Mega high SA/D's - How high?

[Floating Duck 114]

How long is a piece of string huh... But it's a lazy Sunday and I'm wondering;

What are some high SA/D's that you know of for both upwind and downwind scenarios, and under how much wind is this possible?

Ex. a Melges 32 has

• 46 upwind - usable until mid teens TWS?
• 115 downwind, usable well into the 20's TWS?

[Steam Flyer 5,048]

36 minutes ago, Tito said:

How long is a piece of string huh... But it's a lazy Sunday and I'm wondering;

What are some high SA/D's that you know of for both upwind and downwind scenarios, and under how much wind is this possible?

Ex. a Melges 32 has

• 46 upwind - usable until mid teens TWS?
• 115 downwind, usable well into the 20's TWS?

This number all by itself is not as useful as it's comparison to righting moment..... ideally, some sort of RM/disp number.

A boat that lays on it's ear is not fast

FB- Doug

[Floating Duck 114]

1 minute ago, Steam Flyer said:

ideally, some sort of RM/disp number.

100% agreed. 

Perhaps we stick to non-canting monohulls (i.e. Most boats) to make this comparison a bit more fair - seeing how RM numbers aren't usually found. 

[blurocketsmate 81]

How is crew weight being considered, with it being such a big part of both displacement and RM in such a light boat?

[Floating Duck 114]

1 hour ago, blurocketsmate said:

How is crew weight being considered, with it being such a big part of both displacement and RM in such a light boat?

I would absolutely consider it, as you are correct it relates to both. In my simple calculations I have always used 185lbs * # of crew - just as a reference point.

This info however is simple to find. What is not so easy is at how much wind speed do these boats start getting overpowered? For ex. With SA/D of 50 upwind, you may only need 12kts TWS until you need to reduce sail. But with SA/D of only 20 you probably don't need a reef till 25kts.

I guess that's my main question.

[ajbram 78]

I love how the M32 is always the benchmark for ludicrous SA/D ratios.

[Floating Duck 114]

1 hour ago, ajbram said:

I love how the M32 is always the benchmark for ludicrous SA/D ratios.

Hahaha 100% agree, but not much information out there on other models that I can find (the t-boats, shaw's, european lake boats, etc).

Or I would say... not any information that I can find and is readable (i.e. in English) lol.

[ajbram 78]

6 hours ago, Tito said:

Hahaha 100% agree, but not much information out there on other models that I can find (the t-boats, shaw's, european lake boats, etc).

Or I would say... not any information that I can find and is readable (i.e. in English) lol.

It is a lot of sail for a 3700# boat. When it arrived we talked our way into the university field house to measure the sails that came with it... the first kite we stretched out took up a lot more floor space than we anticipated and we were like "Holy shit! How are we going to keep this thing on its feet?" That being said, it's a remarkably well-behaved boat for all its gigantic sail area. Righting moment from crew weight and stability generated by the keel foil means a lot.

[blurocketsmate 81]

What I was getting at is, figures published on sailboatdata.com, etc., may be just for the boat, w/o counting the crew.  So the real SA/D may not be as ludicrous.

These boats designers are certainly figuring it all in, displ. and RM w/ crew, and at what wind speed they're fully powered.

[ajbram 78]

18 hours ago, blurocketsmate said:

at what wind speed they're fully powered.

Exactly... when we're not moving fast (e.g. coming out of a maneuver etc.) the blob at the bottom of the keel does next to nothing if we're powered up. Once we are moving, the foiling action of the keel through the water adds a lot oof stability and SA/D doesn't really figure into it.

 

 

[LionessRacing 560]

8 hours ago, ajbram said:

Exactly... when we're not moving fast (e.g. coming out of a maneuver etc.) the blob at the bottom of the keel does next to nothing if we're powered up. Once we are moving, the foiling action of the keel through the water adds a lot oof stability and SA/D doesn't really figure into it.

that oof stability must be something I am not familiar with.

 

Are you suggesting that a symmetric non canting keel has righting moment that is due to water flow ? 

[duncan (the other one) 670]

Thames A-raters: https://www.thamessailingclub.co.uk/TSCsailing/thames-a-raters-1

350 sqft / 750lb ~ SA/D 68 upwind

 

 

[Left Shift 2,751]

5 hours ago, LionessRacing said:

that oof stability must be something I am not familiar with.

