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Breakthru Hull Design...

 
 
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Old 01-04-2005, 09:54 AM   #16 (permalink)
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You're absolutely right about the wings inducing trim into the hull. The B-28 *does* fly straight and level off waves. The narrow bow, coupled with an abundant surface area under the wings quickly negates bow rise when launching off waves, by adding lift at the transom. The narrow hull (needle-nose) form of the bow offers very little resistence to wind velocity in comparison to the aft section, as the angle of the hull increases relative to the waterline. However, this was one aspect of the design that was not as appealing to me and therefore I didn't elaborate on it. Let me explain...

In a worst case scenario, this is one of the few V-hull craft that "could" be prone to a high speed stuff. It's very simple math. Increased lift at the transom coupled with a lack of displacement/girth at the bow can result in an unwanted catamaran-like characteristic. Newer style cats, with increased sponson girth don't suffer the same effects to the magnitude of older cats, such as the 24' Skater back in the 1980's, which lacked sufficient bouyancy at the forward sponsons to offset wave penetration.

In the case of the B-28, the trim induced by the wings is quite pronounced, as it keeps the boat very level. A little too level for my taste (this is personal). It is remeniscent of Harry Schoell's Duo Delta Conical Hull (or DDC), which utilizes a single step, located at midship, to create a wave surge at the transom. This design is VERY effective at inducing negative trim into the bow. However this hull will never completely "air-out" and runs with a fair amount of wetted surface. (no matter what Pat's propoganda is for Active Thunder powerboats!) The hull simply does not work well for offshore conditions and it is even worse on smooth water.

Ultimately, the Bat Boat needs one appendage to make it the perfect V-hull... an active canard located at the bow. You guys will have to take this up with the APBA!
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Old 01-04-2005, 07:24 PM   #17 (permalink)
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By active canard, do you mean the "anti-stuffing" wing that is seen on some of the Fabio Buzzi boats (run by the Nemschoffs in the APBA)? I think they would be a nice addition, however in my testing I have found that they may hinder the boats ability to quickly pierce the water and continue through. In the enclosed canopy V-24 you are relatively safe in these conditions, as long as the boat is built correctly and won't hydrolock if water were to enter the front section of the hull (not likely with the "bi-lateral unitized constructioin" a term I coined during our construction where we actually bond the deck and hull together while both parts are still in there molds...we used a product called Plexus which cross links the two fiberglass components and then glassed the inside and outside seam 360 degrees around the perimeter of the boat...giving it an almost bulletproof hull.

In the B-28 you are a little more at the mercy of the forces of the water during the stuff...water rushes over the deck and if you're lucky your crew thoroughly bolted the windscreen on with adequate hardware, something I learned was crucial after my first experience stuffing the boat. Once we even bent the aluminum tubing and shattered an acrylic windshield (purchasing agent made a mistake bringing in the acrylic rather than the polycarbonate). Nothing too serious but nonetheless was an intense incident. Another time during testing on Government Cut in Miami during the Miami Int'l Boat Show a slower speed stuff (approximately 40mph) resulted in the polycarbonate windshield (this was a half canopy design like you images of the B-28 running) flexing inward and allowing water to get under the canopy roof (permanent mount) and ripped it off the boat.

We later made removeable canopies that were actually attached better than the permanent windshields which were also better supported and made of a thicker material. We learned that we needed to use a pressed polished polycarbonate in lieu of standard polycarbonate as it didn't show the roller markings in the polycarbonate from the extrusion process when the polycarbonate was laid back at a severe angle....this took some research to learn and made visibility out of both boats (the V-24 and the B-28 far better).

I personally preferred the B-28 with a windscreen in lieu of the half canopy or the inline racing configuration...we built the inline hulls too but simply shipped them unrigged to Europe for UIM racing. The B-28 was banned from APBA racing due to it's dominance during it's first year racing...right along with the Buzzi RIB.

As for the boat flying level, I felt this was an extreme advantage, particularly in the V-24 which had limited visibility in the full canopy boat to begin with. But the B-28 flew extremely level in almost all conditions and simply wasn't prone to "tripping up" when it hit the top of the next wave or swell...I'm sure it could happen but it was very uncommon.

