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Thread: Oceanic Spritsail AKA alpha dory sprit

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    Default Oceanic Spritsail AKA alpha dory sprit

    An oceanic spritsail, or an alpha dory spritsail, or a hawaiin tacking rig, or whatever you call it yourself! Basically, I'm talking about a spritsail that has the part of the sail between the sprit and the foot cut out, so it is just a sort of triangular sail with more sail area up high than down low. The hawaiians sometimes curved the sprit to force more sail area into an otherwise triangular sail, though it looks like modern oc sailing canoes don't do this...





    Advantages as far as I can see: simplicity, most of the sail area is up high (good for light winds maybe, though bad for heavy winds especially in a monohull), can be constructed to have a high aspect ratio and take up little horizontal space, wind can spill out the top in a gust and the sprit can be made to flex, ?

    Disadvantages: not so easy reefing, weight up high, CE up high, not alot of sail area for height of mast (like an upside down bermuda rig) so longer spars, ?

    Since it is like an upside down bermuda, especially if built with a high aspect ratio (many hawaiian canoes did this), does it have good upwind performance? and poor downwind performance? Any advantages/disadvantages that I missed?

    Why put a sail like this on a dory, famous for their lack of initial stability?

    This is the same sail on two opposite types of craft, if you notice in the pics above...
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Lotta stick for the amount of sail area. But all that stick does a pretty good job of supporting and controlling low-strength, high-stretch, low-technology sail cloth. It's a pretty low-aspect rig, with all of the good points and bad points that this implies. The kind of dory that uses this rig is the Swampscott type, not the slab-sided Banks dory. Swampscott type dories tend to have a much more sailing-friendly stability curve. . .they are really round-bottom boats with the vestigial flat bottom and dory-style construction details they inherited from their workboat ancestors. Here's some sections showing the similarities between swampscott dories and other round-bottom types. (Peter, your Bolger Cartopper also shares this similarity, as it is essentially a simplified dory-skiff shape.)



    I think there are better and handier rigs to set or strike or reef that don't use nearly so much wood and which don't require stays or a jib, but there are some like Dan Noyes who really, really love this rig. I think it looks great on a dory hull, but I don't think there's very compelling reasons to use it when you have modern sailcloth at your disposal unless you are trying to keep that period look.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Peter -

    You've got so much wrong from the start, so I'm not sure how any of it can be answered or discussed. The question that I think you are asking is an interesting one, but will get sidetracked by incorrect terms and concepts.

    First, a spar that attaches to the mast with a pivoting fitting (like a gooseneck) is not a sprit. In this case it is a boom because it connects to both the tack and clew along the foot. Spars that connect to the mast with jaws can be booms, gaffs or gunter sections. Spars that connect to the mast with a snotter are sprit-type-spars, sometimes just called sprits (one end at the peak or head) and sometimes called sprit-booms (one end at the clew).

    Second, the sail on the alpha dory isn't an 'upside down bermuda' -- if anything it is like one on its side.

    Third, a big advantage of a boom that raises up as it goes aft (along with an aft-raked mast) is that when you wing it out to the side, the tip of the boom and clew of the sail stay out of the water.

    Last edited by Thorne; 01-27-2011 at 05:42 PM.
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    As a layman, one advantage I see of having the boom point up so high (as illistrated on the outrigger) is that it gives those onboard more head-room.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by peterchech View Post
    Why put a sail like this on a dory, famous for their lack of initial stability?
    You must remember that these boats evolved over many decades, perhaps centuries, and the rigs they carried were chosen for their practicality.

    Your question really answers itself. The rig was chosen specifically because of the boats low initial stability. The cut of the sail with the high boom end eliminates the possibility of the boom dragging in the water when the boat is heeled.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    I have one on my swampscott and it can be a major pain in the ass. I can't really comment on the performance of that type of rig, since mine's cut so poorly (I use the dory mostly for rowing).

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    I wouldn't call it a sprit-boom sail, but simply a leg-of-mutton with a very cocked-up boom.

    The idea of a sprit-boom is that it's self-vanging: the part of the sail below the sprit-boom keeps it from lifting up.

