Newbie with questions

[dbfan]

I've been reading this forum for a couple of weeks now and I've learned a lot from all of your posts, and I really dig the boats, you really have some sweet rides! but I'm not sure I understand some of the lingo and some of the hardware thats used on these boats,so I have some questions that I hope you can answer for me.
What is a whirl-away?
what is a clamshell?
what is a airshifter?
what's the difference between a flatbottom and a runnerbottom and a t-deck and a bubble deck?
why do some boats have the engine mounted forwards and some have them mounted facing the rear?
how fast does a hydro have to be going before it gets up on it tips?
why don't hydros have cavitation plates and flats do?
sorry if these are dumb questions, I'm going to the races at chowchilla nest week and I want to understand as much as I can and to see what all the excitements about :-)

[pgf127rt]

dbfan:
I've been reading this forum for a couple of weeks now and I've learned a lot from all of your posts, and I really dig the boats, you really have some sweet rides! but I'm not sure I understand some of the lingo and some of the hardware thats used on these boats,so I have some questions that I hope you can answer for me.
What is a whirl-away?
what is a clamshell?
what is a airshifter?
what's the difference between a flatbottom and a runnerbottom and a t-deck and a bubble deck?
why do some boats have the engine mounted forwards and some have them mounted facing the rear?
how fast does a hydro have to be going before it gets up on it tips?
why don't hydros have cavitation plates and flats do?
sorry if these are dumb questions, I'm going to the races at chowchilla nest week and I want to understand as much as I can and to see what all the excitements about :-)dbfan, let me see if I can help;
A whirlaway is a ratchet device to let the prop turn backwards in case of a blown engine or a sudden loss of power , it eliminates the prop from wrecking the boat in a word.
a clamshell is the steering apparatus on the rear of a hydro to which the rudder attaches.
An airshifter is an air actuated mechanism which shifts the transmission by pressing a button on the steering wheel.
A true flatbottom has a one piece cavitation plate on the rear and a runner bottom has a 3 piece cav plate which is not unlike a mini-tunnel usually 5/8" up to 2" tunnel. Runnerbottoms have a distinct performance edge over true flats.
Most v-drives are basically engine mounted backwards to hook up to the v-drive, the exception being circle racing flats which hook up from the front of the engine to aid in turning left using the torque of the engine.
All hydros get up on step when they are going fast enough to pack air under the hull, horsepower and setup along with launching style plays a great part in the timing.
The hydros have no cav. plates because the tail is out of the water, however on the unlimited hydros aka Miss Budweiser , they do have a kanard on the arch whis is operated by the driver to lift and drop the tail to optimize turning, and lifting of the tail very quiickly.
uh-oh missed one, the difference between a t-deck and a bubbledeck is the circular area between the drivers side where the steering wheel is and a straight across style of the bubble deck or standard flat.
I hope this gives you the answers you needed and no they are not dumb ?'s everyone who is interested should ask and be as informed as they can it makes a day at the races a lot better.
[ July 28, 2002, 07:55 AM: Message edited by: pgf127rt ]

[CircleJerk]

dbfan, I have only been flatbottoming for 7 years and I know others here can fill in the blanks or correct me. A whirlaway is a simple devise that disengages the propshaft when the motor or the v-drive stops turning. This can prevent the occupants from being thrown out over the deck and run over by their own boat! An air shifter puts the v-drive in gear with a remote bottle of compressed gas much faster that the manual one and is used primarily for drag racing. Lenco and B&J transmissions used in drag cars use a very similar shifter to activate the clutch packs that shifts gears. The T-deck is a notch in the forward deck that allows the driver and especially his legs to be thrown clear of the boat without being caught under the dashboard which messes up your lower body parts! A bubble deck is simply a style that resembles a swelling or bubble directly in front of the dashboard in the shape of a half circle. This was started in the early 70's and like so many other designs was copied by other manufacturers. Sanger bubbles are the most common and popular I believe. A runner bottom is similar to a tunnel hull but not as deep. The runners are 5/8 to 2" deep and trap air at the rear of the hull in an effort to fly the hull faster with less wetted hull area. Without personal experience, I am told one can gain 5-10 miles an hour with this type of bottom. The disadvantage for most of them is they lack turning ability. Flatbottoms for the most part are just that with many variations to the chine and keel areas for performance advantages and handling characteristics. A flywheel driven v-drive or backwards engine mounting is the most common I think because it was easier and for the most part stronger. An engine is designed to be driven off the flywheel flange but this requires the use of a special oil pan with a pickup at the opposite end. This style makes the prop turn to the left so the boat turns right easier than the left. That's why so many circle boats, if not all, use a right hand prop that requires the snout or harmonic balancer driven devise. They turn left better because of the opposite reaction torque cause by the rotating propellor. Hope this helps and I'm sure someone out there will fill in the blanks, it's too early in the am for me! Jerkster, and enjoy the races!!

[dbfan]

pgf127rt and CircleJerk
Thank You for your well informed answers,
this newbie appreciates it!!

[DUCKY]

They are partailly right about the whirl-away. The purpose of a whirl-away is to allow the prop to continue spinning if you lock up the engine or v-drive. Without one, if you lost a motor or drive at 100+ mph, it would instantaeously flip the boat. With one, it just slows down really quick. Also a bubble deck means that the front of the boat comes up like a fake windshield. A T-deck has a cutout for the drivers area so if the driver was ejected from the boat, his legs wouldn't be torn up on fiberglass on the way out. Generally, a T-deck's seating position is much higher to aid in the driver being thrown clear of the boat in a wreck, rather than getting tangled up in it. Everything else I read is correct, I'm just a perfectionist and an opinionated A-Hole! eek!

[pgf127rt]

DUCKY:
They are partailly right about the whirl-away. The purpose of a whirl-away is to allow the prop to continue spinning if you lock up the engine or v-drive. Without one, if you lost a motor or drive at 100+ mph, it would instantaeously flip the boat. With one, it just slows down really quick. Also a bubble deck means that the front of the boat comes up like a fake windshield. A T-deck has a cutout for the drivers area so if the driver was ejected from the boat, his legs wouldn't be torn up on fiberglass on the way out. Generally, a T-deck's seating position is much higher to aid in the driver being thrown clear of the boat in a wreck, rather than getting tangled up in it. Everything else I read is correct, I'm just a perfectionist and an opinionated A-Hole! eek! Ducky, I am pretty sure my answer on the whirlaway was correct, if the motor blows and locks the prop turns backwards thru the ratchet, aka whirlaway, and on the bubbledeck I gave an example of both styles, bubble and straight, if one ever sees a bubble deck I think it is recognizable as such.
[ July 31, 2002, 04:32 PM: Message edited by: pgf127rt ]