Tunnel Hull Rookie Question ...

[viper1]

Building/converting my first tunnel hull;

I know that rear edges of transom, sponsoons and/or steps should be as sharp as possible for best performance. But how about the corners running length-wise,e.g. the inside of sponsoons. Should they be sharp as well ?



Thanks in advance

[marko500]

Yes

[viper1]

Razor sharp?

[Chilli]

I myself don't spend too much time on the sides. I do make sure they are smooth and even. I do put allot of time in making sure the transom is sharp and even more time ensuring the bottoms are flat.

[HTVboats]

Assuming your talking about the point where the inner sidewall attaches to the belly or roof of the tunnel? On a wooded build it is probably left square where in a fiberglass hull you will generally see a small radius, mainly as it is easier for glass to conform to a rounded edge in the mold, leaving less possibility for an air pocket or void that breaks later. A radius is stronger where a square makes more of a shear point.
Dynamically water gathered by the sidewall while turning accelerates vertically against the roof of the tunnel. Into a square corner it may give more lift than a beveled or radius corner. Would this be enough to make the boat roll over easier? probably not. At speed in a forward motion it only traps air. The important edges are on the bottom and transom or sponson rears.
Mic

[Chilli]

I was hoping you were going to chime in Mic. Thanks!

[viper1]

Assuming your talking about the point where the inner sidewall attaches to the belly or roof of the tunnel? On a wooded build it is probably left square where in a fiberglass hull you will generally see a small radius, mainly as it is easier for glass to conform to a rounded edge in the mold, leaving less possibility for an air pocket or void that breaks later. A radius is stronger where a square makes more of a shear point.
Dynamically water gathered by the sidewall while turning accelerates vertically against the roof of the tunnel. Into a square corner it may give more lift than a beveled or radius corner. Would this be enough to make the boat roll over easier? probably not. At speed in a forward motion it only traps air. The important edges are on the bottom and transom or sponson rears.
Mic

No I actually meant the bottom corners. For sport running, I don't think the top corners would make a huge difference unless I'm searching for that last 1/100 sec.
Assuming these are normally not in direct contact with the water.
But the bottom corners I am interested in, not for the speed difference but handling and the like. It is a fiberglass hull so there is a small radius as standard.
I noticed that some wood builds have the bottom sheeting actually overlap the insides, which brought up my question.

Thanks everyone for chiming in !

[viper1]

Update;

I sharpened the edges , marked by the red lines in the O.P.... and WOW I honestly never expected it to make such a HUGE difference!!
Thanks guys, cornering is more than twice as fast now, where she would formerly just 'roll over like a bitch in heat' I can do some turns with WOT!
No spin-outs anymore either with the correct steering dialed in.

Once I figured out how to get the ancient fire-wire working with the PC, I might even get my video of the camcorder and prove it

[kendt]

My rule of thumb is sharp edges and corners under water and rounded above. I find sharp edges ding and nick easier than rounded ones but under water you def want em sharp.

[viper1]

Once I figured out how to get the ancient fire-wire working with the PC, I might even get my video of the camcorder and prove it

Apparently the Firewire port on the camera side has died, so I ended up with only able to do analog capture but here goes:
Mostly 4s, near the end is one pass on 6s, just before the camcorder batt died.

[GLRE Raptor]

Wow great boat!

Sent from my Galaxy Nexus