I’ve used one of the 'mental’fins in a single fin I made about 12 years ago. Rich made it custom for me after seeing the board at a sways campout. When comparing fins I like a wider based fin with a more traditional configuration. The mental fin stiffened the board. I still have it because it is a unique and beautiful fin made by a local fin foiler. Mike
Mike, I felt I was surfing the shaped hull more than the fin configuration. Fins are a dominant force but with the smaller based fin shape the water flow ran more evenly across the contours of the hull.
The interesting concept from Berts comments is any part of a fin shape can be reduced or moved yet still create a similar or better performance. Including the base.
Goden Era
Brett wrote:
“You can’t beat a 41 page thread about fin design from 2004.
I love the early polite discussion about cutaway bases from Bert, Tom, Kokua…”
“it’s full of great ideas and such politeness, which is why I signed up here, people sharing what they know and it goes on evolving.”
The golden era of Sways.
Hail Atlantis…
Most likely the Golden Days of Sways were a product of that moment in time and the assembled cast.
More Halcyon fins…
Can you see what I see ?
Not the girls ass in the background but the concave behind the foil apex ?
I’m still producing a few fins.
The latest are 70/30 glass-ons for a twin fin custom.
Thoughts: There are so many variables when it comes to fin application
to surfboard design. I do like it best when I can discuss the options
with both the shaper and the the surfer and come up with something
that really lights up the board. It’s not uncommon for a fin of any given
template to be miss-sized for a given board. I.E. a 7.5 inch “Mental”
will feel very different from a 7.75 inch mental. A 5% fin area difference
along with relative fore and aft fin placement can be the make or
brake difference in fin performance.
Regarding cutaways on the fin base I have to say that
it’s been my experience that one doesn’t get the low speed drive
from this type of fin configuration that a full based fin gives,
but I do believe that it trims faster and when a proper
template/board combination is applied and the
the pieces or pieces foiled well a very versatile combination
can be achieved.
I will take some photos of what I’ve been surfing later this
week and submit them on this thread.
Stay Stoked, Rich
P.S. Bert knows his stuff ~~ BIG-TIME
give plenty of high speed drive and directional stability
Here’s the fin Les Waddel (tridrles) gave me.
Rich, what do mean by low speed drive? I used to use a 9" cutaway fin on my 8’ eggs, then I put it in a 8’ semi gun and it didn’t work at all. I switched to 9" Greenough 4A and it was better, but I later added side bites and that really woke it up. This was riding in just overhead to 1.5 OH waves on the south shore of Oahu, Hawaii.
Rich has developed herpes hanging out in Stretches rooms 
Black Hole Out !
Sharkcountry, That’s a great fin , I wonder how far the minimal base concept could go ?
Halcyon, what made you think of chasing potential performance when it’s outside the basic dorsal shape ?
Certainly there’s a. strength limit to using fibreglass but with some imagination the foiled section could be raised on Aluminium / stainless / Titanium posts. I think that’s what was great about the Golden Years, it was all open for experimentation and discussion.
Bert has two other ideas on Page 1, concave inside foils and asymmetrical leading edges.
Hey Greg,
Send me some G10 dust. I hear it’s excellent for herpes.
Maybe an occasional sip of super-sap will help. I try some
next time I’m over at Bill’s digs.
UUUUUUUGGGGGGG!
Frankly it’s hard to stay away from Stretch’s factory for more than a couple weeks.
He always has some great projects going. He’s total master of the craft and has
the most progressive set-up and employs doing epoxy work in the 48.
Stay Stoked. Rich
I’ve been watching nature all my life.
Millions of years of evolution have produced shapes that use of fluid dynamics effectively on lot’s of beasts.
Looking at a tern, an owl, a dolphin, or a mako gives one some real perspective about how to manage movement
through fluid effectively.
Interpreting these shapes into ideas to fins is certainly somewhat intuitive.
I some ways it’s like writing poetry.
Stay Stoked, Rich
Thoughts:
Some boards are big tme dogs with a cutaway on them. They’re simply not configured to perform without
fin-base engagement. So it seems you’ve discovered that your board needs fins on the rails and a center
that gives good directional stability in the center.
The variables in board/fin performance go on infinitum.
I have some boards that want a 2+1 set-up to do well. They’re adequate with a single,
but to really get them to perform well they need a center that’s sized down a little
and some moderate sized side bites.
I like fins that have a little snap to them as well. Fins that are completely rigid wash
during the turning moment. For surfs like to break the tail lose this is good. For those
that like to have fins more engaged though the turns a measured amount of flex serves well.
Stay Stoked, Rich
doing my best to apply some of the double cutaway style to fin set of twins im doing up from scrap ply i got out the bin at work.
donw all the foiling by hand so far but i have the sander at work today so i will smash the other one and finish the foiling of this one.
but what do you think of the double concave of the rear foil so far?
first time ever making a fin and they will be a glass on set.
Not sure we can see both sides of the fin.
Hard to see contours you’ve foiled.
I think the template will work nicely.
Cheers, Rich
The inside is just flat my first effort for now and that’s gunna be it for the his set…
This is as good as they are gunna get.
Hi sk8ment. If you can find some high quality cabinet grade plywood you can get some really nice foils. I get poplar ply from the scrap heap of my buddies cabinet shop. The wife finally got your stuff in the mail yesterday. Sorry for the hold-up. Both of us are busy working and the post office hours don’t match up so well with people who work.
I wonder if the cut away fins flex too much at the base and not the tips. The cut away fins I have used have not performed as well for me as fins with a wide base. I’m not a fan of flex, in general. Perhaps in very small waves. Waste-chest high. I’m not a high performance guy. Just an aging soul 70’s down the line surfer.
I’m a fan of halcyon’s whole trip! Had a set of keel fins of his gifted to me from Greg Tate. My all-time favorite keel fins. Make me some more, Rich? Mike
Yo rooster post a pic.
Looks great Sk8. Nice foiling.
Are you glassing on or doing a box conversion ?
Hey Rich. Can’t post a pick. I was hauling some junk to the dump and set the board down to unload. Drove off without the board. Realized my stupidity 15 minutes later, turned around and headed back to the dump, asked around and got the “what board?” comment. Sucked.