TBPNews #46 - September 23, 2003 
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In this issue: 
1) SST 120 National Championship 
2) Yamaha settles suit for $6M
3) Invasive species threaten Lakes
4) F1 Powerboat Championship - Malaysia
5) Boat losses from hurricane total $150 million
6) NEW - Mercury Outboard Trailer Hitch Cover
5) FREE Powerboat e-book
6) 'Family & Performance Boating' magazine - Save 25%!
7) FEATURE ARTICLE - How does a tunnel hull work? (Part 3) 
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1) SST 120 National Championship 

Carlos Kuri of Mexico City, driving his Mercury Racing 2.5 Liter Champ race outboard-powered tunnel race boat, won the 2003 American Power Boat Association (APBA) Outboard Performance Craft (OPC) Champ class National Championship on Monday, September 1. The annual APBA OPC Nationals took place on the Kankakee River in Kankakee, Ill. Over 100 boats competed for OPC titles throughout the three-day event. Weather conditions were less than optimal, with torrential downpours and low visibility creating havoc for racers.  Shaun Torrente of Miami, Fla., kept two-time Champ Boat Series SST 120 champion Vince Voisin of Atlanta, G.A., at bay to win the 2003 APBA SST 120 national championship. Mark Welch, driving a tunnel race boat powered by a modified Mercury 2.5 Liter EFI race outboard, won the Mod U competition. All were powered by Mercury Racing outboards. 
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2) Yamaha settles suit for $6M

Yamaha Motor Corp. and its Skeeter Boats subsidiary have agreed to a multimillion-dollar settlement stemming from a lawsuit filed by a Louisiana man who was paralyzed in an October 2000 boating accident.  The injured man suffered debilitating injuries when he was thrown from a Skeeter bass boat. The lawsuit faults the design and powering of the boat.  Louisiana attorneys argued that the 200-hp engine was too large for the 20-foot boat, and that "the boats wedges caused the bow to go down, leading to a sudden, auto-generated turn."  When the man was thrown from the boat, the propeller hit Davis. The injuries to his head and neck caused total paralysis.  Yamaha agreed to pay the plaintiff $6 million in compensatory damages, and Skeeter agreed to pay $100,000 in court costs. [Editors note: Sure shows how we should always have properly engineered powerboat designs that are dynamically stable!)
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3) Invasive species threaten Lakes

Unwanted species are invading the Great Lakes faster than science can keep up with them, representatives were told at a conference in Ann Arbor, Mich.  The influx of foreign species - often dumped from the ballast water of ocean-going tankers - is turning the Great Lakes into an ecological carnival ride where biologists can only guess what will happen next, it was reported.  More than 160 nonnative species have been discovered in the lakes - ranging from microscopic invaders to the ubiquitous zebra and quagga mussels. The mussels, whose excrement increases phosphorus levels that lead to damaging algae blooms, may be to blame for a dead zone in Lake Erie where almost nothing lives, the newspaper reports. Because Lake Erie is the shallowest of the Great Lakes, it often is the harbinger of bad news.
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4) F1 Powerboat Championship - Malaysia

The next round of the 2003 U.I.M (Union Internationale Motonautique) F1 Powerboat Championship is scheduled for October 5th at the Mines Resort 
surrounding a vast lake (near Kuala Lumpur).  This will be the fourth time that F1 Powerboat Racing has been in Malaysia.  A field of 25 drivers representing 15 nationalities is expected for the Malaysian round of the UIM Championship. The F1 Powerboat World Championship 2003 calendar consists of following events:  Portugal, Finland, Italy, Germany, Malaysia, Singapore, Saudi Arabia and U.A.E. -- AbuDhabi and Sharjah.
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5) Boat losses from hurricane total $150 million

ALEXANDRIA, Va. - Losses to recreational boats from Hurricane Isabel, not including marinas or commercial vessels, will total over $150 million, according to the Boat Owners Association (BoatUS).  Much of the damage occurred in the upper reaches of the Chesapeake Bay and Potomac River watersheds, far from the storm's North Carolina landfall.  Overall, marinas got hit the hardest in this storm, according to BoatUS, and some are not expected to recover soon. It may take months before some yards will be back on their feet.  Boaters who took advantage of the long lead time before Isabel hit and made hurricane preparations by either removing their boat, or adding extra lines, chafe protection, reducing windage and buttoning up tightly, generally fared OK.  The association urged boaters to call their insurance providers and not sign salvage contracts on the spot. Boaters can help further mitigate damage by removing expensive items to prevent theft, and continue to keep water out of their boat, it stated. A list of post-storm damage procedures, such as preserving or "pickling" an engine, is available at the BoatUS Web site <http://www.boatus.com/hurricanes/after.asp>.
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6) NEW - Mercury Outboard Trailer Hitch Cover

