Pro Boat Formula Fastech Jet Drive Project

[Doby]

Nahhh, not the rigger, its cool but not my thing.......the jet drive IS VERY Interesting!!!

[Diegoboy]

Doby, So you want this boat AND the Graupner rigger?

[Doby]

When is this thing going to be done so I can buy it.

[Diegoboy]

I wonder why all jet ski's, seadoo's, etc... are NOT deep V hulls?

[Jesse J]

I am on Diego's boat on this one. Also, flat bottoms support weight better by spreading the displacement out over less surface area as the drawing shows. The mere fact that it would help the intake alone, not to mention we are not talking super speed boat, almost makes it worth it. I was picturing flattening just the back half or so, kinda like the Fastech. The EV tends to flop around a lot, being severe deep vee and so top heavy.

[Diegoboy]

True, but lets take a look at surface area for just a moment.
Look at the picture... I'm no math genius, but I see less hull in the water. take that number and multiply by the length of the hull, I see a huge amount of difference.

[Viking]

Flat Spot

Hey Diego;
You are quite correct the flat spot would make it easier to install the jet.
The shallow Vee is faster than a Deep Vee with a prop for the simple reason that it is easier to keep the hull out of the water.Less drag.
With a Jet boat if the hull is out of the water, it is not picking up water and so there is no thrust. A Jet can't be aired out like a prop boat the Jet intake and so some of the hull Must be in the water to maintain thrust.
No, Yes, Maybe???
Viking

[Diegoboy]

Leave the Vee hull alone ! The less boat in the water the better. A big flat pad is just drag.
Viking

I would have to disagree. Not only would that be wrong, the flat pad makes it easier to marry the jet drive to the hull.

The Shallow Vee has a much flatter bottom which when at full speed has less of the hull touch the water. This make the Shallow Vee faster. But the Shallow Vees tend to slide around corners, instead of carving the turn. Below is a picture of a transom with much less angle.

If a flatter v is faster than a deep v, then a flat spot should be "less" drag.

Source

[Viking]

Hi Jesse;
"Great video! looks like fun! was that full throttle? I was thinking of putting in a sc 700 or like you say XL brushless. I will be watching for more videos under bl power!"
Some of it was full throttle, it is a lot of fun, remember to keep the boat up stream so if it dies or turns turtle you can catch it.

---"How is that hull? would it be worth laying down some good sturdy fg before construction? Do you have any shots of the transom? How do you mount up that jet?
--- YES it would be worth a layer of glass or carbonfiber on the inside. Not just the bottom, the strakes make the bottom very strong. I have a couple of major cracks in the sides of the hull. Study the instructions for the Jet, drilling that huge hole in the transom is a major move. Both of the heavy gray plastic pieces go on from the outside then the white water duct goes on the inside. So cut and fit the housing and nozzle(gray parts) before cutting the hole in the bottom of the boat.

Leave the Vee hull alone ! The less boat in the water the better. A big flat pad is just drag.
Viking

[Jesse J]

Great video! looks like fun! was that full throttle? I was thinking of putting in a sc 700 or like you say XL brushless. I will be watching for more videos under bl power!

How is that hull? would it be worth laying down some good sturdy fg before construction? Do you have any shots of the transom? How do you mount up that jet?

Had a thought, what if the V were flattened like the Fastech during the fg job? It would take some guts to chop of the hull, but could be done right and might help.

[Viking]

Electro Vee

Hey Jesse;
I have an electro Vee with that same jet Here---http://www.dickieeng.com/Jet%20Vee/index.html-- and a Vidio of it Here---http://www.youtube.com/watch?v=sLurjY0OYkQ-- Running in the White water of a local river in March.
Hey Diego;
I Gutted my Electro Vee again. This time I am going Brushless. I just couldn't get enough power in her to run right.
In order to get the COG any where near correct I had to cut 3" off the shaft and tube, so I could move the motor back. I put in a Feigao 10XL. 2 2S LiPos are going along side the jet up against the stern. I am dieing to try it out but there is too much ice in the river.
Viking

[Diegoboy]

I first did this to a Pro Boat Shockwave 26 (because of the flat spot on the bottom) It was great. I wanted to do the same thing in a fiberglass hull, the Pro Boat Fastech is the only one I found with this flat spot like the SW26.

[Jesse J]

Exxxcellent, even closer to seeing it GOOOOOO. Great work, looks real clean!

Any particular reason for this hull? I have an old electrovee I am saving for this very type of project. Although, you may have a better hull, being a modified V.

[calcagno45]

Awesome! Some progress!!!

Good call on the pushrod change. I think the thicker, stiffer pshrod will keep it where you want it.

[Diegoboy]

I'm probably going to change the push rod from the 2-56 to 4-40!