hey crew,
just getting back into wave-sailing after a few years off.
Found a nice cheap twin, which i'm stoked to ride.
just wondering what the basic idea with twin fin sizes and shapes are??
i've got my head around singles, just wondering how small and soft you can go?? (with twins)
insight would appreciated.
cheers
your a twin man maris.
just trying to get funky with shapes and sizes.
theres so many small US box fins around.
got some numbers??
Hey there,
I ride an Evo 86, last years' model, can run it as a single or a twin. It came with a pair of Drake 16s which look nice but I found it real difficult to point upwind with them with the cross-on winds we get in Perth. I just got a pair of 17.5 Maui Ultra X-twins, slid them right to the back of the fin boxes and they are great for pointing upwind but still nice and loose when you need them to be.
sorry
couldnt resist
i am actually over us boxes and overpriced fins
futures boxes are way cheaper and lighter and their new sup range are ideally suited to windsurfing IMHO at first glance and much cheaper.
probably more for quads than twins, but im in the process of expirmenting and ripping us boxes out of old twins and sticking in futures. easy to stick two futures in twin and make a quad too
Interesting idea using SUP fins.
But my Maui Ultra fins (slot box BTW, not US box as shown in the stock photo) shipped from UK cost the same as an equivalent size pair of Futures SUP fins.
I'm using makini 15" weed twins on my rrd 74 wavetwin...sweet. yes very loose when needed but I have no problem tracking upwind. I set them all the way back and being weedies already have a fair bit of rake back.
Oh and im 65kg. Prob should have said that 1st up 
I'm using the same on my JP 82 Twinzer/Quad and yes..because of the Rake..I it's going quite good Upwind, it also have a more "drivy" feel than a more upwrite fin..specially like the Maui Ultra Fin.
a pair of 7.3" ~ 18.5cm with wide base is a lot of fin area on the back of a 79litre board Josh
I would go smaller....
How about telling us:
1.what brand/ model your board is
2.year
3. volume
4.how much you weigh
5.a little about what u used to ride as a single
6. maybe what kinda conditions u ride in (on shore/ side shore/ beach brak/ reef/ jumping???)
Then you will get some better answers.
Fins are just like boards and sails... ask a group of wave sailors which one works best and you'll get a range of responses.
Working out what works best for you is pretty much a trial and error approach BUT a lot can be gleamed from what others say when put into context.
Context:
What conditions are they used in
What board are they used in
What is the sail size to board volume ratio
and the number one factor IMHO... what is the riders weight
As a backgrounder, on a 10 day sailing trip (late last year) with 8 or so mates, fins and their various pros and cons were discussed and trialled at length due to the arrival of multi finned boards onto the trip.
Long story short, fin set ups of different sizes, shapes and manufacturers were shared around so everyone could get a feel for how they performed for them.
One of the guys swears by K4 fins, loves how they flex and talks of a 'slingshot' type effect when the board comes out of a bottom turn and flings him into an upward trajectory... almost whip like.
Context:
Rider 1
84 lt twin fin (board)
Conditions (cross shore wave sailing)
Conditions (22 knot + so 4.7 size sail)
Fin size 16cm (soft/flexi fins)
Rider weight 80kg
Rider 2
Same conditions except for rider weight 92 kg VS 80kg and bigger sail (5.4 vs 4.7)
Found fins over flexed to the point of feeling like they were actually folding over at which point the board would slide out, grab a rail and pitch on the bottom turn
Consensus: rider weight plays a huge impact, the heavier the sailor the hard (flex perspective) the fins needs to be
Trial 2
Rider 1
84 lt twin fin (board)
Conditions (cross shore wave sailing)
Conditions (22 knot + so 4.7 size sail)
Fin size 16cm (hard/stiff fins)
Rider weight 80kg
On this set up majority of riders around this weight (75 - 85 kg) found the board a lot harder to turn and did not like the new feel
The heavier guys preferred the harder/stiffer fin as it allowed far greater control but did not report the same difficulties in turning the board.
Greater weight = greater control/drive when using harder/stiffer fins
Most of the riders were somewhat surprised to learn that fin flex did not necessarily correlate to height of the fin
IE inserting harder less flex based fins allowed much smaller fins to be used (to the point where some of the heavier guys were running much much smaller fins than the lighter guys)
*Can not comment on early planning ability as conditions were wave orientated, that said, pointing ability did not seem to suffer when smaller stiffer fins were inserted
When applied to a quad set up the variance between fin flex was even greater.
Rider 1
Same conditions as above
weight (90 kg)
Stiff/hard fins
13.5 cm mains
6.5 cm fronts
Rider 2
Same conditions as above
weight (80 kg)
soft flexi fins
16.5 cm mains
8.5 cm fronts
Consensus: rider weight plays a huge impact, the heavier the sailor the hard (flex perspective) the fins needs to be
Conclusion: Try before you buy AND experiment with fin placement on your board before trying different fins.
*A couple of the riders marked their fin boxes with permanent marker pens so they could accurately set their fin positions and record what position had a specific effect on the board. Once they knew how fin placement impacted on their individual set up they began experimenting with different fin types
Finally: Ask ask ask... but put the various responses you receive into context in trying to determine what is going to work best for YOU.
Horses for courses !
Apologies for the long winded response, but hope this casts a little more light on the topic... and for the record this is just an opinion based on the events as stated above.
Cheers
Kev
To add to Kev's post here is my experience as an intermediate wavesailor having got back in to it this year from a few years speed sailing.
Conditions: Cross onshore 5.3 and some 4.7, small waves with the occasional trip to somewhere better.
Weight: 75Kg
Board: 85L ish custom twin.
I started off with K4 (plastic) 16cm fins and found that I could not get upwind and they did not cope with the larger sails (5.8). Since had advice that they are not good for onshore but good for down the line.
Swapped them for a pair of 7.5 inch (19cm) JP G10. Set them in a recommended position of just under the front strap screw and found they made a huge difference without costing too much turning performance. Coped well with waves up to half mast at Lancelin. Big advantage was the ability to get upwind to be in position for waveriding. It is very difficult to improve your riding if you can't get in a good position on the wave. Downside was that on low speed slog days they were catching weed and were hard to clear.
Just recently bought a pair of Makani Walu weed wave fins in 17cm. Very stiff fins in G10. Placed them more forward in the box to put the centre of the fin in the same place as the JPs. Less drive upwind (as you would expect) yet perfectly adequate but enabled a much tighter turn on the small waves I sailed in.
So.. I would say for someone of JB's experience/weight in side off conditions a smaller 15/16cm flexier fin would work. For less experienced sailors in cross on, bigger fins will improve your experience.
