Aftmast rigs???

[brian eiland]

I was just cruising back thru this subject tread, and ran across this old vessel design that was a definitely an influence on my thoughts at the time.
http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-56.html#post755009

Hi RHP,
There was another Frank MacLear design of about 70-80 feet built for a guy on the Chesapeake Bay by Palmer Johnson also,...with this same type of rig, but I think it was a cutter style. The name of the vessel also began with an 'A'. I just can't remember what the name was. Perhaps you could recall?

I do remember it had an influence on my thoughts at the time I was developing the idea for my aftmast configuration.

ah-ha,...I just found her
Angantyr

In a cutter, such as the MacLear & Harris Angantyr, two sails instead of one are set in the foretriangle. This rig has much in its favor for cruising. Despite its size, the 61-foot Angantyr (named after an ancient Norse king) has been sailed by small crews on most of her passages, which include 7 Atlantic crossings. Indeed, her owner, Jim Crawford, made one of the latter single-handed. Twin centerboards…..

 

[sharpii2]

I was just cruising back thru this subject tread, and ran across this old vessel design that was a definitely an influence on my thoughts at the time.
http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-56.html#post755009


View attachment 108647

This is what I think off, when I think of a masthead rig cutter. It's nice to see how everything sort of just works out.

The mast ends up at the widest point of the deck, so it gets excellent shroud angles. The fore stay and the back stay are both roughly the same length, and they too have excellent angles.

The two stay sails make balancing the boat relatively easy, by furling one or the other, depending how much the main is reefed. And the mast is not too far from the cockpit either, in a part of the boat which will experience the least amount of pitching.

Not only is this rig handy but it is also potentially quite strong for the amount of sail area it sports.

The only fly in the ointment is the inner jib has no direct back stay support. This could hamper its luff tension and windward ability, as well as risk over stressing the mast. Two possible solutions are:

1.) making the mast strong enough to take the stress, or
2.) provide running back stays.

despite this potential flaw, it is one of two of my favorite Bermuda rigs.

The other is the 3/4 sloop.

After that, it would be the masthead sloop with an over built jib furling system.

 

[brian eiland]

Roller Furling Genoa

Over the years there has been many naysayers expressing reservations about roller REEFING sails.

I just ran across a few little discussions/references to roller furling genoas utilizing more modern sail materials.

Off the wind, the boat went well with the genoa rolled to half-size and the main double reefed.
http://www.uksailmakers.com/news/

Nick Southward and UK Sailmakers' Barry Hayes have become the first team to race the 590-mile Hong Kong to Manilla race double-handed, and they did it on a 36-foot J/109 named WHISKEY JACK. Most of the race for WHISKEY JACK was sailed in 30 knots of wind -- with 40-45 knots for almost the whole second day of race. Sailing against fully-crewed teams, the duo finished third in IRC 2. They broke and fixed a lot of gear, but their sails were not on the "to repair" list

Passagemaker Titanium - Carbon Single-sided Taffeta


Titanium Beidseitig Taffeta - Cruising Genua

 

[brian eiland]

Lash Tangs instead of Terminals attach rigging to spar

Rigging Force Review for Aft-Mast
..... AND it will NOT consist of two individual jumper stays (wire cables), but rather will be fashioned of a continuous loop of ‘cable’ that would wrap around the back-side of the mast at its lower ‘termination’, and might even do so at its upper ‘termination’.

The actual jumper stay ‘cable’ itself will be constructed from one of the new-age synthetic rigging materials such as Dyneema, Spectra, PBO, LCP, Aramid, C-6 carbon tow, etc. Ideally this stay material will have NO pre-stretch requirements thus no pre-loading. It should be very strong upon immediate application of force, and in a minimal diameter that it can be looped around the mast section in a continuous manner, at least on one end, maybe both. As a continuous loop, ‘both sides’ will always be carrying ½ the total load, rather than one side under load, while the other might be slack. There will also be a minimum of ‘fittings’ required to attach them to the mast (less weight, less failure pts). I imagine a simple ‘block’ of material attached to the mast around which the loop of this jumper stay can not slide any further along the mast….and one end needs to be adjustable

Not exactly my idea of a 'wrap around connection'. but it is a soft fiber technology in lieu of traditional tangs..