    This might be a disadvantage on a tender ocean-going boat since it could cause the sail to drag in the water.
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    There are some major differences between what the dory is carrying and the tri. Previous thread already noted that neither are spritsails, both are boomed. On the dory the after end of the boom is cocked up enough to clear heads and perhaps not roll into the sea downwind, although I have not seen that as a problem in my similar cocked up somewhat ducker boom. The tri rig is trying to turn itself into a crabclaw with the clew very high, well over head height. As I recall the old ones had booms with curves in them so they were about vertical ( I am thinking about Cook engravings) and on some of them the mast had forward rake.
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    That dory has a low-aspect Leg-O-Mutton and much of the reason that it appears to look like the sail on the tri is due to the heel angle of the boat and the angle the photo was taken from. You don't need to be Hawaiian to figure out that the tail of the boom dragging in the water and preventing you from easing the sail out to save your bacon (or Spam in Hawaii) can be bad, but in a more typical shot I doubt the boom is raised at an angle that would approach what the photo makes one think.

    No sprits are involved in practice or concept in either situation, so that term shouldn't even come up in this conversation. The steeply-raised boom can work pretty well in some instances though. I have one customer who is a really hard-core canoe sailor in town here. I frequently see him out on days when I would certainly think twice about the sanity of even going out. He actually wears-out canoe sails....which is pretty rare. During our most recent new-sail brainstorming session he wanted to cover all the bases, weather-wise, with his lateen rig, so I built him a pretty typical, 67 sq. ft. lateen sail and added a reef that will bring it down to about 52 sq. ft. Then for moderate air, we can adjust the boom angle, kicking it up by moving the mast boom junction (even to a point where the boom is vertical and behind the mast) and added a jib. The little mitre-cut, 20 sq. ft. jib is rigged on a floating jib boom, with it's tack downhaul part-way aft along the boom, the way it is done on ice scooters and a lot of radio-controlled sloop models. In this configuration it makes the jib self-tending and self-vanging, so it's pretty easy to manage. It's a lot of sail area on a canoe, but seems to work pretty well on lighter-air days. Here is the original concept drawing and a shot of the rig at work (notice that I took the liberty of upgrading his boat on the drawing.)





    I think one reason for the curved booms on the native boats may simply be to increase sail area without going higher. It essentially adds some roach, the same way you would on a Hobie Cat sail with a big leech roach. Boats with sleek hulls that reach nicely can benefit from it, speed-wise. When you make sails, you end up with a lot of small scraps of expensive cloth left over and I've been saving them. One of these days, I'm going to build this sail from them - just to see what it can do. Should turn some heads.


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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by Todd Bradshaw View Post
    One of these days, I'm going to build this sail from them - just to see what it can do. Should turn some heads.

    haha I may be doing just that on my almost finished OC! hence, the thread... interesting canoe sail too, kind of like a lateen as much as anything else...

    James- interesting comment, about the advantage of this sail being mainly that it controls stretchy sailcloth.

    Thorne- I didn't call it an oceanic spritsail because I think that's what it is. Pretty much all the literature on polynesian sailing canoes refers to it this way, whether correctly or incorrectly. Besides terminology, is there something else I have wrong, like the advantatges/disadvantages of the rig?
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by peterchech View Post
    Disadvantages: not so easy reefing, weight up high, CE up high, not alot of sail area for height of mast (like an upside down bermuda rig) so longer spars, ?

    ...
    I would also mention Sunfish Lateen as similar sail, a popular boat and the simplicity and excelent performance of the rig have alot to do with the success of the boat.

    Reefing difficulty...
    in the two yrs. sailing my alpha and 10+ yrs with a sunfish I have never reefed a sail... I dont know if that is difficult or effortless as far as reefing goes, but yes the geometry of the sail with the raked foot is difficult to reef, Todd had an illustration... but the sail is sooo well mannered over such a wide wind range there is far less need to reef than with four sided sails.

    Weight up high? the historic Alpha dory mast is 17' on a 21' boat... and the mast tapers to just over an inch at the mast head... so as far as comparisons with other boats this is a particullarly low light rig... also no spar at the top of the mast, so very light rig.

