Author Topic: The ventral fin from Larry W. Allison  (Read 25450 times)

upwinder

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Re: The ventral fin from Larry W. Allison
« Reply #15 on: January 04, 2013, 03:17:38 PM »
I think the fin is a cool idea but how is it in a down winder? I understand the board is more stable but will it cause the board to start tracking when your at speed on the bumps or keep the board from releasing when trying to get the bump?

So with the forward fin in could you go with a smaller rear fin to reduce the drag? or would that make a difference?

Thanks


Good question, I may have something of an answer. I haven't used the 17 on a DW since fitting the fin (we typically have quite short-period swells here and rockered 14s just work better). Interestingly the 14' board I DW on came ex-factory with a ventral in box fitted (here's a pic or two) and I've experimented a little.





The WoW ventral is about 1/3 the size of Larry's

Here it's rare that swell and wind line up perfectly and our waters can be quite chopped up and confused, especially on lighter (15-20knot) days. In these lighter wind, confused conditions I've found the combo of the bigger Larry ventral plus the red PCF fin (as seen in my earlier post) works better than the smaller fins because tracking through the slop to maintain a heading becomes a bit more important

On big days, above 25-30 knots like yesterday, the swell and wind tend to line up better, then I prefer the combo of the smaller WoW ventral and a 10-10.5" dolphin style fin because it feels a bit more surfy.

In both cases I reckon the ventral contributes to tracking between runners but doesn't seem to interfere with release/performance on a runner when my weight is back on the board.

BUT...when I tried the bigger Larry ventral with an upright, smaller base tail fin (the one pictured in the orange board, only has about 5" base compared to the 8" base of the Larry Ventral and it doesn't have much area in the tip) things turned to crap.  The ventral seemed to dominate the tail fin, the board wanted to pivot around the ventral and was very difficult to control. The smaller WoW ventral (base about 3 1/2" doesn't have that effect with the smaller tail fin and together they seem to work nicely in more orderly conditions when the swell and wind line up. The bigger Larry ventral works well with a bigger area/base/tip tail fin.

So it seems to me there's a size relationship between tail fin and ventral that one needs to be mindful of (maybe Larry could comment on that if he's watching).

I should maybe add the qualification that I'm a big clumsy guy (6'2, around 265) and  boards /fins do behave differently with big units like me on them so YMMV.
« Last Edit: January 04, 2013, 03:31:52 PM by upwinder »
In theory, there should be no difference between theory and practice, but in practice, there is...
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westbeach

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Re: The ventral fin from Larry W. Allison
« Reply #16 on: January 05, 2013, 03:37:05 PM »
14 M&M?! When did that happen?

Corey, got the 14' M&M a few weeks before Bjord the Fjord.

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #17 on: January 06, 2013, 10:47:44 PM »
I did one of the first ones of these with Larry.  I was one of his guinea pigs.   :P

This is from 2008.  How time flies.








jd, See what you did! Just kidding. Thanks for pushing things my friend. Here's a pic of the transition of Allison Ventral Sup Fins from the large Ventral fin 6" of jd's 12'6" Ron House of 5 years ago to the Hi Performance Flex Ventral Fin 2" of today.

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #18 on: January 06, 2013, 11:02:48 PM »
I think the fin is a cool idea but how is it in a down winder? I understand the board is more stable but will it cause the board to start tracking when your at speed on the bumps or keep the board from releasing when trying to get the bump?

So with the forward fin in could you go with a smaller rear fin to reduce the drag? or would that make a difference?

Thanks

Surf Monkey you are right, when added a Allison Ventral fin concept you can go down in rear fin size depending on conditions and boards. The middle board in the pic is a 12'6" board with a 2" Ventral Sup Fin and a 7" rear Stealth Fin.

Also because of the location of the Allison Ventral fin it won't interferance  with the performance aspect of catching a bump, like in the pic below with Brandon Sauls riding the 12'6" board in this last BOP at Dana Point coming in 3rd in his group.
« Last Edit: January 06, 2013, 11:21:47 PM by ProBox-Larry »

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #19 on: January 06, 2013, 11:16:17 PM »
I run a small 2" Red Flex Ventral with a Ninja on my 14' Bark in pic. In the open ocean I sometimes use the larger Black Ventral like seen in the pic Below. The pic below shows me flexing the smaller Ventral fin which is foiled in a "S" flex.

