TBPNews #57 - 
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>>>>>> Tunnel Boat Performance News >>>>>>>>>>>>>> (now over 4500 members!)
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In this issue: 
1) UIM RULING DICTATE F1 DRIVERS RETIRE AT 50.
2) BUDWEISER TO END UNLIMITED SPONSORSHIP IN 2005
3) Jimboat writes Features in HotBoat & World of Powerboats mags
4) Mercury unveils new X-Site test facility 
5) Boat transformations to air on Trading Spaces program
6) Miss Budweiser Shatters World Speed Record 
7) Feature Article - "Step by Step" (step design in powerboats)
8) 'Hot Boat' magazine - Save 51%! 
9) ** NEW ** 'Tunnel Boat Design' Software - Version 7.5

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1) UIM RULING DICTATE F1 DRIVERS RETIRE AT 50.

Although the concept has been in the pipeline for three or four years, the first person to be effected by the age limit ruling hangs up his helmet after the last F1 race of 2003.  The Abu Dhabi Grand Prix will be the last F1 race  for Franco Leidi when a new UIM ruling is enforced.  At age 54, the UIM hierarchy feel that Franco is now too old to participate and in 2004, the age limit will be reduced to 50.  That started alarm bells ringing in the camps of Fabrizio Bocca, Andy Elliott, Guido Cappellini and Scott Gillman who all will .be celebrating their 50th birthday's in the not too distant future. 

The UIM have evidence doctors that it takes longer for a person over 50 to recover from a serious accident. However few would argue the evidence is hardly 'rocket science.'  It is argued however, that if a driver, regardless of age passes a strict medical, it must put in doubt the legality of such a ruling.  A recent test at an F1 meeting in which driver's reflexes were put to the test 44 year old Scott Gillman was tops, ahead of many 25 year olds. 
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2) BUDWEISER TO END UNLIMITED SPONSORSHIP IN 2005

Love them or hate them, this will be the last year Unlimited hydroplane fans will have to watch Miss Budweiser compete.  Anheuser-Busch announced it will no longer sponsor the tour, Miss Budweiser or race events after the 2004 season. Miss Bud driver David Villwock said he will retire after the season unless Budweiser reconsiders its decision to leave the sport.  "Based on our long-standing relationship with the sport of hydroplane boat racing and the Miss Budweiser team, this was a very difficult decision," Anheuser-Busch said in a statement. "We wish the series and Miss Budweiser team members well in the future."  Miss Budweiser is the top boat in the sport, having collected 23 World Championships, 14 APBA Gold Cups and 136 race wins.  "They've helped put the sport where it is today," said Bart Garbrecht, president of Hydro/P.R.O.P.  The season and farewell tour for Miss Budweiser starts June 25th in Evansville, Ind.
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3) Jimboat writes Features in HotBoat & World of Powerboats mags

Check out the NEW high-tech, high performance powerboating feature articles just published:

WORLD OF POWERBOATS (UK) - 'Rocket Science' - "...an article on high performance powerboat design and the technical opportunities for performance improvements in aerodynamic design" [editor-WOP] http://www.aeromarineresearch.com/adverts/WOP_winter04.html

HOT BOAT (USA) - 'Flight Path' - "...Jim Russell explains the aerodynamics of powerboat design" [editor-HB] http://www.aeromarineresearch.com/adverts/HotBoat_April2004.html
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4) Mercury unveils new X-Site test facility 
FOND DU LAC, Wis.  Mercury Marine will open a new 8.4-acre, integrated research-and-development site on Watson Bayou near Panama City, Fla., the company said in a statement Friday. The new facility, named X-Site, will feature multiple in-water slips, as well as an office, laboratory and boat-rigging building. Operations from the companys former Florida testing site, called Lake X, including offshore race support, will also be based there, Mercury said. 

X-Site is scheduled to open by April 14, though the exact date will depend on the progress of construction. Mercury selected Watson Bayou over 52 other potential sites based on criteria that included realistic boating conditions, available marine technical personnel and a degree of seclusion.  Watson Bayou also offers suitable calm and rough conditions in both saltwater and freshwater, which will allow the same facility and staff members to test everything from high-end offshore race boats to small outboard-powered tenders. 

Lake X Operations Manager Bill Harris will oversee Mercury Racing's customer support and offshore race activities at X-Site. Bill Nesslar, manager of Mercury's former saltwater test facility in Placida, Fla., will oversee all Mercury production research-and-development testing at the new Panama City site. John Sherlock will oversee Mercury Racing's research-and-development testing. 
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6) Miss Budweiser Shatters World Speed Record for Kilometer Run

OROVILLE, Calif. - Dave Villwock and the Miss Budweiser team shattered the kilometer (Kilo) World Speed Record by 22.323 mph for an Unlimited Hydroplane boat here today on the Thermilito Afterbay, setting a new world record of 220.493 mph for a kilometer run, unseating the previous record of 198.17 mph which had stood for 42 years. 

The team made history just shortly after 8:30 a.m. PT, as Villwock piloted the Miss Budweiser on the first leg of the run to an average speed of 213.437 mph and to an average speed of 227.550 mph on the return leg, resulting in the new world record of 220.493 mph. Villwock peaked the Miss Budweiser on the return leg at a top speed of 229 mph before the boats rudder and propeller failed, leaving the Miss Budweiser damaged and dead in the water. 