 

Are you suggesting that a symmetric non canting keel has righting moment that is due to water flow ? 

More like "wronging moment" given leeway and the angle of attack of the flow over the keel foil.  

The Melges 32 SA/D number is very high, but less so when you add 1,000# of crew weight.  I suspect that a TP52, which as a downwind SA/D of about 96 is equivalent or more extreme than the Melges when adding crew weight into the equation.  Same with upwind.  

 

[ajbram 78]

15 hours ago, LionessRacing said:

that oof stability must be something I am not familiar with.

 

Are you suggesting that a symmetric non canting keel has righting moment that is due to water flow ? 

I wouldn't call it righting moment. It's more stability. When the boat is not moving forward, all the crew weight and the weight of the keel bulb cannot counteract the heeling moment of the sails when they power up. When the boat is moving fast, changes in crew position or wind speed are dampened by the keel tracking a straight line through the water.

[LionessRacing 560]

3 hours ago, ajbram said:

I wouldn't call it righting moment. It's more stability. When the boat is not moving forward, all the crew weight and the weight of the keel bulb cannot counteract the heeling moment of the sails when they power up. When the boat is moving fast, changes in crew position or wind speed are dampened by the keel tracking a straight line through the water.

So if I understand you, you are asserting that the narrow deep keel (& Rudder) is resisting heeling more when there is significant flow over it than when it's static.

Since it's symmetric, the only "lift" it generates is due to angle of attack not differential camber.

As that angle of attack changes with yaw more than heel, don't you have a coupling; where a puff that causes the boat to start to round up, creates a hydrodynamic lift on the keel due to change in angle of attack (keel now pointing to weather of stream flow) which actually forces heeling? 

[ajbram 78]

3 minutes ago, LionessRacing said:

So if I understand you, you are asserting that the narrow deep keel (& Rudder) is resisting heeling more when there is significant flow over it than when it's static.

Since it's symmetric, the only "lift" it generates is due to angle of attack not differential camber.

As that angle of attack changes with yaw more than heel, don't you have a coupling; where a puff that causes the boat to start to round up, creates a hydrodynamic lift on the keel due to change in angle of attack (keel now pointing to weather of stream flow) which actually forces heeling? 

I'm not asserting that there is lift. Of course there is lift that is generated due to angle of attack and not camber. 

I'm not an engineer so I won't try to use proper terminology here, but what I'm describing is the same stabilizing effect as the tail fin on an airplane. With a flat angle of attack at speed, a foil tends to just stay put. Think of a dinghy with no ballast in the centerboard (or old ones where the centerboard is wood, and therefore has negative righting moment). When that dinghy is at speed, the centerboard tends to hold its track through the water as long as the angle of attack is flat. 

All I really know is when we are on step with wind at 90 AWA (which ought to be the maximum heeling moment), we are more stable than when we are dead slow with the same TWS at ~130 AWA, even with the exact same crew weight placement etc. I attribute this to the fact that the keel is tracking through the water. Am I crazy?

[Floating Duck 114]

14 hours ago, duncan (the other one) said:

Thames A-raters: https://www.thamessailingclub.co.uk/TSCsailing/thames-a-raters-1

350 sqft / 750lb ~ SA/D 68 upwind

Now we are getting somewhere, nice! 68 upwind SA/D with a very thin B/L. Probably overpowered in... 5kts of wind?

I hate to speak these words on here, but... Does anyone know the SA/D of... THE CONE ?

[monsters inc 13]

Go the Cone

[Floating Duck 114]

55 minutes ago, monsters inc said:

Go the Cone

Ah damn I hope this thread only gets briefly derailed what have I done. 

[daffy 6]

On 8/9/2019 at 10:14 AM, Tito said:

CONE

 

[Steam Flyer 5,048]

On 8/9/2019 at 1:14 PM, Tito said:

...    ...

I hate to speak these words on here, but... Does anyone know the SA/D of... THE CONE ?

 

             cone

        cone cone

    cone cone cone

cone cone cone cone

FB- Doug

[ols 7]

On 8/9/2019 at 1:14 PM, Tito said:

I hate to speak these words on here, but... Does anyone know the SA/D of... THE CONE ?

