Author Topic: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard  (Read 13695 times)

ukgm

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #30 on: August 19, 2016, 10:39:13 AM »
Some of you here mentioned they wanted to see testing for a longer distance, I felt the same way as I wanted to see results for half of mile so I ran my own test. While not as comprehensive as John Judge's tests, it still paints a clear picture.



Thanks for this. I love technology and I've read enough of this thread by now in that once I know what I'm going to be paddling on (or who for) next year (I have no idea right now), I'm seriously tempted to see if I could get the race board modded to have a ventral fin added so that I could run my usual full battery of scientific tests.
« Last Edit: August 19, 2016, 10:44:47 AM by ukgm »

supuk

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #31 on: August 25, 2016, 12:20:16 AM »
I put a ventral fin in my 12'6 x 21.5 board this week and got to try it for the first time last night, conditions were glassy with zero wind and i paddled  both on the flat still lake and the ocean. On the lake it felt good, a little more stability and slowed the roll rate a fraction and it held direction a little better two so it did seam to feel a little better over all. On the ocean the tide was just turning and current. We were running a triangular course going in every direction, the ventral fin was very noticeable in these conditions and you could suddenly feel the current pushing you side ways wanting to throw you off especially when you pass over a swell so i think the gains from a ventral on the ocean would be minimal for me at least and i probably won't run one again in these conditions however i will be experimenting more on the flat. I have a few ideas that may solve all these problems though so will have to see if i can test them out soon.
« Last Edit: August 25, 2016, 12:22:12 AM by supuk »

ukgm

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #32 on: August 25, 2016, 03:57:05 AM »
I have a few ideas that may solve all these problems though so will have to see if i can test them out soon.

Sounds intriguing !

PonoBill

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #33 on: August 25, 2016, 06:57:33 AM »
Mark Raaphorst did a switchblade ventral fin that could be flicked out with a paddle blade and pulled back the same way. I did front steering and tried wind compensation with a tiny front rudder that had a little sail on top. Worked great upwind--almost felt like it was powering the board in whatever direction you aimed. But it was horrific downwind.
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.

burchas

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #34 on: August 25, 2016, 11:45:24 AM »
I put a ventral fin in my 12'6 x 21.5 board this week and got to try it for the first time last night...

Which ventral did you use (measurements)?
in progress...

Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #35 on: August 25, 2016, 01:41:08 PM »
Mark Raaphorst did a switchblade ventral fin that could be flicked out with a paddle blade and pulled back the same way. I did front steering and tried wind compensation with a tiny front rudder that had a little sail on top. Worked great upwind--almost felt like it was powering the board in whatever direction you aimed. But it was horrific downwind.

I seen that, delighted about Mark doing it but not happy about the placement and fin design because it made the board fin dominate, which is what you felt off the wind. This is another point I am making also, experimenting is great but tweaking a concept that works in one position to another the results vary. Same problem with this guy making Twins. Looks the same but dose not work the same. Just saying compare apples to apples, not apples to oranges. I have the specs public for people to see and follow.
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supuk

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #36 on: August 25, 2016, 01:47:08 PM »
I put a ventral fin in my 12'6 x 21.5 board this week and got to try it for the first time last night...

Which ventral did you use (measurements)?

i placed it 20" forward of the balance point as per larrys suggestions, the fin was just a fairly small is one i quickly shaped up i forget the exact size.

I have just prototyped one of my ideas so i will try and test that in the next day or two.

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #37 on: August 25, 2016, 02:45:44 PM »
Mark Raaphorst did a switchblade ventral fin that could be flicked out with a paddle blade and pulled back the same way. I did front steering and tried wind compensation with a tiny front rudder that had a little sail on top. Worked great upwind--almost felt like it was powering the board in whatever direction you aimed. But it was horrific downwind.

Mark offered to put it on my board back at the time. I sent Larry the specs, the placement and template of the fin did were far from ideal to serve me well in all conditions.
I decided to stick with Larry's ventral, I'm glad I did.
in progress...

burchas

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #38 on: August 25, 2016, 02:51:03 PM »
I put a ventral fin in my 12'6 x 21.5 board this week and got to try it for the first time last night...

Which ventral did you use (measurements)?

i placed it 20" forward of the balance point as per larrys suggestions, the fin was just a fairly small is one i quickly shaped up i forget the exact size.

