Any one have some tips for the placement of Quad Fins?

I've got a thruster shape that I'm working on and I've finished the glassing (eps foams with 2 layers of 200g @ 0°/90° & ±45° of carbon top and bottom no stringer), I'm thinking of putting a Quad Fin set up on it because I'm going to use it for kiting. Or should I just throw the thruster set up in it and make a new one for a Quad?

Really should put a pic of the board up but I don't have one, tomorrow.

Cheers
CC

As far as I have seen, people are doing 2 sorts of quad configurations: They either mimic a thruster, or a twin fin. Which one are you after?

I don't know much about the quad thruster setups, but they look like you put the rear fins a similar distance back as you would the rear fins on a traditional thruster. I am dubious about the benefit of these sort of quad setups as you are increasing drag significantly with the addition of a second rear fin.

The twin fin setups are drastically different. They work by taking the twin-fin keel outline and splitting it into two fins. These two fins together have the same plan area as the original keel, but they interact with each other in a "canard" relationship and generate more lift for the same amount of drag. The front and back fins need to be about half a chord length apart for the canard relationship to work well. The rear fins also need to be toed in less than the front fins (5deg front toe in, 2-0deg rear toe in).

I have a good picture at home showing one way to set up a canard quad, which I will post for you when I get home.

However, if your board has a narrow thruster like tail, I wouldn't suggest going for a canard quad setup.

Yeah it's got a thruster tail.



Deck at tail


Bottom at tail


I'll probably go with something like the Cabrinha S-ride because of the way the tails set up




I'll put a bit more thought in it might have to go with the tried and trued thruster set up and get a new blank for the Quad (which already designed )

Thanks for the photo DL

The board looks sweet!

What dimensions and weight?

The board is 6'1" (before I chopped the point of the tip), 1'7", 2.75" and weights in at 3kg on the spot with no finish and fins or tail pad probably looking at another 1.5kg or so

I got in touch with the Shapers Australia guy's they've got a new Fin web site www.shapersfins.com and they've got some new fins up on the site. Was thinking of going glass on so I can adjust them if I find there in the wrong spot but I'm having second thoughts. looking at the Quad-E 120mm high in the front and 111mm high in the back or the JK.7030 (JK's are 3mm smaller in the front and 10mm smaller in the back)

If you want to adjust the fins slightly, you could get a finbox that allows forwards and backwards adjustments, like red-X or lokbox.

I've used lokbox on my latest board and they are pretty good. And it was lucky I was able to do those adjustments because the quad is super sensitive to the spacing between the front and back fins.

DL, have you used probox fin boxes at all? Im a bit sceptical about moving away from FCS as a fin box as it hard to find fins for anything else.

Nope, never heard of them before.

Just had a squiz at the website though. Looks like a pretty cool idea being able to adjust the cant.

Yeah they've got a decent range of fins as well which is kinda nice. Plus the look a bit easier on the install than the LOKbox (but that's me).

I'm like'n the flaxibility so I might have to hit'em up and have a try at them.

So I got the fin boxes in and now I've just got to paint it, which may take a while as I dislocated my shoulder this weekend so I'm not doing much of anything other than feeling sorry for myself.






I'll point out for a DIY'r these are really easy to install if you have a panel router, easier than trying to put in FCS I found as you don't need to use a fin jig to get the fin cant right the template does it for you. It's not a bad price all up either

What brand of boxes are they?

Their Probox, unfortunetly there's no Aus distributer so you have to buy them from the head office in Hawaii. The Probox guys are really helpfull as well, unfortunetly the dollar tok a dive so there a bit more expensive than when I got them. That said it's probably $220 or so for the install kit, fins, boxes, cant insert sets (all 4) and shipping which isn't too bad if your buying some of the install parts from fcs.

www.proboxhawaii.com

coming late to the party

did a conversion of thruster to quad for my kite board

used future fin boxes who sell quad set

interestingly delta design's marty ( who is shaping north kite/surf boards)has gone to quads

set fins parallel to rail as opposed to thruster toe in

works real good for kiting

i'm not convinced surf fin set ups are right for kiting given different loads and that the fins are important for stopping side slip under kite load

hope it goes well

for an alternative to the probox set up, motivational lines make their own fcs type fin box, very similar to probox and $8 a hit...

they are local in wollongong area, don't know the contact details, but i'm sure if you were motivated (hahhahaha) you could find them easy enough...

industrial road, oak flats

.... a relo of mine who shapes boards swears by them, i have a couple of boards with these inserts and have never broken one, unlike fcs which seem to constantly break

What are u guys doing to FCS boxes to break them?? Ive used only FCS other than one board that has fixed fins, I have never broken a fin box, ripped some tabs off fins ect but never a plug. Intersted to hear other peoples probs with them.

Haven't ripped a FCS plug out (though it does happen to people), I went with the Probox for fin placement flexibility.

Edit - just finished painting it so I'll get some finished pictures up soon, unfortunetly the board looks better in the shade than it does in the light

Yea I have heard of it but never seen that type of dammage, people seem to dis FCS but they have to be one of the better systems out there for availability of fins & general parts.
The boxes that you are using look great, can you use FCS with them

You se it in kiting when guys have hit stuff fully wicked up.

