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Stand Up Paddle => Gear Talk => Topic started by: Ripple on July 10, 2018, 06:40:42 AM

Title: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 10, 2018, 06:40:42 AM
So I have bought a few weeks ago a 2018 14' x 25" Infinity Blackfish. The main reason for the choice of board was that I wanted to try the Larry Allison four fin setup which the Blackfish has a factory option. Included in the deal was supposed to be a set of Larry Allison fins to match.

The board was delivered instead with a set of Stavron fins. The main issue is that the Stavron side fins have FCS tabs but the board has powerbox boxes. The powerbox canted inserts were not delivered with the board so I cannot install any side fins at the moment. Also, the Stavron ventral fin, despite the box is marked "Stavron", does not fit in the box as the base it's too thick and I would have to hammer it in place.

According to the dealer this year Infinity has switched from Larry Allison to Stavron fins, but for some reasons my board has still powerbox boxes, maybe the factory did a mix and match of whatever boxes they had left in stock?

I have followed the many post about the Larry Allison setup and would like therefore use his fins, but I am based in Brisbane Australia and cannot find anyone selling the L.A. fins anywhere in the whole country. The dealer has been promising me for ages to get me the right L.A. fins "next week" but I am starting to lose confidence that this will ever happen.

Can anyone help me to work out exactly which fin set is right for my board and where I could get it from? TIA
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Bean on July 10, 2018, 07:28:30 AM
When you say powerbox, are you referring to LA's ProBox?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Bean on July 10, 2018, 08:01:59 AM
FCS fin bases actually do work well in the ProBox fin box system, so it sounds like you might just need the correct inserts.  The ProBox system is pretty scarce on the east coast US too, but it is a great system. 

Your ventral fin base might just need to be sanded down a bit.  A simple sanding block with 100 to 220 grit sand paper, while keeping everything square and even on each side should do it.  Just keep in mind that sometimes when a board is hot, (say in transport or right out of storage) the fin box will be really tight until it cools back down. So, if you decide to sand the ventral's base down, make sure you fit it to the box while it is cool otherwise it will end up too loose once it gets in the water.   

No one should have to jump thrugh hoops on a new board purchase, but it does sound like your situation is very salvageable.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: FloridaWindSUP on July 10, 2018, 09:14:02 AM
I'm not sold on the LA fins and the four fin setup. I've never seen someone actually be fast on it. I've just seen slow paddlers spend a lot of money on endless varieties of the fins and spend a lot of time bs'ing about how the fins make them feel while they're still paddling slow as turtles. I think the LA fins are good for fin salesmen and for people who collect fins like they collect stamps and comic books. 
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Bean on July 10, 2018, 10:01:11 AM
I wish I was as fast as a sea turtle...and, as good looking!

The multiple fin arrangement, like on any other simply provides more options. 
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 10, 2018, 06:55:14 PM
Yes sorry I meant probox. It was past bedtime when i posted. :-)

I did start sanding down the ventral base but then I thought that not knowing if the fin is too wide or the box too narrow, it would be better to wait for the Larry Allison fins to arrive to make sure I sand the right part......

What bothers me the most is that I’ve made very clear to the dealer that I was buying that board from him specifically because it had the 4 fin boxes and because he included the fins in the price. I would have probably bought a different board otherwise, or a 2017 blackfish from a different shop for 33% less than what i paid for his, but he promised that he could get me a set of LA fins within few days so took the plunge on that.

I appreciate that maybe I will never get to the point of noticing any appreciable difference in performance between single and quad fin setup, but Moreton Bay is strongly tidal, and sometime two inches difference in fin depth can make the difference between having to carry the board from/to the shore for 100 metres or not, hence my intention to try the 4 smaller fins setup.

Also, the Stavron centre fin seems to be almost a full size fin, so adding the side fins, which seem also big compared to the LA, would probably slow down the board considerably.

By the way, is the flat side of the side fins supposed to face inboard or outboard on a race sup?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 10, 2018, 07:05:06 PM
Photos attached
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Luc Benac on July 10, 2018, 07:54:10 PM
Best if you put your photos in JPG instead of pdf that need to be downloaded. Less chance to pass on a nasty bug.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 10, 2018, 08:12:20 PM
I was wondering why they would not show on the post.... will do.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: FloridaWindSUP on July 10, 2018, 08:56:50 PM
Flat side supposed to face outboard on race sups (opposite of how it is on surf sups).
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 10, 2018, 09:13:54 PM
Flat side supposed to face outboard on race sups (opposite of how it is on surf sups).