....found on Rigging Projects blog and Facebook pages.
"One of the details we specified for a new Hall Spars & Rigging Swan 82 spar: We used Blew Stoub lash tangs instead of t-terminals to interface the Future Fibres supplied Aramid runners with the spar. The lash loops give us better articulation, easy servicing and lower profile."

 

[brian eiland]

Old meets New

A sort of older lashing method updated by new materials.

Sort of wrap around...

 

[brian eiland]

https://rigpronewport.wordpress.com/tag/carbon-rigging/

Big Loups

We just made these fine LOUPS for securing the runners on the Rambler 100. Used in basket, they have a
SWL of 44,100 lbs. Break strength =176,400 lbs.

 

[brian eiland]

new Flatten Batten developments

http://riggingnews.blogspot.com/2014/05/new-flatten-batten-development.html

For those who only have a few spare moments in the day, here is a quick overview of the key points that have come out of the last two years of development that Dan and Simon have done, that ultimately led to a J-111 in the USA, called "Spaceman Spiff" winning her class at Quantum Key West Race week earlier this year, with a full set of Flattens in their Light-Medium Jib. The feedback from the trimmers and sail makers on and off the boat was nothing but extremely positive and the Flattens had allowed them to trim the sail in ways that were not possible with existing furling battens systems

This just might be a solution for battens in my roller furling mizzen sail :idea:

https://www.youtube.com/watch?v=nNRc2IX82s4

 

[brian eiland]

Not exactly my idea of a 'wrap around connection'. but it is a soft fiber technology in lieu of traditional tangs..

....found on Rigging Projects blog and Facebook pages.
"One of the details we specified for a new Hall Spars & Rigging Swan 82 spar: We used Blew Stoub lash tangs instead of t-terminals to interface the Future Fibres supplied Aramid runners with the spar. The lash loops give us better articulation, easy servicing and lower profile."

Looking for more photos of 'cheek blocks', or whatever might be the best name for these items? Reference these postings:
http://www.boatdesign.net/forums/multihulls/soft-rigging-solutions-47997-2.html#post735744

proper name for these connection items

couple more photos

 

[brian eiland]

http://www.colligomarine.com/mastconnections-gallery/

Another type of soft fiber rigging connection to the mast.
( I like these but they are not quite what I am looking for in this instance)

 

[brian eiland]

Aft Mast on Trimaran, failure

Please note that I am willing to face up any failures of my aft-mast rig concept, and attempt to determine what the problems might be.

I remember this one that was brought up a number of years back (2006), on this subject thread. During some recent websurfing I discovered that I had not addressed this failure with the same explanation on this subject thread, that I did on that other one. So here is some of that story.

When I was first made aware of his original website and his rig calculator, I was very surprised at the exact wording on his site that copied the wording right out of my website verbatim. Here is a gentleman who never once had contacted me about this subject he had such a great interest in, nor ask any permission of me, nor given any references on his site back to mine. I wrote him a letter about these matters, which he chose to ignore answering, and instead took down some of his web pages from his site.

In that letter I also expressed some concerns about his interpretation of my design. I was particularly concerned about his lack of a resistance element to the forward force that will be generated by the upper aft facing jumper strut over which the masthead backstay passes. In contrast I have provided a triangulated (diamond) jumper strut arrangement to help counter this forward pressing force. I have also provided two additional backstays at this point to counter forestay loads.

…photo of vessel under discussion:
http://www.boatdesign.net/gallery/showphoto.php/photo/6863
(BE notes: nice looking vessel and rig, just not adequately stayed)

In other words I was concerned about his variation of my design. But since he had chose not to communicate with me about my concerns, and since he had already built it, there was not much left to do but wish him the best. Maybe his mast section would stand up to the loads, but I seriously doubted it. I was also concerned about his disproportionately long, lower mast panel.

Another of my concerns was his use of three headsails. To my way of thinking this placed the headsails too close together to be practical. We know from past cutter arrangements that should we have the headsail and the staysail too close to one another it became difficult to maintain the trim on both such that they were always fully engaged. Plus, it became more problematic in a tacking situation. And he obviously had not sailed enough to recognize the balance that can be had with a jib-mizzen combination.

Your reference to the rig being replaced with a conventional one was rather brief, leaving the impression that this mast aft experiment was a total failure.

