Power Trimaran Adastra-Extraordinary!

I have to admit, I'm not all that thrilled by the execution - though I'm absolutley certain that McConarghy (the builders) would have done an exceptional job. It's actually the concept that has me a little puzzled... if all the owner wanted was to stand out from the crowd, then the SOR has most certainly been met. But this is a 42 metre yacht, with accomodations that wouldn't be considered generous in a boat half the size - which would in itself result in at least the same levels of efficiency!
We are not, of course, privy to the SOR - but it goes without saying that 'easy for the crew' wasn't a part of it! Having been aboard the 'late' Ady Gill before she was sent to the bottom, I can attest to the fact that these things are an absolute ***** to park....
But hey... if nothing else, boats are meant to be fun... so lets hope her new owner has all that he/she wished for...

 

Adastra should have an advantage in slow speed maneuvering and docking with a prop under each ama. The Ady Gill, if I have this right, had rudders on the amas but both props were under the main hull.

 

I can't remember if she had rudders on the ama's but yes - all the propulsion was located in the main hull, so Adastra ought to be a bit better in that respect. But where the Ady Gill had at least the odd flat surface to walk on, here there appears to be an almost complete absence of ways for the crew to move about on deck. And it was that, as much if not more, than the ability to maneuver that makes tri's so awkward. Then again, if all she ever has to do is berth stern-to, it won't be quite the drama...

 

Take any published numbers with a grain of salt. They are fairly cagy and don't mention the load condition at those consumption rates, so we don't really know anything. As the boat was recently launched I suppose those numbers come from tank data. Real world is different and they don't have real consumption until trials have been run........We'll never know the actual finished weight of the boat. The fuel load (in a boat with 30,000Ltr capacity) will have a major impact on consumption at various speeds, as will windage and sea state.

 

I've also seen the boat pics and I'm not truly impressed by the aesthetic design. Not very original...The upper part... bof-bof, but it's the actual trend. Look at the lousy boxy toy yachts now...with lot of useless curves and rounds. True couch potatoes and beer.

The ama design with a lot of the hull in the water and the round bottom is the limit of speed. I smell that these amas cost a lot of ponies. But these kind of amas are tender so the general comfort will be better. And it's a "rich" family cruising boat... A faster planing ama would be shaky.

The price is very high, but that counts for a lot of amenities, gadgetry and electronics that skyrocket the cost. The 3 (!!!) generators ( 110 KW at total) show that there is a lot of electrical appliances...

The empty weight is not specially light, in spite of the kevlar and carbon. That's the proof that the amenities are the big penalty. Trimarans are "small" slim boats so the amenities are more in relation with a monohull of same weight but half long...Do not judge the amenities of a boat by its length but rather by its weight.

The engines in the amas are for docking and auxiliary power in case of premature death of the main engine. These amas's propellers must have also a drag penalty.

Visibly it is a comfortable cruise boat in a space ship design package, so the speed and efficiency have not been the first of first priorities although for such a weight 49 metric tons empty to 77 maxi (65 normal disp.) it's not bad at all.

A very rough calculation du power used ( from the consumption ciphers) gives at
13 knots around 450 HP
17 knots around 600 HP
and it's compatible with the 1150 HP for the 20-21 knots. The hump in the drag curve must be around 19-21 knots. That explains why the tri is not trying to go to the 25 knots. It seems that the ciphers are for a half weight so around 57 tons on flat sea or state 1-2. It's rather good, a 23 meters monohull with similar amenities would use far more than 120 liters hour for 17 knots!!! Length and slimness do pay...

The cipher of 4000 miles@17 knots is realistic with 32000 liters of fuel, so around 26,50 tons. The drag at 77 tons must be rather big, as the boat is getting lighter the consumption will improve.
A very rough calculation gives at 28800 liters (10% of reserve) 240 hours of autonomy. Around 4000 miles at 17 knots. Not bad for a boat weighting 77 tons at departure (so 12 tons "overweight") and
53 tons at arrival. Surely the design for keeping a good seaworthiness on a slim hull with such a variation of displacement (more than 30%) has been challenging.

Do not compare with a light tri like Ilan Voyager. A scaled by 2 Ilan would weight 56 tons "overloaded" of fuel (not 77 tons), 32 tons empty (and not 50 tons) with a 1500 HP to get the 26 knots mark...and the main hull has a ratio length/width of 17.... Not the same program.

A lot of pics, specs and amenities drawings at http://www.john-shuttleworth.com/adastra.html

 

The interior is as nice as the exterior, although there are quirky aspects to both.

I'm thinking of the exterior the way the glass goes down to the wing root. I think setting the glass rounded corner back some and allowing a walkway, even if slanted would be nice.

On the interior, the sink photo with many steps up to the seating area, it just does not flow, many other interior areas do however "flow" nicely.

 

I see what you mean there it doesn't quite flow, strangely enough though I quite like it, an intimate meals area on an enormous yacht is sort of a rarity. You can tell the owners had a lot of input on what they wanted from their craft.

 

Lewisboats provided a link with additional photos, one of Adastra under construction.

http://www.dailymail.co.uk/news/art...-signalling-new-dawn-long-range-cruising.html has a good launch photo showing the underwater hull.

 

Some more photos of Adastra delivered to her owner in Hong Kong. Posted by mh111 on Sailing Anarchy.

https://picasaweb.google.com/103539218974574927814/ADASTRAHongKongArrival?authuser=0&authkey=Gv1sRgCPn95PWq19yqOA&feat=directlink&gsessionid=bUDta4t8pPcEY3LT-tDTow#

 

And presumably occupying 3 berths in the marina is part of her "efficiency"?