Whitewater Jetboat Racing Basics

Racing
The basic idea is to take a boat powered by an automobile engine and a jet pump and race it on a river from point A to point B, wait for everyone to make it, then race from
point B back to point A. You are competing for total time for the weekend AND points per leg. The three lowest times in each class for the weekend are awarded
trophies and cash. Everyone also accumulates points per leg by time, and these go towards your standing in the local Country Championship.

Starts
On most rivers, there is not enough room to safely race two boats side by side so we use staggered start times, generally one minute apart. You will see a white flag go up
ten seconds before each start time and then a green flag ON each start time. You cannot cross the start line BEFORE the green flag goes up (significant penalty) but
you can, if you are good at it, charge the start line and ideally cross it at a high percentage of your top speed just as the green flag goes up. Boats are put in
the start order by their estimated speed compared to the other boats, fastest boats first.

From the start you carry on to the finish line as fast as you can make it. This generally involves aerobatics, close calls and dumb boat tricks all
of which makes it an interesting spectacle to observe and compete in!

 
 

Sweep Boat
The sweep boat runs last, is usually a family type boat and usually has rescue people aboard. It's function is to sweep the course. It is also carrying race
officials and the starter/scorers.

DNF / DNS
If you start a leg but break down and the sweep boat passes you, the leg is over for you and you are awarded a Did Not Finish (DNF) time which is calculated
from the slowest finishing boats time for your class plus a calculated percentage of the slowest time. DNS: A Did Not Start (DNS) is a penalty for not making
a start at all, usually what happens on the next and subsequent legs if you are sitting on the bank, broke down. It carries an even stiffer time penalty than a
DNF. Lots of motivation there to get it running again and catch the next leg if possible.

If you can get it running, you ARE allowed to motor to the next start AFTER the sweep boat has passed and a set  time before the next set of starts. At some
races this rule is modified and you end up on the bank at least until a lunch break if you break down. This is done when it is a series of short turn arounds
and is done for safety.

Time between legs
The next legs start time is set ahead of time and is determined by an estimate of how long it's going to take everyone to complete the course and for the
sweep boat to cover the course looking for broken boats and making sure that anybody that needs help gets it.
Usually on a short course the leg start times will be a minimum of 45 minutes apart. On long courses and with lots of boats they go an hour or more between
start times. If all this starting, stopping and scoring sounds like a lot of stuff to coordinate, it is and usually takes a dedicated team of 4 or 5 people and a
couple of boats to accomplish. All the boats are carrying a clock that is synched to the official race time, to the second,  for use in getting to the line at the right time.
 

Boat Classes

We have several classes of boats, each competing for their own set of trophies, prizes and times. This is done to allow folks to compete at there own comfort
level, money and speedwise. The common rules are that they all have to be motivated by a jet pump and all the safety rules apply.

Unlimited Class, numbers 300 to 399
Any hull, minimum 16 feet in length.
Any motor or motors, of any type of any displacement.
This means 640 cubic inch motors, helicopter engines
or 52 Wankels bolted together if that's what you think would do the job.
speeds over 135 mph

A-class, numbers 200-299 or lower with the letter A affixed.
Any hull, minimum length 16 feet.
displacement 367 to 470 cubic inches, naturally aspirated.
These boats are capable of 120 mph.

B-class, numbers 100-199 or affixed with the letter B.
Any hull, minimum length 16 feet.
displacement 310 to 366 cubic inches, naturally aspirated.
These boats are capable of  110 mph.

CX, numbers 100-199
Any hull, minimum length 16 feet.
Chevy LS3 CT525 crate motor 525 hp, Dodge and Ford equivalents
Very limited modifications, none for performance.
speeds around 100 mph

SBFX, numbers 0-50
Any hull, minimum length 14 feet.
350 Chevy ZZ4 crate motor Dodge and Ford equivalents
Very limited modifications, none for performance.
speeds around 90 mph

SBFXV, numbers 0-50
V and Step-tech hulls, minimum length 14 feet.
350 Chevy ZZ4 crate motor Dodge and Ford equivalents
Very limited modifications, none for performance.
speeds around 80 mph

The Boats

Engines range from exotic (Turboshaft, Nascar heads, dry sumps, sheet metal intakes, etc.) to extremely ordinary (ZZ4 crate engine). The single attribute they all have to have is longevity
 as they typically spend 95 percent of any leg at full load and full throttle. That is very similiar to a dyno pull if dyno pulls lasted 30 minutes at a time. Most cooling systems are simply river water
at around 15 psi routed through the engine and then overboard, temperature controlled by flow which is controlled by a ball valve. Most, but not all, boats run alternators.

