Gardner,

  I just took a second look at the design, and had a few thoughts:


AUTO RUDDER ROTATION THEORY

  That's a neat idea!  It wouldn't work well with tillers, but I'd love to see how it performs with a wheel.

COCKPIT

  The other side of the cockpit seatbacks is just a flat plane.  Is this for people to sit with their legs stretched out, either to watch the world approaching or drifting away?  If so, you might want to angle both sides of the seatbacks.  If not, I'd consider enclosing the whole area the way Rapscallion is enclosed.  That would be a cleaner look, offer less wind resistance, and provide some interior storage area for lightweight items (outleader kite?  series drogues?  sea anchor? spare fleece and blankets for when someone gets doused?).  Or perhaps a wider bed so you can really stretch out.  I don't imagine it would add much weight.

WIDTH

  Is the folded beam 9.2' because you need to keep the ww hull at a width that fits into a container?  If so, I get it.  If not, an extra foot or two in that cockpit would be nice.  If you're serious about a container, and don't mind an extra step when loading or unloading, you could always get a high-cube container, which has an interior height of 8' 9", and get an extra foot by turning the ww hull on its side for shipping.  Of course, that adds weight, which requires a larger rig, which may bump into your container size limits. (see next item)

MAST

  There are definitely good reasons for going with an easyrig, cost included.  But with one mast, it might be tough to get the sail area you want for those light Chesapeake summer winds.  If so, I'm starting to come around to the idea of a two-part mast.  I personally can't get on board with a telescoping mast until I see one work for a while, but there's no reason why a two-part mast couldn't work.  If the join were in the upper third, or even upper fourth, you could avoid most of the stresses in the mast.  The biggest trick would be in making sure the sail can easily pass by the joint.

SAIL HANDLING AND RIG

  I personally would want something I could easily drop in just about any wind, just with gravity, so I'd be hesitant to go with a bolt rope luff.  In which case I'd seriously consider a Tides Marine track and slide system.  Instead of a traditional sail track, which requires expensive cars with bearings (sources of failure), this has a semi-flexible UHMW Polyethylene track  that slides into an existing bold rope channel, or onto an existing track, with stainless slides that move within the track.  http://www.tidesmarine.com/sail-track.shtml

  The UHMW is so slippery, and the slides machined at a such a close tolerance, that the entire system is extremely smooth.  I use this on my catamaran and the mainsail drops as if it weren't even attached to a mast.  It's also easy to get the main off the track -- just remove an enclosure at the bottom of the track and the slides fall out.  Very simple and robust.   What would make it good for a two-part mast is that you could slide the track through the joint at assembly time and then not worry about any slight movement in the mast creating a jam for a car on bearings. 

  Alternately, there's always the even less-expensive Wharram rig that requires no sail track at all, and also allows you to use less expensive soft cloth that's not impregnated with resin.  You'd have a gaff to raise and lower, and its extra peak halyard, but could then get away with lower sail loads, no worries about flipping battens, and other benefits.

  Finally, there's the swing-wing rig, which also would not require any sail track, and which additionally would even not require a boom or a rotating mast.  This might be the cheapest, easiest, and perhaps most aerodynamically efficient option of all.  If you were to go this route, I'd come down to Pasadena for a long weekend to help build the wishbones (not as good as paying for the rig myself, but at least I'm putting some effort where my mouth is).  I really want to see this rig on a proa, and since we just bought another sailboat for renovation (long story), and are in the middle of building a 16' wooden dory, before starting a construction project on our new house this summer or next, I'm just not in the position yet to play with it myself.

  - Mike

 

Gardner Pomper wrote:

 

Hi all,

I haven't posted a design in a while. I have been working on one that is more involved than the others, I have done; particularly when it comes to drawing them. Anyway, there is a new directory, Raider, under "Gardner's layouts" in the file section.

To get through the basics, this is a design for the "raids" that are becoming popular here in the states. This will sleep 3, for short periods of time, and is designed to be easy to transport and launch. It can be shipped in a container, folded while on the water and trailered. Bare weight should run about 1000 lbs, but I have not calculated it out exactly yet.

Now to get on with the odder things about the design. I don't know how well I can explain these with just words, so you will probably have to refer to the drawings to make sense of them.

It has a new folding system, where he beams pivot around the masts (it is a 2 mast schooner rig). By having the masts support the beams, the lw hull can be truly minimal. As drawn, it can be made from a single 8' wide panel, 38' feet long. The beams come up the mast and there is a bearing so that they can pivot around the mast to let the boat stay upright while folding. The beams are each a single piece from the mast to under the bridgedeck area, so they should be easy to make strong. There is a second, half-length, lightweight beam with a pivot pin under the bridgedeck and another at the midpoint of the real crossbeam. This secondary beam only has to be strong enough to support the boat in calm water while folding.

The rudders are beam mounted. The are also asymmetrical, so they don't need to flip 180 degrees when shunting. Instead, the beam bearing is free to rotate +/- 20 degrees or so to let the rudders cant to bring the center of pressure "aft". I know this was tried before and found that the rudders will not cant on their own, due to the water pressure. So, I have added a mechanism that will pull the rudder into the correct position automatically.

The direction the rudder should cant is the same as the direction of movement of the boat. The wingmast and boom will always be trailing aft of the direction of boat movement, so I have added a bulge on each side of the mast, to act like a cam when the mast rotates. When the boom is brought around to the opposite direction during a shunt, the cam will move a lever, which is attached to a bungee, that will pull on the rudder assembly to make it rotate to the new position. As the boat stops at the midpoint of the shunt, there will be no water pressure on the rudder and the bungee with rotate the rudder assembly to the correct canted position.

The rudder assembly is constructed around a beam mounted drum, to allow the canting back and forth, and also has a breakaway "fuse" that allows full rotating in case of the rudder striking something in the water. There is an arm coming out from the bearing, which has a vertical pin, allowing the port/starboard rotation of the rudder for steering. The arm is positioned to act as a stop to prevent the rudder from oversteering to the point where there would be excessive stress. It is anticipated that a steering range of +/- 30 degrees should be adequate. The steering pin is attached to a daggerboard case, which secures the rudder blade, but also allows it to be raised and lowered. When fully raised, it can be above the level of the boom, because in the event that the boat is backwinded, the boom hitting the rudder blade will act like a grounding and break the fuse, allowing the rudder to rotate out of the way.

The rudders are mounted inside the beams, because the canting mechanism means that the rudder is lower in the water when the boat is travelling in one direction vs the other. With this rudder placement, the stern rudder will be deeper in the water that the forward rudder, moving the boat's center of lateral resistance aft.

I have put quite a number of ideas into this design that I have not seen drawn up this way before, so i am particulary interested in how it looks to the rest of the group. Please give me feedback.

- Gardner Pomper

Pasadena, MD