RidingSails

[Krusty]

Please excuse repetion, but someone on these forums might benefit:
Reference a very recent post: 'In Wind at Anchor':
This is where I wish I knew how to post photographs on here!
I have a purpose-made riding sail that can be rigged in three minutes and dropped in one, and it 'Does the Business' to the extent that we have NO ranging about at anchor and the only sheering is to meet wind-shifts: then the response is so rapid that the boat barely heels.
The boat just sits quiet, gently pitching if there is a sea running. Because she is always within about 5 dgrees of the windline, the windforces are minimised, loads on the anchor and deck gear markedly reduced.
In Orkney in 2000 we had to endured hurricane-force winds. Not for the first time, I had set my 'bullet-proof' storm staysail as a riding sail on the backstay, in the manner suggested by others on that post: as previously, it was fairly effective up through f7 & F8. At F9 we were sheered about rather more, and as the storm really wound up it could not cope with the sheering and heeling: the sail was being thrashed to shreds and the whole rig was being shaken violently. As winds came up to 60Kn it had to come down, leaving us ranging and plunging even on anchors spread 45 degrees.
A few days later, in Shetland, we were lucky enough to meet John Armitage (co-author of the Norwegian Cruising Guide). John rode out the same storm in relative comfort with his (home-made) riding sail, and kindly demonstrated it on my boat, with suggestions for making our own.
THE KEY is to use a V-twin configuration: like two small jibs joined at the luff, the clews spread apart by a spar (ours doubles as a boathook) The luff is vertical, just clear of the boom end, the head hoisted on the main haliard. The clews are just forward of the stern-rail, with the 'sheets' hitched round it. The tack has twin down-hauls with clips onto stanchion-bases. All lines have been made to the correct length. It is not attached to any stay: it is set 'flying' (rapidly!) and winched up bar taut: there is no flogging, no vibration, no attrition: and it is silent!
It has become almost standard practice, after anchoring, to set the riding sail if there is any wind about, and we have used it a lot for six years. It has been a boon in several severe gales in the Hebrides and Norway.
As one very experienced visiting skipper remarked ''One of these should be standard equipment on all cruising yachts!'
It is ideal for a modern sloop rig on a fin keel, and would probably adapt well to a ketch, but the physics of it suggest that it may be ineffective for a traditional long-keel yacht.
If there is enough interest, I am willing to follow up with how to go about designing one to fit your boat, and technical info on how and why it works: BUT not until October! (I'm off cruising again in a few days time, and expecting to be using it some more).
Anyone seriously interested can PM me at that time.
This is NOT commercial! I just don't like seeing/knowing-about fellow sailors wasting time and money on ineffectual practices when there is something far better.

 

[Norman_E]

Sounds good, but I don't understand one point. How is the luff kept vertical if the head is attached to the main halyard, wich must surely angle the luff forward towards the masthead?

 

[Roger_D]

Thanks very much for the detailed post. The twin vee sail(s) sound like a very sensible development and it can be seen how it provides more stability. Your description was clear enough not to warrant a photo, but can you try to put one on anyway? In plan, what was the angle of the V? Too small would give less stability, too big would give more anchor load. Can you tell us the approx dimensions for the riding sail? (presumably for your Pioneer 10)

 

[Krusty]

The line of the main haliard (extended), almost bisects the angle of the head of the riding sail, putting similar tensions on luff and leech(es).
The whole thing is self-stabilising: as long as it is set up tight.
It is easy with two people, but I can prepare it in the cockpit, leave it in a bundle, walk to the mast, then hoist and set it in two seconds; another two to fully tension.

 

[Krusty]

Dimensions for my Pionier 10:
Luff 8ft, : Leech(es) 9ft.8in. : Foot(each) 5ft.6in. Spar Approx 7ft.
Leech and foot are hollowed to prevent flutter.
The sail was made as the 'opened-out' triangle, a broad webbing sewn down the centre to become a fairly stiff, rounded (aerodynamic) luff when the flat triangle was folded, and to carry D-rings for the tack-lines and haliard.
D-rings at the clews accept the plastic boat-hook ends of the spar and carry the sheets, which angle inboard to the sternrail, so holding the spar in place by compression.

 

[Roger_D]

Thanks again

I'll try and scale those dimensions to some appropriate for a Sigma 38!

 

[ChrisE]

I guess it's not for nothing that most Norwegian small (<10m) fishing boats have a V-mizzen rigged sail.....

 

[Krusty]

[ QUOTE ]

I'll try and scale those dimensions to something appropriate for... (a larger yacht)

[/ QUOTE ]

CAUTION: The sail needs to be of adequate size; the design determines how sensitive it is and how quickly and effectively it does the job: its construction determines how robust it will prove to be.
BUT: scaling up my boat's dimensions according to hull size may not be enough!
WHY? A yacht ranges about on her anchor because her ''Centre of Windage'' (CW) is forward of her underwater ''Centre of Lateral Resistance'' (CLR): it is an 'unstable configuration' in that direction, and like all unstable systems, it is easily set oscillating.
A Riding Sail works because it shifts the CW behind the CLR, to become a stable configuration.
Piota has hanked-on sails. A modern yacht with roller-furled headsails has far more windage forward, and if it has a shallow fore-foot and deeper hull sections aft, the CW and CLR are even further unbalanced, in the wrong direction!
THAT is the primary reason why so many modern yachts are wild creatures at anchor: nothing to do with all-chain cables or snubbers, or whatever!
Such a yacht will need a larger riding sail than mine: possibly so much larger that it cannot be fitted in the space between boom and backstay. A riding sail will help, but may not achieve total stability on its own:
The best way to begin soothing the antics of such a yacht at anchor in a wind is to remove that furled genoa!

