HPBCANADA.COM

It’s great to see the stages of the boat build. His first motor is a 50D tohatsu... interesting because it’s the same model that has the current world kilo record in T750 at .65 mph. ....his initial performance is similar to the bone stock 50D2 model tohatsu that was raced in our T750 class about 56-57 mph....he blows the motor up and after waits 3 years for its return as a modified 50D making approximately 65 hp and turning 7300 rpm ...it becomes a 65-70 mph boat. He then switches motors to the tohatsu 40C twin and turns that combination into a very competitive boat.

http://www.dillon-racing.com/customerbo ... /index.htm

We started to see many former Sport C, SST 45, Formula 50 and homemade tunnels return to racing overseas in 4 stoke 50 hp class in 2017. The key to their performance improvement is the sponson water pickup. That enables the motor to be raised so the gearcase bullet is above the water. That reduces the drag and the boats run approximately 10% faster.
These tunnels run different engine manufacturers and they are all very competitive....speeds are in the 65 mph range.

2018
https://www.youtube.com/watch?v=Kbt8GrfBI6E
2024
https://www.youtube.com/watch?v=ekBPPIM_u2Y

Just thinking
Wonder If?.
On a hydro if you installed the motor’s water pickup on the turn fin....wouldn’t you be able to run a stock gearcase outboard high enough on the transom that the gearcase bullet is completely above the water . At speed only the lower portion of the prop and the skeg would be in the water. That would have less drag than a current stock hydro setup so wouldn’t it be faster?

What if you took a current “D” hydro design and extended the sponsors so it became a tunnel hull.
That would allow you to run a new 15 inch outboard with sponson water pickup. Wouldn’t that result in a competitive 70 mph plus raceboat?

In T Class what if we allowed transom mounted or low water gearcase water pickups and power setback jack plates? Wouldn’t that make the class more of a driver’s skill class.

I was asked about the difference between CBF & APBA Sport C, and 550 classes in other countries.

First off a “C” class is a class with a maximum engine displacement of 35 cubic inch or 573 cubic centimeters. The 550 classes in other countries are based on engines with a 550 cubic centimeters or 33 cubic inches.
The small difference in engine displacement doesn’t really make any difference because there isn’t an outboard in the displacement size between 33 and 35 cubic inch.
In fact the most common run outboard is the 2 cylinder tohatsu 40C which is just over 30 cubic inch.
https://www.apba.org/documents/15013520 ... ations.pdf

Sport C had a very short life in Canada in the early 1990’s. Class numbers have gotten smaller in other countries in the last few years. Sport C is an entry level class to tunnel boat racing . It’s a 55 to 60 mph class. The class was started in the late 1980’s. Most children today entering this class of racing now start in the GT V bottom classes. Many countries have good boat counts in these classes. You also see many countries combining several classes together which have similar speeds. Those races have a variety of boat types, 2 stroke and 4 stroke motors. Event organizers do this when they don’t have a lot of entries in several classes. It’s an excellent way to showcase the different combinations and have more entries in a single race. The increased number of entries makes those races better for the fans, the racers and increases the clubs revenue . For the event schedule it also reduces the number necessary races.

Here is an impressive 50 hp tohatsu on an SLT.
121km......that is 75 mph.
https://www.youtube.com/watch?v=0BzjTefU-Iw