I tried out the Evil Twin conversion today. I found the Evil Twin great in the waves on the Oregon coast and at the Gorge but struggled to stay up wind at Columbia Beach unless I was powered up and it wasn't gusty which is pretty much never. I figured mini tuttles and slot boxes would be hard to put in and are not readily available so I went with the FCS system. I haven't had any problems with the FCS type forefins on the 71 l SB. Stefan said the new FCS system is bomber. Plus I figured I didn't need big fins as I had the A boxes for the twin fins already. Most people seem to go with the big fins in the back so I figured it would be fine.

The board was a good candidate. Similar shape to the SB quad. Got a killer deal on the board when I bought it new so I didn't mind putting some dough into a solid board. I didn't think I would do it any harm. I probably should have weighed the board before I started but it didn't seem much heavier after. Although some of my thinking for the FCS forefins was the weight I am now thinking that it's not as big a deal as the companies are making it out to be.

Stefan Aftanas at Aftanas Surfboards did the work. He makes his own boards and does tons of repair work in Tofino. He was helpful and did a great job. Specs came mostly from BWD's 78l 2011 quad and where the front fins were on my 71 litre 2010 quad. I was waffling on the toe in. I had read about it on some forums. I don't think any production boards do it so I was hesitant. Winddoctor suggested I go with it so I tried it. I went with 1.8 degree toe in.


So the first sail was today. Powered up to over powered on the 5.0 at CB. It was unbelievable right off the bat. First reach I cranked up wind so the biggest box was ticked. Hit my first wave coming and the board just cranked the turn. Still had the twin looseness. I threw more spray on the cut backs than I have ever done. Found some peeling waves up north and it was really smooth and loose. Just tempts you to smack more lips. Ended up late on one and got buried but had a big smile on my face. Tracked well. I don't know what the toe in did but no negatives. Only negative is that it seemed slow but I don't think it was any slower than the twin. I was on the Starboard symmetrical 11 cm fcs and 17 cm Black Project Fins. I was surprised that the 17s still worked so well in the strong wind as that's what I would just use on the twin.

Next up will be the thruster and single fin tests. The single fin should speed it up. Although if I had known that the quad would work so well I might not have put the single box in. But this was an experiment so why not experiment. Incremental cost of the single fin was negligible. Covering up the spare boxes with Tuck tape worked well.

wow, Stefan did a wicked job, nice work.

I would think the new fins are much too large, u'd gain serious looseness going with something smaller without sacrificing upwind ability. Also get more skate with the twins down a size. Also that would speed it up lots. Not sure why you'd do single fin at any time with this board but it sure looks cool with all the boxes.
Doubt you need to tape things up, there is not that much drag, the tuck tape is a bitch to get off without solvent that will also remove your nice new paint

Great successful experiment.

Will go out now and peel the Tuck tape off! I have some 16 cm fins but they are thicker, as are the stock fins. I will try them, but probably will get some more Black Fin Project fins to keep the speed up. Probably 15 cm. I was surprised though that the 17 cm fins worked so well in the conditions. 25-33k.There seems to be plenty of different opinions on the open fin box drag issue.

Stefan did a flawless job. He has definitely come a long way since my brother taught him to shape his first surfboards! My brother still shapes his own boards but takes them to Stefan's shop for glassing.

Getting back to the topic I have one question? I can't tell from the photos, are the forward fins in the FCS boxes symmetrical foiled (both sides) or are they flat on the inside like most surfboard fins?

Echo Kus here, those fins are way bigger than you need. The biggest difference between the SB 2010 and 2011 quads was the astounding difference in fin size, having sailed them both in the same volumes the 2011 was waaaayyyyy better (faster, looser, turnyer, funner) with 25% or so smaller fins.

Also - Just measured my Quatro quad 85L and it is running 14's and 8's stock so I would think you should go that small at least given similar volume.

The fins are fibreglass 11 cm symmetrical. They came with the 2010 71 Starboard quad. I tried an asymmetric 11 cm set on the 71 today. This board puts the fcs in the rear position. They seemed to sort of spin out a bit sometimes. I think people put the symmetrical fins in the rear boxes on surfboards sometimes. Any thoughts on symmetric vs. non symmetric. I am going to probably order some 10 cm fins. Not that easy to find symmetric in that size as they mostly come as centre thruster fins which are usually 11 cm. Other problem is that the surf fins are mostly sold as sets. Any good sources of smaller surf fins?

