thanks, Ed. You have decided me. However, whilst I have always maintained that one of be benefits of gaff rig is that you don't need to fill your forepeak with headsails, that is exactly what I have gone and done! Only two jibs, but three, and now maybe four, staysails!

The problem, applying to all boats, is the bagging of light weather sails. A sail which is carefully folded and rolled takes very little space, but, in the nature of things, big light sails come down in a hurry and are stuffed roughly into their bags, occupying five times the space that they would otherwise need. And the heavy weather sails have to be on top of the pile....

John B
12-15-2002, 03:22 PM
I haven't really got a big problem with the jib standing Ed. It's just a general comment. I've come to believe that the gaff main isn't quite as bad as a windward sail that people make out but it's the most visible difference so all problems get attributed to it. The fact is, I'm not going to get the jib luff as tight as a modern . Even when we had bermudan and a standing backstay we couldn't carry the tension needed for a really straight luff. Windward wise We go best either in the light because it stands best, or the heavy when the jib is off and the staysail does the job.
That mid range... 15 to 20 ,we sag off a bit but we're still only just outside the windex .
I've been playing with an idea on that throat problem too. Might be really simple. We've only sailed reefed this year so far so I can't tell if I've fixed it LOL.
Have you got any of your boats down here this year?. I stood and gazed for an age at Nomad last time.

Ed Burnett
12-16-2002, 12:10 PM
John -

As you say, much of the performance difference between the average gaffer and the average bermudian rigged boat may be attributed to things other than the shape of the mainsail. However, all other things being equal, the higher aspect ratio of the bermudian main will have a significant effect.

One thing I have done is take a very simplistic look at the theory of setting a topsail above a reefed main, this being an old wheeze that increases aspect ratio but gives about the same sail area as a full main with no topsail. Suffice to say it looks like a total winner on paper, but like all these things you have to work out a way of doing it on the water that realises the potentail gains.

It is interesting to hear that you don't bother with a jib when it gets breezy. One thing that is very noticable with the relatively straight stemmed English cutter types is that they don't really go too well in a seaway without a jib set. One possible explanation of this is that even the tiniest of jibs on a long bowsprit provides pretty powerful pitch damping and stops the boat going up and down in the same hole. It may be that Waione's bow overhang makes her less prone to this than might otherwise be the case.

None of mine in your area at the moment (unless someone has headed off on a long trip without telling me). Let us know about the gaff saddle thing when you have had a chance to set the full sail.

Wild Dingo
12-16-2002, 01:08 PM
Originally posted by ACB:
OK, folks, I've got Ed's drawing safely saved - now how do I post it?Well seems no one has told yer how yet Andrew so I will enlighten you!... but then you did head of on a tangent so perhaps you just forgot to post this drawing?... maybe you just emailed it to those who requested??... anyway no worries... I too would enjoy seeing it so I shall give you some hints on posting the drawing

1) get yourself an album at Imagestation.com
2) follow the directions to upload the pic of the drawing from your computer to imagestation
3) put the picture in an album
4) right click on the picture in the album
5) right click and copy the pictures properties {html address} from the box that appears
6) come back here open a post a reply box
7) say "gidday all... {or some such English gidday words} heres that drawing Ed sent me"
8) click the little button under the box you just wrote in
9) right click inside the little box that will jump up... right click and paste hit the ok button

wallah... done... peice of cake! ;) now if you have any problems with that please feel free to send the pic to me in an email and I will put it up for you with compliments and thanks :cool:

Take it easy
Shane