Always nice to do a comparison.

I don't seem to have a nice shot from the side of either the VWM marine Blade or the Viper so if anybody does then please mail these to me and I'll add them to the picture. Perferably a shot from the boat sitting on its trailer and take a good number of meters away with a high resolution camera. That way the dimensions are not significantly distorted and we can take measurements of the pics.

Some of those measurements as taken from these pics


Bow height

Aussie Blade and Falcon have as good as the same bow height and it looks like it is 0.42 mtr (1.38 ft)
I know the Aussie Blade has about 20 to 25 mm more freeboard then the VWM Blade. I think the Viper is higher still but but not by much, however still need official confirmation of that.

Main beam clearance

fore beam on the Falcon is 4% lower with respect to the keel line then the Aussie Blade, this amounts to about 20 mm difference (4/5 inch). The VWM Blade never had any problems with main beam clearance and it appears the Falcon F16 has maintained the freeboard there. I think the Aussie Blade has a total of 0.50 mtr main beam clearance may own Taipan F16 (with raised mainbeam) has 0.475 mtr and I know Phill raised it another inch when he designed the Blade. I too have no problems what so ever hitting waves with my mainbeam and I have significantly less volume in my hulls then any of the new F16's. Phill and I (175 kg combined) tested it back in 2004 in the nice Zandvoort mix of waves and chop and its was precisely enough. So no the new boats should be absolutely fine here.


Rear beam clearance

The Falcon F16 has the same freeboard under its rearbeam as it has as bow height; therefore it should be something like 0.42 mtr. The Aussie Blade appears to have 0.39 mtr or 30 mm less (5/4 inch). This means the Falcon has ALOT of rearbeam clearance. My own Taipan F16 has only about 0.340 mtr there and does very occasionally slap a wave when loaded up with lots of crew weight, think 160+ kg. I think this means that the Falcon and Aussie Blades are Tybee 500 qualified in this respect. Or ready for the absolute worst you can at it. As an additional 50 to 80 mm (2 to 3 inches) is ALOT.

Sterns

Both have about 0.34 mtr tall sterns.


Additionally,

Beams are as good as in the same place and sidestays are a little further back on the Falcon. It appears the Aussie Blade has them at about 0.66 mtr and the the Falcon at about 0.71 mtr. a difference of 50 mm.


The Viper

I got very unclear pictures but it APPEARS that the Viper has more bow height (close to 0.50 mtr) then the Aussie Blade but the same mainbeam clearance (0.50 mtr) and a little less rearbeam clearance (0.37 mtr). The side stays on the Viper are at about 0.63 mtr back from the mainbeam at max. But again, this still needs to be confirmed with a higher degree of accuracy !



Wouter

But what about the important bit " volume " and where on the hulls it is. EG the volume at the Vipers beam looks huge alongside the Blade.

From other pics of both the VWM Blade and Falcon in one picture, it looks like the Falcon has about 25 mm (1 inch) more bow height and the same beam height / clearance.

It also appears strongly that the falcon hulls get wider quicker when going from the bow to the mainbeam. This will have added volume to the bows. I suspect the underwater body of both boat not changing much. So to my eyes it appears there is more reserve bouyancy in the bows with maybe a tad more at the keel line as well (as the side now go straight up). This could well just be the mod that it needed. On the upwind the VWM Blade was already a rocket so the underwater body was alright there. It just needed an extra bit for reaching and broad reaching in big wind. Would seem logical to put that extra bit a volume just above the waterline (as reserve bouyancy). The more rounded decks at the bow do help in the dive recovery; I know that much from the modification on my own boat.

Wayne,

Personally I think the item volume has always been overrated when talking about the F16. It's clear the Viper has more volume and higher bows then any other F16 design, but I'm convinced this added volume will not contribute to the performance of the Viper compared to the Blade/Falcon.
I think one of the major improvements of the Falcon compared to the Blade is that there is less volume at the transom and that it is higher out of the water.

What I mean is that we do not have any pitch pole problems with our Blade now, but that if we sit/trap out far enough aft not to pitch pole the transom is in the water causing quite some drag. Even upwind (in heavy seas/winds) this sometimes happens. The new design seemes to cope with that which should be a speed improvement up and downwind.

But this is ofcourse only my personal opinion.

Gill

I don't think there is any significant difference in the overall volume of the Viper compared to the other modern F16's, this excludes the Taipan 4.9. There maybe some difference in the placing of it but even there is will not be alot.

I remember Greg Goodall stating several times at the GC 2007 that he learned that bow height was more important then actual bow volume. He also said that he didn't really understand it but that that was his experience. So the Viper has a tall bow but there is not much volume enclosed in the top so the overal bow volume shall not be significantly more then say the Falcon or Aussie Blade. (Can't comment on the Stealth as I lack measurements for that design). Take a look at a pic of the Viper from the front.

I think from looking over several pics of either that the Falcon has fuller bows; they are just lower. Actually, I feel the Viper bows resemble the VWM Blade F16 very closely if that design would have had a 0.50 mtr tall bow. Both have the same, almost triangular, bow deck.

Wouter

Probably one of the bigger differences between the Viper and the others is in the stern shape although those cut-aways do give the impression it is actually small then it really is.

Wouter

I would disagree in regards to the amount of volume on the Viper, it is a big boat and ideal for double handers, I think in single handed mode its a fat boy and a bit too much volume but that is a personal observation and as I haven't had the opportunity to sail one, merely that of an observation.

