Author Topic: Ventral Fin and fin tests  (Read 10485 times)

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #60 on: September 22, 2016, 05:48:21 PM »
Hey Bill,
you almost need a table of definitions of the fins and an Excel spreadsheet with the combination and results.

So your latest results look like:
Larger surface blade => larger surface central/kick fin
Smaller surface blade => Smaller surface central/kick fin

My fins and boxes should be arriving hopefully this week and I should have the board retrofitted the first week of October. I can then test with both the Mana 82 and Mana 90 (same blade shape, different surface) but I will need to borrow a small kick fin from the friend I sold my previous board to. Curious to see if this also apply to a weaker and lighter paddler.

Cheers,

Luc



If I was going to theorize, it would be that the Mana, catching way out front, is torquing the board more, and needs the bigger kick fin. The Konihi pulls steady and straight so it doesn't torques as much. At least that's my story for this afternoon. I think I'm learning a lot, I'm just not sure what.



YEAH BILL,  You are Not Theorizing, You are EXACTLY right now you are talking Sup fin Language. Right ONNNNNNNNNNNN!!!!!!!!!!!!

Luc Benac

  • Teahupoo Status
  • ******
  • Posts: 1157
  • Super Natural British Columbia
    • View Profile
    • When not paddling...
    • Email
Re: Ventral Fin and fin tests
« Reply #61 on: September 22, 2016, 06:11:02 PM »
Actually I think it's more a matter of the catch differences in the Mana vs Konihi, though at this point any explanation will work for me. For me, the Mana catches big right away, and then softens up a little as I pull it. The Konihi catches softer, but pulls hard all the way to the end of the stroke. the Konihi also pulls straighter, no draws allowed, it just won't do it, and I have to push the Konihi deep--good for the Puakea stroke--or it gurgles.If I was going to theorize, it would be that the Mana, catching way out front, is torquing the board more, and needs the bigger kick fin. The Konihi pulls steady and straight so it doesn't torques as much. At least that's my story for this afternoon. I think I'm learning a lot, I'm just not sure what.
Fortunately I just stumbled on a cache of two Larry Allison ventral fins that I have for my Speedboard. One bigger than the one I have, and one smaller. They aren't the click-in fins, they have a normal fin screw, but they'll be great for further testing. I'd go out now but the wind is up a bit.

Works for me. After paddling exclusively the Konihi 84 for a season, I still bury the Mana just like the Konihi...
Cool that you have now all three sizes of ventral which might end-up kick fins actually.

Cheers,
Luc
Infinity Whiplash - 14' x 25" 262L
Ace-GT - 17'4" x 27" 313L
Bark Vapor - 14' x 26" 271L

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #62 on: October 03, 2016, 12:49:37 PM »
Nice to see the other side of the world follows me and understands Allison multiple fin combos like this that popped up on my facebook this morning.

Quote from facebook:

Sup Race Fins
31 mins Edited
 
CROSSWATER Running Allison Ventral Fin combo in Sweden
Like This Page
Henrik Friberg shared a photo to your Timeline.
1 hr
Waveriding a 12'6" raceboard with a ventral here in Sweden works great. Probably works great in the rest of the world too :)
Ulrik Kursten med ventralfena.

Bean

  • Cortez Bank Status
  • *****
  • Posts: 2978
    • View Profile
Re: Ventral Fin and fin tests
« Reply #63 on: October 03, 2016, 01:10:38 PM »
That is a pretty awesome shot!

Larry, has anyone done a ventral fin using a ProBox instead of a traditional single fin box?  Does the ventral fin-tab need to be longer than a ProBox?

BWilliam

  • Sunset Status
  • ****
  • Posts: 288
    • View Profile
    • Mongrel Combative Arts
    • Email
Re: Ventral Fin and fin tests
« Reply #64 on: October 03, 2016, 01:18:23 PM »
New wallpaper!!  8)




Will

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #65 on: October 03, 2016, 01:36:50 PM »
That is a pretty awesome shot!

Larry, has anyone done a ventral fin using a ProBox instead of a traditional single fin box?  Does the ventral fin-tab need to be longer than a ProBox?

Yes Bean Thomas Max of Future tried using this set up for a Ventral which failed the performance test and they stopped in 2012. The base on my small Ventral is 7 inches long. You could use a Probox but the lateral torque will give you less  lateral resistance and the foil section of the Probox verison would be to thin which also plays a role in performance of the Allison Ventral.
« Last Edit: October 03, 2016, 01:42:20 PM by ProBox-Larry »

stoneaxe

  • Cortez Bank Status
  • *****
  • Posts: 11114
    • View Profile
    • Cape Cod Bay Challenge
Re: Ventral Fin and fin tests
« Reply #66 on: October 03, 2016, 06:25:11 PM »
Be ready Larry....I'm going to ask Patrick to talk to you about fin placement on my new unlimited......you guys will be talking for hours. I'm getting cauliflower ear just thinking about it..... :) 8)
Bob

8-4 Vec, 9-0 SouthCounty, 9-8 Starboard, 10-4 Foote Triton, 10-6 C4, 12-6 Starboard, 14-0 Vec (babysitting the 18-0 Speedboard) Ke Nalu Molokai, Ke Nalu Maliko, Ke Nalu Wiki Ke Nalu Konihi

Bean

  • Cortez Bank Status
  • *****
  • Posts: 2978
    • View Profile
Re: Ventral Fin and fin tests
« Reply #67 on: October 03, 2016, 08:03:25 PM »
That is a pretty awesome shot!

Larry, has anyone done a ventral fin using a ProBox instead of a traditional single fin box?  Does the ventral fin-tab need to be longer than a ProBox?