The boats themselves are fairly simple, a driveline from the engine spins the pump. Steering is via a steering  wheel moving a cable that looks like a giant throttle cable. It ultimately controls
which direction, left or right, that the water stream leaves the nozzle which of course controls the direction of the boat. The underside of the boats are pretty much smooth,  not very much
hanging down as whatever there is gets to the rocks first. The driver has two controls, steering and throttle. No brakes, no clutch, no shifter. Sort of the ultimate expression of stab it and steer it.

Safety equipment is different from most types of boat racing in that roll bars are required as are full racing harnesses. The rollbars are useless in deep water, but they are absolute lifesavers if
you roll over onto a gravel bar or into shallow water. This has happened, the most recent occurence known as the Hoopa Guacomole Episode. Crews wear helmets, fire suits and
specialized racing lifejackets. Some typical marine good sense rules are applied also, such as venting fuel tanks overboard and the carrying of two fire extinguishers.

 Most of the real wizardry in these boats is in the pumps, intakes and hulls. The great strides in speed that has happened in the last 10 or 15 years is mostly from advances in the hulls and
pumps. All the boats are aluminum, with sometimes a high abrasive steel bottom added, but the rules do allow construction from other materials.

From the driver's seat

A crew of two
Each boat crew has a driver and a navigator. The driver is the primary set of eyes and, in theory, has the whole course fixed in his mind. They can read the river and adjust for
 changing conditions and compensate for problems with the boat. They are responsible  for getting the most out of the boat and the course. The navigator is the second set of
eyes, and also has the course memorized. The navigator also watchs engine gauges and  may be in charge of controls other than the steering and throttle such as the valve for
controlling engine temperature or mixture on fuel injection systems. The navigator is also  usually the primary for watching for overtaking boats. The navigator also keeps the time
 for starting and for red or yellow flag delays. Depending on who you talk to and what kind of run they just had, the driver's  job is to do their level best to scare the Navigator and themselves silly by driving like
an idiot, the navigators job is to do everything else.
Duties and jobs are different in each crew, these are general duties.

It's very loud. Most of it is the motor howling right behind you. The wind rushing past and through your helmet contributes as does the squall of the pump and the
water sliding by the aluminum hull. Most drivers wear earplugs.

Seeing is everything. Different sun angles, overcast and wind blowing on the water all affect how the track (the river) looks. It is utmostly important to be able to read
the water, sometimes its easier than other times. Sometimes it's impossible and you are relying totally on memory. Then there is the classic debate of whether it's easier going
upriver or down. The look of a riffle or rock changes completely depending on if you are going up through it or down through it. A rock you can plainly see going
up river might be totally invisible going down river. Ideally, you would be good at reading the water in both directions.

There are multiple fast lines through each corner and riffle. Some are faster than others of course, but to the 'fast' attribute you can add or subtract: smoothness, danger-close
obstacles (because these boats move around from were you point them quite a bit), rollers that may launch you or send you off sideways. As in road sports, the best line is the fastest
one that sets you up for the next corner, riffle or obstacle. Unlike most road sports, sometimes you can gamble that you can miss obstacles so that you may take advantage of a really fast line.
To do this, you need to know the river of course. (AND remember it correctly)

The boat hits HARD sometimes. But you get used to it. Makes you think quite a bit about things like motor mounts, stringers and pump intakes. Hitting water is usually rougher than hitting
objects, depends on how you hit the object.

Getting air is fairly normal. How much depends on what you just jumped and how fast you were going. Sometimes it's the best way through. Jumping once is better (faster) than plowing through three rollers, kind of like motocross.

If you have run hard enough and you have good sense, your knees might be banging together at the top end. It is a decent indicator of how hard you pushed yourself.