 

[rrees]

Just thinking aloud what about something off the stern possibly a sea anchor ??

 

[Krusty]

To stay as close to 'head-to-wind' as possible, the stern must be free to move sideways as easily and rapidly as possible.
Anything that hinders or delays that is counter-productive; even an inflatable in the water off the stern is a drag, and makes matters worse!

 

[rrees]

That's interesting will look at lifting the dingy up onto the backtransom even when at anchor

 

[Roger_D]

More good advice, thank you. If I have to hold position under power in a wind (with no waves) I do it stern to wind for the reasons you list....this argument would lead to considering anchoring stern to in somewhere like Scavaig (complete shelter from waves) where strong variable gusting winds occur (forgetting of course how one would effectively arrange the anchor rode in such a case). For the limited cruising we do we would hope never to be caught out having to anchor in storm or greater winds......................hmmm, but yes, taking off the furling genoa would be good.

 

[Roger_D]

More good advice, thanks. When holding station under power in a wind I do it stern to for the reasons you have given (provided waves are small) This leads to arguing that stern-to anchoring would be good for places like Scavaig ( full protection from waves, but strong and variable gusting wind from the mountains) For the limited cruising we do we would hope never to be caught at anchor in a storm or stronger winds........hmmm ..taking off the furling jib would be good as you say..

 

[Krusty]

I have two reasonably clear photos if my set-up, scanned as jpeg files, sizes 68kb and 248kb, but I don't know how to put them on the web and don't have the time to learn it at present.
I will gladly e-mail them to a forumite capable and willing to post them to this topic.
Any volunteers please PM me with e-mail address a.s.a.p.

 

[Dyflin]

pm sent

 

[Drascomber]

Life is simpler with a Drascombe.

Furl jib, lower main and sheet in Mizzen.

In strong wind, wrap mizzen sail around mizzen mast until desired reefed size is acheived. Re-attach sheet and haul tight.

In extreme conditions, lower main mast.

 

[John_Clarke]

Thank you for your most interesting post. I have used a small conventional riding sail for one cruise. We only had wind up to F6 but the sail reduced the veering about at anchor to about 5 degrees either side of head to wind.

I found that initially the sail had a tendency to shake the backstay (and consequently the rig) as you describe when hanked to the backstay so I set it flying; this solved the problem in a F6. I used loose tape loops between the piston hangs on the sail and around the backstay which kept it under control during hoisting.

See http://www.ocean33.btinternet.co.uk/steadying_sail_3_800h.jpg for a 103k photo.

As a gust hits the sail fills (but stays very flat) and gives to the wind by moving sideways a bit until the boat swings into the new wind direction. I guyed the tack forward with 2 lines to stabilise it – for this I use the kicking strap tackle and one of the genoa sheets. The sail is slightly angled to the centreline. The boom is moved to the end of the track to keep it clear of the kicking strap. I might try 2 lines to the clew to give it more stability as well.

I wonder if flying the sail free like this might enable the sail to work in storm conditions? Your experiences have given me some doubts about using a ‘conventional’ riding sail but I think I should stick with this idea to see if it can work.

My wife has given the new sail the thumbs up because of the reduced motion and less slapping of waves under the stern. Both of these advantages I think can be attributed to the boat always pointing into the wavelets in the anchorage.

The area is 2.8 sq m (which is less than half the recommended area for a storm jib for a 33’ yacht); this size was determined by browsing the net to find other users and what worked for their boats and scaling by the relative lengths of the boats. The area seems to be right but I will need to ride out heavy weather to really test it. I calculate that half of Piota’s sail is 2 sq m which is quite close; I realise it works in a slightly different way and our boats are different.

 

[Krusty]

'' I have used a small conventional riding sail ''
In an anchorage on the North-west recently, I was invited on board the beautiful and widely-voyaged all-teak yawl 'Sai See': I noticed that instead of keeping the small mizzen up as a riding sail, her skipper furled it and replaced it with a special-purpose, very flat one fed into the mast track.
I wonder if by 'conventional' you mean a specially made flat sail? I'm sure these work well enough in moderate to fresh winds, as my flat storm-jib did, but without the support of a mast, the luff takes a lot of punishment by flutter and rippling (which becomes thrashing, in harsh conditions).
The virtue of the V-twin is that the luff is much smoother aerodynamically (like a mast) and the sail is much less stressed as well as more efficient.

 

[John_Clarke]

Yes, that makes sense.

I carry a windsurfer mast onboard so perhaps I should sew a luff tube to the riding-sail and slide the top half of the light carbon-fibre mast into it to stop it fluttering and trashing. I like that the sail does not add much to the windage of the boat.

 

[Kylora]

[ QUOTE ]
I have two reasonably clear photos of my set-up, scanned as jpeg files, sizes 68kb and 248kb, I will gladly e-mail them to a forumite capable and willing to post them to this topic.

[/ QUOTE ]

Unfortunately, Piota has sent me two copies of the same photo.

I've posted the one which I have, and hopefully will sort out the other.

Clicky Pix



Cheers Piota

Ash