Have a look a this photo:
http://www.bimare.net/fotox4/X-4-6-bis.jpg
The new BIMARE X-4 Formula 18 looks really different from the other F18s pictured (Cirrus, Hobie Tiger, Mattia Flash).

wow what a beautifull backdrop. That picture will make an excellent desktop background. HINT HINT!

Do all Cirrus boats have that paint scheme?

I found some MORE X-4 pics at:
http://www.bimare.net/fotox4/

Looks like a half decent race going on, any results for the new boat

Paul

Inf GBR7

Good looking boat. A class hull shape was predictable.
Interesting mainsail top treatment to transfer sheet loads to mast tip. Should go well.

Are you talking about the triangular reinforcement patch? That is different.

looks like it needs more bow.

IMHO

Yes the triangular patch. There is an inherent problem with big square tops. The last two battens need to be very stiff to hold the top corner out against the sheet load, which goes in a straight line to the mast head.

The A class has used that bow for some time now and if the other accompanying design features are included, and the boat is sailed to design, it works fine.

It seems like this boat may be at an advantage in waves. Looks like a lot of freeboard and not much bow (will limit pitching).

In my opinion, I think you are right but to a point. Most F18s are already quite sensitive to driving in bows in the heavy stuff - those bows look like they could be very sensitive and the lack of rocker on the bottoms might make it difficult to trap far back and keep the bow high.

Lack of rocker? Maybe I don’t understand what rocker is. When I saw the first picture (6 months ago) of the prototype from the side, the first thing I thought was “wow that’s a lot of rocker.”

I ain't buying that this is a stable boat with spin up.

IMO

Perhaps your thinking about the decks <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />...I don't know - it's kinda hard to see from the angles - but it looks pretty flat.

As many on here are fond of pointing out, an F18 ain't no Acat.

Not even the same ballpark.

I think it looks quite like the Jav2 18HT, except more freeboard and slightly larger throughout. The rear beam looks to be higher than the HT. Once the rear beam was raised on the HT it solved a bad habit the HT had of pitching forward when the rear beam slapped a wave. Hopefully this one is high enough. It looks fine in the pictures, but the only way to tell for sure is in a nice spicy blow.

I think the bows will be fine with the kite up. It will definetely be sensitive to weight placement, just like the HT.

I think its got lots of rocker, at least thats what it looks like to me.

The rudder castings look like the same Bimare treatment as the HT and the Bim ACats, which was locked down and didnt allow for kickup. A weak point in my opinion. Rudders and daggers are black, are the just painted or are they carbon? Does the class allow carbon foils?

Good looking boat, sails look great. I'm suspicious of the rudders.

Make sure to sharpen your trailing edges really well so you need stitches in your forehead after they do that 180 degree thing while you are leaning over the back of the boat trying to get them unlocked.

Rocker = amount of curvature along the keel line in the vertical plane

Sheer = amount of curvature along the deck line in the vertical plane

Tumblehome = amount of curvature from the topsides towards the gunwhale/deck centreline

Ain't that the truth !

There are indeed major differences in the design between these two boat types. There are things in either design that you simply won't do in the other for risk of ending up with a bad boat. An F18 needs to be designed as an F18 fully from "the ground" up.

Bill,

you hit the nail on the head.
Evidently you have a deep knowledge of BIMARE catamarans.

I was told from Daniele Saragoni that the X-4 was designed to be the MOST sensitive to weight placement F18 on the market.

It departs quite a lot (much more than it looks at first sight) from the Capricorn, the Nacra Infusion, the Blade and the other so called wave piercing F18s.
Its hull has almost the same width and volume at the bottom (actually 3-5% less) than the above mentioned boats, but with a different allocation: quite the same at the bow and in the middle but less at the stern.
On the other hand X-4's hull has some 25% less volume in the upper part:
the bow is no less than 15 cm (or 6 inches) shorter than the one of its shortest competitor and the deck is on average 12 cm (5 inches) less wide.
While the other F18s have quite vertical sides the X-4 shows a distinctive elliptical shape.
As a consequence of its general design it features roughtly 20% less windage upwind.
Besides, due to the elliptical shape of the outer side of its hull, it has actually more rocker than its competitors when sailed heeled. In such circumstances (as the Javelin 2 does) the X-4 is expected "to rest on" its downwind stern and to lift the bow clearly out of water surface.
The X-4 does not feature canted hulls because, according to BIMARE, this solution does bot help heavy two crew 18 footer to go faster.
The foils are carbon since the F18 class rule allows carbon for rudders and daggerboards.

F18 class allows carbon boards now. They have to otherwise they can't make their boards as long as they are now. The F18's are now using board that as over a meter long (as in the part that sticks out below the keel line) The stresses in these are pretty high. The newer F18's are running with aspect ratio's between 5 and 5.5 now. And that is very high.

Wouter