It was really different to run hard, hit big water and each time the boat launched you never lost vision of the horizon...this too meant that the boat, in flying level, was not scrubbing off the speed that the "moon shot" conventional V-Hulls were when they hit transom first and then slapped the rest of the hull down later...particularly with the older boats like the Apache's and Cigarette's that were heavy to begin with and had the majority of their weight in the engine compartments with the big horsepower engines (read: unreliable and expensive) that were required to propel these boats to just average speeds by todays standards.

If any of you ever get the chance to run in a batboat I would suggest you take full advantage of it as it will be something that not only won't you forget but more than likely will not believe once your feet are back on the dock.
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Old 01-04-2005, 09:18 PM   #18 (permalink)
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Ahhh... Plexus! NASA's JB Weld!! I don't know what's more hazardous... the vapors from that stuff or dating in the 90's.

On the active canard, it's a small wing on each side of the forward section of an airplane fuselage, usually found on rear wing pushers, such as the homebuilt LongEasy airplanes (Rutan design). These are control surfaces that can be activated via a high speed servo and piezo (or similar) gyro. Basically... fly-by-wire technology. Ohh!! I just remembered, Lars added some canards to the rendering on this thread. Look closely at the forward section of the 2nd rendering...

http://www.yachtforums.com/forums/general-yachting-discussion/1975-new-water-world-speed-record-attempt.html

I can relate to being a test dummy and the laughter that follows. Been there... not much wiser from the same. It seems we've travelled the same waters, but never crossed wakes. If you ever got down to the land of heat & humidity, I'll buy the first round.

Carl Camper
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Old 01-05-2005, 06:33 PM   #19 (permalink)
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I'll be down for Bike Week in March, but not as far south as Lauderdale. We're displaying some product (aluminum trailers) at the speedway.

My worst test dummy experience was out of Lake X on a very hot and humid day. We were testing the V-24 for the first time with a Bravo One drive and the Scorpion Motor. Well, as it turned out, to dial in the X dimension and the right propeller they asked me to run the boat, watch the GPS and monitor a handheld scan tool that was telling me precise RPM. The boat turned out to be more than a handful at WOT (set up the way it was she was running in the mid 80's) The boat would just get wild right at top speed...violently kicking from side to side...the narrow beam really made it feel like it was worse than it was...but I was thinking I was bouncing the wings off of the water from side to side. You couldn't just chop the throttle as I felt like it might flip on me, so I had to ease off the the throttle until it settled down. I went right back in and they decided to try a four blade prop (in lieu of the three blade) and see if this would set her up better. Same thing happened, and although I was ready for it to happen this time, it still scared the **** out of me. After going back and forth with a few different props and no fix to the problem we were talking with Dennis Cavanaugh (who has since passed away) the prop guru at Mercury...he suggested raising the X dimension by removing the spacer in the shortie drive...I was thinking this would free the boat up and make it more likely to repeat but with a more tragic outcome. Well...I was as wrong as could be...the higher we raised it the faster she got (which I expected) but she also handled better and the violent bucking left the boat. Even turns at high speed were extremely predictable...not like with the Volvo Penta Duoprop (which was like running on rails) but it was a lot of fun. In the end while I enjoyed both setups (the Merc and the Volvo) I preferred the Volvo setup...the Bravo was more demanding and not as forgiving, definitely a drivers boat...but the Volvo was like put the throttle forward and run off the rev limiter...she could handle it all and any small mistake didn't get amplified into a major mistake.

On the flip side I can tell you that Mercury's customer service was second to none while Volvo Penta of North America was a complete and total joke...no service, no technical help...nothing...especially if you were having problems. The only exception to this and it must be noted was Ed Szylagi...he was fantastic, knew his stuff and was always glad to assist...he had a special interest in the batboat and I think he was excited to see Volvo show at least some interest in the high performance program.