I have just prototyped one of my ideas so i will try and test that in the next day or two.

Interesting to hear the results of the experiment.
I found that the 2x9 ventral works best for me. I tried the medium in many conditions, did not feel good. Probably better for larger guys like Bill.
in progress...

krash

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #39 on: August 27, 2016, 07:19:04 AM »
Ok I'm a rookie and by far not a Surf guru.. Have read many post about center, ventral, or center forward fins on SUP.

Specific purpose use SUP for standup fishing, mainly flat calm waters or light winds. Currently have a Rivera Voyager 12'6" board, purchased as a project, supposedly a displacement style hull, but its mostly flat bottom seems to be more of a planing hull. Very noisy in any chop.

I have a BoneFishHippies style shallow water fin, so I can paddle/pole in very shallow inshore flats while standing and sight fishing very spooky fish.

Problem is it works very well in calm flat water, or floating/drifting down wind. But when the wind picks up  much more than a few mph it is very hard to get upwind or forward momentum in any quartering wind off the bow as the board will immediately stop its glide and blow the bow around trying to turn down wind.

I am thinking of some sort of "ventral" style fin or small keel. Don't really want to install a fin box, (cost is an issue for me), and have not found any glass on style ventral SUP fins.

I am looking at something like a wakeboard fin, 7.5" or longer 1" deep fin, like the fiberglass Liquid Force fin.. its meant to be bolted thru but I'd remove the bolts and use an epoxy adhesive or glass this in place instead of retro-fitting a fin box. Based on the expert advice presented the rear point of the fin would be set at 20" forward of the central balance/standing point.

Any thoughts or suggestions ?

« Last Edit: August 27, 2016, 07:26:23 AM by krash »
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PonoBill

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #40 on: August 27, 2016, 08:15:35 AM »
Do a fin box so you can swap it out. Not hard to do, and they're cheap--less than 15 bucks. But make it a Chinook or other one-piece box. Lots of info on the web about how to do it. You can take any old fiberglass fin and make a ventral fin from it with some cutting and grinding. Get an old dinged up fin for free and you'll be out less than twenty bucks for the whole deal, assuming you have a little glass and epoxy sitting around.

Yeah, Larry I told Mark he had that fin in the wrong place and it was too big. He drives me crazy with this stuff--goes straight to a beautifully finished product in one step without experimenting to get the thing to work optimally. I have the opposite problem, my stuff always looks like crap but I get it to work. I go by rocker to place any front fin--about ten inches behind the beginning of the nose rocker, no matter how slight the rocker is, but I suspect we wind up in a similar place unless a board has no rocker at all, in which case I'd have no idea where to put it. Haven't done any experimenting with them for years, but I liked the low drag effect of front steering and the stability/tracking of ventral fins, though you have to pick the whole nose up to turn.
« Last Edit: August 27, 2016, 08:26:10 AM by PonoBill »
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.

Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #41 on: August 29, 2016, 01:56:55 PM »
Ok I'm a rookie and by far not a Surf guru.. Have read many post about center, ventral, or center forward fins on SUP.

Specific purpose use SUP for standup fishing, mainly flat calm waters or light winds. Currently have a Rivera Voyager 12'6" board, purchased as a project, supposedly a displacement style hull, but its mostly flat bottom seems to be more of a planing hull. Very noisy in any chop.

I have a BoneFishHippies style shallow water fin, so I can paddle/pole in very shallow inshore flats while standing and sight fishing very spooky fish.

Problem is it works very well in calm flat water, or floating/drifting down wind. But when the wind picks up  much more than a few mph it is very hard to get upwind or forward momentum in any quartering wind off the bow as the board will immediately stop its glide and blow the bow around trying to turn down wind.

I am thinking of some sort of "ventral" style fin or small keel. Don't really want to install a fin box, (cost is an issue for me), and have not found any glass on style ventral SUP fins.

I am looking at something like a wakeboard fin, 7.5" or longer 1" deep fin, like the fiberglass Liquid Force fin.. its meant to be bolted thru but I'd remove the bolts and use an epoxy adhesive or glass this in place instead of retro-fitting a fin box. Based on the expert advice presented the rear point of the fin would be set at 20" forward of the central balance/standing point.