In a previous thread, SA/D for the cone was calculated at 141.1, with the numbers supplied as: displacement 5124 pounds;  jib + main area 721 and downwind SA ~2400

 

previous SA thread: 

http://forums.sailinganarchy.com/index.php?/topic/41412-another-phrf-debacle/&tab=comments#comment-876773

archived website for the cone measurements (but do not seem to show sail areas):

https://web.archive.org/web/20060615034313/http://www.gothecone.com/boat.html

 

[Monkey 1,326]

I wonder where Peerless fits in here? 

[12 metre 365]

The problem with SA/D debates is that most of the numbers thrown out are made up - i.e. someones own definition of SA/D - making equal comparison difficult - unless everyone agrees to he same methodology.

In the traditional SA/D calculation (there is no such thing as upwind and downwind SA/D) - SA is calculated as .5(IxJ+PxE) - simple as that.  Using that the Melges 32 has a SA/D of 36.7 while an Olson 30 is 26.5

Nothing wrong with making up numbers like downwind SA/D as long as you're not comparing apples with oranges.

[Monkey 1,326]

This should fit the requirements. 

[Raz'r 3,346]

My international 14 clocks in at about 48 upwind, 125 downwind. With crew added of course, lets not get silly.

The 12s would be higher yet.

[blurocketsmate 81]

I sailed Cherubs in Australia nearly 40 years ago, and did a few races in Twelves.  Twelves then were just silly -- short sprints between crashes.  We were always just  surviving, never really racing.  Modern ones look much better, with lighter rigs and easier handling, more like a modern I-14.

These days it seems more about reducing drag, and with skiffs, keeping the sails full and flowing with flexy rigs that "give".

Do modern Twelves have more, or less sail than they used to?  Are they still unrestricted?

 

[treskeppare 1]

The FAREAST 28R 538 sqft upwind, 1464 sqf downwind, weighs 2866 lb

SA/D=42,6

SA downwind/D=116

Enough power for the top boat to top out at 21.5kn on our National Championships o Sweden.

 

[Monkey 1,326]

[Amati 1,405]

On 8/6/2019 at 12:10 PM, Tito said:

I would absolutely consider it, as you are correct it relates to both. In my simple calculations I have always used 185lbs * # of crew - just as a reference point.

This info however is simple to find. What is not so easy is at how much wind speed do these boats start getting overpowered? For ex. With SA/D of 50 upwind, you may only need 12kts TWS until you need to reduce sail. But with SA/D of only 20 you probably don't need a reef till 25kts.

I guess that's my main question.

Depends on beam and length too, we’re around 24 upwind with Amati (40t and narrow), but we pretty much do at least wind speed  upwind until 5-7 knots, and then we’re looking at ~ 12-14 apparent, and we put in the first reef at 10-12 TW.  Our U20 had IIRR 36 upwind, but almost as much beam as Amati- but  we could carry that until 15-20k easy upwind.  

Roach has a lot to do with it too-  we got tired of reefing in 10k, so I had our sailmaker take off some roach at the top, and we now don’t have to reef as early, but  she’s sticky in the light.  Not as fun.  Next sail gets the roach back, ditch the big assym, go back to a 3/4 rig w blade, 3/4 shrouds, 3/4 running backs only, and 3/4 assym.  This drives me crazy, because you start thinking about how many sails, and running and standing stuff that you really need.  The U20 had 3 sails, and that was nice.  Jay and Pease put such nice twist in those sails-.  

Bombing around in the light is fun.  Bombing around in the heavy is easy...

part of this belongs in  SHA?

[Amati 1,405]

Fwiw, I’ve found that 3:1 SA:WS (sail area :wetted surface) is the point where things get crisp in the light, but prismatic matters too, and then the design fun really gets sporty-

[carcrash 377]

Garfield, the Libera Classe on which we won the Deutsche Cup in 1987(?) on Chiemsee in Bavaria. I have no photos -- this was in the long dark era before the iPhone.

The boat looked similar to a longer cold moulded soling. Beautiful. Approximately 36 feet long, 6 feet wide, 6 feet deep ballasted keel (but ignore for RM, as the boat was sailed flat), 8 foot racks out each side, a 66 foot spar, #1 genoa tacked to the bow and sheeted to the transom, a big roach main, and spinnakers that skimmed the water even when fully drawing.

