Breakthrough 7.5cc Tunnel/K&B outboard

[BradSpencer]

Hi guys,

A quick vid of the Breakthrough 35(35 inch) WOF tunnel by David Moyle.

K&B 7.5cc 8702 mod engine.

 

[dion smith]

Nice one Brad!! Should have the 46 on it though can't wait til mine is ready!!

 

[Hayden Bright]

Tunnels rock \m/..... That looks very nice scootin across the lake, the way a tunnel should ride- light but predictable

 

[Greg Moss]

Nice Brad, real nice Looks like the 7.5 cc Breakthrough is going to handle well. Looking forward to next year's racing season all ready!

BTW: Put a few tanks through the Nelson today in the rough and managed to get some good handling and reasonable speed out of it.

Best

G/

 

[BradSpencer]

Nice one Brad!! Should have the 46 on it though can't wait til mine is ready!!

Loving the hull, flys high but stable

One of these should be a rocket with your Nova.

Tunnels rock \m/..... That looks very nice scootin across the lake, the way a tunnel should ride- light but predictable

Thanks Hayden, Looking forward to putting a bigger wheel on it for SAW

Nice Brad, real nice Looks like the 7.5 cc Breakthrough is going to handle well. Looking forward to next year's racing season all ready!

BTW: Put a few tanks through the Nelson today in the rough and managed to get some good handling and reasonable speed out of it.

Best

G/

Thanks Greg,

Your Nelson/Vision combo was working really well at Penrith the other week. I have no doubt it will be putting in some quick lap times.

 

[Greg Moss]

Only problem, the big nut behind the wheel!!

Seriously though; the Vision is a very good boat and the Nelson engine seems to have the grunt required. It looks to me like B-O/B is getting some numbers back and will be strong next year.

Let's all keep it going.

 

[Tim_Duggan]

Hey Brad,

How did the hull feel for full throttle turns into a corner? Any understeer?

Tim

 

[BradSpencer]

Hi Tim,

I havn't pushed it hard on entry to a corner yet, its flying that high I suspect there would be some understeer without easing off for a moment to settle the hull. Although it is tracking nicely around the corners, and is very driveable.

I'm am focusing on the SAW event which is going to be held by WDMBC(Western District Model Boat Club - Cherry Lake), hopefully in April.

Running a super short skeg, and mainly interested in its straighline characteristics for now. Its ticking all the right boxes

I'm finding out the video looses its quality once uploaded to Youtube. Will get some better footage in coming weeks.

 

[Tim_Duggan]

Thanks Brad! Best of luck with those record attempts mate - if your oval boats are anything to go by you should get a few.

 

[BradSpencer]

Thanks Tim, means alot coming from you.

Couple of pics:

 

[Shane Bastick]

Hi guys,

A quick vid of the Breakthrough 35(35 inch) WOF tunnel by David Moyle.

K&B 7.5cc 8702 mod engine.

http://www.youtube.com/watch?v=EKDPtRnYj0Y

Hi Brad,

is that hull available as a plan to build being a WOF boat

thanks

Shane

 

[David Moyle]

Hi Shane, it's currently not available as a kit. Mainly because of the extra work required to modify the design to make assembly more 'user friendly'. It's something I will think about doing at a later date though...

 

[Shane Bastick]

Hi Shane, it's currently not available as a kit. Mainly because of the extra work required to modify the design to make assembly more 'user friendly'. It's something I will think about doing at a later date though...

Thanks David,

I was only interested in plans for one anyway, I scratch build all my boats from either plans or own design, so a kit wouldn't be required, just the drawings and then I can build my own, I have built quite a lot of WOF tunnels, so am used to this method

 

[RonShaw]

Thanks Tim, means alot coming from you.

Couple of pics:

View attachment 42535View attachment 42536View attachment 42537View attachment 42538

You have the right pipe, that's for sure. Good luck!! Boat looks great.

 

[Nitro boater]

Ron what pipe did you refere toooooooo

 

[RonShaw]

Ron what pipe did you refere toooooooo

The Equi pipe with Irwin center section. Great pipe.

 

[BradSpencer]

You have the right pipe, that's for sure. Good luck!! Boat looks great.

Thanks Ron, the pipe seems to be working well. Once I get the package dialed in and get a good feel for the setup, I will "back to back" test some other pipes. Appears to have very similar Charcteristics to a Silverbullet pipe.

 

[CamcorderRacer]

Wow, sure wish my K&B tunnel went that fast. I seem to have a lot of trouble tuning and keeping it running. And for future reference what pipe are you using and are you using a stock lower unit?

 

[BradSpencer]

Wow, sure wish my K&B tunnel went that fast. I seem to have a lot of trouble tuning and keeping it running. And for future reference what pipe are you using and are you using a stock lower unit?

That pipe is a Equi pipe modified using an Irwin centre section, hard to get.

The HTB Silverbullet is a very good option and easy to get, currently the pipe of choice for my oval boat.

The lower is a K&B modified to allow for the tune pipe.

Prop choice and bad bearings are the two most common problems regarding tune IMO. Check the bearings and try a smaller prop.

A S/B Prather 225 is a good baseline prop I use when running a K&B 7.5 OB. Most 7.5 OB setups will pull a 225 easy, making it easier to get the tune ball park.