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #20 on: January 06, 2013, 11:36:47 PM »
Looks like it's time to get in touch with Larry again. ;) I am considering adding this to my 14' M&M. Thanks for feedback Henrik!

Westbeach, Here's some pics of a 14' M&M with the Allison Ventral Sup Fin set up. Notice the M&M has 3 different fin setups using the 3 1/2" Ventral fin in all 3 pics. Along with 6 1/2" Dolphin Keel, 7" Stealth and 6 3/4" Gladiator for Rear fins in this M&M.

corlot

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Re: The ventral fin from Larry W. Allison
« Reply #21 on: January 07, 2013, 08:46:52 AM »
Awesome info Larry!! I think I need to contact you on putting one on my Starboard Ace Pro 25''. The narrow width and my weight of 188lbs can be a handful in choppy conditions.

Can anyone tell me an approximate level of stability it will increase with the smaller ventral fin? Really interested in this discussion.

Thanks again Larry for being so helpful!

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #22 on: January 07, 2013, 09:08:04 AM »
Awesome info Larry!! I think I need to contact you on putting one on my Starboard Ace Pro 25''. The narrow width and my weight of 188lbs can be a handful in choppy conditions.

Can anyone tell me an approximate level of stability it will increase with the smaller ventral fin? Really interested in this discussion.

Thanks again Larry for being so helpful!

Remember corlot, The smaller Ventral fin still has a 8" core length. It as to do with flex along with placement in relation to paddle power and depth for drag. If you go to short of core length the Ventral Fin actually has a negative effect and is noticed in your paddling to give you the feel of a tugging on your board and start to yaw again pulling you side to side which is different then the feel of towing something when the Ventral Fin is oversized or I should say when the pair (Ventral and Rear are oversized). Don't forget balance of fins just like the center fin in the single world balance to the board and conditions. People will tend to focus on one elimente and forget the rule of Balance.
« Last Edit: January 07, 2013, 09:16:55 AM by ProBox-Larry »

Area 10

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Re: The ventral fin from Larry W. Allison
« Reply #23 on: January 07, 2013, 09:57:41 AM »
Guys, bear with me for being so pedantic, but, please, before this term takes irrevocable hold upon our community, can I please ask for a possible change in the term used?

The term "ventral" is not a good one to describe this type of fin. "Ventral"just means on the underside or belly. So all fins are "ventral". What you need is a word that describes the forward placement of the fin, which is the special thing about it, not the fact that it is pointing into the water. If you want to adopt a terms from anatomy (like "ventral") to do this, then probably the most accurate term to use would be "rostral". Rostral means "in the direction of the nose" of something, so would seem particularly appropriate for this situation. You could also call it an "anterior fin", perhaps.

Or maybe if you just want to use plain language, then "rear fin" (for the normal fin) and "front fin" would do just fine - although sound far less impressively scientific...

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #24 on: January 07, 2013, 11:23:52 AM »
Guys, bear with me for being so pedantic, but, please, before this term takes irrevocable hold upon our community, can I please ask for a possible change in the term used?

The term "ventral" is not a good one to describe this type of fin. "Ventral"just means on the underside or belly. So all fins are "ventral". What you need is a word that describes the forward placement of the fin, which is the special thing about it, not the fact that it is pointing into the water. If you want to adopt a terms from anatomy (like "ventral") to do this, then probably the most accurate term to use would be "rostral". Rostral means "in the direction of the nose" of something, so would seem particularly appropriate for this situation. You could also call it an "anterior fin", perhaps.

Or maybe if you just want to use plain language, then "rear fin" (for the normal fin) and "front fin" would do just fine - although sound far less impressively scientific...

