Bill Thrailkill, you owe me a new surfboard

Well, I'm delighted that you had a good first session.       That setup always provides a more dramatic experience, if it is put into a board that the rider already has dialed in as a single, or other fin configuration.    That is when you really feel the changes in speed coming out of turns, and the crispness of cutbacks.   Your performance envelope just got bigger.    Always nice when that happens,eh?    And YES, the bucket will help you recover your prior performance level.

Aloha Mike,

Good to hear from you.     The board was built by Tyler, as a single fin, and I dropped the two extra boxes in some time after he had ridden it as a single.   I don't think I'd like to tackle a three box set, at one time.    Too much chance of a hiccup.   I also did a 2 + 1, glass ons in 1964.    It was interesting, but did not confir any advantages to the performance of a 9' 6'' 30 pound surfboard.   Too loose, by the then standards of performance.    I came up with this twin setup in 1970, though I didn't bother to put it into a board until 2000.    No one else had blundered onto the concept, so I put two more boxes into an existing board, and went surfing.   It changed a very good board, into an exceptional board.   Thank you for the kind words.

=

Tuna,

The first boards the setup was put into, are what people now define as '''hulls.''     In every instance, the performance of the board improved.     The fin setup WILL NOT make a poorly shaped/designed board perform beyond its design limitations.    It will however, allow a board to reach its potential.   In many instances a board is hampered by poor fin design, or improper fin placement.   

Hi Bill, I just rode my double fin for the second time. I can't really say if the board rides better or worse than it would as a single or a thruster. I can say that I haven't felt anything negative about the setup.

I don't have a leash on the board so I'm not really throwing it around. The waves have been small and slightly windy, and I've had fun riding the board. You might be right about the board gliding better and not bogging on the turns, but I'll have to ride it with a single to see the difference.

For those that have eyes to see and ears to hear.  Read Bill’s statement out loud and listen.  He’s given us all a piece of gold for free.

Gotta love that guy!

D.R.

Hi Mike,

I have attended 2 of Bill’s get-togethers so am familiar with the concept.  And do have this on my to do list…  always adding to the data base.  But, I’ve got a lot on my plate right now.

It’s an easy retro fit however I currently don’t have a Penetrator or any other board that I’m willing to retro fit right now.  I’m sure it will change performance characteristics. That said and me being me, I’ve got to test stuff at least for my own knowledge base before I make anything available.  

Speaking of fins. John Peck does have his own fin design available now; you may want to go with that on your board.

D.R.

Bill,

Do I remember right that you’ve used this set up with single foiled fins and the flat side out?

Considering will how long it takes to lay out and rout out two additional fin boxes, plus the risk if weekining the tail, it would be easier to fabricate a double fin that would fit into an existing single fin box.  There would be issues with respect to their connection, but with a little thought and some R and D it could be done. 

I'm not sure you could make a fin that would be strong enough without having some sort of bump where they are set into a single fin box.

I routed out all three fin boxes and set them all at one time. I have 1/4" strips of Balsa wood running perpendicular to the fins under the skins. The balsa attaches to the top and bottom skins for strength, and they go past the outside edge of the boxes. The 3 boxes were glued together once I set them in the board, so the whole thing ends up one solid block. Not sure, but I think that gives the boxes a bit more strength. I think you could route a couple of small holes all the way to the top glass on a PU board and get the boxes attached to the top, like FCS fins.

FYI... I ran into a guy at the beach named Carlos who said Dave Parmenter is his brother in law. He was very interested in the Compsand aspects and I explained how I made the board. I also told him that the guy who taught me how to make the compsand (CMP) did balsa skins on boards for Parmenter. Carlos has seen those boards. It will be interesting if he tells Dave about the fin setup and then Dave tries it.

soooo....looks interesting. Now would you be able to reduce your "normal" single fin size or use a differently raked/shaped fin? Or do you just slam another of the same on your tried and true original fin set up? Photos look like "normal sized" fins, but with all the drag and slightly offset center line placement, would reducing fin depth add or subtract from performance? It's not like you've added a second fin (like a front tri/twin/etc) set out on the rail where turning and pivot point seemingly would be effected by addition of another mate out there?

hmmm. any ideas or theory. I'm looking and thinking I'll give it a try (?), some of the info in the thread lends me to believe I most likely don't know much about fins in general but I'm open to trying most stuff a few times. Need a new longboard soon anyway.

thanks for the interesting mind diversion.