Thanks!
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: TallDude on July 10, 2018, 10:23:44 PM
Mark Stavron hand makes most of his fins. I have a number of them. He's designed hundreds of fins and his fins have been mass produced by others. I stopped by his shop to pick up some fins for a board I made. The fins were all a little to tight so he sanded them down by hand right in front of me. He got them to fit perfectly. I so many different fins and fin boxes, but the ones Mark sanded to fit are the best fitting setup I have. 
I'd rather sand them to fit, than jamb some tape into the boxes to stop the rattle.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 11, 2018, 03:02:11 AM
I'm not questioning the quality of the Stavron fins, it's just that the side fins don't fit without inserts, and the 3 rear fins to me seem too big to be used all three together, as the central on its own is almost a full size single.

Also, before sanding the fin, I want to make sure that is the fin base which needs sanding, not the box.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Bean on July 11, 2018, 06:13:59 AM
Ripple, your board is designed to be run as a single, single plus ventral, twin, or twin plus ventral.  That does not mean that you couldn't experiment with other combos and fins for that matter.

The ventral box should be the same width as your center box.

A few years ago when I was playing around with LA twin fin system, with Larrys guidance, I added a ProBox twin system and made my own fins.  The twins worked great.  On flat water with the flat side out the board tracked as well as the big factory single but handled side wind much better.  In surf, with the flats turned in, is was a real novelty ride.  That's a board I wish I still had. ;D

Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 11, 2018, 06:49:00 AM
Thanks Bean for the advice, testing all the possible combinations is the plan as soon as I manage to get hold of probox inserts. Do you have by any chance the dimensions (lenght & depth) of the twins, centre and ventral fins you were using, to check if my impressions that the Stavron fins are too big is just that, an impression?

Also, I remember reading a while ago in a thread which I cannot manage to find that there are two fin box standards (US and cannot remember the other) that are very similar but differ by a small amount in width, does anybody have the width of the two box types?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Luc Benac on July 11, 2018, 07:16:12 AM
You need some information of what you need and regretfully it looks like Infinity did not provide that to you.
The inserts for the ProBox comes in four different colors/type that reflect the angle compare to vertical the fin would be subject to.
The purpose is to ensure that regardless of the bottom of the board, the fin once secured are vertical.
I have seen several time boards shipped without inserts, with wrong inserts and you then need to try which insert is the one that work for the board.
this also assume that the fin came with no cant or again this will need to be ascertained manually.

There are a few companies that stock the inserts and you will need do do a search for them as I have npot kept teh names and link. You can also contact Larry directly but be aware that turn-around can be uncertain at best.
Some shop sell a package but not sure if all four types come with it:
https://www.paddleboardspecialists.com/Pro-Box-Fin-Set/productinfo/LAPROBXFIN/ (https://www.paddleboardspecialists.com/Pro-Box-Fin-Set/productinfo/LAPROBXFIN/)
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Bean on July 11, 2018, 07:40:03 AM
Thanks Bean for the advice, testing all the possible combinations is the plan as soon as I manage to get hold of probox inserts. Do you have by any chance the dimensions (lenght & depth) of the twins, centre and ventral fins you were using, to check if my impressions that the Stavron fins are too big is just that, an impression?

Also, I remember reading a while ago in a thread which I cannot manage to find that there are two fin box standards (US and cannot remember the other) that are very similar but differ by a small amount in width, does anybody have the width of the two box types?

Ripple, the board I was using was a 14' Fanatic Fly Race, so the tail alone will be different enough to render any comparison worthless for your more modern Infinity.  Also I was using the keel or elliptical style fins only.  As you probably already know, your fin size will be dictated by ability, conditions, your physical size and the board size and shape.

Yes, there are at least two different center boxes out there, primarily US Box and SURF Box.  The fins that have a hump on the bottom fo the tab are US Box.  For some reference, take a look at the black project web site.

http://www.blackprojectfins.com/which-base-do-i-need/

Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 11, 2018, 07:42:31 PM
Cheers, this is all very informative and i can see the light at the end of the tunnel. :-)

Bean, I would still be interested in knowing the dimensions of the fins you were using, not so much for knowing what’s the best setup for  my board, but just to understand if the central fin the board came with is supposed to be used in conjunction with the side fins or only as a single. I’ve seen some photos online of the blackfish being ridden with that same fin as a single (which I also do with no particular problem) so i am dubious that it would also work on a multi fin setup as it would probably be too big; as far as I understand the principle of the multi fin setup is to have an equivalent or similar area of a larger single not to increase drag. I am only after ballpark figures for the dimensions of the fins for a multi fin setup just to understand if the ones i have are way too big or not.

Also, does anyone know which angle correspond to the different inserts colours?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 11, 2018, 07:46:40 PM
Ps my side fins seem to have 0 cant, I have not yet checked if the boxes have any.

