Hey Cheyne
Ben was a classic I new him in perth when he was known as Bob Miller
and I was involved with him while sailmaking in Perth in the early AC days
If you got in at the end of the day and things were still in one piece he would drill holes in them to make them lighter
He would say If it didnt break it must be too heavy!!
Regards Mike
I’m new at this forum, so pardon my interupting the flow that you have going. I’d like to get your opinions on the included sketches. I’ve been following this thread for a couple of weeks now and am blown away by the sharing of knowledge that is going on. My 17 year old son is a talented beginning shaper. Thanks!
Wow. I’m almost as impressed with the drawing as I am of the concept. Without the top hoop, it reminds me of a canard quad but with high aspect ratio fins. Seems like it would have similar characteristics as the supercharger setup, which seem to have been quite positive.
Seems they would need to be made of carbon though so as not to be too flexy, that and it would probably take a few tries to get that shape foiled right. Please build them and let us know how they go.
Thanks for getting this thread pointed in the right direction again.
Good start from scratch design idea. There is, however, prior art on this concept. Greg Loehr’s slotted fin. That should indicate to your son that there is merit to his idea. I dont have one, and as far as I know Greg’s only personal sample is in the hands of True Ames/O’fish’l but perhaps Lawless has or has access to a picture. I’ve seen the actual fin and I saw it discussed on either Barrier Island Graphics or 2nd light forums (both CFL sites) within the last 6-8 months. You might try looking there. Once you see it and have a chance to think about it I think you will see the advantages.
But dont stop there. Inventors mantra: If at first we dont succeed…
Good start from scratch design idea. There is, however, prior art on this concept. Greg Loehr’s slotted fin. That should indicate to your son that there is merit to his idea. I dont have one, and as far as I know Greg’s only personal sample is in the hands of True Ames/O’fish’l but perhaps Lawless has or has access to a picture. I’ve seen the actual fin and I saw it discussed on either Barrier Island Graphics or 2nd light forums (both CFL sites) within the last 6-8 months. You might try looking there. I believe Rainbow made about 200 of them a few years ago so they are around. Once you see it and have a chance to think about it I think you will see the advantages. Slot effect, two separate fin foils with one tip vortex etc…
But dont stop there. Inventors mantra: If at first we dont succeed…
Wow, if that one came down to strike me from on high, I would ride it…
Quick question, I notice the loop runs from inboard to outboard as you move toward the tail, have you considered reversing it so that the forward upright is outside? that way, the footprint would be similar to the fwd fins on a bonzer-5, and the uprights would be a similar distance from the rail…
Oh, goody, if these things catch on, there will be a third dimension of fin placement to consider: toe-in, cant, and now pitch!
The loop rail fins look like a glass-on unless you put a combination of fin boxes in that will suit the fins. You’d have to have a special jig to do that with. And then there’s foiling them. No small task! Good luck.
Mahalo, Rich
Back to the subject of dimples.
Morey Boogie with dimples.
OK, I’m browsing through the next issue of Scientific American and there’s a whale fin sticking up out of the water. Thanks to Swaylocks I start looking for hydrodynamic efficiencies and how it’s applicable to surfboard fins. It’s got a cutaway base as had been discussed, but the most striking feature is the knobs along the leading and trailing edges. Big knobs. Hey why not? Why does the leading edge need to be smooth?
Turns out the article does deal with aerodynamics and what “wing makers” can learn from the whale fin. Will read in on the way home.
Not the best pic but you can see some features.
Another good application for the small foot print of Red X.
Wells - Could you post a picture of the Bonzer-5 please (or someone)?
Thanks for the feedback!
Halcyon - I was hoping you would see the other fin idea and comment...
The variable rake fin??
Several fighter jets (MIGs, F18s) have variable rake wings, more rake at higher speeds.
Of the two ideas, I think the other has more merit and will be much easier to prototype. And, I at least would find it easier to do one new thing at a time.
Hey Daddio,
By the other fin I suspect you’re referring to the tuck-in fin.
It looks like a spring loaded affair. A completely different mecanical approach but none the less reminiscent of Blakestade’s rotating fin design because of the fact that water pressure either is or could be the energizing force in changing the fin attitude. It is, no matter how you cut it, a mechanical approach to performance and a valid one IMHO.
The beautiful thing about this approach to fin performance is that it imitates nature. To the careful observer of tuna swimming adjustment of rake along to the tucking away of fins are both apparent techniques used to enhance speed and directional control. The trouble for the surfer is the adjustment of these fin attitudes can’t be pluged directly into the brain of the ship like it’s done inside the tuna or with our the best imitations, those being stealth fighters and the new super fighter/bomber that Lockeed is building.
Where’s the government funding when you need it?
Mahalo, Rich
Did you see the other sketch?
This fin would tuck-in as speed increases changing from an upright swept to low profile keel
Or picture that you run over kelp…
Thanks for the reply - I guess I was posting as you were also!
Disregard - what looks like impatience…
Your two side fins in the first drawing have a horizontal control surface component which will have to be considered when predicting the likely behaviour of the complete setup.
Regards, Roy