TheSpawningGrounds

Project is slowly moving forward. New hull design is easier and faster to build compared to the previous designs, also involves less foam wastage. Going to continue to work on the interior layout of the hulls, to make them as practical as possible.

DesignProgress 190710

I've been working on the hulls again. And will be working on them even more. I was disatisfied with the entry points in the hulls, need a safer entry point for the fore cabins as well. I'll probably ditch the central pod, uselless weight in the stay rig configuration.

DesignProgress 080810

New central pod si now part of the rig support structure, made from developable foam panels, 'stitched' and glued. The new pod is also the support for the centerboard, side loads taken by side stays to the hulls.

RigCandidate

Posible StayRig setup, lower CoE for the same SA, easier reefing, better beam setup.

HotSun

Sunshade with minimum materials and weight. Currently working to see if the setup is usable while sailing leisurely. Using just the boom, a halyard and a couple of lines.

SoftTop

Currently working on a convertible splash/wind guard, easy to pop up&fold down.

A for AFRICA

I have modified the steering linkage, too many components previously, less components now, lighter.

DesignProgress 010710

Project is moving forward, I was able to lift the bow foil with about 10cm, that also raises the pole a bit, very beneficial. Also making progress with my cnc machine, will be ready 'some' time soon. I cut the rig back to 12m height, some reduction in sail area, but still plenty.

HullEvolution 3006010

Still working on the new hulls. Trying to add as much reserve buoyancy possible in the fore part of the hull. Will also be downsizing the rig just a bit. With a shy rig downsize the boat will still have plenty of power for its weight, that's why I'm trying to focus on buoyancy distribution and nosedive recovery improvement. The new hulls sit a bit higher near the bows, that not only adds volume but allows the bow foil to sit higher too, avoiding or minimizing a handbrake effect when the beam will hit the water.

HullEvolution 2304010

The newer design is much closer to a true monocoque design instead of a classic hull+deck shape. The bow shape provides better nosedive recovery and a more rigid loadbearing behaviour, possibly lightening the internal structure of the hulls.

HullEvolution 1804010

Old vs new. New hull features a creased foredeck for faster dive recovery and wave drainage, a bit more volume, especially in the first 3rd of the hull, while maintaining the overall surface area.

Hull developement

I'll begin working on what would hopefully be a finall hull design, a bit more rocker and modified forward deck to improve nosedive recovery.

Remember

Things I have to remember and follow if possible: "if you can do without it, get rid of it".

http://atomvoyages.com/articles/krislarsson.htm

DesignProgress 1702010

Preliminary design is pretty much complete except the location/type of the boards. A rough weight estimation of the platform is around 900kg, with spars but no rigging.

DesignProgress 1202010

Tiny mods to cockpit well, galley layout, lenghened prod and added another forestay. Current rig can take up to 100sqm of SA for light winds, quite substantial for a low aspect rig. The galley can sit 3 crew max for a quick meal.

DesignProgress 0602010

Did some rig tuning, moved it aftwards with beams and all, redid bulkheads.

DesignProgress 0302010

Boring sloop rig. If I'll keep it I'll have to move it a bit further aft.

DesignProgress 0202010

Minimum cooking gear. Obviously the real utilities will allow tilting. Since most of the platform and interior is layed out the next step is to take care of the rig and the following modifications the rig will impose on the design, also harbour propulsion is an issue that needs to be sorted.

DesignProgress 0102010

Optional center pod with hard deck. Pod provides sufficient storage for sails and other, cooking facilites possible, also stiffens the platform.

RedPeopleEverywhere

Enough room for storage, enough bunks indoors, enough room for cooking. Still, I'm uncomfortable with a big opening in the deck just forward of the mainbeam. But I guess enough carbon will make it stiff enough. The head might even have enough room for a reservoir, for inshore use, just to make it legal.

DesignProgress 3001010

Aft bunk is convertible, while unused it turns into a chart map/navigation station in one of the hulls, while the other one will turn into a galley, or a mix of those functions. Under the foredeck there will be a shitter and possible sitting shower in one of the hulls, while the other one will house another bunk, sleeping 5 crew inside currently. The big skipper bunks are almost double size. Storage under the crew bunks, fore triangle, under cockpit. Crew bunks and loo accesible via a big round hatch. Galley functions up next.

DesignProgress 2901010

I was never happy with those top hatches that slide to open. I'd rather have a swing door, even if it is small, at least it can be truly watertight. Moved the interior partitions and tried the Farrier style rudder setup -kickup daggerboard rudder. By design those entry hatches/doors do not stay open, so water/splash getting in will be minimum. New cockpit/transom layout made me lower the rear beam to about 95cm above WL, probably enough clearance for crusing. Interior will be modular, will be my next focus.

KickUpRudder

The first version lacked the ability to steer the cat in shallow waters. That is something I forgot about. I abandoned the tapered rudder planform in order to have as much usable area for steering in shallow water, moved the rear beam forward and tweaked the system to enable steering with the rudders partially up. A 35 degree rotation around the upper pivot will allow a 35cm rudder draft, good enough for beaching. The system needs tweaking for sure but I hope I can make it work without the need of casings, boxes, cassetes etc.

KickUpBusiness

I've been scratching my head for a while trying to come up with a kick up design for the rudders. There are some interesting variables in the equation. First of all my rear beam is very close to the transom, basically it is the transom as the rear beam is fixed in a double bulkhead configuration, so I tried to push it aft in order to be able to use the space inside more efficiently. Since the rear beam is at the transom, the hulls being low and the beam connection to the hull is a high bend, there is no room for a cockpit facing tiller, that means I have to invert the tiller config. A regular beach cat kick up system uses a pivoting rudders in a casing, depending on the height and configuration of the transom that foil usually gets pretty tall, which I don't want. I will only be able to make moulds on a cnc machine up to 134cm tall. The usual beach cat kickup system has slop nomatter what you do to it. I really don't want to be fairing a 170cm rudder or remake one in case it gets smashed. I'd rather have a shorter rudder, less carbon, less material, easier to make, cheaper. I wanted to eliminate slop if possible so I came up with this system. The tall post can be made by laminating carbon over wood, doesn't need to be faired to perfection, requires less finishing. If the foil gets damaged I'll remove it from the post and make another one, stick the post into it, glue it and that's it. Cheaper. I wanted all the parts in the kick up system to be very simple, easier to improvise all over the world if I need to. Brackets, bearing bolts and some levers. If the rudder hits something the lower joint will pop a calibrated bolt, breake it , swing and rotate around the upper pivot, clear out of the water, and clear of the tiller crossbar, that means the other rudder will still give control. Asess damage, swing it back to position, refit bolt and move on. The system parts are pretty heavy duty and obviously not not very light if engineered by hearsay. Apart from the weight, the odd looks, I'm pretty comfident it should work quite well and be very robust. No casting or case that can brake, I would say slop free, and easy to maintain, just check slop in bearings, if any, lube it, check calibrated breakable bolt and that's about it. I guess...

TheScaleModel

In a few months I will be able to make a 1/10 scale model of the boat. The model will hopefully be used to determine the behaviour of the hulls. This is my first attempt so it should be interesting. The hulls will be carved on a 3 axis CNC machine. The scale model testing should provide info for the further development of the boat dynamics, weight distribution, wake patterns, max beam etc. I hope the testing will output some solid information, however since this is all new to me I'm not expecting too much out of it.