Jim Neece : Duncan and Malcom
Cambell's Bonzer, 1973. Jim Neece : The Bonzer. Surfer
Volume 14 Number 3 September 1973.
Original design 1973 by
Campbell brothers (USA) characterised by forward concave
leading to double concave each side of the centre fin with two
keel- type fins set on the rails (radically toed-in and
Bottom design based on the shape of
Rigalto hang gliders. Bonzer :Australian
expression for excellent, occasionally spelt Bonza.
The design quickly spread across
the Pacific and to several Australian exponents including
Peter Townend (Gordon and Smith Surfboards) and Terry
Richardson (Skipp Surfboards).
Preceeded by the Tri-fin 1971,
Influence on the Thruster 1981,
Adaptation 1988, the Phazer.
By Two Surfers in Search of Speed
A bit, perhaps.
The possibilities are intriguing.
The word "Bonzer" is Aussie slang which
translates into something like bitchen, fantastic
That's the tag that Malcolm and Duncan Campbell,
two surfers from Oxnard,
California, put on their new idea a couple of
Their dad is an avid sailor and very much into
His main interest was speed, and he encouraged
his sons to come up with something different on
Something to allow them to go a little faster, to
work better in general.
They started out with two side fins
mounted just ahead of the center fin, thinking it might
increase speed, and sure enough it did.
Then they started tuning the fin shapes and positions,
and over the course of a year or so, worked them into the
present size and attitude.
Everytime they went through a series of changes, they
MALCOLM: "We got the fin positions down just about to where
we have them now, canted in towards the nose of the board
about seven degrees before we had any concave, so then we
began looking for a way to create even more speed.
And so we were looking through some books that my dad has on hydrodynamics.
We were looking for a way to channel the water."
DUNCAN: "And detour the water
away from turbulence."
MALCOLM: "To keep the turbulence away from the fins.
So, as a result of our research, we decided to add a double
concave area in the tail to help channel the water off and
increase the total effect.
Most of the turbulence occurred behind the trailing edge of
And so what we did with our fins and channels was to detour
the water away from that area behind the center fin while
altering the shape of the center fin (straighter trailing
edge) to further reduce drag." DUNCAN: "It forms a venturi."
MALCOLM: "The concaves added a lot of speed, and they made
the riding characteristics much smoother."
MIKE EATON: "An idea that occurred to me was that they're
channeling the water through the fin area, right?
So if you can start channeling the water right away, the
effect is just amplified."
BING: "Like if the water escapes off the side of the board,
you're not making use of that water at all.
If you can make it
"You've never seen a gimmick go so fast." - Jim Neese
(If you can make it) go all the
way down the bottom and out the tail, you really reduce the
EATON: "Like when you're planing on the water, you're
pushing water out from under the board in all different
directions, so if you put a channel or a concave through
the bottom of the board, this gives the water another
direction to escape to; instead of escaping off the side of
the board, it would tend to run down this channel, so when
it gets into this channel, the surrounding water tends to
throw it out the back, instead of just escaping out the side
and dissipating itself.
So if you can get it flowing out the back end of the board,
it's actually pushing you.
And you can feel it. Listen, when they first brought this
in, my reaction was, oh wow, here we go again, and I didn't
make one for myself for a while.
But the minute I got on it, you could feel the difference.
They paddle easy, and they get into a wave real easy, and
the minute they get into a wave, you can feel it.
They just go whoossh.
It's like a similar thing with those planing boats that have
strakes on their bottom, you know.
The water that normally just goes up into the bow wake, what
they've done with those boats is to put those strakes in
there so that the water that's going out in a big sheet is
deflected back and under, and is actually giving them
MALCOLM: "That's something right there.
Okay, now you've got your speed, for straight out speed,
that's something we've already discussed, but when you drop
in and you're going for a bottom turn, you've constantly got
a vertical fin in the water (Malcolm pointing to one of the
canted runners, points out that when the board is on edge,
the fin actually has a more or less vertical attitude to the
face of the wave).
