The return of the quadrilateral

[Presuming Ed]

Saw this on the Infiniti 36 DSS facebook page. A quadrilateral code 0. Not legal under IRC (21.3.1 No headsail or spinnaker may be sheeted from more than one point on the sail.), and if it measures as a spinnaker, then it's also illegal under ORCi (208.2 Spinnakers shall be sheeted:a) from only one point), but AFAICS, a quad jib is legal. (207.4 Jibs may be sheeted:a) to any part of the deck or rail b} to a fixed point no higher than 0.05*MB above the deck or coach roof c) to the main boom within the measurement limit according to IMS F5.3. d) to the spinnaker pole in accordance with RRS 50.2 and 50.3 c}.and shall not be sheeted to any other spar or outrigger.

Hoyt, Sherman Hoyt's the name. How do you do?

 

[hughw]

Saw this on the Infiniti 36 DSS facebook page. A quadrilateral code 0. Not legal under IRC (21.3.1 No headsail or spinnaker may be sheeted from more than one point on the sail.), and if it measures as a spinnaker, then it's also illegal under ORCi (208.2 Spinnakers shall be sheeted:a) from only one point), but AFAICS, a quad jib is legal. (207.4 Jibs may be sheeted:a) to any part of the deck or rail b} to a fixed point no higher than 0.05*MB above the deck or coach roof c) to the main boom within the measurement limit according to IMS F5.3. d) to the spinnaker pole in accordance with RRS 50.2 and 50.3 c}.and shall not be sheeted to any other spar or outrigger.

---

Theres a bit more too as regards ERS definitions, which are supposed to be in use by IRC and ORC - vis

RRS - Part 4 #50 - nothing in there about multiple sheets.

ERS - Definition of a sheet - this is attached to a clew of a sail. And then the Clew is defined as intersection of leech and foot....so from ERS again on quadrilateral sails, then we only have one clew! So only one sheet...F.1.6. ( vi )

So a prohibition on sheeting from more than one point is actually meaningless as we might have four or more 'corners' but only one of those is a clew, and a sheet is only a sheet if attached to a clew!

This all came about from CFD work I was doing on reaching sail configurations, and from those results we went into the twisted flow wind tunnel in Auckland. The quad that Richard Bouzaid from Doyles designed and built turned out to be a glamour when related to all the other reaching combinations we tested.

 

[Presuming Ed]

Interesting! Can't actually see them letting you get away with it and rendering every single jib top obsolete!

I note that the defintion of G.4 SAIL CORNER MEASUREMENT POINTS

G.4.1 Clew Point:The intersection of the foot and the leech, each extended as necessary. [My emphasis]

And the diagram:



Hint that for measurement purposes, they might well include the "missing triangle"

Is it still worth if if measured as a triangle?

 

[hughw]

Interesting! Can't actually see them letting you get away with it and rendering every single jib top obsolete!

I note that the defintion of G.4 SAIL CORNER MEASUREMENT POINTS

G.4.1 Clew Point:The intersection of the foot and the leech, each extended as necessary. [My emphasis]

And the diagram:

View attachment 181722

Hint that for measurement purposes, they might well include the "missing triangle"

Is it still worth if if measured as a triangle?

See the rules for measuring quadrilateral sails for foot and leech definitions - can only have one of each.

So yes, under ORC Nicola Sironi allowed us to to use this for and ORC club certifcicate, measured as to the notional LP point for a triangle and yes, the efficiency gain is worth the rating 'loss' of that bit of sail area.

we also saw very clearly in the tunnel that you don't want to use a staysail under the Quad, so thats one sail less, and then with a much wider range of wind angles than a classic zero you can ditch a kite as well.

In practice too its easy to use - lower sheet is hardly moved, so power is controlled on twist by the upper ( not a ) sheet. Its rolls up without fuss, doesn't require any more gear on the boat, so whats not to like!

 

[hughw]

as a PS - if you look at the video of the 36 on the DSS site heading off at 20 knots plus - then they are using the quad there. Its great to sail on as you can move the boat wherever you want without those nasty moments where you have to wind on a ton of helm to keep on track.

And surely mylar/kevlar/carbon have consigned a whole load of sails to scrap bin in the past??!! And continue to do so with each material development.

Its a sail that is sorely needed - not necesarily by all and sundry, but for the modern quick boats then it really is the missing link where they are sailing so much with apparent wind and resulting angles.

Progress should not be halted if its useful - and dragging up historical rule remnants and thinking they are all still relevant is ridiculous.

After all, IOR was killed off and that cost owners a damn sight more than one new sail

We are already suggesting this as a good general purpose sail for cruising guys as well.

 

[Chet]

Fascinating stuff, thanks.

Abraham Lincoln once wondered?

q - If you call a dog's tail a leg, how many legs does it have?

a - four, calling it a leg doesn't make it a leg.