The righting moment was extremely high, as the crew consisted of ten German Olympic Team Star sailors on trapeze, and two lighter crew (me and the sailmaker) who would trim when not on the wire. The crew on the wire would organize as a pyramid: six the first level would have their feet on the racks. Four the next level with their feet on the shoulders of the first six sailors. And the two light crew would stand on the shoulders of the four. So my eyes nearly 30 feet from centerline when on the trapeze. We could carry the full #1 upwind in about 12 knots of breeze, when we would be a fair amount faster and pointing higher than a well sailed double trap Tornado catamaran.

Genoa 36’ x 66’ = 1188 sq ft

Main 66x18x1.2 = 712 sq ft

Upwind = 1900 sq ft

 

Spinnaker = 80’ x 40’ x .75 = 2400 sq ft

Main = 712

Downwind = 3000 sq ft

 

Displacement = 5000 lbs + 12x220 = 7600

WL Length = 36

 

Righting moment, ignoring the keel ballast: Crew in 6-4-2 pyramid

(6x220)x(4+8+3) = 1320x15 = 19800

(4x220)x(4+8+6+3) = 880x21 = 18400

(2x150)x(4+8+6+6+3) = 300x27 = 8100

RM = 46300 ft lbs

 

Upwind SA/D = 79

Downwind SA/D = 124

Displacement Length = 73

[carcrash 377]

On 8/22/2019 at 3:10 PM, Monkey said:

Which boat?

[Monkey 1,326]

Just now, carcrash said:

Which boat?

That’s Juggernaut (Used to be Peerless).

[Floating Duck 114]

That spinnaker looks absolutely beautiful. I guess there really is no such thing as as too much sail area in light winds.

[ryley 421]

if you want to peruse a list of boats with published upwind and downwind SA/D ratios as well as LPS and RM20's, you can go here: https://regattaman.com/cert_list.php?goback=/certificate_page.php?cp_tab=0

There's a pretty good mix of boats. Mine has an U/W SA/D of 25.7 and DW SA/D of 57.9, RM20 of 126.7 with 1100 lbs of crew on board. we are into a full main and #3 in about 18 knots, and full main and A2 in 22 or so.

[Mike in CT 15]

This thread make me miss my V830

[Floating Duck 114]

7 hours ago, Mike in CT said:

This thread make me miss my V830

Was somebody actually able to trim that huge 900sqft kite without a winch? (in low winds...)

[Irrational 14 172]

830's are a riot to sail. In capable hands, they are almost unbeatable in the heavier and lighter venues as long as there is a good downwind runway.

[Boink 661]

Cannot find the figures associated to do the full analysis, and from what I do recall, the boat never saved its time after correction, but she was quick......

Jo Richards 36ft design for Stephen Fein - "Full Pelt X" - a pumped up 49er.

 https://www.yachtsandyachting.com/news/13498

[Mike Hunt 25]

On 5/5/2020 at 6:35 PM, Irrational 14 said:

830's are a riot to sail. In capable hands, they are almost unbeatable in the heavier and lighter venues as long as there is a good downwind runway.

We love ours!

 

[Mike in CT 15]

On 5/5/2020 at 5:18 PM, Floating Duck said:

Was somebody actually able to trim that huge 900sqft kite without a winch? (in low winds...)

In light air yes. for the most part it was on the winch though. 

[ryley 421]

somewhere there's a boat under all that sail!

[barefoot children 20]

Azzura 310 fitted with Mumm/Farr 30 rig Isp=43' , Jsp=19.2' Diaplacemewnt about 3600#

[Christian 72]

On 5/7/2020 at 12:27 PM, Mike in CT said:

In light air yes. for the most part it was on the winch though. 

Pussies

 

[Christian 72]

On 5/6/2020 at 12:21 AM, Boink said:

Cannot find the figures associated to do the full analysis, and from what I do recall, the boat never saved its time after correction, but she was quick......

Jo Richards 36ft design for Stephen Fein - "Full Pelt X" - a pumped up 49er.

 https://www.yachtsandyachting.com/news/13498

It's initial IRC rating was in the zipcode of 100 footers- just under 2.0 - the calculations showed it should be able to plane upwind.......which it couldn't.  Fun boat though just not winning with anywhere to that rating

[Christian 72]

On 5/7/2020 at 8:43 AM, Mike Hunt said:

We love ours!