That fin gives you added control through a turn, so there's
Then you've got water coming across the bottom of the board.
Now on a single fin, all that water that's traveling across
the board is just escaping off the outer edge.
That water's wasted, but on the Bonzer, the water comes
across, strikes the outside runner, and is deflected down
and back through the channel, and that water that's
deflected back gives you an increase in acceleration.
And with your inside runner canted towards the nose, it
automatically has a tendency to turn your board in towards
the face of the wave, or to pinch it in and up.
So it has a tendency to pull your turn even tighter; and
added to that is the force of the water against your outside
runner which allows you to put more pressure on your inside
EATON: "Of course, if those fins aren't put on right, you'll
just track out in a straight line."
MALCOLM: "That's right, that's what happens.
"Bernuli's Principle: the lateral pressure is inversely
proportional to the square of the velocity," or in lay
terms, "the faster a fluid flows through a restricted area,
the lesser the pressure."
A venturi: works like the nozzle of a garden hose.
DUNCAN: "Actually the water is leaving the board at a higher
speed than it encountered the board at."
MALCOLM: "That's right.
You see, the faster a board's going, the looser it is.
Like you can be running on slow water, but you have faster
water moving between your fins.
And, of course, the runners help; in fact, I think they're
really the main factor."
The Bonzer boys say that you would ride a
plan-shaped board similar to what you might be liking now.
MALCOLM: "It still just really depends on what kind of shape
You wouldn't change the outline shape in consideration to
this bottom except that you might not have as narrow a tail.
The wider the tail, the more planing area you have, and thus
Like a kneeboard with a 15-nch tail goes extremely fast."
EATON: "It seems that they're so positive that you can ride
a wider tail.
The only reason you ride a narrow tail is that you need the
control on a big wave.
You pull the tail in to keep the fin in the water, but on
these boards they're real positive anyway, so you can widen
them up, and you can get more punch out of them because you
have more planing area right under the area in which you're
punching your turn."
As far as performance is concerned, those that have had a
chance to ride a Bonzer have been stoked.
Mike Eaton took one to Hawaii this summer and tells the
EATON: "Well, I went over there on May 2, and there wasn't a
whole lot of surf.
I took a little Bonzer over with me- it was 6'6" and about
I figured we'd get some maybe three- or four-foot surf and
try it out, but Sunset came up one day, I mean nothing else
had broken, but Sunset came up on this afternoon, and I
paddled out, and the whole time I was paddling out I was
looking at this board I was on thinking, what am I doing?
And I got out there, not really expecting it to work, and I
took off on a wave, and it ran down the face- it was hard to
get into waves because the board was so small - but it went
down the face with real nice control, real positive, and it
had a lot of speed; you could really feel it over there.
It was really
apparent; you could really feel the difference. I rode a couple of
waves, went over the falls on one because I had
trouble getting into them, but I was really stoked,
so I went up to Jeff's (Hakman) house and pumped
him, because he was pretty skeptical.
Anyway, I got him on the board the next day and let
him paddle out before I hit the water.
I had his board, and he got all the way out before I
hit the water.
I didn't want to give him a chance to renege
And it was good eight-foot, clean, spring Sunset. That's an Island
eight foot, of course.
And he took off on one wave, and mind you I had his
board, his 7'4", so he could get it back if he
And he took off on this one wave, and when he
paddled back out, I said, hey, what do you think?
And he just looked at me, and really didn't say much
And he took off on another wave, and this just kept
going on and on.
He didn't really know what to say, but he was really
I mean I was out in the back, and so I really
couldn't see except that he was getting in the waves
late because the board was really so small.
And pretty soon, guys were paddling out, going,
'what is that thing?'
It's like Bruce Webb came out and said, I can see
why Jeff really likes that African board.'
Jeff had a board similar size and clear that he had
made in Africa that he had really liked.
And I said no that's a Bonzer.
And other guys came out and said
Jeff was going really fast.
