Offset radio boxes and transoms for .21 tunnel hulls ?

[riggerman]

Hi all back about 10 or so years ago there where several .21 outboard tunnel hull designs that offset the radio box and transom to the starboard side the VS-1 was one and the other was a Jerry Dunlap design which offset 1/2'' to starboard side from what i remember i believe this was to help with cornering. Did this design feature work good ? Is this offset feature still used today in newly designed tunnel hulls ? Regards Andris Golts.

 

[Kris Flynn]

Hi Andritz,

I believe you are correct, it aided cornering and maybe also counteracted motor torque.

I have tried offsetting, but did not find it beneficial to me...it actually seemed to corner better left than right (center was offset to the starboard) haha

Cheers

Kris

 

[Jarcaines]

Id be interested to hear Rod Geraghtys opinion on this. My dad ran several of his designs in the 80s and 90s, and I remember most of them being offset.

 

[Jerry Dunlap]

My new tunnel has the engine centered and corners really well.

FYI - The very successful Lynx 20 Tunnel has the engine centered on the transom.

JD

 

[Jarcaines]

My new tunnel has the engine centered and corners really well.

FYI - The very successful Lynx 20 Tunnel has the engine centered on the transom.

JD

Yeah, doesn't seem like many do that anymore. I assume it's been figured out it doesn't make too much of a difference.

 

[riggerman]

Thanks to all that replied to my ? . Regards Andris Golts.

 

[Jarcaines]

So, I talked to Rod today on the phone and he explained this to me. The inside sponson edge in a tunnel is suppose to act like a turn fin in the corner. The more you can get that sponson edge to dig in on the corner, the better its going to turn. The idea of offsetting the motor and radio box was to get more weight over that inside sponson. Makes a lot of sense.

I am paraphrasing. He said it a lot better then I did, but that was the basic idea.

 

[RonShaw]

Thats exactly right. Many mastered this concept even more by making the starboard sponson 1/16-1/4 deeper than the port sponson. If the bite was too much experimenting with a slight 45 degree angle on that sponson edge forward of CG helped solve the problem.