    Long spars? Heck Yeah! the boom on my Alpha big rig was 18' long and 1 1/2 inches thick, very light and flexible... but actually the mast is quite short, even with my big rig all the spars fit inside the boat, and the traditional Alpha rig with a 17' mast fits easily in the 21' dory, short spars that fit inside the boat are often the main selling point for four sided sails but the dory rig is really just as good at short spars, the longger boom means you can have a shorter mast

    Last edited by Daniel Noyes; 01-28-2011 at 09:33 AM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    We seem to have ventured into treacherous waters here, as there is a lot of fluctuating terminology flyin' around -- not only here but on the web and other publications. http://indigenousboats.blogspot.com/...implified.html



    Let's define our terms:
    From my personal perspective, there is a distinct difference between a sprit and a sprit-boom. This is the European sprit rig, not Pacific as they've really got a mix of terms and all the possible confusion with the crab-claw, what is a mast and what is a sprit, etc...a perfect example being this "double-sprit rig" -


    Again, this my personal definition: A sprit runs across the mast and up to the head or peak of the sail -- no matter what the angle is. In most cases the sprit will be attached to the boom via snotter, but some of the very large historical Dutch (and contemporary Danish) sprit rigs have the sprit attached to the deck in some manner.

    A sprit-boom runs across the mast and across to the clew of the sail.

    As for the definition of a Leg o' Mutton sail, I'd like to ask Todd what he considers to be the definition. I'd always thought that the boom (usually a sprit) ran nearly horizontal to the clew, and the foot of the sail angles up from the tack to the clew. Taking a stock marconi/bermudan sail and putting a sprit-boom on it doesn't make it a Leg o' Mutton sail in my book, even though I used that rig on my dory skiff for a year or so. I called it a faux Leg o' Mutton sail.

    Michalak calls the below rig a "sharpie sprit sail", which although accurate seems to me to be confusing. http://marina.fortunecity.com/breakw...0701/Index.htm

    Leg O' Mutton rig from polysail.com -


    My faux Leg o' Mutton sail, in my terminology a sprit-boomed Bermuda sail -


    Same sail and mast with a gaff-jaw boom -
    Last edited by Thorne; 01-28-2011 at 09:35 AM.
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    ...in the two yrs. sailing my alpha and 10+ yrs with a sunfish I have never reefed a sail..
    Dan, I have to say I find that absolutely astonishing. Don't you ever go out storm sailing? 25+ knots is when it starts to get fun!





    And as someone who owns both a long-boomed sloop and a balance lugger, I don't think your "less need to reef" comment is even remotely accurate from my experience. In fact, the balance lug which is self-vanging is easier and more docile to feather in gusts than the long-boomed Stonehorse mainsail which is held down only by the sheet and the weight of the boom.
    Last edited by James McMullen; 01-28-2011 at 09:48 AM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Gary Dierking's Ulua rig



    and he says of it

    "The sailing rig
    shown is of a modern Hawaiian type. The
    availability of fiberglass windsurfer masts allows for
    a very simple lightweight plug-in rig which can be
    lowered entirely while at sea and stowed on the
    iakos. A brailing line folds the boom and sail up
    against the mast for quick furling, and avoids
    dumping the sail onto the crew."

    http://homepages.paradise.net.nz/garyd/plans.html

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by Thorne View Post
    ...First, a spar that attaches to the mast with a pivoting fitting (like a gooseneck) is not a sprit. In this case it is a boom because it connects to both the tack and clew along the foot. ...
    --- And yet the rig is called an "Oceanic spritsail" and the boom is often called a sprit in the Oceanic sailing micro-culture. Now is this is a terminological shift between sailing "ethnic groups" or a statement about how those familair with the pacific rig see the function of the sprit/boom? I am interested.

    To the extent that the "boom" forces the corner of the sail up like a sprit..... good to consider?

    The habits of sailing also needs to be clarified to put the oceanic sprit in better context. I seem to recall the OC's are not often sailed high to windward. Some do not even have boards, and some do. Some crews tend to paddle to windward and use the sail for downwind. Given the consistent high wind in that area, the OC sail area may not be comparable to an area one would choose for coastal sailing. Their mode of reefing also may not the same as other boating micro-cultures. Boom/sprit angle makes brailing lines useful as regular power-control devices (brail up sail into a deep U-profile to reduce power with the windward brail, or use the leeward brail to "cut" through the top of the sail and spill the wind as well as spoil it). This is a method good for gusts, in conditions where you might wait it out and see if you can relax brails to continue. I do not know if this is something the OC's do, though in other Pacific sailing cultures it is common. --Wade
    Last edited by wtarzia; 01-28-2011 at 11:07 AM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by peterchech View Post
    haha I may be doing just that on my almost finished OC! hence, the thread... interesting canoe sail too, kind of like a lateen as much as anything else...

    James- interesting comment, about the advantage of this sail being mainly that it controls stretchy sailcloth.