Best regards

aa

 

[Presuming Ed]

Absolutely see the discrepancy between the ERS and IRC 21.3.1 especially, so it'll be interesting to see what happens, but given IRC 2.2, and 2.4, and the fairly clear intentions of 21.3.1, I can't really see the IRC rating office not shutting the loophole, in the same way that the spinoa loophole was closed. If the whole fleet has to buy one....

And weren't exotics banned when they first came out? Then suffered a rating penalty?

(Not stirring, btw. Just pondering/discussing)

 

[hughw]

Absolutely see the discrepancy between the ERS and IRC 21.3.1 especially, so it'll be interesting to see what happens, but given IRC 2.2, and 2.4, and the fairly clear intentions of 21.3.1, I can't really see the IRC rating office not shutting the loophole, in the same way that the spinoa loophole was closed. If the whole fleet has to buy one....

And weren't exotics banned when they first came out? Then suffered a rating penalty?

(Not stirring, btw. Just pondering/discussing)

IRC 2.2 - protection is one thing, but why is this something that people need to be protected from? Any boat can have one if it really wants it - after all if you are club type racer then you'll never need or want something like a specific reaching sail. If you do any offshore/coastal racing then you are already having to buy sails on a regular basis and then you're ahead of the game as you've removed other sails from the list that need to be updated.

IRC 2.3 - ticks every one of those boxes big time.

IRC 2.4 - You've replaced three sails ( minimum ) by one, so thats an overall saving.

Also, IRC is ( was ) intended to be a permissive rule " ITC is permissive and open to all " at the very beginnning of the year book!

Its easy enough to deal with - count it into your kite numbers, rate it as the triangle headsail and to keep that in check then notional LP not greater than 150%J.

I don't see it as a loophole at all - what I do see is that we shouldn't be forced into building sails that are not fit for purpose simply because historically obsolete rules say you can't.

After all, that attitude is what led to the IOR and wooden keels - and we know how that ended up.

 

[Amati]

What about clews with multiple holed cards for self tacking setups?

Or a quad with two lines running to a large jib car that is in essence one unit, but with the ability to sheet and control two lines independently at once?

 

[Junkyard Dog]

What about clews with multiple holed cards for self tacking setups?

Or a quad with two lines running to a large jib car that is in essence one unit, but with the ability to sheet and control two lines independently at once?

In the case of sails with the clew boards you describe, you have to use the extend method of measurement as described in post 3 to find the actual clew point for determining LP.

 

[mcsailor0303]

Very interesting

 

[Bruno]

Love it, i was actually thinking about quads a few weeks ago watching the trim during a jib reach, good on you guys for bringing it back, puts alot of high drive in a rig, i bet. With an athwartships car and floating lead bet it is pretty easy to rig, could be a winner for multis, etc.,. Kudos to Mr. hoyt.

 

[Tucky]

The jib on my F-31 is full battened. Done to match a square top main. My screecher was developed originally as a rule beater (jib measures as spinnaker) but everyone quickly realized it was a great sail. The original code zeros on the then Whitbread boats measured as a chute and some folded when the "real" luff was pulled taut.

It is a shame when rules try and prohibit more effective sails that result from modern materials and improvements. Rate them fairly, but don't prohibit them.

 

[Presuming Ed]

Sherman Hoyt was actually the chap who spotted the quad on T.O.M Sopwith's Endeavour, and cabled his chums in New York. So when Endeavour got over to the US, the crew found their secret weapon wasn't quite so secret.

(This is Ranger)

 

[Somebody Else]

I wanna get in a tacking duel against that clown.

 

[P_Wop]

Nice one, Hugh. This little secret was going to get out sometime, so it's good to see an informed discussion about it.

All except Somebody Else. Tacking duel with a reaching sail? Really?

 

[beauvrolyk]

We just spent the last two weekends ocean racing with the Zero up over 40% of the time - this is of REAL interest.

BV

 

[SemiSalt]

Is there an advantage over a triangular sail sheeted through a strut?

 

[hughw]

Is there an advantage over a triangular sail sheeted through a strut?

Yes there is - this one that we ran in the tunnel ( and thats nearly 10 years ago now ) was up against the zero and despite being smaller in area was quicker all the time - and the greater the AWA the bigger the difference.

Certainly make no claim to have invented the thing, but what we have done is seen the value of the sail configuration as applied to the current boats.

So this was generation 1 up against the sail of the day in the zero, and proved itself superior in all aspects. 36 used it in the Palermo race as a light airs sail - which it is not - and worked well. Was even better blast reaching in 25TWS as you can see in the video on the DSS website.

However the light bulb really went off when I was running the CFD cases on assorted overlapping sail and wingmast configs and that led us into the tunnel and here we are at long last