Any thoughts or suggestions ?



krash, I would take Ponobills advise and add a box but if you want to glass on a Ventral Fin then using something more than a wakeboard fin would be my call. I started with fins small at first but all you are doing is creating better drive in flats but when the wind along with current and water movement kicks in the Wakeboard fin will become useless because it is not enough surface area to create lateral resistance to fight the pull of the nose.. If you glass on the Ventral make sure the back of the base of the Ventral fin is 20 inches forward of your balance point, not the release off the tip.
Allison Race Fins

Larry Allison

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #42 on: August 31, 2016, 02:40:07 PM »
Ok I'm a rookie and by far not a Surf guru.. Have read many post about center, ventral, or center forward fins on SUP.

Specific purpose use SUP for standup fishing, mainly flat calm waters or light winds. Currently have a Rivera Voyager 12'6" board, purchased as a project, supposedly a displacement style hull, but its mostly flat bottom seems to be more of a planing hull. Very noisy in any chop.

I have a BoneFishHippies style shallow water fin, so I can paddle/pole in very shallow inshore flats while standing and sight fishing very spooky fish.

Problem is it works very well in calm flat water, or floating/drifting down wind. But when the wind picks up  much more than a few mph it is very hard to get upwind or forward momentum in any quartering wind off the bow as the board will immediately stop its glide and blow the bow around trying to turn down wind.

I am thinking of some sort of "ventral" style fin or small keel. Don't really want to install a fin box, (cost is an issue for me), and have not found any glass on style ventral SUP fins.

I am looking at something like a wakeboard fin, 7.5" or longer 1" deep fin, like the fiberglass Liquid Force fin.. its meant to be bolted thru but I'd remove the bolts and use an epoxy adhesive or glass this in place instead of retro-fitting a fin box. Based on the expert advice presented the rear point of the fin would be set at 20" forward of the central balance/standing point.

Any thoughts or suggestions ?



Smaller is not always better as this rider for Future Figured out 3years back trying this combo using a Future box which didn't get far for a Ventral option.
Allison Race Fins

supuk

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #43 on: August 31, 2016, 03:28:18 PM »
Ok I'm a rookie and by far not a Surf guru.. Have read many post about center, ventral, or center forward fins on SUP.

Specific purpose use SUP for standup fishing, mainly flat calm waters or light winds. Currently have a Rivera Voyager 12'6" board, purchased as a project, supposedly a displacement style hull, but its mostly flat bottom seems to be more of a planing hull. Very noisy in any chop.

I have a BoneFishHippies style shallow water fin, so I can paddle/pole in very shallow inshore flats while standing and sight fishing very spooky fish.

Problem is it works very well in calm flat water, or floating/drifting down wind. But when the wind picks up  much more than a few mph it is very hard to get upwind or forward momentum in any quartering wind off the bow as the board will immediately stop its glide and blow the bow around trying to turn down wind.

I am thinking of some sort of "ventral" style fin or small keel. Don't really want to install a fin box, (cost is an issue for me), and have not found any glass on style ventral SUP fins.

I am looking at something like a wakeboard fin, 7.5" or longer 1" deep fin, like the fiberglass Liquid Force fin.. its meant to be bolted thru but I'd remove the bolts and use an epoxy adhesive or glass this in place instead of retro-fitting a fin box. Based on the expert advice presented the rear point of the fin would be set at 20" forward of the central balance/standing point.

Any thoughts or suggestions ?



The experiments I did at the weekend just used some Acrilic sheet that I foiled ( you could use any ply wood or cut down a old fin for material) and then used hot melt glue to temporarily fix it to the board and a bit of bondo to make a nice fillet it's a hours job at most. It worked a treat for the testing I did and was easy to remove by sticking a pice of tape to the board first to which you stick the fin. Personally unless you are heading stright up or down wind the ventral tends to make you drift a little so it would be worth testing before you go installing boxes.

krash

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Re: 4 Fins vs Single Fin in depth test by Paddler in New York on a Raceboard
« Reply #44 on: September 01, 2016, 03:44:39 PM »
Hot glue sound like a good idea, I was thinking silicone-adhesive.... for temporary testing, which I can easily cut free with a piece of braided fishing line.

What kind of tape did you use, tape seems like it would come off when exposed to water and strain.


Also "ProBox-Larry", I got the 20" rule.. assume you are saying to the back end of the fin/box, but the start of the 20" are you suggesting from standing position heel or toes, or simply the center balance point of the board ?
« Last Edit: September 01, 2016, 03:48:39 PM by krash »
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