As a new shaper who is ambitious almost to the point of being retarded, I am thinking of a new challenge for my (hopfully) next set of boards. I have been so amazingly stoked with the results of my 6’8" 2+1 egg (it rides…like butter), I think I would like to make another one, this time (insert dramatic pause here)… A bonzer!
I know there is a lot of mystique surrounding bonzers, and I just hope that someone (or multiple someones) here will be willing to steer an earnest newbie in the right direction. This site has already been my primary source of information for board making (see my “mostly harmless” boards in the resources), and I hope you guys can be as helpful on this endeavor as you already have been through the archives.
So, the questions begin: The bottom concaves; how deep, how wide, where do they start, where do they end? The fins; where can I find glass-on front fins, or templates to make them; where can I find a template for placement, cant and toe; is there a “magic mysto element” to shaping and finning bonzers that is kept secret by the guild of the dark arts, or is it just proper placement of fins and concaves?
Triple concave designs are more subtle versions of bonzers.
They have their place Im sure…they will likely work best in good conditions
where water flow under the board is parallel to the stringer. In rail
to rail surfing where water flows mostly at angles across the bottom, a bonzer would
likely yield less than stellar results, perhaps worse. If bonzers were so amazingly better most guys would be riding them. Perhaps that why many guys prefer the more subtle triple C. The main benefit of concaves is lift not speed. For pure speed a flat or very shallow concave is hard to beat.
The film “SHELTER” has some bonzer surfing on a 4+1 fin board. The bonzer afficionados claim amazing speed and thats fine but many of those boards are single fins with training wheels and they will always have more line speed than a thruster which has to be pumped and driven. If you have a thruster, go surfing with only the center fin…amazing speed there too.
You should make one anyway if you can afford it…it will be a good learning experience and youll have fun shaping it.
But I really need a source for fin placement specifics… I really don’t want to glass on four fins just to find that I’ve placed them incorrectly…
And yeah, I’ve checked the archives, no luck there.
Anyone feel like pointing me in the right direction? You can message me if I’m asking for “top secret” info here. Hell, I’ll even tell you my secret of fuzz-free razorsharp posca pinlines in return!
Oh that’s right, you are in Texas, and can’t personally measure any bonzers!
My shop has over 600 boards in stock, and no bonzers…sorry.
You know, placement of the fins has to do with concave placement, rider placement, outline placement, and sizes and intent. There is no ONE way to make a good bonzer. Key is the concaves to redirect water out the back, to get the shoot out of hard turns.
The old bonzers were only about 3/8th inch deep concaves. I had 3 around the early '70’s.
No exact formula there. In surfing, almost EVERYTHING works, the rider can adapt, the waves change, and are constantly changing.
Your needs are for a wider than 22" wide board. That alone changes the equation.
Shwuz, the bonzer 5 fins set up (placement and cant angles) can be found be searching either here or at suffermag’s forum. The side fins are similar in size to wakeboard fins. You can get wakeboard templates off the net. Make them from Lexan (search archives). The concaves start about mid-board and run off the ends. Center channels are about a hand-width; you can start with those; set the fin marks along the outside edge; then run another channel between the fins. From the side each row of fins overlaps the next.
These boards are faster. Lift does translate into more speed. The redirected water (channels & fins working here) adds some additional thrust lost on most surfboards.
Level against the foremost fins; highest point was the stringer (level not touching board at rails).
Hard to see actual depth here (about 1/2"); level teetering even more on the stringer. Level at top of center box.
The more I think about these pics I realize there is a whole lot going on with the bottom and fins. Glad I didn’t fin it or sand it. More than happy just to ride this magic thing.
Tom@daum can help you with fins; templates, and fin layout.
How to measure fin cant with a very uneven bottom? Glass-ons are probably easier than boxes. I do love these Lokboxs though.
Malcomb Campbell drew us up an outline for five fin bonzer type placement. We make Malcomb's fin templates with the cant already in place for the side runners. If my attachment does not link, e-mail me and I'll send it to you.
Rolliges, thanks for the pics, those are great! Good view of contours and depth. so, are they deepest at the top of the fin box (second picture), and do they carry that depth off the end of the board, or do they go back to flat? How far towards the front of the board does the concave carry? is there a concave between each set of front fins too? Yours is a board I’d like to get my hands on for an afternoon, as the egg I’m going to make has a very similar design, just a little shorter at 6’8".
Thanks for the help all, I’m sure I’ll be back sooner than later with more questions.
Oh yeah, how does everyone cut concaves and keep them straight, even and symmetrical? I was thinking maybe gluing 60 grit to a section of really big diameter PVC pipe… Ideas?
The single concave starts way forward and blends to a double concave ahead of the side runners which transitions to vee in the tail from mid center fin back. The stringer is deeper than the rails as the double concave exits the tail.
I made a 7 foot hybrid thruster with a bonzer type concave a while back that works great. I basically shaped it as a flat to panel vee bottom, then shaped in two concaves about 5/16" of an inch deep on either side of the stringer, in between the fins, the last third of the bottom of the board. Kind of looks like the 70’s bonzer with thruster fins instead of the large fin/keel runners. The thing I like about this board is its versatility. I can use it in small gutless waves and juicy stuff too. I know youre probably thinking about the 5 fin version, but I just thought I’d mention my experience with you. Good luck with yours.
Thanks foamdust, that sounds like good way to do it, start with a panel vee… Now, what did you use to cut your concaves to get them equal and symmetrical?
anybody try the eaton zinger? (twin fin bonzer) i’m interested in making a 6’6 egg for 1-6’ surf. anyone familiar with the size and placement of fins. i’ve owned several 5 fin bonzers over the years and loved um but the twin fin bonzer sounds great for smaller waves. mahalo
I drew the lines out where I wanted the concaves to be placed. The inside edge of the concave was about 1/2" from the stringer that ran paralell with the stringer for that last third of the bottom (this left a spine so the board could bank off the vee). The outside edge of the concave was paralell with the position of the side fins, about 1/4" in from the fins. I didnt have a single concave feeder like the bonzer diagram. The concave started really subtle up front and got deeper toward the the tail. I put in a little bit more vee since some of the foam in the tail was shaped out with the concave, so the added vee kept the stringer higher than the rail for that rail to rail action that I desire in a board. I used a half round surform blade to start things out then a dowel wrapped with sand paper to finish the concave.
I finally got my blanks ordered, so I would like to resurrect this thread to ask a few more questions.
Foamdust, how deep a vee did you shape into this board before you cut the concaves? How far up did the vee start? Any chance you have a good picture of the finished tail?
Hell, I’ll even tell you my secret of fuzz-free razorsharp posca pinlines in return!
