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Old 26-06-2016, 05:53   #16
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

Yes the naming of sails is a wonderful thing, full of all sorts of illogical historical quirks and romance. Traditionaly staysails were named from the mast that the top of the stay attached to so you got some salty sounding terms like the foretopmast staysail, and the main topgallant staysail.

For some reason the jibs were never called staysails, and I think that stems from the fact that the earliest jibs were not on stays but were set flying, before they even thought of making wooden hanks to attach the sail onto the hemp stay.

In yachting most of the cutter yachts had a stemhead staysail and a jib set flying off a bowsprit. Where as a sloop only had the one hanked on headsail on a shorter more sturdy bowsprit (or none), sometimes with an extra jibboom and a flying jib. I guess as yachts developed into something different the terms stayed.
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Old 26-06-2016, 06:32   #17
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

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Originally Posted by Snowpetrel View Post
Yes the naming of sails is a wonderful thing, full of all sorts of illogical historical quirks and romance. Traditionaly staysails were named from the mast that the top of the stay attached to so you got some salty sounding terms like the foretopmast staysail, and the main topgallant staysail.

For some reason the jibs were never called staysails, and I think that stems from the fact that the earliest jibs were not on stays but were set flying, before they even thought of making wooden hanks to attach the sail onto the hemp stay.

In yachting most of the cutter yachts had a stemhead staysail and a jib set flying off a bowsprit. Where as a sloop only had the one hanked on headsail on a shorter more sturdy bowsprit (or none), sometimes with an extra jibboom and a flying jib. I guess as yachts developed into something different the terms stayed.


Enjoyed these recent posts of yours. Close to my understanding of the terms and development of the traditional cutter (with long bowsprits) and sloops.

Got a chuckle about the one inch taller foremast if you want a ketch instead of a schooner.

Flying jibs are cool.
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Old 26-06-2016, 09:43   #18
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Upside down mainsail

BTW I think the term 'fisherman sail' is incorrect with respect to the rig under discussion in this subject thread. Most references describe a fisherman sail as a four-sided sail, ie
Notes on Sailing Small Schooners

More than likely the sail depicted in this jib-schooner plan might be termed a 'trysail' ?
Quote:
Originally Posted by Yobarnacle
Trysail Barkentine. Fore-n-aft rig more than two masts is a barkentine. The upsidedown mainsails ARE "Trysails".
reverse staysails, as it pertains to ketches, particularly the reverse or upsidedown - Boat Design Forums
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...or perhaps even a 'mule' which is also a 3 sided sail rather than a 4-sided fisherman.
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Old 26-06-2016, 19:08   #19
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Re: Upside down mainsail

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Originally Posted by beiland View Post
BTW I think the term 'fisherman sail' is incorrect with respect to the rig under discussion in this subject thread. Most references describe a fisherman sail as a four-sided sail, ie

More than likely the sail depicted in this jib-schooner plan might be termed a 'trysail' ?

...or perhaps even a 'mule' which is also a 3 sided sail rather than a 4-sided fisherman.
How easily we get off topic and how enjoyable it is...

Firstly I jave to say this is not the correct terminology "Trysail Barkentine. Fore-n-aft rig more than two masts is a barkentine":what: I know this is not your quote...

A Barkentine has the foremast rigged as a square, not a fore and aft mast. The rigging is totally different, its not about the staysails, as in you can't convert a three masted topsail schooner to a Barkentine just by removing the foresail and replacing it with a few staysails. The masting is completely different. Even though superficially it may look similar.

On that weird fisherman sail. Id probably still call it a fisherman myself. It rolls of the tongue nicely and isnt easily confused with any other sail. Its function, and postioning is similar to a "proper" four sided fisherman for me to be comfortable enough with it. The term mule is usually associated with something run up the backstay on a ketch. So I wouldnt call it that myself, and its not really a nice pleasant name for a sail. With its (possibly apt) connotations with the stubborn animal.

Trysail is what they often call the same sail on a wishbone ketch. And probably is the most correct term, but personally it us to easily confused with the modern use as a storm trysail.

So overall if it was me Id call it a fisherman and be quite happy to argue with any traditionalists who want to argue that that term only applies to four cornered sails. Most people would understand its function as a big light weather sail filling the space between the tips of the masts on a schooner.

If a big four sided overlapping fisherman spinnaker/light airs sail was used Id call it a Gollywobbler because it is the best name ever for a sail.
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Old 27-06-2016, 06:04   #20
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

Probably spent enough time on 'naming' those sails

Perhaps we can return to the aerodynamics of the situation as I started to discuss in posting #9
http://www.cruisersforum.com/forums/...ml#post2152198
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Old 27-06-2016, 14:36   #21
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

The report says that the force coefficients for the sloop rig were derived from the ORC VPP aerodynamic model, i.e. *not* computed with CFD. Then, it's like comparing oranges to apples. A *serious* aero analysis would consist of 2 parts:
  • comparison of CFD computations for the sloop rig with VPP results, for calibration
  • CFD computations with the jib schooner rig
The shape of the jibs in the 90° AWA computation seems wrong to me: I can't understand how the sails remain so flat.

The CFD aero analysis says nothing about the vertical wind gradient considered in the study: in the real world, the friction of air on the sea surface causes a boundary layer to develop, reducing the true wind speed at low altitude (the first meters above the surface). This reduces the aero force generated by the lower part of the sails. If this were taken into account, it is possible that the 2-jib rig would give less aero force.

The analysis says nothing about the increase in drag resulting from the standing rigging (shrouds and spreaders) necessary for the second mast.

And it says nothing about the performance in reefed/furled condition or in a seaway (when the sea isn't flat any more and boat motions continuously change the apparent wind speed and direction).

Note: part of my work is subcontracting CFD computations and analysing the results...

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Old 27-06-2016, 15:05   #22
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

Thanks Alain, I was looking for something like that analysis of the Doyle study.
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Old 28-06-2016, 12:58   #23
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

It's funny how posters were more interested in naming the sails than in comparing the performance of the rigs.

CFD computations taking into account the boat motions in a seaway would be at least 10 times more costly because this would imply coupling between boat motions and airflow on the sails.

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Old 16-12-2019, 07:47   #24
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Re: 50’ Jib-Schooner Sail Plan, aero analysis

You guys need a drink ---or two we are in the age of ultimate strength fibers we can do new things with masts and strings. I found a sketch I made when I was 14 (long time ago) Catamaran one mast each hull leaning towards each other 10 t0 15 degrees
Joined by foil hoop top. leaning forward------ back stays ---- Finite Chord forestay /foil with a luffgroove . short very swept back foil spreaders on the foil so you could bend foil center to windward a relatively small amount. All it needed was a wishbone boom ( I had never seen one at that time) One's mind is less cluttered at that age. I thought SEX was just a way of designating long hair people from short hair people! OMG
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