New Zealand Mod Vp circuit racing

[NZ Sidewinder]

This is a video of how we circuit race Vee bottoms at the bottom of the world.
The initial part of the video shows the boats getting lined up with the start boat in their pole positions, 0which can take a few circles at the top end of the lake.
Note the torque of the 280hp on the red boat outside the camera
https://youtu.be/6uc6-_sGs2g?si=LXmTYu9LXVY6Iz1t

[Instigator]

Great video!

Thanks for sharing.

[NZ Sidewinder]

Cheers
I often think of your Quote about being competitive with stuff you built in your shed.
That's what I strive to do also

[motexas]

Great Video and Run- Thanks for sharing

MO

[CUDA]

How fast are you going? What is your setup?

[CUDA]

Cheers
I often think of your Quote about being competitive with stuff you built in your shed.
That's what I strive to do also

I don't think he's built any junk in 20 years,

[NZ Sidewinder]

85mph@ 7000rpm
2.5 merc
Propshaft 2 1/4 below pad
26p Ballistic Michigan Wheel.
19 foot Cyclone 1950rx mono.
Highly modified underside.
Pad has a substantial rocker in the pad and will out corner most boats.
Engine is a cast iron liner f block running wmv 80/82 jets.
F1 type 4 petal reeds in 7 petal cage width ,( each carbon petal is over an inch wide.
Exhaust chest is hogged out to as close as a fishing 2.5 can be to a 280hp.
8118 rods and the reed cages are stuffed in 1/8 inch.
Heads are just .100 cut stock heads 145psi.
Wiseco pistons.
Exhaust ports 1.575 and squared up a little with a Pro max type chamfer
Rod slots opened moderately.
2 piece exhaust plate and simple home made stainless tuner.
Squish .040
Transom mounted low water pickups running 15-20 psi.
Basic nose cone.
1.87 ratcheting fishing gearbox but with the heavy carrier and caged propshaft bearing.
Overall low cost motor.
Hull is not light weight.
Engine is set back 28 inches.
This is a molded pod.
The pad is an unusual design imo.
Its formed from a pair of strakes that remain parallel as they go forward but get shallower.
This results in the vee keel protruding through the pad from zero at the transom but more as the pad goes forward.
However there is a 1/2 inch rocker cut into the pad from about 4ft, back toward the transom.
This rocker allows the boat to sit up on the pad as in the photo, then when trimmed down for the turns, allows the pad to bite in for its full length and take the hull strongly through the turn.
Those little fillet pieces on each side of the pad were a way for the original designers to help keep the hull from chine walking due to the tall pad.
The earlier generation of this hull didn't have those and were difficult to handle at speed.
Subsequent generations used a pad that was not as tall and are more stable at speed.
However this model is my favorite.
The video shows at one point the boat chine walking for about 150m.
That's the trade off for using this hull, it will do that sometimes.
I don't drive this boat anymore, my Son does, and he just keeps his boot in it and goes through the Chine walking.
Next day though he did barrel roll though at about 70mph but that was caused by crossing a very deep wake of a larger boat.
Both boat and driver survived.
The boat is currently getting a driver cell added, similar to that red boat on his starboard side at the start.

[LakeFever]

85mph@ 7000rpm
2.5 merc
Propshaft 2 1/4 below pad
26p Ballistic Michigan Wheel.
19 foot Cyclone 1950rx mono.
Highly modified underside.
Pad has a substantial rocker in the pad and will out corner most boats.
Engine is a cast iron liner f block running wmv 80/82 jets.
F1 type 4 petal reeds in 7 petal cage width ,( each carbon petal is over an inch wide.
Exhaust chest is hogged out to as close as a fishing 2.5 can be to a 280hp.
8118 rods and the reed cages are stuffed in 1/8 inch.
Heads are just .100 cut stock heads 145psi.
Wiseco pistons.
Exhaust ports 1.575 and squared up a little with a Pro max type chamfer
Rod slots opened moderately.
2 piece exhaust plate and simple home made stainless tuner.
Squish .040
Transom mounted low water pickups running 15-20 psi.
Basic nose cone.
1.87 ratcheting fishing gearbox but with the heavy carrier and caged propshaft bearing.
Overall low cost motor.
Hull is not light weight.
Engine is set back 28 inches.
This is a molded pod

You make it sound so simple, meanwhile the above has thousands of hours of effort and tens of thousands of years of highly focused experience required before anyone can apply said effort. Really amazing build NZ

[CUDA]

At the start of the race, it looked like the 280 had everyone covered,

Then, in the first turn, you showed your driving skills

Well, I enjoy looking at boats upside down.

So do you have any pictures of your mods and reasons you made them?

I've built a few 20ft boats.

[NZ Sidewinder]

Yes
I'll sort some.
I'm very interested in undersides and have done a reasonable amount of work on them.

[NZ Sidewinder]

I'm very interested in undersides and have done a reasonable amount of work on them.
This is the Pad of the Mod VP boat as it was in that race.
There was rocker (from that line with arrows) in both the Hull and Pad from the mold but someone had modified the Hull rocker with filler so it was gone and the hull was true (flat)
They had even taken the rocker out of the strakes using filler.
Id had the boat upside down a few times working on the pad before I even noticed that the aft 4 ft of the Hull each side of the pad all the way to the Chines was filled in order to remove the Rocker.
Id never seen a hull with so much rocker.
However the boat got badly damaged in a rough race and some of the filler along with a large piece of the underside got ripped out.
It was then that I saw how the boat was originally designed and so decided to put it back to stock, but with more rocker in the pad.
Originally the rocker out of the mold was about 5/16 inch in hull and Pad.
I left the hull rocker at 5/16 and increased the pad rocker to 1/2 inch, maybe 9/16.

So going back to how the Pad on this boat was formed geometrically,
Its a Vee hull with a pair of 5 inch wide strakes fitted each side of the vee.
At the transom those strakes are level with the bottom of the vee so that from the stern the hull appears to have a plank typ Pad, but in reality, that cross section is only true for the profile of the transom.
As those strakes travel forward on the hull they remain parallel but get shallower until they vanish.
So looking at the photo of the pen outline, that's the point where my new, more radical rocker starts and its a cutting plane that starts 4ft forward of the transom and aggressively slices down into the pad back toward the transom to create the Rocker.
Remember that the Pad already had some rocker in it from the mold.
I've also put some small, adjustable trim tabs on the transom each side of the pad to help stabilize the Chine walk.

The Guys that originally designed these Hulls were very, very smart but I feel that the market judged the boat to be inferior because it just missed the mark by a few %.
It was a Hull that a tinkerer like me could improve on, and not a Hull that was Turn Key.
Later models were very good ski race hulls and very fast.
I believe that one owned by the manufacturer still holds the Hamiltom 40km Bridge to Bridge sprint record.
That said, I strongly suspect that those very fast, very stable boats wouldnt have a chance of getting around rectangle course like this one does.
However, much credit to the original designers.