I don’t think we can assume this just yet with the VERY limited information we have. All I see so far is a failure of a piece of ordinary rigging, “a Norseman backstay fitting failed, crystallized in the threads. That could happen with any rig. Certainly it appears to be a backstay component, and if he had only a single backstay with this 3-headsail arrangement that would be a real problem. But lets not condemn the mast aft concept in general based upon this flawed design experiment.

And finally I might even have to give some credit to this fellow. At least he went out there AND DID IT, more than can be said for many dreamers.

The quote above was what I posted on this forum.

However I also reviewed the gentleman's logs he had posted, and discovered this quote that I posted on another forum:

So here is one portion having to do with the tri named Windwalker. I had previously looked back thru his log postings and made these following excerpts from them:

…excerpts from log of aftmast trimaran Windwalker
Sat, May 14:
then set sails slogging to windward close hauled heading 045° making 3-5 kts. I experimented with various sail settings, depowering the main and genny to 1/3, and finally, at about 0915, for the first time setting the three foresails together, set the jib at 1/3 also. It all balances well, all three sails are pulling nicely about 35° off the wind. Held heading all day to get a better tack to Bermuda. This is the 5th day of easterly headwinds, right on the nose and no end in sight.

Tues, May 17:
I have a lot to learn about tweaking this aft mast rig to get best performance. The helm is well balanced, nearly neutral, holding wind course unattended for as long as 24 hours. It sails well hard on the wind in light air, but as yet I HAVEN'T had an opportunity to sail it off the wind or in stiff blows.

Fri, May 20:
0600, wind E - 4-6 kts, seas 3 ft, mostly clear, high 60s. Wind veered dead E right on my nose. On stbd tack heading 045° making 5 kts northing. Swell making for a rough ride. Motored for 1/2 hour getting sails set and on heading after being hove to. Big ketch on port tack crossed my bow at 0700, distant 1/2 nm. I went on a port tack, set the heading, went below to fix another cup of coffee when WHAM ------
Disaster…0800…Dismasted Norseman backstay fitting failed, crystallized in the threads. 116 miles from Bermuda - vicinity of 32° 05'N, 67° 16'W - drifting and securing what I can. All wreckage, mast and sails on board and secured by noon

Mon, May 13:
After that I will spend a few days arguing with myself about how to go about the salvage and rebuild. Most obvious right now is to re-rig as a conventional cutter, as I have most all of what is needed in hand or can be modified.

Wed, May 25:
After consideration of damages and what I have left to work with, the only option apparent is to re-rig as a conventional cutter, recutting the sails to suit. I may be able to begin next week after I make arrangements to get the mast off the boat and on land.

So it appears as though his reasoning for changing from his original aftmast configuration over to a conventional configuration was based on the materials he was left with following the incident and his insufficient funds.
He never really had negative comments about the rig, in fact most were praise. And both regrettable and inexplicable, he never made any more comments about rigging subjects at all, positive or negative?? I never understood this guy.

 

[DennisRB]

http://www.cantierino.it/AGALLERIA/orsobianco/a.html

 

[brian eiland]

Central Nacelle

Interesting new design just brought to my attention today.

Includes a wave piercing central nacelle, and a aft-mast option as I have championed for quite some time.

http://www.o-yachts.com/models/class-5

Will have to give this a closer inspection real soon.

Appears as though they have taken down their website ?

 

[brian eiland]

http://www.cantierino.it/AGALLERIA/orsobianco/a.html

I'm assuming that is Italian language? Wonder if we can get an interpretation of that text?

Ah ha, I used google for an interpretation:
https://translate.google.com/translate?hl=en&sl=it&u=http://www.cantierino.it/AGALLERIA/orsobianco/a.html&prev=search

Surprisingly I found very little text about the rig design itself. I did find this:

Here we are finally at the firm conclusion. We did the first exit on board Ing. hull calculator, Alessandro Suardi, and the captain Giancarlo Basile, besides me. Little wind but just what we needed.

Surprises, largely planned and hoped for, were many. The first finding was that the respective boom mainsail with you, you can put them in that place. They do not need to absolutely nothing and worse not just the problems of navigation. We found that the main staple (which replaces the mainsail) has an area comparable to the mainsail but it makes a lot more, not having to deal with the turbulence of the tree) It 'clear that speaking of flakes there is no problem for issali and ammainarli. Also a nice thing is that by removing and replacing the flakes the sailing center remains almost unchanged.