Anyway, we were out for two-and-a-half hours and he never
asked for his board back.
And finally I went in with his board; he was still out
there, and I watched from the beach for a while.
He was getting in late, really hitting turns hard, like he
does, on this real wide 14" tail, 6'6" board, and just
hitting his turns really hard and getting a lot of drive
out of the turns, and right up into the lip with the wave
going over him and going extremely fast.
It was amazing on such a little board.
Anyway, he finally came in, and he was pretty impressed with
Now that particular board is pretty parallel.
It doesn't really suit his style of surfing, arcy, you know,
it's more of a trimmer.
You know a lot of the same things that influence regular
boards work the same on these.
But they're really good for nose riding, which is what that
one was made for.
You could actually turn it up on the nose.
Anyway, Jeff wanted one after that."
Even though Malcolm and Duncan's Bonzer theory seems
practical on paper, they have encountered the usual
skeptical response from many surfers who just can't accept
that a board that weird looking can work better.
MALCOLM "We've been messing around with this for three
years, and people up by where we live have been looking at
them and saying, well that's a joke.
But as soon as word got out that Bing was even considering
producing them, everybody went, wow!
That must be a good idea.
Everyone's first reaction is usually, well, it sure looks
like a lot of drag; the more you put back there, the more
drag you're gonna get.
They've been seeing them work everyday, and they still were
thinking there's no way they can work.
We were afraid that the percentage of favorable responses
wouldn't be that good, because up where we live, people that
hadn't tried them were so down on them that we got kind of a
complex about the thing."
DUNCAN: "How many have we sold?
Twenty-five, thirty, justto people that live around where we live, and everyone
of them are stoked.
There isn't one person that ever wants to ride a single fin
again." The general qualities of the Bonzer are speed,
looseness and positive control.
And although the combination of those qualities seems
contradictory, feedback from those riding them now tends to
support the claim.
BING: "We sent a Bonzer back to Claudie, and his wife was
having a baby at the time, and so he couldn't get right on
the board, so he gave it to Dickie Munson, and Dickie took
it up to Hatteras, and just called me and said that the
board worked well." EATON: "And he called without being
propagandized or anyone talking to him or telling him about
the qualities of the board, or anything.
It was just a cold shot.
He got the board, didn't know much about it, took it up,
rode it, and was stoked enough to call us." BING: "The one thing that I've noticed most in
the comments that I've gotten from the guys who have tried
them have been cutbacks.
Everyone says, wow, they cut back, they cut back." DUNCAN: "It sounds far out, but you actually
gain speed out of your cutbacks.
You can be drifting out into the flat and hit your cutback,
and you'll actually gain speed, because you're racing the
water faster through the tail section and it actually gives
you acceleration." MALCOLM: "The main thing has been that anyone
that's ridden a Bonzer for any length of time has not wanted
to go back to a single fin."
But again, as in all new surfboard ideas, the proof of the
Bonzer's true functional value will come from a wide range
of surfers trying them over a period of time in varying
One thing's for sure, the Bonzer is definitely worth looking
The BONZER breaks
thru into a new dimension of speed and high
performance, based on the proven physics of the
The venturi bottom contour of the BONZER shape draws
energy from the water flow off your board,
decreasing drag while increasing acceleration and
The BONZER is remarkably loose, yet positive; it
squirts out of cutbacks.
No spin-outs even in the steepest situations.
After three years of basic testing and refinement,
and after three months of fine-tuning both in the
shaping room and in the water, the BONZER is ready.
Malcolm Campbell carves a Bonzer track.
It will be the most exciting surfboard
you've ever owned.
Finely crafted by Bing.
Don't get stuck with one
fin in one place! Tim Lynch, Gordon and
Smith Surfboards (detail) Fins Unlimited, Encinitas,
TW Systems: Dale Dobson and
Dave Sagraves of Walden Surfboards
Volume 14 Number 3
Cover: Buzzy Kerbox, Velzyland
Photo: Steve Wilkings