I'm interested to know the difference between asym and sym as well if anyone knows please chime in.

the asymmetric foil (flat on the inside face) creates lift, like an airplane wing. now think about your board railed over on a turn with a asymmetric side fin buried in the water. the direction of that lift is going to work to hold your rail in so you can carve that much harder or tighter. that's the idea anyway. there are a few other variables involved!

downwind dave wrote:the asymmetric foil ... lift is going to work to hold your rail in so you can carve that much harder or tighter. that's the idea anyway. there are a few other variables involved!

any lift would be nice to help keep the board's speed up but in the end I would think it slows the board on a run as does the toe in, I'd have skipped both on a prototype for our onshore conditions. I would like to try the unit out next good wind day tho for a few minutes. Sure sounds like a great success. I have never even tried a twin, do you think it is now somehow not as good at something? Wdoc felt if I recal correctly that his twin is looser and quicker/tighter in turns but not as easy to plane which in onshore is a serious issue for me. I still lose speed more with the quad than a single fin but the skateyness and mobility, throwing spray makes more than up for it on a day like yesterday

There is a number of threads on the Boards site related to quad fin placement, toe in, and assymetrical fin profiles. There's a lot of BS to sift through in the threads, but I've understood a few interesting things from reading them.

First, toe in seems like a desirable thing for the front fins. In a turn, you don't want a bunch of lift; it tends to make the board want to track straight. A forward fin with no toe encourages this behaviour as I understand it. Interestingly, the Goya and Quatro quads don't have toe in for the forward fins (or rear ones). My custom Nelson's twin fins have a little, and it is SUPER loose and turny, but so much of that is also due to rocker, outline etc. I've noticed the Goya tracking straight in the middle of a turn occasionally in sessions on the Oregon coast, but had none of this effect yesterday; I think I'm just adapting my technique to how it likes to be sailed. Kus' 95 quad had this same trait for me when I tried it the first time, and I kept tripping the rail on short, hard carves. He seems to get it turning just fine. The designer of Witchcraft boards, amoung others, sees lack of toe in for the quads' front fins as a design flaw. He is a huge proponent of tri fins though.

Assym front fins apparently also sound like they offer better wave and even planing performance in some cases.

Fin placement and style (big fins forward or big fins in rear) give different strengths. The Goyas and Quatros offer more of a twin feeling with more stability by having the small fins in the forward position. They give the board a more solid feel through the turn than a regular twin, but they give up some looseness/radical feel in a hard cutback or sharp bottom turn. Big fins foreward apparently give more drive, but still offer a "hooked" top turn. The Starboards offer both configuratiosn, which is cool for dialling in the feel.

So far the biggest advantages from sailing my Goya quad are: range, upwind ability, planing, drive, jumping, security in hard and fast turns, and general ease of use. Compared to my custom twin, I give up looseness and ultimate riding performance, but let's face it, ultimately I'm still a wave kook and we don't often get the conditions that my custom shines in. The flatter rockered designs of the quad shaped Quatros and Goyas (for frame of reference) do nearly everything better than a twin fin, and with some tweaking of technique, they can be just as radical. So no real downsides that I can see!

At CB I'm noticing that I can get up to speed so much quicker on the quad than on my twin which is key for jumping there. A slow to plane board sucks if the best jumping is 20 metres off the beach!

Sorry for the ramble, but the advances in board and fin system design are doing some pretty cool things for the enjoyment of windsurfing.

Uh oh, I just noticed a pic of Levi Siver riding a new SINGLE fin at Hookipa...

I think we missed a critical point of discussion; obviously this board is no longer an 'evil twin' so whats the new nickname?

i thought of a good one; "E.T. (the extra three)"

Evil Quint?

I like the Evil Quint moniker Wingnut.

Day 2 tried the assymetric fins in the front. Didn't really notice the difference which is good because there are lots more assymetric fcs fins around.

Winddoctor tried the board and he figured it worked. Like a papal blessing

eastside wrote: Winddoctor tried the board and he figured it worked. Like a papal blessing

SURF, MY SON!