Volume, beam and sail area are very relative to how fast a boat goes, particularly upwind. This was demonstrated on the water to me by the Shadows at Rutland over the weekend. The Shadow is a smaller boat volume wise to the Stealth, has a smaller sail area and smaller beam and yet in the stronger breeze they were more than capable of matching the F16's upwind. Some where in that mix of volume, beam and sail area ( dependant on wind strength of course ) we get an ideal water line displacement which achieves good speed. I suspect the A Class's are getting into that zone.

Well, the shadow is not that much different from the F16's.

13 sq. mtr mainsail
7.5 mtr luff
mast height 8.0 mtr
100 kg ready to sail
4.80 mtr length
2.40 mtr wide

Basically, they are under 10% in all aspects BUT sail area.

However, when going upwind in "the stronger breeze" you don't need 15 sq. mtr. on a 8.5 mtr tall mast as the 1-up F16's do. You are then only downhauling it away, while the righting moments are as good as equal.

So the Shadow performance is not really a suprise to me in this respect.

Wouter

What is the handicap rating of the Shadow then, I thought it was quite a bit more than ours. ?

The handicap also rates the downwind legs and races in less then "a strong breeze". It is therefor lower then ours.

You focussed attention to the performance of the Shadow on only the upwind leg in a strong breeze. And to that I replied.

Wouter

Yes on the downwind legs we were that bit more faster, their spinnakers are about the size of my mums " tea towel " but still does the job.

I have to say I admire the thought and design that went into the Shadow, really nothing extra anywhere and like a productionised A Class. Nice design and build quality.

Before I bought the Stealth it was on top of the list to buy but as there were only Stealths at the club I intended to sail at, it was a no brainer.

The Shadow IS very quick up wind in a blow.

It has a small mast section as the kite is small and has a short luff (so lesss stress on the mast).

It also appears to have a good "upwind" hull shape; it's a bit more of a challenge to sail down wind as there is a lot less volume up front than the Stealth / other F16's.

Classic comments when sailing at my club is that they might be first to the first windward mark in 15+ but if more (20+) I just slam the kite up around the windward mark and disappear in a cloud of spay and they "survive" down wind and may well leave the kite in the bag at times....

Yeah, I wondered about that short luffed spi for a while now. Only just did I realize why it is so short. It has to do with how the spi is carried without a spinnaker pole. They have a bridle of wires to keep the spi tack forward. However these will move back and forth under different sheet loads if they are not supported by other means as well. And here comes the trick. The spi tack bridle is ALSO support vertically by a line coming of the forestay. Now this means the whole spinnaker needs to stay below the hound fitting or the top will just wrap itself around the forestay after a gybe.

Nice simple setup but does limit the spi area and luff length considerably. No wonder they only have 10 sq. mtr. of it.

Thanks guys, I learned someting new today !

Wouter

On the beach the Viper looks like a stunted F18, whilst the Blade actually looks a 16ft cat.

Another aspect of the Viper is that they took their experiences with the Capricorn sailing downwind and fixed it up. The Capricorn in 15 knots plus had a tendency to want to pitchpole quickly or trip up when pushing hard compared to other F18s which would require drastic bearing away to stop a swim. In close F18 racing this is slow as you lose quite a bit of time and boatlengths. Changes to the rocker (location and depth) compared to the Capricorn makes the Viper a better all rounder.

But in relation to Goodall's comment repeated by Wouter about bow height. I am assuming that this applies directly to spinnaker cats. A-Cats are going the opposite direction with the A3 and the newly modded Flyer2 reducing bow height and bow area. However they are compensating by moving the front beam aft and increasing effective bow area that way but reducing overall volume.

And if the shadow with its 13sq m main and 10sq m kite is quick compared to the bigger sail area F16, well what does that make of my 8 sq m on the moth. Embarrassed a Viper completely last weekend in 10-15 knots upwind and down..... hehehe

Well i can tell you that the Viper has aboslute more hull volume then any other F16 , it is really big hull in comparison to the other F16 hulls, it can carry a lot of weight.

Hans

THe shadow has it's moments when windy upwind, but I/we disappear downwind. With my extra advantage of T Foil rudders, thus allowing me to push very hard down wind, I'd suggest the boat is about 15-20% faster down wind - I can sail deeper and faster!

I'm not knocking the Shadow at all, I think it's an excellent boat, but it is only single handed and I wanted the option for both single handed and 2 up.

I guess you guys don't get alot of surf at your club ?

I would simply LOVE to see a Moth sailor swim his boat out throught any surf !

Just playing with ya ! Well done, must have been a wild ride.

Wouter

In my opinion, the A-cat designs and Formula boats have started to diverge noticeably about 5 years ago. And I expect this to continue. I don't expect to ever see a modern A-cat bow on a formula boat. Also the freeboard is getting larger and larger on the formula boats.

I can't say that this divergence makes the formula boats less performant so the two classes must be subject to different dominant principles.

Wouter

Please note how I'm refering to the Aussie Blade and the new Falcon. Not the VWM Blade that as you have in Singapore. You'll find that the Aussie Blade looks bigger then VWM Blade as well. In my experience adding freeboard to a hull makes it look alot bigger very rapidly. Placing the bow decline more horizontal has the same effect.

Wouter