I took my 5'10" twin out again this weekend...

I caught 3 waves on Friday before the sun went down, and each one was perfect, glassy, and wide open.  I was absolutely flying... or at least it felt that way.  My 3rd wave was from the General's house all the way to Fred Kiko's white wave house which is nearly a football field in distance.  I was putting so much into that wave, that I felt like puking when I kicked out and laid back down to paddle out... When I got out of the water, my neighbor, Pat, yelled down from his balcony, "David, you looked like you were twenty years old again... nice job out there, kid!"  That made me feel like a million bucks.

Saturday, I surfed from 7am until 10:15am, and just couln't surf anymore.  I caught too many amazing lefts and rights.  My turns made me feel like I was just all style, but I know it was just the board, doing all the work for me.  I can't really describe the feeling...

Saturday evening, I surfed again for about 3 hours and just killed it.  I was just cranking the shit out of my bottom turns, and just flying back up the face and blowing the lip apart, and re-entereing the face, flying past the sections back up into the upper 3rd, cutting back, makeing sections into shallower water going top to bottom in seconds, just mind-blown at the performance aspects that this new fin setup has added to my "used-to-be-fish-template".  It is night and day (this template) ridden as a fish, quad, or twin.

I was too pooped to even paddle out on Sunday... my arms were noodles.

Thanks, Bill, for making me feel like 35 ain't so old afterall!

Afoaf,

If you, or any other attendees of the upcoming workshop in San Diego, would like to get an existing board routed for the twinfin setup, I'll bring  my equipment to do the routing.    Probably be able to do two, or possibly three boards.  The report of your experience has stirred quite a bit of interest in the setup.

I pulled up to a beach where a long board contest was going on a couple of years ago here in NZ.  There was an enthusiastic young shaper there with some boards with a very similar fin set up to this.  I think the fins might have been set a bit wider if I remember correctly.  He was raving about them and there were some guys competing on them.  At the time I just thought huh.  Might have to have a go at it on my next long board.

You got the wrong site.

The Gay Sway's is thru the San Francisco server or you can check the Sydney one too.

Hope that helps.

Got Mik?

...hello DS, may you explain a bit more how this set up can produce lift?

you say for the proximity that can produce kind of Venturi effect...

regarding this set up I just have been thinking in all type of things except in generating lift (to really have sense of that in the water in a notorius way)

thanks

Afoaf,

Bring the board, and the intended fin/fins.   10 1/2 inch, or 8 1/2 inch boxes?    Let me know.

Bill,

 I am interested in the set up and was wondering, does the dual setup decrease or increase a longboards nose riding performance?

  Thanks

Tony

Hey Bill, I think you're right............oh Fock it.

Maybe the box fins fetch more profit than the little tri's.......although nowdays everything seems over the top in this economy. I'm gonna make some of my own out of compressed cockroaches.

I have a 9'6" Parole that has a great deal of concave in the nose and bunch of rocker in the tail that rides pretty well at the points here in V-County.  Beach breaks are hit and miss, on bigger days I get pushed up alot and have a hard time dropping in when it get more than a foot or two over head.  That is the board I was considering trying it on. 

I have another diamond tail 6'3" x 21 x 3 that I was going to try it out on, but that one I have not even hot coated yet.  Have either of you done they dual set up with a smaller bitter plug or box in the middle for use with a twin or quad? If I have my way this board would be a 7 fin monster.  But that maybe me getting a little over ambitious.

What is the spacing between the boxes? Butt them up or space them alittle bit?

Thanks for the input

Mike,

The first single foiled fins I did for the twin set-up, were in the 6 1/2 inch range.  They worked fine, but I found that my personal preference is a pair of

7 5/8th inch ''Brewer'' fins.     I think the set-up you describe, above, would work just fine.     I set the fins on two inch centers.   One inch on either side of the

centerline of the board.    Fin size selection is a subjective thing, though too small or too large for a given board, will be readily apparent.    In general,

any size fin that works as a single in the chosen position, will work better paired.