 

No reason not to.

Still have some awesome sails and other bits for it if interested

 

 

[Christian 72]

On 5/5/2020 at 9:37 AM, Mike in CT said:

This thread make me miss my V830

Same

 

[Mid 2,905]

On 8/5/2019 at 2:18 AM, Floating Duck said:

How long is a piece of string huh.

twice the distance from the middle to one end ...

 

next .

[Mike Hunt 25]

12 hours ago, Christian said:

No reason not to.

Still have some awesome sails and other bits for it if interested

 

 

Christian - Your account isn't taking PM's.  Let me know what bits and pieces you'd like to part with.

[Christian 72]

3 hours ago, Mike Hunt said:

Christian - Your account isn't taking PM's.  Let me know what bits and pieces you'd like to part with.

Here is a list of the bits and pieces I have for the V830

 

Vang – Vang Master VM5 with purchase system

2 Primary winches – Antal XT 30 – 2 speed self tailing

Sea-Rig rigging screws spares (new)

 

All Doyle sails are designed by Richard Bouzaid

Main – Doyle Stratis Carbon Ice – Squaretop – full battened – 33.15 m² – one 6 foot reef – floating tack setup - low mileage

Main – DP D4 (design by Doyle NZ) – carbon/kevlar - big roach – full battened – high mileage/old – Free (without battens)

Main – DP D4 – carbon/kevlar - class roach – high mileage/old – Free

Jibs – both have Dyneema soft-hanks

Light jib – Doyle Stratis carbon Ice – 18.2 m² low mileage

Spin – AP(A1.5) – Doyle NZ – Dynakote 75 – 87.5 m² – New – Only been up once to check for fit

Spin – A0 – North franken A0 cut down from a M32 A0 – medium mileage – Free

Spin – A3-5 – North reacher – 68.5 m² – medium high mileage

 

Sent you a PM with my email addy

[Christian 72]

Here is a small sample of ratios

I added the numbers for a sligthly turboed V830 calculated the same way as the others.  The numbers for the T7 and T8 (SA/D light) are a little off - they are both lower than the V830 in reality

 

 

Comparison Ratios.pdf

[TocToc 2]

T780

with crew: 44.5 up > 116.2 down

light:  73.4 up > 191.5 down

[Christian 72]

That's the canter right?  What are the numbers for SA ballast Disp crew weight just out of curiosity

[TocToc 2]

correct - small canter with this numbers:

Displ: 695 kg (ready to sail with all equipment)

ballast: 280 kg

Crew: up to 450 kg (4 to 5)

Sail area: 32.4 + 18.6 + 82.5 m2 (first generation gennaker was 105 m2)

 

[Irrational 14 172]

On 5/7/2020 at 5:43 AM, Mike Hunt said:

We love ours!

 

A modern sailplan like this was exactly what the 830 needed. Looks great.

 

[Christian 72]

On 5/15/2020 at 12:55 AM, TocToc said:

correct - small canter with this numbers:

Displ: 695 kg (ready to sail with all equipment)

ballast: 280 kg

Crew: up to 450 kg (4 to 5)

Sail area: 32.4 + 18.6 + 82.5 m2 (first generation gennaker was 105 m2)

 

Sounds like it is lit up in the right conditions

[JMOD 77]

how would an IC do

[JMOD 77]

or the class libera?

 

[ALL@SEA 257]

3 hours ago, JMOD said:

or the class libera?

 

Discussed in post #32.

[zks7 3]

Christian, how do I reach you? No reply from your IM.

[Christian 72]

On 5/24/2020 at 4:35 PM, JMOD said:

how would an IC do

Fine as a dinghy (which it is) - it wouldn't as a sportboat (which it isn't)

[SENDITBOYS 3]

Eh, SA/D really stops becoming anything of meaning once you're into the realm of "the ballast is just there to stop it turtling". Might as well be sailing an 18 footer.

[SCARECROW 582]

23 hours ago, SENDITBOYS said:

Eh, SA/D really stops becoming anything of meaning once you're into the realm of "the ballast is just there to stop it turtling". Might as well be sailing an 18 footer.