    Thorne- I didn't call it an oceanic spritsail because I think that's what it is. Pretty much all the literature on polynesian sailing canoes refers to it this way, whether correctly or incorrectly. Besides terminology, is there something else I have wrong, like the advantatges/disadvantages of the rig?
    While your drawing has one fewer spars, the HSCA boats are more like a gunter in some respects since they have a stub mast to which they draw up the yard or whatever you'd like to call it. It allows one to dump the whole rig and furl it beside the boat on the tramp. With the version you have pictured you can brail it up and pull the whole mess out of the freestanding setup. The stub rig can be unstayed or stayed which can be nice. I think an 80 sf rig like that would be pretty spectacular on my ulua. Wish I had the money....

    Dan

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by keyhavenpotterer View Post
    Gary Dierking's Ulua rig



    and he says of it

    "The sailing rig
    shown is of a modern Hawaiian type. The
    availability of fiberglass windsurfer masts allows for
    a very simple lightweight plug-in rig which can be
    lowered entirely while at sea and stowed on the
    iakos. A brailing line folds the boom and sail up
    against the mast for quick furling, and avoids
    dumping the sail onto the crew."

    http://homepages.paradise.net.nz/garyd/plans.html
    One of those upped a bit in square footage to match the longer hull of my ulua would be so cool. I went with a leg o' mutton with a sprit boom instead and don't like it as much because it is tougher to use due to a couple design decisions that weren't ideal for the outrigger.

    You could use a long carbon windsurf mast and a more flexy fiberglass one for the boom--super light and easy to stow--but difficult to reef.

    I've found my 128 square foot main to be great up to about 12-15 knots and the reefed sail to be great above that. I didn't want the boat to break due to the leverage of the mast on the open canoe. A flexier mast helps a bunch.

    Dan

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Thorne, as I learned it, a Leg-O-Mutton is just a pretty simple, low-aspect, 3-sider, hung from a typical, one-piece mast (often raked a bit). It may have a modest roach and battens, or be battenless and hollowed on the leech. It can have either a conventional boom (usually laced, rather than loose-footed) or a sprit boom. More than anything else, it seems to me that the aspect ratio is the key. Many of these sails seem to look almost as wide along the boom as they are tall. I don't know if there is some more official designation (or an "International Soceity of Sail Part Namers") and there are always regional variations. Any time you're using a boom that long, you're likely to have the foot angled upward aft in order to keep the clew out of the water on a reach.





    The sprit boom on that Polysail L-O-M photo is rigged dead wrong (why am I not surprised?). Sprit booms should always be angled so that they are higher up front at the mast than they are back at the clew. That's what keeps the clew down and works with the straight foot to keep them self vanging.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Clc's Northeaster dory has a handy 68sf sailplan that might work well on a small solo proa or tri





    The sails can be purchased ready to go.
    Last edited by JimD; 01-28-2011 at 12:32 PM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Could this be made as an extreme type of gunter? Gary calls it a stub mast rig. The luff spar does not attach to the stub mast but sits in a universal joint at its base.





    It looks like it ought to be very easy to raise and lower and stow on deck.
    Last edited by JimD; 01-28-2011 at 12:52 PM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Todd - Thanks for your perspective on this! I hereby and forthwith appoint you as the Chair of the ISSPN, and look forward to your next book. (grin)

    Jim - Again just from my perspective, a crabclaw sail mounts on a very short mast, with two sprits or spars crossing the mast. Todd has made a good distinction in previous posts that there are two types of Gunter top spars: folding and sliding. So my answer would be , "No".
    Last edited by Thorne; 01-28-2011 at 12:47 PM.
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    And what would you call this


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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    and set, never seen anything quite like it before. On Lake Geneva, France.


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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Is it a lateen with a super high steeved yard maybe?

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Yes, sort of lanteen crossed with a lug. Notice the line running from the front of the yard to the base of the mast. Pull on it, and the yard swings vertical. It was great to see something I had never seen the like of before. The large cargo ships which still trade the Lake with tourists onboard are lanteen rigged so it would seem the sail and oar dinghy could be a very old design indeed.

    This is the same boat in harbour. Boat's about 22' long. Just look how far forward past the bows the yard sticks out. These craft specialise in fishing for the local perch which is a delicacy of the area.



    Brian

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by JimD View Post
    Could this be made as an extreme type of gunter? Gary calls it a stub mast rig. The luff spar does not attach to the stub mast but sits in a universal joint at its base.