Luc,
Do you mind measuring your fins as well?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Luc Benac on July 11, 2018, 08:01:48 PM
If you are talking about a center fin, Larry has been promoting a 6" Stinger with a 7" base and 32 sqi surface. It has always been too big of a central fin for me when used with side fins.
When I still had a Blackfish, my favourite side fins where the 9" elliptical, the other again where too big for my use (I am only 6' and 170 pounds).
I am not running a multi-fin setup anymore anyway except sometime a ventral on my Whiplash. I had been trying to get the original center fin for it, a small triangular fin like the side  but could never get Larry to send me one so I decided to just give up on the whole thing and keep it simple after-all. I just use a board that is wide enough and stable enough for me in the first place without further ado. I keep it very simple and I stop trying to run a board too narrow for me and gaining some stability with the multi-fin.

Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: BrentP on July 12, 2018, 12:22:55 PM
Yes sorry I meant probox. It was past bedtime when i posted. :-)

I did start sanding down the ventral base but then I thought that not knowing if the fin is too wide or the box too narrow, it would be better to wait for the Larry Allison fins to arrive to make sure I sand the right part......

What bothers me the most is that I’ve made very clear to the dealer that I was buying that board from him specifically because it had the 4 fin boxes and because he included the fins in the price. I would have probably bought a different board otherwise, or a 2017 blackfish from a different shop for 33% less than what i paid for his, but he promised that he could get me a set of LA fins within few days so took the plunge on that.

I appreciate that maybe I will never get to the point of noticing any appreciable difference in performance between single and quad fin setup, but Moreton Bay is strongly tidal, and sometime two inches difference in fin depth can make the difference between having to carry the board from/to the shore for 100 metres or not, hence my intention to try the 4 smaller fins setup.

Also, the Stavron centre fin seems to be almost a full size fin, so adding the side fins, which seem also big compared to the LA, would probably slow down the board considerably.

By the way, is the flat side of the side fins supposed to face inboard or outboard on a race sup?


Hi Ripple i worked at Infinity for a few years and am familiar with the set up. FCS works in the boxes just fine but yes you need the cant inserts to use even the ProBox fins in the boxes. Larry can sell them to you or email direct Dave they can get you dialed i am sure. That's the whole point to the system. The Blackfish usually fits 6 degree or 8 degree depending on which year you have. I am not sure which degree it would be for 2018 sorry. The Stavron set is a good starter kit. The center fin is not too big or full sized at all it's a "kick" fin. If anything it may be too small. They made this set to have access to the system quicker since Larry's stuff is in high demand and usually a little tricky to find them available. I would check with him directly. It looks like you have fins sounds like you are over thinking it already (which is easy to do!) don't worry so much about it just put them in and paddle then adjust from there!
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: BrentP on July 12, 2018, 12:27:45 PM
I'm not questioning the quality of the Stavron fins, it's just that the side fins don't fit without inserts, and the 3 rear fins to me seem too big to be used all three together, as the central on its own is almost a full size single.

Also, before sanding the fin, I want to make sure that is the fin base which needs sanding, not the box.

You will need inserts whether they are FCS tab or ProBox that's how the system works. All you do is take 200 and sand both sides of the base from just infront of the pin to the front screw hole. The 3 rear fins are not too big if anything they might be too small depending on what you want to do.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 12, 2018, 08:36:24 PM
From what I have read in the many posts on this forum from Larry himself, the concept is to have three fins at the back that have a similar “side lift” of a standard size single fin, so not to increase drag. Considering that the centre I have is pretty similar in size to the oem centre fins on my other sups, and that everyone seems to use the same fin as a single on the blackfish, adding side fins to it would be contradicting the principle above and make the board overfinned - more drag. At least this is according to my logic, but I’m happy to listen to different opinions. Maybe I should ask to the man himself. Is there a way of tagging forum members?
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Larry Allison on July 14, 2018, 10:39:57 AM
From what I have read in the many posts on this forum from Larry himself, the concept is to have three fins at the back that have a similar “side lift” of a standard size single fin, so not to increase drag. Considering that the centre I have is pretty similar in size to the oem centre fins on my other sups, and that everyone seems to use the same fin as a single on the blackfish, adding side fins to it would be contradicting the principle above and make the board overfinned - more drag. At least this is according to my logic, but I’m happy to listen to different opinions. Maybe I should ask to the man himself. Is there a way of tagging forum members?
Sorry for problems my friend. I cant control what board companies do but I can help you. PM me here and I will Square you up with the right set up. Mahalo,,Larry
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Larry Allison on July 14, 2018, 10:51:26 AM
 Considering that the centre I have is pretty similar in size to the oem centre fins on my other sups, and that everyone seems to use the same fin as a single on the blackfish, adding side fins to it would be contradicting the principle above and make the board overfinned - more drag. At least this is according to my logic, but I’m happy to listen to different opinions. Maybe I should ask to the man himself. Is there a way of tagging forum members?

This is because something is better then nothing which drives me crazy by these companies to sell Stuff. You are right DRAGGGGGGGGGG. Dave at Infinity is my buddy and sometimes when trying to make stuff like fins isn't the easiest. But that is why I am here to help you and Dave get it right for your liking my friend.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on July 14, 2018, 05:17:50 PM
Thanks Larry, PM sent.