I've tested a longboard side bite fin (tab size and placement is the same as a thruster fin) and they fit in the box the set screw distances are also the same distance apart that you'd set up for an FCS fin. One thing you might have to do is take a flat file to the FCS fin tab to grove it like the probox fins but that's a test for another day. For now they fit and if you broke a fin and had to find something over overseas you could use an FCS fin set.

Select to expand quote

effovski said...

used future fin boxes who sell quad set

I don't like future fins as they get loose in the box over time and you have to shim them up. It could be easily fixed if they had a screw that came in from the side, or used a tapered box (like lokbox do).

Select to expand quote

set fins parallel to rail as opposed to thruster toe in

at the tail of a board, having fins parallel to rails would result in toe-out... interesting.

Select to expand quote

i'm not convinced surf fin set ups are right for kiting given different loads and that the fins are important for stopping side slip under kite load

I'm not convinced that surf fin set ups are even good for surfing! Can anyone here explain what the thinking is behind toe-in on fins a surfboard? (apart from slowing you down)

Select to expand quote

DL said...

effovski said...

used future fin boxes who sell quad set

I don't like future fins as they get loose in the box over time and you have to shim them up. It could be easily fixed if they had a screw that came in from the side, or used a tapered box (like lokbox do).

set fins parallel to rail as opposed to thruster toe in

at the tail of a board, having fins parallel to rails would result in toe-out... interesting.

i'm not convinced surf fin set ups are right for kiting given different loads and that the fins are important for stopping side slip under kite load

I'm not convinced that surf fin set ups are even good for surfing! Can anyone here explain what the thinking is behind toe-in on fins a surfboard? (apart from slowing you down)

Mate if you have no toe in the board will tend run as straight as an arrow, if you have the side fins with toe out it will surf like a wet log. The toe in lets the board turn when you go onto the rail, yes there is drag involved. A lot of twins that I have seen have a small amount of toe in but not that much. If you want a fin set up with little drag use a single fin. The thruster is the best we have and we have been refining it for years, quads are good and are actually getting better. 26+ years of development cant be wrong. Prove me wrong

My quad goes good It's a shipload faster than my thrusters.

The problem with surfing is that it is so hard to "prove" anything because every wave is different. You never know if it was changing the board that made the difference, or a change in conditions.

I think I understand how toe-in will initiate a turn when you sink a rail, but maybe there is another way to achieve this? Possibly with tail, rail, rocker, or bottom design?

How bout this shape DL



Freaking weird if you ask me!

Select to expand quote

DL said...

My quad goes good It's a shipload faster than my thrusters.

The problem with surfing is that it is so hard to "prove" anything because every wave is different. You never know if it was changing the board that made the difference, or a change in conditions.

I think I understand how toe-in will initiate a turn when you sink a rail, but maybe there is another way to achieve this? Possibly with tail, rail, rocker, or bottom design?

I was talking to Steve Derosso a couple of months ago and he was telling me about Mick Fannings boards and how much tail rocker they have in them, 3 1/4 tail lift or close to that. The point he was getting at was when they make the Fanning rack boards they have to dial alot of the tail rocker out so that normal people (non world champs) can use a board that is close but in a lot of respects is detuned. He also said that he saw the board that Mick used for most of 07 and couldnt beleive the tail lift in it. Its why he can do those mad top turns at mach 10.
So what you are saying is right in that there arre other ways, and the quad is faster due to a lack of a center fin but still have toe in so the toe in isnt doing the most of the dragging its the middle fin.

Select to expand quote

cRAZY Canuk said...

How bout this shape DL

Freaking weird if you ask me!

That is some mad shapin goin on there, is there any footage of these things surfing?

Select to expand quote

effovski said...

coming late to the party

did a conversion of thruster to quad for my kite board

used future fin boxes who sell quad set

interestingly delta design's marty ( who is shaping north kite/surf boards)has gone to quads

set fins parallel to rail as opposed to thruster toe in

works real good for kiting

i'm not convinced surf fin set ups are right for kiting given different loads and that the fins are important for stopping side slip under kite load

hope it goes well

For kiting fins parallel to the rail would work, as the water passes through the fins @ a different angle than surfing I think.........dont quote me on that but it sounds right..

The new kite course race boards have no toe in, all the surf specific ones are still using toe in.

There's a couple clips kicking around of those boards surfing, apperently they can nose ride for ever.

what i meant was a neutral setting, not toed out but parallel to the mid rail ( not rail direction at the back)
for fins on kite quads (i think dave lewey does same for his tow in boards) board going much faster, but in chop too, so i figure a kite board needs to be different,

i 'd like a really deep concave and sharp rails to mid board too, latter i did, but couldnt do the concave

and more parallel rails mid board

anyway it works well for me so i'm happy and was fun doing it

That is one weird shape!

man, i'm one weird guy

other thing at one stage could buy these fin boxes that allowed rotation (len dibben had them ?swivel fins?) an you could muck around with toe in out whatever
surfboard certainly a lot looser with toe in

Select to expand quote

effovski said...

man, i'm one weird guy

other thing at one stage could buy these fin boxes that allowed rotation (len dibben had them ?swivel fins?) an you could muck around with toe in out whatever
surfboard certainly a lot looser with toe in

You can change the toe in with 4 way fins www.4wfs.com