amatasi

[Mick]

Hi all, anybody here has something to say about the amatasi project? for example what do people think about the Tahiti way farer type of hull shape? Does that really create enough lateral resistance?

[Hector de Ezcurra]

I'm also curious about it. How those rudders/oars work? Are they as confortable and efficient as normal rudders? (I'm aware they must be much safer for beaching.)

[aerohydro]

I just received the study plan. This is certainly an interesting boat. One of the drawings shows an extra steering paddle being used as an "optional" leeboard. This would seem to imply that performance of the hulls alone is not entirely satisfactory. This will be proven one way or the other when the prototype is sailing.

 

I like the look of the hull shape, it will have much less wetted surface than a vee-section of equivalent length/displacement.

 

The rig is designed for low cost and ease of handling, but I wonder if windward performance will be acceptable. The laced-on luff and sprits must surely create a significant amount of drag.

 

The steering paddles are much higher aspect and seem more efficient that the standard Wharram plywood slabs, but more prone to ventilation and damage one would think.

 

I wonder what the price will be for the building plans?

[Mick]

I'm helping out building the prototype now. And when we have a nice tide we go sailing on the tahiti wayfarer. Which has a similar hullshape and thus a similar sailing performance.It goes to windward pretty well under the condition that there is enough sail pressure and weight in the front of the boat. under light conditions you assist by giving the odd paddle or if you are too lazy you just stick an extra paddle in somewhere in the front to create extra lr. steering is done by lowering or raising the steeringpaddle,not turning it as if it was a rudder. thus changing the clr, causing the boat to roundup or fall off. this method of boathandling is copied from the va'a alo or bonito canoe from vanuatu or fiji or so, I don't remember which island

[Hector de Ezcurra]

Mick:

Could you explain a little more about the steeringpaddle and how it works? I still don't get de picture.

Thank you.

[aerohydro]

So with the Tahiti Wayfarer, you steer with a hand-held paddle, right? On the Amatasi study plans, the steering device seems more like a side-hung rudder. It pivots on a block and is secured to the hull by a tensioned rope. The steering paddle has a tiller perpendicular. It seems that this paddle could pivot fire/aft as well as like a conventional rudder, so this would give extra steering options. I think I have read that Glenn Tieman uses these same steering paddles on his Child of the Sea, and has the tillers linked with a crossbar as normal.

Mick said:

I'm helping out building the prototype now. And when we have a nice tide we go sailing on the tahiti wayfarer. Which has a similar hullshape and thus a similar sailing performance.It goes to windward pretty well under the condition that there is enough sail pressure and weight in the front of the boat. under light conditions you assist by giving the odd paddle or if you are too lazy you just stick an extra paddle in somewhere in the front to create extra lr. steering is done by lowering or raising the steeringpaddle,not turning it as if it was a rudder. thus changing the clr, causing the boat to roundup or fall off. this method of boathandling is copied from the va'a alo or bonito canoe from vanuatu or fiji or so, I don't remember which island

[Mick]

the paddle on the tw can also be hung up in the same way which is easier going downwind or on long tacks. the larger the boat the bigge the steering paddle,so it becomes heavy to lift it out totally. instead you can pivot it out on the rope/hardwood hinge called the rudderboss. one can use one or two and connect them if neccesary. The principal of steering is as follows; Instead of a deep v hull/keel/daggerboard the lr is produced by the sharp forefoot which lives at the bottom of the stempost/front bit of the keel. Since the rest of the hull doesn't create lr if you pull out the steeringpaddle,which is held on the leeward hullside, you round up.insert the paddle on the other hulllside  and... you fall of to in to the new tack. so, if you raise the paddle you round up if you lower the paddle you fall off. When it is hung it functions as a normal rudder with the extra option of lifting it out by pivoting the top end forward. if you use a mizzen you can make it selfsteer by sailtrim. normally one steering paddle is enough but under heavy circumstances you an use two and link them up. the optional leeboardsteeringpaddle is for circumstances in which the sail doesn't provide enough pressure to dig in the forefoot(light weather/lack of ballast). also the steeringpaddle allows  you to givethe odd levering swivel in case a tack is by it self not totally succesfull.

[Mick]

Hip Hip Hurray! Amatasi building plans are now Available! spread the word!