We had lunch in the cockpit by lowering the genoa. The boat has quietly continued on its route with only the main jib and with your autopilot. In addition, the boat turns like a dinghy, with a breath of wind. Returning on the Tiber in the midst of the myriad of boats all equipped with boom and jib looked like a scene from Giurassic Park !!!

I think was probably having lunch like this:

 

[brian eiland]

Pertaining to the subject of a central nacelle and the longitudinal stiffness it adds to the catamaran hull form,...there was this photo of an America's Cup cat posted recently:

...back in 2003 I had posted this....
http://www.boatdesign.net/forums/boat-design/big-cat-alt-cbs-sail-rigs-2225.html

Alternative Centerboards & Sail Rigs Aboard Big Cat

One item of your thought processes caught my attention in particular; your desire for a single centerboard, and real shallow draft capabilities. I'll certainly second that motion, that shallow draft idea. One of the greatest attributes of multihulls is their capability to really go exploring ALL the water areas including those tributaries, lagoons, reefs, etc. That's why I had kick-up CB's in each hull of my design.

BUT, what you may not have noticed was my alternative to the CB's in each hull. Look at the attached drawing, (or the very bottom profile drwg that denotes "asymmetrical CB's, nacelle mounted". First, imagine a flat plate, on edge, mounted down the centerline on the underside of the bridge deck. This flat plate will act as a rib to strengthen the fore-to-aft rigidity of the vessel, a somewhat weaker characteristic in a catamaran structure vs. a keeled monohull. If a tow bundle (rope, etc) of carbon fiber (kevlar, PBO, etc) was laid along the bottom edge of this flat plate, the rigidity could be even greater (sort of akin to a bottom truss structure, or a flange of an 'I' beam). Now on either side of this flat plate I propose to mount a centerboard, not a single, symmetrical one, but rather two asymmetrical ones; sort of like a single board split in half. The flat sides of these asymmetric boards would fit up against the flat plate nacelle, and rotate on oversize (possibly 1-foot) diameter bearings. The flat fit & big bearings would together supply a great big surface for the large bending moments to bear against. Only one board at a time would be lowered. In fact the two could be linked together such that the act of lifting one automatically lowers (& powers) the other down. And they both could be rigged to 'kick up' upon hitting any solid object and/or for shallow cruising. The control lines (cables) could be routed right up to the cabin top and back to the cockpit.

There are several advantages to an asymmetrical shaped centerboard. First, it requires less total board area to develop a leeway reducing force....so the board size is reduced. Secondly, since it is asymmetrical, it does not require an angle of attack (does not require the boat itself to be sailed at a skewed angle) to develop the 'board's lift' (leeway reducing force). This actually
may result in the vessel making less leeway. Plus the drag forces associated with the CB lift forces are on the centerline of the vessel, rather than offin one hull that produces turning moments about the center of the vessel.

This centerline mounting may also improve the tacking capabilities of the vessel as it allows the 'clean' hulls to slip a little while pivoting about the central board.

The front of this nacelle/plate could be configured to act as a wave splitter to actually attack, up front, the formation of those peaky waves under the tramp areas that eventually slap at our bridge deck underside. We kind of slice those waves down a bit. A lightweight fairing might also be added to this 'flat plate nacelle' so it appears outwardly much more esthetically pleasing, as well as more curvature to shed those peaky waves.

And how about the maintenance factor, particularly in remote cruising areas. No need to haul-out the vessel to repair kick-up CB problems, or even bottom painting problems. Everything, including the cables, bearings, and boards is all above the load waterline. The initial building cost should be less by eliminating the trunks in two hulls, and the watertight integrity is much
better. The twin boards might have to be made a little bit longer as they operate with a 'free-surface' end, but then they are asymmetric so they can be correspondingly shorter. I would further suggest that surplus helicopter blades are prime candidate sources for both CB blades and rudder blades....high tech, extremely strong carbon fiber fabrications that have a
prescribed limited life span aboard aircraft, but are perfectly happy for our use......

 

[CT249]

I think the central "spine" dates back to Amaryllis, and of course a more recent example was seen on the Prout's Phantom Wake in about 1980, which was definitely shaped as a wave splitter.

Centreline centreboards were common in Aus for years but were dumped because of the end-plate issues, I think