"Dave Villwock is lucky to be standing back on shore," said Joe Little, president of Hydroplanes, Inc., owner of the Miss Budweiser. "Losing a propeller and the rudder at 227 mph is an extremely serious problem. It was on a similar speed record breaking attempt that the Miss Budweiser team lost driver Dean Chenoweth in 1982 when he lost a rudder and a prop and the boat went out of control, killing him." 
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7) Feature Article - "Step by Step" (step design in powerboats)

We have had many questions regarding the design and implementation of steps in performance hulls.  Here is a short answer - step-by-step.

- The design of effectively performing steps is VERY difficult - and will most always achieve a 'benefit' (more than the losses) at ONLY one planing velocity. A step design is only good for a single angle of attack with a single dynamic center of gravity (CofG). That is why it is so complicated to find a step design that can "help" the performance throughout the speed range of a performance boat.

For example, the design and manufacturing tolerances are far more critical in stepped hulls than in non-stepped hulls. A slight change in plane angles, particularly the angles of the aftermost plane, has a marked effect on the running of the boat. Changing the after step by only one-eighth of an inch can change the boat performance from one that runs smoothly to a porpoising hull.  Even the change in weight of passengers, or fuel weight can be enough to throw off the CofG so that the step design no longer works as intended.

- It gets worse, too! When a stepped hull turns, the wetted surface of the stepped portion can change, which changes the center of pressure of the lifting surface, which changes the dynamic CofG of the hull - scuppered again!  The results can vary from loss of lift to "step-tripping" to the ultimate "hook" accident.

- The theory...
On a planing hull, the highest-pressure water is just aft of the leading edge, so we want to take advantage of as much of that pressure (lift) as possible without the drag penalty of the low-pressure water farther aft. The efficiency of a planing surface is a strong function of its aspect ratio, (the relation of the width to length). The most efficient planing hull is one that is very wide, but very short. (The aspect ratio of an efficient prop-driven airplane is perhaps 8:1, while the aspect ratio of a non-stepped planing hull is on the order of 0.5:1)

Now, the design of a simple non-stepped hull, we must select a built-in angle of attack and the center of gravity. We can control the angle of attack by specifying keel camber, deadrise, and chine warp (all of which may vary over the hull length). Stepped hull design includes all these considerations, but now we ALSO have to balance the angle of attack of each step section with the distance between the step and the transom or between multiple steps! 

At speeds that are different than the speed that the step is designed for, the steps are often entirely immersed, so each step actually adds drag to the hull.

- Introducing "air bubbles" to the pad surfaces?  Good grief...why would we do that? 
A myth about stepped hulls is that the introduction of air into the water that flows under the hull reduces the viscous drag and makes a stepped hull go faster than a non-stepped hull. But in reality, running on air bubbles doesn't reduce the frictional resistance at all. The hull lifts on the water, not the bubbles. So bubbles or "two-phase flow" (water and air) will actually increase the drag.

- And finally, there is the question of "multiple steps". There are two problems with multiple steps: 
1) If the steps are located too close to each other, the water attaching to the second step is "contaminated" by the aerated low-density water from the first step (as per my explanation above), so the aft step does not produce the high lift forces desired. 
2) Where do we locate the center of weight (CofG) so that the weight is balanced across the steps? Remember, the running trim of your boat changes dramatically as you go from zero to full speed, and this makes a huge difference in the lift-force distribution on your steps. It takes only a small change in the relative locations of the dynamic CofG (and the center of pressure) to change your boat from a stable, efficient boat to one that porpoises at several velocities.

OK...I've already written too much on this.  Steps is really complicated design issue. Most don't work...and it should be easy to see why. When you read about, or experience the many boats that behave really nasty with steps, we can appreciate how they got there - probably not designed at all!
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8) 'Hot Boat' magazine - Save 51%! 

We have obtained great deals on Powerboat magazine subscriptions. This month we have a great deal on the popular 'Hot Boat' magazine. 

Hot Boat is prop and jet driven boat enthusiasts bible. Each issue featuring tests, technical and product reviews, adventure travel, outboard and drag racing coverage, high performance tips, and outboard RPM tricks.  11 issues Published: Seasonal; Cover Rate: $54.89; 
Our Rate: $27.00 (Save 51%)
http://www.aeromarineresearch.com/boating%20magazines%20discounts.html 
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9) NEW 'Tunnel Boat Design' Software - Version 7.5

We've just released the new Tunnel Boat Design Software - version 7.5. This is the best release yet - with the most dynamic and plentiful new features ever! Check out new features at http://www.aeromarineresearch.com/tbdp6.html, or download the summary of new features http://www.aeromarineresearch.com/New%20in%20TBDP%20Version%207.zip
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See you next time!

/Jimboat

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Note: The articles presented in TBPNews are edited excerpts from the "Secrets of Tunnel Boat Design" book, by Jim Russell, published by AeroMarine Research.  The STBD book explains the theory in full, and outlines example design calculations, step-by-step.  The "Tunnel Boat Design Program", software, does all the force calculations, dynamic force balances at all speeds, and reports the analysis automatically, including complete graphical performance results for any tunnel or modified vee hull design.
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