We now have this completely unique addition to your rig! A stock Mercury Trailer Hitch Outboard Decoration for most any commonly owned trailer hitch. Make Waves with this Realistic Boat Motor Hitch Cover!  This unique item is not found in stores, so Order now! Watch the propeller spin you down the road! Only $26.95 + Shipping 
http://www.aeromarineresearch.com/mercury_hitch_cover.htm
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7) FEATURE ARTICLE - How does a tunnel hull work? (Part 3) 

We have had many requests to explain each of the many factors that can influence the performance of a tunnel boat.  There are literally dozens of factors that have an impact of performance, and most all of them influence the other factors.  This makes the prediction of tunnel hull performance a tricky business - to maintain the inter-relationships of all of these factors throughout the operating velocity range of the boat.  The good news is that most of these factors are controllable (by design and setup).  We usually rely on computers, and the advanced ": TBDP(c) (Version 7 now released) to do the hard work for us.

In the last two TBPNews letters, we looked at the factors that influence performance resulting from lift & drag and thrust relationships.  This week we will review the influencing factors of the performance and stability, looking at the location of weights & measures and the "outside" influences on performance.

Much can be done to optimize the balance of all the forces acting on the tunnel boat in motion.  This balance can be achieved for a range of speeds at the design stage, by optimizing the location of the forces involved.  By selective designing of all the aerodynamic and hydrodynamic surfaces that become critical at high speeds, each tunnel hull can be tuned at the design stage.  It is important to do this "dynamic balance" at all speeds through the boat's operating range - since balance at one speed just is not enough!  (So balancing your boat on the trailer, by moving weight around is only going to help if you boat never leaves the trailer).  Here's some of the design measures that we have control over:

  *  Boat Length - Overall length of hull, measured from sponson tips to aft most deck or sponson point.
  *  Driver/Passenger Length - Location of the driver and passengers, measured from the transom to the driver and passenger center location.
  *  Motor Length - Location (horizontal) of the motor, measured from the transom to the motor center of gravity (C of G).  May be either fore (+), or aft (-) of the transom.  Often adjusted by use of motor setback brackets.
  *  Fuel Length - Location of the fuel tank(s), measured from the transom to the fuel center.  Usually best to have the fuel located aft in high performance boats; can be located fore if optimum speed and control is not as important a factor.
  *  Miscellaneous Length - Location of additional equipment that is concentrated mostly in one location, such as hydraulic systems, batteries, ballast, etc., measured from the transom to the (average) load center.
  *  Motor Height  - Location (vertical) of Motor/engine from the water surface to the top of the engine casing/housing.  This locates the C of G of the engine for purposes of dynamic stability analysis, and defines the "form area" of the motor/engine if the engine (or part of) is exposed to the air flow and thus generates aerodynamic drag.
  *  Boat weight - Total weight of hull (only), including rigging, but excluding motor, fuel, driver and other significant additional equipment.  This weight should include all rigging weights that have not otherwise been accounted for.
  *  Motor weight - Total weight of motor, drive unit, propeller, and accessories such as hydraulic trims, plates, etc that are attached to or built in at the motor.  
  *  Driver/passenger weight(s) - Weight of driver with all clothing and safety equipment.  Test analysis should also be done with higher and lower values of passenger weight, to understand the sensitivity of the design to weight and location of payload.
  *  Fuel weight - Weight of fuel tanks and normal fuel supply.  Test analysis should also be done with higher and lower values of Fuel weight, to understand the sensitivity of the design to weight and location of fuel.
  *  Miscellaneous weight(s) - weight of additional concentrated equipment such as hydraulic systems, ballast, batteries, etc.
 
At AeroMarine Research, we use the "Tunnel Boat Design Program(c) " software to make the analysis easy.  The TBDP calculates all hydrodynamic and aerodynamic lift forces by all lifting surfaces, all drag contributors, and does a dynamic balance of the hull at every speed defined in the performance specification.  Doing this all in seconds makes it very easy to make small changes to the hull design, power or setup, and to determine the effect on performance and stability.  Whether done manually (as shown in the "Secrets of Tunnel Boat Design" book, or by computer with TBDP, designing a tunnel boat that will optimize performance and ensure stability is possible when we understand how these factors influence performance and stability.

Well, that's enough for this issue.  Next issue (part 4, and the last of this article series) will address lower unit design and setup influencing factors of performance and stability.


See you next time!

/Jimboat