    It looks like it ought to be very easy to raise and lower and stow on deck.
    That's what's used on the big HSCA canoes as well--but their's are stayed to the bow and amas rather than wrack (wreck?) the canoe with its more massive sail area. I'm comfortable with about 100 sf on a freestanding rig--especially if it's bendy to relieve some gust pressure. Over that, I'm wishing for greater bury and more decking structure to deal with that racking force.

    Dan

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    I think one example of the 'extreme' gunters are the ones used on the paraws in Boracay and Iloilo in western Philippines...especially the racing paraws. A sailing friend there tells me the 'shunting' crab claw was replaced in many parts of the Phils in favor of easier rigs...although they are still used some in the southern locales. A couple of types of the triangular oceanic lateen sails are used as well, especially on the smaller bangkas.





    Last edited by ShagRock; 01-28-2011 at 04:21 PM.

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by keyhavenpotterer View Post
    and set, never seen anything quite like it before. On Lake Geneva, France.

    I'd say more of a high-peaked lugsail, as lateens seem to always have either the spar or the sail lead to the stemhead.

    Here's a video of a lugsail that has a similar configuration -
    http://www.youtube.com/watch?v=sTyUU...eature=related
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Don't you just hate it when other cultures (especially primitive ones) refuse to adopt our perfectly good and well defined standards for sail design, rigging and parts-naming? Who do they think they are, anyway?

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    That's the ISSPN sprit, Todd! Damn the Torqueedos and full speed ahead!
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by Todd Bradshaw View Post
    Don't you just hate it when other cultures (especially primitive ones) refuse to adopt our perfectly good and well defined standards for sail design, rigging and parts-naming? Who do they think they are, anyway?
    I know, right? What do non-western cultures know about sailing multihulls anyway? :-)
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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    And if the natives call it a sprit, then it is so. But they probably do not call it a sprit. Historically, what westerner first started calling them Oceanic sprits? I have a feeling that Haddon and Hornell may have some info, but my "Canoes of Oceania" is at the office. -- Wade

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by wtarzia View Post
    And if the natives call it a sprit, then it is so. But they probably do not call it a sprit. Historically, what westerner first started calling them Oceanic sprits? I have a feeling that Haddon and Hornell may have some info, but my "Canoes of Oceania" is at the office. -- Wade
    --- So....Haddon and Hornell were calling it an oceanic sprit in 1936 (p. 25 of the newest edition of C.o.O.) in the Hawaiian section. They mention that a more western sprit with sail laced to mast and boom was seen in use as early as 1839. The Hawaiian sails pictured are not like the modern form, though (they were tall, narrow crab-claws), with the loose foot and nearly equilateral form. -- Wade

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    I don't know about performance but they just look so beautiful...
    “The difference between an adventurer and anybody else is that the youthful embrace of discovery, of self or of the world, is not muted by the responsibilities or the safety-catches of maturity.” Jonathan Borgais

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    Default Re: Oceanic Spritsail AKA alpha dory sprit

    Quote Originally Posted by peterchech View Post
    I don't know about performance but they just look so beautiful...
    --- The aero of those "extreme" traditional crabclaws is intriguing. Were they sacrificing performance for what the anthropologist would call "costly signalling" (a form of ethnic affiiliation or status signalling by using some very inconvenient way to say "I am tough, healthly, and wealthly, and here I am"), or were those forms more practically solving engineering problems of which we are only dimmly aware? The engineering hypothesis should be worked out first, but the "costly signalling" hypothesis should remain in the background, because people have done some physically (efficiency-wise) unpractical things to boats in the name of tradition and ideology (I am thinking of vertical scallops adzed into Ghanaian canoe hulls, huge prow decorations on some Kenyan canoes, and other things).

    The huge scallop in the leach (I guess you would call it the leach) of the crabclaw would tend to stretch out the sail fabric (here usually a mat weave)
    as the sail was tensioned between halyard and sheet (the u-shape as stretched pulls out on the sail fabric). Was that to maintain some sail shape they wanted, or to account for materials that stretched easily? Or did the ends of the claws induce some tip vortexes that had a beneficial aerodynamic effect? It makes me want to cut some of these shapes out of tarp, rig them up, and take them out in an open place on a windy day with a smoke generator (or lots of talcum powder flung into the air!) to film the airflow. --Wade

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