You should have seen the faces on the Volvo execs when they came into our booth at the IMTEC Show in Orlando and we had a Bravo One hanging off the transom with Mercury Racing decals all over the boat...they flipped out and were actually yelling at us. But when it came time to pony up for the racing they just didn't have any interest and they lost their chance...worse they were dethroned by Mercury as our exclusive choice of power. I don't think they actually thought we would convert but we had just invested a large sum of money in the program on a single purpose raceboat...so either they were with us or not. It was their choice...we even offered to pay the entire homologation fee that the APBA was demanding from us to allow a One Design Series. It was a no lose, no investment program for them but they were simply too dense to see it.

Oh well...that ran from test dummy to dealing with dummy's...I should write a book on my adventures, who knows I might sell ten copies!
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Old 01-15-2005, 10:27 PM   #20 (permalink)
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OMD

I was finally able to get my program running where I can resize some images so they fit on the server...here's the Ocke Mannerfelt Design I was talking about, I think this is one of the best looking boats I've seen...if the performance and handling are anything like I expect this would be one amazing boat. Flying the American flag, I wonder if it was built for an American owner, I would love to see this boat in person and possibly drive it.
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Old 01-30-2005, 01:41 PM   #21 (permalink)
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Very good looking boat!!! Can someone explain the "rising" hand-rails on the bow?
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Old 01-30-2005, 01:56 PM   #22 (permalink)
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This boat was built for a guy living ten minutes from me. I have never seen it go faster than on the picture, but there are a couple of sister-boats with "normal" transoms and they are pretty fast and seems to go well. The shape of the double "sharkfins" on the fore deck are most likely to follow up the overall design theme.
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Old 02-01-2005, 06:39 PM   #23 (permalink)
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With the American flag flying on the back I was under the impression that it was of American ownership. Nonetheless it is a gorgeous boat.

I would agree that the front middle "lifeline" rails are to follow the design aspects of the boat...they would also be functional as for going forward on the bow as you would more than likely get to your knees on this kind of boat the farther forward you went. If it were my boat I would consider a lifeline that is just a few inches above the deck...I think the current one would distract me a bit as I was navigating.
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Old 02-01-2005, 06:44 PM   #24 (permalink)
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I knew it was a handrail/lifeline... of sorts, but I've never seen anything like it on this side of the pond. Previous drone development by the military came to mind when I saw this contraption. They used a launch rail for reconnaisance aircraft to get them off the deck in short order.

You should have seen the "net" they used to catch them when returning to the FBO. They missed constantly!
OK... so we loose the hand-rails and bring it to America?
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Old 02-01-2005, 06:45 PM   #25 (permalink)
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Running Shot

It really lifts up...the hull design is impressive to say the least...very beautiful boat in my opinion.
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Old 02-01-2005, 06:47 PM   #26 (permalink)
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Zero Cavity

This is Zero Cavity which was owned and driven by Dr. Santiago, a dentist in Florida...he spent a lot of time and money dialing this boat in and ran it in the One Design Series briefly before jumping over to the Performance Class...the boat simply flies!
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Old 02-01-2005, 06:51 PM   #27 (permalink)
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Now that's a "Wing In Ground Effect" vehicle! Nice shot.
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Old 02-11-2005, 06:35 PM   #28 (permalink)
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Thought some of you may find this one interesting.....

The Earthrace
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Old 02-11-2005, 07:21 PM   #29 (permalink)
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Same idea but in a smaller scale, a young Swedish design student, Josefin Carne, has developed a Kajak with outriggers to be towed by a Kite (remember the TRY Kite-kat) when you are not paddling. She calls it Trijak and a model is made but no fullscale production that I know of yet. But I will surely buy one the day they are reality, since I don´t trust my ability to stay on the right keel with a normal kajak...
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Old 02-11-2005, 09:28 PM   #30 (permalink)
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Mr. Offshore...

You will be happy to hear, your boat is available! However, it's somewhat smaller than the original production version. This model is being manufactured by Graupner. It is 930mm long and it's remote control. Graupner is a leading manufacturer of remote control models and this boat represents the 2nd model they have produced of an Ocke Mannerfelt design. (the first being the B-28)

A big thank you to YachtForums member "PromoceanModels", for sending me this picture to pass along to you. Enjoy!
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