Futuristic Mast Aft Design

Just today I had a gentleman send an inquiry to me along with a reference to a VERY FUTURISTIC mast-aft design.
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He wrote, Brian,

I have been interested in the idea of a forward raked mast with an
unusual sail layout for quite some time now, originally seeing the
idea at a student design show. The boat looked like the sailboat
equivalent to a future speculating auto show "Concept Car", with wild
ideas that gave little concession to practicality.

http://danielsimon.net/community/arno/arno_gaudier.html

When I read your proposed idea of the fishing / leisure catamaran, the
idea seemed much more plausible if not advantageous......Kyle
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Brian added: Since I have talked of mast aft concepts in the past I thought I would spice it up with some new futuristic concepts.

...some other mast aft references on these forums:

Revisiting a Mast-Aft Sailing Rig .....http://www.runningtideyachts.com/sail/

Aftmast...... http://boatdesign.net/forums/showthread.php?t=623

Why does a cutter rig point higher & sail faster...... http://boatdesign.net/forums/showthread.php?t=5596

Sail Aerodynamics...... http://boatdesign.net/forums/showthread.php?t=457

 

I discovered the link to the futuristic design was wrong. Try this:

http://danielsimon.net/community/arno/arno_gaudier.html

 

That is indeed the most fantastic design I have ever seen!!! Believe it or not but I like it!!! That is out of the box thinking!!!!

Brian, what is your opinion? would it sail? Point is that 40 mtrs is a bit big, and forces that come lose at such scale are not to laugh about.

If you scale this boat down to say somewhere between 16 and 19 metres, or thereabout wouldn't that be a better option to see if this sytem works?

3 years ago I build a model with similar characteristics, not so refined as this one but basically same - and it did sail.

 

Luff on lead sail will sag too much, me thinks.

All the vectors are against it. And the rear spreaders will have to be both longer and much more massive.

This sort of thing gets tried about once every decade or two. Phil Bolger tried a single sail version once in the '80's IIRC. It did work, but it wasn't copied. Going to a divided fore triangle, as this design does may help the cause somewhat. For as the luff tension for the outer jib gets intolerable, it can be dropped.

If the hull is stiff enough, it does work. The trouble is, is that it is hard to get sufficient luff tension without setting the mast at around station 6 or 7, or roughly 2/3ds back.

Further back, one simply cannot get sufficient leverage to do the job.

Besides, all this trouble only buys you big improvement on one point of sail; upwind.

I think this is a great experiment, and I secretly hope it works. (sail boat design gets so boring over the years) But, in my heart of hearts, I expect to be dissapointing.

Maybe the reason 'traditional' rigs keep on comming back is that they are really the most practical and useful and deliver the most 'bang for the buck'.

After all, sail boat design is probably the fourth oldest proffession. Preceded only by prostitutes, preachers, and polititians.

Bob

 

Bob, I thought already that there was a snake in the lake, so to speak of. It looked too good to be true. But what do you think - could such a design be worked out so that it will perform?

I was indeed puzzled by the system that keeps the mast erect. The hull design, however is great!.

 

I am concerned about the surface at the stern open to slamming when waves or speed (or both) reach certain height/speed.

This would be better in a catamaran form, with a wingsail. True that traditional sails give the most bang, but in all honesty the bang is not all that big. Instead of thinking like old wrinkled grannies, we should look for alternatives and make them efficient. Evolution. The traditional sail is old and tired, just like the other three colleagues. And we need new options.

I'm glad that d'artois liked this design...being traditionalist and against the futuristic designs...

 

I think the designer is counting on the extraordinary strength and stiffness of carbon fibre composite to do the job.

To this, I claim full ignorance. I have no idea how stiff the mast in the drawing is. Or how much stretch one can expect from the various trussing stays. I'm just going by 'blow of the eye'. And my eye says, in a strong puff, she's gonna blow. (carbon fibre is notorious for its lack of 'give').

Suffice it to say; I'd much rather be on a sectator boat 1/6th the length than on this creation in an unexpected gust and have to dodge flaying Carbon 'rope' that is as thick as my thumb.

It would be interesting for one of us to sit down and calculate the loads imposed by a 2 to 3% sag in the luff on this thing, then vector it through the whole rig. (I wonder if the designer, even, has done that.)

In answer to your question, D'Artois; as drawn, I think not.

Bob

 

Wow!

Hydrofoils too-nice start to a project! Hope it works extraordinarily well!

 

Bob, 40 metres in carbon - hardly feasible. Unless laminated thoroughly and than it looses it's advantages. The larger the size of the composite hull, the closer it comes to the weight of a metal boat.

But hull material put aside, what will be the effect of the aft mounted mast; what will be the torsion in the hull? Why is the keel still in the same place and not designed more aft?

I like to play the devil's advocate because I like the design.

 

The CA should end up pretty close to where it would be on a more conventional design. And I'm not worried about the hull at all. It can be judiciously stiffened where need be. Bolger's version was, of course, a sharpie. He just made the chines and shear clamps more masive. He also had a derreck like spreader aft the mast that was about as long as a short IOR boom. Ugly as hell, but it worked very well. But the boat was only 24ft long. It had a fin keel that was pretty conventionally located too.

The rig on this design does not look stiff enough for even a twenty four footer let alone a boat five times as long. It too needs a large, long derreck like aft spreader possitioned right at the intersection of the 'fore' and 'main' mast. The compression force on the 'fore' mast is going to be enormous, but that can be worked around. The hull could have massive ring frames coupled with compression beams to stand the strain. The main thing is to keep the 'fore' mast from being pushed through the bottom of the boat. Or, failing that, preventing it from pushing the bottom down and thereby pulling the sides in.

With a lot more careful engineering, it could probably work. The question that needs to be asked is: can similer improvements in performance using the same high tech matterial be made by using a more convetional design? It's important to remember that a Carbon fibre mast is much lighter than a conventional mast, so using them to make this boat a schooner (which it really resembles) with greatly raked masts and a large jib might make more sense. That way the rigging stresses would be orders of magnitude lighter and the boat could be much lighter as well.

It wouldn't go upwind as well, but how many ocean races are all or mostly up wind anyway?

The other innovations on this design may be well worth trying.

Bob

 

tackton40

Hi Just joined the forum.

Well I have to admit that thinking of a 40 meter toy with such features is indeed very scaring and shocking, but that was one of my intentions for the final degree show in pforzheim in 2002. Making it smaller would not have been that provocative and visitor on that annual show do not know a lot about boats, although for them size is what’s impressing.

Basically it is meant to be very futuristic craft from coming decades with lot of electronics, self balancing and navigating – a robot if you want to call it that way.

 

That it is futuristic - nobody will contest that. I find it even beautiful. Awhile back I made something similar and Brian Eiland also thinks a long time along this way.
No what has Pforzheim (home of the German Jewelry Industry) to do with your design?

 

Well pforzheim has one of the most famous Car design Schools in germany and maybe one of the top five in the world ( at least we were told to believe that . I fact we went there officially to study transportation design, but everybody is only into sportscars and the rather speeding vehicules for roads. I choose to design something different. that happens there occasionally.

 

Thanks for joining us. Welcome aboard.

And as far as provocative goes, I think you have done the job.

Hope to see you around for future threads.

Bob

 

I think this board needs a standing dictionary and acronym source. These discussions occasionally go overboard (especially the acronyms). How about a forum where questions could be submitted, and the answers or corrections would be posted to a master directory -- sort of like a wiki for sailing. While I find wiki an excellent source -- many of the terms used here are missing from their site.

Edit -

Fascinating thread, BTW.