Futuristic Mast Aft Design

Mast-aft design

This is a gorgeous conception. I especially like the idea of the gimbal-mounted cabin. Very slick.

While the technology doesn't yet exist to build such a boat, I believe the mast-aft rigged boat is being built by at least one company today. Of course, the design isn't nearly as radical. The mast is canted about 10deg. forward and set at the front of the cockpit. Note that the mast can be up to 25% shorter and still carry the same sail area as a comparable sloop rig. One of its big advantages is the lower center of effort.

Years ago I saw a similar design from a boat builder in Australia. He called it a Caravel, after the renaissance-era trading vessel. All the sails were stay-mounted and roller furled so that the 18 meter boat could be single-handed from the cockpit.

I think the mast-aft design is both practical and a significant improvement over the standard Bermuda rig. I won't be surprised to see these appearing everywhere in the next few years.

Some links:
http://boatdesign.net/articles/mast-aft-sailing-rig/
http://www.runningtideyachts.com/monohull/
http://www.barefootsworld.net/windwalker/aftmastsailingcalc.html

 

do da ding

 

There is a related discussion going on in another thread -
http://www.boatdesign.net/forums/showthread.php?t=11164 - discussing the practical applications of the mast-aft rig. I have posted my reply to some of the excellent points you raise there, as it wasn't my intention to defend the rather fanciful Gaudier design, but rather to comment on the possible advantages and practical applications of the concept to today's boat builders.

 

Replaceable bow cap?

 

A less extreme mast aft design

Here is a possible example of a 'mast aft' design that is a little less extreme and deals with most of my objections with the design concept which I stated in earlier posts.

This boat is designed for a class I invented where the sail area, Length, and draft are limited. The class is also supposed to be able to carry a 1,000 lb payload.

Here the jib does not hank onto the forestay, but rides on a pivoting boom that is attached to the deck by a stay and a swivel. This jib will sheet just like a mainsail will. Only the sheetline length will need to be changed to trim this sail.

The main acts mostly as a 'spanker' to ballance off the big jib. It will be last to be reefed. Because it has no spar in front of it, It should even provide some drive of its own.

The ladder like bipod mast eliminates shrouds and just steps on the deck, but is attached to the deck solidly. With clever enough design, the mast will be relatively easy to raise and lower. Only its extra weight might hamper that goal.

Bob

 

Now that is sexy.

 

I don't understand this explaination. Your 'boom' I assume is along the foot of the sail, not the luff.....what used to be called a 'club footed' jib. So how is the luff of the sail supported ("does not hank onto the forestay")??

Are you basically talking about this configuration with the bipod mast stepped a little more aft, and the self-tailing jib attached to a club-footed boom??
http://www.boatdesign.net/gallery/showphoto.php/photo/2094/cat/500/ppuser/399

Or maybe a wishbone mast like these two variations with the mast located a little further forward and a main rigged behind it:
http://www.boatdesign.net/gallery/showphoto.php/photo/5630/cat/500/ppuser/399
http://www.boatdesign.net/gallery/showphoto.php/photo/1075/cat/500/ppuser/399

Here both sails are club-footed and self-tacking (and the mast is leaning forward by the way):
http://www.runningtideyachts.com/articles/othermansboat1.html

 

Brian:

The luff is unsupported. It might have an internal wire or extra thick luff 'taping'. The boom attaches to the foot of the jib. It is different from most 'club footed' arrangements because the pivot point is aft the luff by a considerable margin. this is to keep the aft end of the boom from cocking up. Most 'club foot' arrangements I have seen have travelers or horses for that purpose.

this is not an original idea. I once had a scow designed by someone else with this rig (except without the bipod mast). I can attest to its effectiveness. Even with crude matterials and (must I admit) crude craftsmanship on my part.

I like the pictures you have shown me. I just don't like the complex staying on some of them.
The bipod sloop is nice and is very close to my concept. But one of the goals of my concept was to have the biggest, most user friendly jib possible while keeping things reasonably simple at the same time.

Maybe bipod sloops should be tried for trailerable boats. If the bipod hinges on the deck, cross winds during mast raising time might lose much of their terror. Going with a straight mast head arrangement and putting up with jib over laps may keep the heavier mast sufficiently short.

Then the only standing rigging that will have to be dealt with would be a fore stay and a back stay. Just two wires. And only one will have to be detached to lower the rig.

Bob

 

that thing shure looks pretty, but it dosent have any apparent purpose other than that and it requires a material which is in demand driven short supply world wide and requires a computer to sail, ERRRRRRT! wrong answer! in my book, seawater/eletricial field disturbance + required computer for boat handeling..........nooo thanks...pretty though unless u can find a giant spider to run the rigging for u while u sail then u still need cargo space for carrying the the spider and food for it lest u become a snack yerself...

 

I have come across an aft mast design that seems to "solve" the structural hassles.

There is a "boom' mounted about half way up the mast that extends beyond the stern by a good bit.

The back stay runs from masthead , to the outer boom end and then to the deck.

A loose footed mainsail of small size was hoisted , and sheeted to the deck.

FAST FRED

 

Hi Fast Fred, do you have any links / photo's of said rig / yacht ??, sounds interesting !
Pete.

 

Here's an aft mast design for sale


http://www.yachtworld.com/core/list.../core/listing/boatDetails.jsp&boat_id=1699447

 

cross reference

Thanks for that reference Mike. I thought this subject was more in line with this other discussion I had started on 'wishbone shaped mast' configurations, so I did a cross reference between the two discussions:
http://www.boatdesign.net/forums/showpost.php?p=146538&postcount=51