You are right Area 10, when I was using the term Dagger fin everyone starting comparing and putting the fin box in their boards like a Windsurfer which is wrong placement. So I thought Ventral like a fish #11 called a pelvic(Ventral) #12 called the Anal Fin and #13 called the Finlet, but Ventral is the rear fin at the bottom of a plane to control yaw or roll in simple terms. So yes I can see your concern my friend if Ventral is used in a Fish world it is the opposite of Dorsal. But in the Airplane world it's at the rear slightly forward. Let me think about it and I will come up with something. Mahalo, Larry
« Last Edit: January 07, 2013, 11:47:14 AM by ProBox-Larry »

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #25 on: January 07, 2013, 11:55:49 AM »
Guys, bear with me for being so pedantic, but, please, before this term takes irrevocable hold upon our community, can I please ask for a possible change in the term used?

The term "ventral" is not a good one to describe this type of fin. "Ventral"just means on the underside or belly. So all fins are "ventral". What you need is a word that describes the forward placement of the fin, which is the special thing about it, not the fact that it is pointing into the water. If you want to adopt a terms from anatomy (like "ventral") to do this, then probably the most accurate term to use would be "rostral". Rostral means "in the direction of the nose" of something, so would seem particularly appropriate for this situation. You could also call it an "anterior fin", perhaps.

Or maybe if you just want to use plain language, then "rear fin" (for the normal fin) and "front fin" would do just fine - although sound far less impressively scientific...

You are right Area 10, when I was using the term Dagger fin everyone starting comparing and putting the fin box in their boards like a Windsurfer which is wrong placement. So I thought Ventral like a fish #11 called a pelvic(Ventral) #12 called the Anal Fin and #13 called the Finlet, but Ventral is the rear fin at the bottom of a plane to control yaw or roll in simple terms. So yes I can see your concern my friend if Ventral is used in a Fish world it is the opposite of Dorsal. But in the Airplane world it's at the rear slightly forward. Let me think about it and I will come up with something. Mahalo, Larry

Area 10, I gave it some thought and I like the flow of "Anterior Ventral Sup Fin" Thanks my friend. We just confirmed and set the pace for others to follow. Thanks for your guidance this comes together nicely after 5 years of playing with this concept. Mahalo, Larry

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Re: The ventral fin from Larry W. Allison
« Reply #26 on: January 07, 2013, 12:18:05 PM »
I've been out today trying the ventral fin from Sup Race Fins, Larry W. Allison. In a bit choppy conditions. First I paddled without the ventral and just a Ninja. Then with the ventral fin and the board was a lot more stable. Not tippy at all :)
Then I paddled into the more calm conditions in the marina. I like the Ninja because it allows me to take more strokes per side than the fin that comes with the board. But with the ventral fin attached... It felt like I could have gone on and on. This is a serious improvement. Probably to any board that you use in flatwater or chops, whitecaps... Brilliant!

Henrik F



What I forgot to mention is that the Anterior ventral Sup fin also eliminated the very irritating backwash from the jetty. The board became so stable.

Henrik F
crosswater.se

Larry Allison

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Re: The ventral fin from Larry W. Allison
« Reply #27 on: January 07, 2013, 04:34:35 PM »
Thought I would share some more "Allison Anterior Ventral Sup Fin" set-ups from 12'6" to unlimited class. Enjoy the ride and Thanks for the support my friends. Mahalo,Larry
« Last Edit: January 07, 2013, 04:46:45 PM by ProBox-Larry »

Area 10

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Re: The ventral fin from Larry W. Allison
« Reply #28 on: January 07, 2013, 05:36:09 PM »
Area 10, I gave it some thought and I like the flow of "Anterior Ventral Sup Fin" Thanks my friend. We just confirmed and set the pace for others to follow. Thanks for your guidance this comes together nicely after 5 years of playing with this concept. Mahalo, Larry

Yep, that works. Maybe we might find it easier to say e.g. "AVS fin" for day-to-day use?

I've got to get one of these fitted to my 17...

jdmotes

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Re: The ventral fin from Larry W. Allison
« Reply #29 on: January 07, 2013, 05:46:22 PM »
  Since I like to 'keep it simple' with the use of initials, I'm with A10 and calling it an AVS system  ;D...          Paddle on,     JD
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