Just to clarify the situation and to avoid spreading unnecessary bad feedback on companies/people not directly involved, my dealings were with an Australian retailer, not directly with Infinity or Dave himself.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: oceanAddict on August 27, 2018, 05:47:35 AM
Hi,

I recently became a happy owner of 2017 Infinity BF. It came with Infinity's single fin and a set of ProBox fins, including 2 center fins (pic attached). But I also came with only one set of cant inserts (white ones). Haven't tried ProBox fins yet as I want to get a feeling of the board with a single fin so I could feel the difference after switching and wondering what fin I should use with ventral/twins? And if white inserts are optimal for BF bottom's shape? I tried to insert twins and the angle between the board surface and fin looked strange to me (will post a pic later). Looks like the previous owner used a smaller center fin in this setup (pic from DM listing).

(https://3qeg6h2gvfew18lgwa41w5fz-wpengine.netdna-ssl.com/wp-content/uploads/2018/07/65456_IMG_2510-1-1-1-1.jpg)



 
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on August 28, 2018, 05:48:01 AM
oceanAddict, the side fins on a LA 4 setup must be vertical.

Can you please let me know what angle are the white inserts, it's stamped inside the insert slot, I don't have these.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: oceanAddict on August 28, 2018, 08:28:41 PM
oceanAddict, the side fins on a LA 4 setup must be vertical.

Can you please let me know what angle are the white inserts, it's stamped inside the insert slot, I don't have these.

Is this vertical? I might have to bring it to water to check if these are perpendicular to the water surface to be sure.
And white insert is stamped 8 degree

p.s. Disclaimer. Ignore that center fin, obviously, I'm not going to use these together ;)


Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on August 28, 2018, 08:50:06 PM
I can’t really say just by the photo, I use a spirit level to make sure that the board is horizontal and then that the fins are vertical. 2 degrees is not easily distinguishable by eye in my opinion.

By the way the side fins can be used with the centre too according to LA
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: oceanAddict on August 29, 2018, 10:42:33 AM

By the way the side fins can be used with the centre too according to LA

Yep, I'm aware of it and I asked about possible options in my post with pics above. I currently run Infinity's single fin and inserted a side fin just for photo-op. Not getting a lot of traction here, so I might repost my question as a new topic.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: burchas on August 29, 2018, 11:15:34 AM
is this a custom board or production? if Production you're probably good with the white inserts.
You'll feel the difference if somehow these inserts are not the right for the board, which is rare
in the case of production. If custom it is more possible.

if not aligned you'll feel like you're dragging a seaweed and the board will decelerate very fast,
you'll know immediately something's wrong if you rode the board as a single fin, if all good, you
probably won't feel the difference in flat water, in rough water the difference is more
substantial as the twins really help in eliminating the side to side roll.

If riding with twins, the 6 inch center LA fin (the one in the picture) is a good start.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: oceanAddict on August 29, 2018, 04:44:35 PM
Thank you burchas, very informative. 

I'm almost positive it was production board so I will start with the combo you suggested. I already tried to run a combination of ventral and Infinity single, now I'm gonna try all in :)
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on August 29, 2018, 07:05:45 PM
p.s. Disclaimer. Ignore that center fin, obviously, I'm not going to use these together ;)

I was just replying to this, where you seem to think that they cannot be used together because of the word “obviously “ and I was informing you that you can in fact use them all together in a 4 fin configuration.

By the way, that centre fin is not an LA, it’s a Stavron fin which is the stock infinity fin.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: burchas on August 29, 2018, 07:39:50 PM
By the way, that centre fin is not an LA, it’s a Stavron fin which is the stock infinity fin.

Yes, the 6 inch fin in the picture above the picture of the Stavron it is the LA fin, just
to make sure everyone is on the same page.

The other center fin in that picture is the Thresher (5.75 inch), Another option if you
want your tail looser.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: Ripple on August 29, 2018, 08:00:12 PM
Yep sure, I was just pointing out that the Stavron centre is also sold as part of a 4 fins kit so I would assume it could work fine with other side fins too.
Title: Re: Advice needed on quad fin setup for a 2018 Blackfish
Post by: burchas on August 29, 2018, 08:16:56 PM
Yep sure, I was just pointing out that the Stavron centre is also sold as part of a 4 fins kit so I would assume it could work fine with other side fins too.

Yes, though I've never tried it, I'm sure it's going to work. I'm going with the 6 Stinger inch
due to the fact it is shallow yet still maintains a wide base (assuming he's going for speed).

Shallower fin have less drag and will provide less tail "suction" than a larger area, deeper fin
hence even less drag. So assuming stability is not an issue, this setup provides a good start.
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