Yes Bean Thomas Max of Future tried using this set up for a Ventral which failed the performance test and they stopped in 2012. The base on my small Ventral is 7 inches long. You could use a Probox but the lateral torque will give you less  lateral resistance and the foil section of the Probox verison would be to thin which also plays a role in performance of the Allison Ventral.

Rats!  I suppose a carbon fiber fin would be too stiff...but what about a hybrid CF fin tab and base with a FG blade?

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #68 on: October 04, 2016, 08:59:03 AM »
More pics show up from PPG showing Ventral and Allison Probox Twins in the Elite Race. Kristin Thomas for Infinity here in these pics.
« Last Edit: October 04, 2016, 09:03:03 AM by ProBox-Larry »

PonoBill

  • Cortez Bank Status
  • *****
  • Posts: 20431
    • View Profile
    • Ponohouse is for sale. Great house but it's time for new adventures
Re: Ventral Fin and fin tests
« Reply #69 on: October 04, 2016, 10:00:10 AM »
I did find that pounding my ventral fin into the cobble on my clumsy PPG dismount didn't do the fin box much good--it sprung a leak even though I glassed under it. I guess that's a bit too much to ask of an ounce of carbon and glass.
Ponohouse is for sale: http://www.ponohouse.com
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #70 on: October 04, 2016, 10:24:47 AM »
I did find that pounding my ventral fin into the cobble on my clumsy PPG dismount didn't do the fin box much good--it sprung a leak even though I glassed under it. I guess that's a bit too much to ask of an ounce of carbon and glass.

Ponobill, You are lucky with a leak my friend. Because some of the boards I seen that hit the beach were done period. Great seeing you on the party video Dave Boehne was doing for Supthemag. , but missed you at the beach. Got to give you thumbs up for doing that event conditions were crazy.

ProBox-Larry

  • Site Sponsor
  • Peahi Status
  • *****
  • Posts: 893
    • View Profile
    • http://www.allisonsupracefins.com/
Re: Ventral Fin and fin tests
« Reply #71 on: October 04, 2016, 01:40:18 PM »
Larry W. Allison
16 mins
View on Instagram
Glad to see after this last weekend at Pacific Paddle Games people are realizing and understanding the need of having a Allison Ventral assist added to their 3 fin combo. Super excited to see major board companies like @infinity_sup leading the charge using Allison 4 Fin Race Combo and now Starboard in Testing mode. Super excited to see companies in 2017 moving into the next level of evolution in the Sup world using Allison Probox 4 Fin Race combos. Think super hard when buying your next board, that it comes with the Allison Race Combo to give you all the options to enjoy your paddleboarding experience. Tell them Larry sent you.#twinstowin,#sup,#suprace,#supracefins,#paddleboarding,#standuppaddle

ukgm

  • Peahi Status
  • *****
  • Posts: 680
    • View Profile
    • Email
Re: Ventral Fin and fin tests
« Reply #72 on: October 12, 2017, 01:37:05 AM »
No, I didn't plug it. The side fins are toed a little, according to my laser the intersection point of the toe is about six feet in front of the nose of the board (about 19' total), so pretty small. I'd convert to degrees, but who cares other than my old trigonometry teacher, who is probably safely dead.

I'm finding this very odd. I think your explanation might be on the money DW, which leads me to wonder how small the fin can be and still get the same result. I'm pretty certain that bigger fins are slower for me (stronger paddlers might not have the same result), but will smaller be faster. I think all the work of making the board track and resisting the torque is being done by the nubs, and the middle fin might just be a flow straightener.

I'm just guessing, but it opens some interesting options. Larry is definitely onto something.

UK, I suspect you're right about the refresh for SpeedCoach being triggered by stroke. Makes sense for what it's made for. I didn't think of tagging fin changes by distance. Duh.
Any updates on this Bill ?

I'm waiting for calm weather to do my usual scientific testing but i've now had a 4 fin set up in the water for a couple of weeks with mixed impressions so far. I'm certainly not sure either way yet based on how it feels so far. I've now got a smaller ventral on order to stick between my two twins to see how that feels on flatwater.

PonoBill

  • Cortez Bank Status
  • *****
  • Posts: 20431
    • View Profile
    • Ponohouse is for sale. Great house but it's time for new adventures
Re: Ventral Fin and fin tests
« Reply #73 on: October 12, 2017, 07:05:13 AM »
Nothing in any way scientific, just a lot of impressions. I'm currently (currently being two months ago) using two small Larry fins that I made even smaller--the trapezoidal ones that came with the board. They are now 3.5 inches long and 1.5 inches tall. I have a .040" aluminum fence with the edges sanded round between them that is 4 inches long and two inches tall, pushed all the way back in the middle slot. And my smallest ventral fin--I don't remember what that is. This is the fastest setup I've found for flatwater. It's fine for chop and even upwind too, though if the nose gets too far across the wind it's a challenge to get it pointed back upwind.

This setup is more than 10 percent faster than a big single fin with my limited testing. I'm sure that number isn't real, but it's a big enough change to be interesting even without disciplined tests.
Ponohouse is for sale: http://www.ponohouse.com
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Luc Benac

  • Teahupoo Status
  • ******
  • Posts: 1157
  • Super Natural British Columbia
    • View Profile
    • When not paddling...
    • Email
Re: Ventral Fin and fin tests
« Reply #74 on: October 12, 2017, 07:10:17 AM »
They are now 3.5 inches long and 1.5 inches tall.

Whoa, that small.
Infinity Whiplash - 14' x 25" 262L
Ace-GT - 17'4" x 27" 313L
Bark Vapor - 14' x 26" 271L