AN UNCLE JAFFA FIN EXPERIMENT

[Roy Stewart]

Too many words, not enough on the visual front.

[jaffa1949]

Old fins C drives as side bites, held the line I chose and released for turns happy with the results in Mentawai proving grounds
Happy with the the Bonzers today similar size to the pictures, at my home break but unfortunately unlike Roy I do not have 12 children to help with a video.

The bar is also a little to far from shore for good shooting, no excuse, I'll have get around that and get video shots done. Kudos Roy for posting your videos, they do allow us to share the wooden incarnations performance.

My mission will be to achieve shots of the success or otherwise of the bonzer fin experiment.

[Roy Stewart]

[Katsura]

Got a real buzz out of that, thanks

Now I know how my 60,000 female working slaves get around.
I'm an apiarist! In my own garden!

But that would make you a QUEEN, surely? I jest

[jaffa1949]

Got a real buzz out of that, thanks

Now I know how my 60,000 female working slaves get around.
I'm an apiarist! In my own garden!

But that would make you a QUEEN, surely? I jest

Thanks Honey

[themathteacher]

Regardless, I am sure the concave bottoms are very fast anyway but for different reasons.

So, my shaper told me that one those other reasons to have a slight concave on the bottom of the board is that when you turn the board bends, under stress, it bows ever so slightly. By having a concave (or double) it ends up being flat or slightly less concave, which is better than it ending up curved and producing drag. In other words, the concave straightens under stress making the board glide easier than if the concave was not there. I don't know of the actuall stress points of fiberglass to know if it is true or not, but he says it works that way.

He also concurrs with the venturi effect theory, but the above I found fascinating, true or not.

[Roy Stewart]

Tell him he's dreaming !

[esonscar]

^^ What Roy says [you ever seen a concave sea creature?]. I'll do the physics if you’d like but you ain’t got the years to learn this stuff so go surf a nice non concave / slight concave and enjoy - it'll be the same outcome - you'll be surfing

[jaffa1949]

Hi Esonscar, you've come back with a large load of posts. Welcome back!
Don't worry about the maths, did that with my uni degrees, way back, the basis of my "surf science" opinions is experiential , if what ever I shape or have shaped , either works or it goes elsewhere.
What is currently working very well for me is what I describe above. been now up to about double overhead and it hasn't show characteristics I don't like!
This my 54th year surfing having gone from hollow ply toothpick surf club boards through balsa (which I loved) down through the short board "revolution" and back through to modern long boards, which if they are any good, have borrowed and evolved heavily from the logs of the past.

I don't understand false retro boards as they often represent surfing evolutionary dead end and IMO they are a bit like Jurassic park resurrections.
In the end it is all only one opinion in the range of surfing, correct answer is if you are out there having fun and your equipment allows you to surf as you wish then that's the end of any debate.

BTW i have seen a sea creature go concave, there are videos of the ventral aspect of a dolphin at high speed being compressed to twin concaves, but on mentioning that that may be more about flexibility of skin to high speed water movement rather than a physical adaptation?