Seen a few mentions of bonzers here and there, can anyone explain the functionality of a bonzer.

From having read a bit on thrusters, quads and twins I can't figure out why the 5 fins!!! or is it the design of the fins???

all you need to know
www.bonzer5.com

The official word is that the the fins along with the single to double concaves work on the venturi principle. forcing the water flow through a narrow opening creates speed.

Personally I don't buy into the theory, because the board creates the speed on a rail.

IMHO The speed comes from grabbing the wave energy from a big rail fin (with 18* of cant) then using the hold from the center fin to give the effect similar to a bar of wet soap being squished between your fingers, its projected forwards.

The reason for the 2 rail fins instead of one is simply that it makes it easier to turn while giving the same speed. (Same as a speed dialler Quad Vs Keel fish)

The deep concaves, which some bonzer designers say are unnecessary are there to allow the water pressure built up by the rail fins to release. What is also significant is the amount of V in the tail to loosen up the board. However this also limits the board to waves with a bit of push.


Again this is just my theory on Bonzers and not the official version.

Can a Bonzer therefore have just one fin on either rail (as long as it's large enough to create the drive)

Will leave the lads try and explain this one

Called a bumblebee

The original bonzers had 3 fins as posted in the picture above. I think Herbie has one. It's still a valid design and still produced. It is even more drivier but stiffer.

I think they call them light vehicles now and they use glassed Bamboo for the siderunners to get some flex going on

For the un-initiated, Why a bonzer over a thruster/quad etc. i.e what would the main differences be?

IMHO
longer smoother turns,
speed comes largely from good trim rather than but wiggling,
generaly more volume so higher wave count,

I have onle surfed my bonzer a handfull of times and I am not a great surfer but I am already blown away by the speed that can be taken out of a decent bottom turn.

That's it the speed that comes off the first bottom turn without really trying. The other thing you get with that speed is control. They are so solid at speed.

The bonzer fin setup works with any board shape not just high volume boards.

But it's used in high volume boards / wide tails because they are heavier and harder to pump as a thruster so a bonzer setup complements them.


On caveat is that they only show their colours in a good wave, not necessarily a big wave. you need some steepness to the face. In fat conditions the excessive cant and Vee just cause drag.In these conditions a quad with more neutral bottom contours is preferable and is definitely a more all around board, but it does not have that magic 5th gear.

now thats what im talking about

Ive had a lot of boards in my time and the sensation i got the first time i nailed a bottom turn on the bonzer was just awesome. I'm sitting here with a big grin on my face just thinking about it.
youre right about the drag though, no use in fatter waves.

Anyone want to explain this

looks like a mike eaton zinger

I suspect it has to do with Matt Calvani's experiments with to exaggerate the concaves so that the bump in the middle acts like a fin for hold and water bending but without the drag.

He is marketing his quad/bonzer mutant with this theory


Hard to tell from the angle, but it probably has a center box too

Good timing for this thread I'm just on the point of ordering one of Matt's designs..
http://www.bingsurf.com/surfboards.html#synchronizer

Want a board for the more powerful days and a travel board, I'm getting hacked off with travelling with mals!!

Anyone ridden one?

Andy