Hi all I have used a delta fin a few times recently due to an unusual amount of weed at my local and I have trouble turning the board broadside let alone downwind it makes the board feel like it has a centreboard. It is a 30 cm maui ultra xt 50 g10 cut and rounded off to 28cm and I have been using it with a Fanatic Falcon Lightwind and 8.5 and 9.5 camless sails. It doesn't have any more surface area than the big pointers I normally use with this rig but it feels like it has massive grip and is impossible to spin out even if you try really hard. Is it just too big for this set up?
That's a much bigger Delta than any I have used. I have 16 to 20, I thin my Fangyfin is 22.
Highly likely that fin is far too large.
That is the exact fin we use in our Gemini Tandem at Lake George and it worked well it that huge board. 
Select to expand quotemob dog said..
Hi all I have used a delta fin a few times recently due to an unusual amount of weed at my local and I have trouble turning the board broadside let alone downwind it makes the board feel like it has a centreboard. It is a 30 cm maui ultra xt 50 g10 cut and rounded off to 28cm and I have been using it with a Fanatic Falcon Lightwind and 8.5 and 9.5 camless sails. It doesn't have any more surface area than the big pointers I normally use with this rig but it feels like it has massive grip and is impossible to spin out even if you try really hard. Is it just too big for this set up?
Why not use a normal weedy? Unless you are sailing shallow water they are much better.
Not many deltas will handle 30cm + chop. I'm surprised that one does! 
I've got the delta xt50 in a 28 and use it with anything from my ultrasonic with a 9.4 to my fox 120with an 8.6 and I actually found the opposite, great downwind and terrible upwind. Some of my quickest runs are using it on the fox with the 8.6
My experience with my 30 cm is more like Ben's - insanely fast off the wind but it will spin out in chop. I'm not expert but I get it off the wind when starting by footing hard with my front foot near the mast, then scoot back on a pump to get my front foot in the strap with back foot not far behind, then back strap once fully planing. I'll still push it hard off the wind until nearly at full speed at which point I'll tighten it up to a close reach or whatever. I use it with 8.6 mostly
My experience with my 30 cm is more like Ben's - insanely fast off the wind but it will spin out in chop. I'm not expert but I get it off the wind when starting by footing hard with my front foot near the mast, then scoot back on a pump to get my front foot in the strap with back foot not far behind, then back strap once fully planing. I'll still push it hard off the wind until nearly at full speed at which point I'll tighten it up to a close reach or whatever. I use it with 8.6 mostly
Maybe it's no good with the 90cm wide falcon. The one time I found it not to bad was on 80cm wide patrik f race. I'll try it out on that board again.
Maybe just need to get used to it, I found it horrible the first few times after using race fins for years
Select to expand quoteBen1973 said..
Maybe just need to get used to it, I found it horrible the first few times after using race fins for years
Gave it another crack today on my JP SLW which is 92 cm wide but narrows in the Tail compared to the falcon LW and it was not too bad. Still had to push it hard to go on reach or broad but once there it seemed to hold there comfortably. Had to stomp really hard to get it to carve tight though, but again once carving seemed to go round comfortably. It definitely does not like boards with really wide tails. Next I will just try it briefly on my formula board to see if I can confirm this.
You should be using the fin on the right for deep water surface weed ( less rake angle and deeper length) not the delta style fin on the left this fin is for shallow water weed ( Budgewoi , Primbee, Lake George etc).
You will have more power and be able to point higher with the weed fin on the right.
Apart from most people saying his fin choice is wrong, does anyone actually have technique advice for delta use they wish to share?
Mast track back.
Harness lines a little forward.
I use this in moderate wind 15-20 knots, 6.8 sail/68wide board/20cm Tribal delta. The stronger the wind the more you can load the back foot and fly the fin. If having issues getting back upwind hold the uphaul with your front hand, gets the sail more upright and loads the front foot to drive leeward rail and fly the fin with your back foot.
Once over 20knots and on smaller kit and well powered all my settings go back to normal.
That said if the water is not flat don't use a delta....