You're on your way to become NZ's next great sport boat designer.

Jim Young looked at what everyone else was doing, reduced ballast and displacement and increased sail area.
Farr looked at what Jim was doing, reduced ballast and displacement and increased sail area.
Elliot and Ross looked at what Farr and Young had been doing, reduced ballast and displacement  and increased sail area
Thompson looked at what Elliot and Ross had been doing, reduced ballast and displacement  and increased sail area
Shaw looked at what Thompson had been doing, reduced ballast and displacement and increased sail area
Leech looked at what Shaw had been doing, reduced ballast and displacement and increased sail area

[The Q 443]

The next ultra light displacement boat..

 

[The Q 443]

Thinking about my post, dinghies have bouyancy bags, would it be class legal to have dinghies and yachts with bouyancy , or come to that crew matresses etc helium filled?

[barefoot children 20]

Taylor 32:

 

[Senator Seditious Maximus 359]

Looks exactly like the Moore 30 from late 80s.  Deathtrap.  Just ask the dead man from ChiMac couple years back.

[ryley 421]

18 hours ago, JimBowie said:

Looks exactly like the Moore 30 from late 80s.  Deathtrap.  Just ask the dead man from ChiMac couple years back.

Dead men sailing

[Senator Seditious Maximus 359]

https://www.sailmagazine.com/racing/chicago-mac-panel-wingnuts-shouldnt-have-been-racing

 

[ryley 421]

I completely agree they had no business being in a KIWI 35 in the Chi-mac. Thankfully the organizers have changed the rules to keep that from happening again. But...

1) Danger Zone isn't a Kiwi 35.

2) a Kiwi 35 isn't a Moore 30.

3) Danger Zone's design brief specifically calls it an "inshore racer" and points out that the wings flood in a knockdown to keep it from turtling. But even with the safety features this would not be a boat for the chi-mac either, but that's not what the owner wanted anyway.

But a deathtrap? Danger Zone's been tearing it up on the east and west coasts since 1994 and if anyone has died on board it's been of happiness at going so. damn. fast. any boat sailed incompetently or outside of its design brief can become a "death trap." 

 

[mathystuff 368]

2 hours ago, JimBowie said:

https://www.sailmagazine.com/racing/chicago-mac-panel-wingnuts-shouldnt-have-been-racing

 

From the article:

"Coupled with this effort, the panel is recommending that pre-race inspections be conducted “in order to advise skippers and crews on (1) the importance of stability, its implications, and how it’s calculated; and (2) preparing the boat and themselves for the rigors of distance racing.”

 

It is alarming how little a lot of sailors actually know about the physics that keep their boats upright. "Ballast ratio = stability" and "heavy = safe" seem to be burned into a lot of heads.

Yacht clubs need to up their game in the education of young sailors to be. Licenses should include some knowledge about this aswell.

[bacq2bacq 243]

Is this the ultimate in high SA/D sailing?  Certainly not much displacement.  Amazing how "sailing" evolves...

 

[solosailor 367]

That's not sailing.   It's kite boarding/foiling.   A "board" sport.   Sailing requires a boat.

[Floating Duck 114]

A good point is brought up through. 

Once you start reducing drag (through foils), it stops being about just horsepower doesn't it? (SA/D)

When I first posted this question it was actually with great intrigue as to how to sail multiples of wind speed, say going 18kts in 9kts (2x), or even 18kts in 6kts (3x)

As you get into this realm, it seems like it's much more than our classic "muscle cars"(waterline length + SA/D)?

[barefoot children 20]

On 9/10/2020 at 4:09 PM, mathystuff said:

From the article:

"Coupled with this effort, the panel is recommending that pre-race inspections be conducted “in order to advise skippers and crews on (1) the importance of stability, its implications, and how it’s calculated; and (2) preparing the boat and themselves for the rigors of distance racing.”

 

It is alarming how little a lot of sailors actually know about the physics that keep their boats upright. "Ballast ratio = stability" and "heavy = safe" seem to be burned into a lot of heads.

Yacht clubs need to up their game in the education of young sailors to be. Licenses should include some knowledge about this aswell.

Here she was at start in 2013.  I had talked to the crew at the dock before they cast off.  So sorry for the loss of 2 lives in later mac..