SVG version of Image:Triskele-Symbol-spiral-five-thirds-turns.png .

Converted from the following PostScript code:

%! /archimdouble{ %%%%%%%%%%%%%%%% % PostScript program to display an Archimedean spiral by approximating % it with Bezier curves.  Can display a double spiral (two spirals % rotated by 180 degrees with respect to each other). %%%  Parameters:                  % centerx = horizontal coordinate of center of spiral                  % centery = vertical coordinate of center of spiral                  % rotf = degrees to rotate /sepwid 110 def  % width separating successive turnings of spiral                  % (half this if double spiral is selected) /incrm 15 def    % insert a curve point after this number of degrees /sweeps 1.67 def    % number of 360 degree turnings to show /double 1 def    % change to 0 to display single spiral %%%  Procedures: /pi 3.1415926535898 def/radians 57.295779513082 def /sepwid sepwid pi div 2 div def gsave centerx centery translate rotf rotate /aspiral{/prevbezy 0 def 0 0 moveto     0 incrm sweeps 360 mul{7{dup}repeat         phase add cos/costh exch def         phase add sin/sinth exch def         costh mul radians div/thcosth exch def         sinth mul radians div/thsinth exch def         thcosth sepwid mul/x exch def         thsinth sepwid mul/y exch def         /slope sinth thcosth add costh thsinth sub div def         sinth 0 gt sinth 0 eq costh -1 eq and or{/flag -1 def}{/flag 1             def}ifelse         /A exch def A 49.29348 lt A 180 gt A 196.273450852 lt and A 360             gt A 368.8301 lt and A 540 gt A 545.9907 lt and A 720 gt A             724.5217 lt and A 900 gt A 903.6281968 lt and or or or or             or{/flag flag neg def}if         incrm sub 3{dup}repeat phase add cos sepwid mul mul radians div             /prevx exch def phase add sin sepwid mul mul radians div             /prevy exch def         incrm add 3{dup}repeat phase add cos sepwid mul mul radians div             /nextx exch def phase add sin sepwid mul mul radians div             /nexty exch def         /prevdist x prevx sub dup mul y prevy sub dup mul add sqrt pi             div def         /nextdist x nextx sub dup mul y nexty sub dup mul add sqrt pi             div def         /normaliz slope slope mul 1 add sqrt def         0 eq{/prevbezx phase cos nextdist mul def}{prevbezx prevbezy         x 1 flag mul normaliz div prevdist mul sub y slope flag mul             normaliz div prevdist mul sub         x y curveto         /prevbezx x 1 flag mul normaliz div nextdist mul add def         /prevbezy y slope flag mul normaliz div nextdist mul add def}ifelse}     for stroke}def /phase 0 def aspiral %%% If different sweeps parameter for second spiral, define here: /sweeps 1.34 def %%% double 0 ne{/phase 180 def aspiral}if grestore %%%%%%%%%%%%%%%% }def gsave 792 -230 translate -.95 .95 scale -4 rotate /centerx 304 def/centery 550 def/rotf 120 def archimdouble /centerx 634 def/centery 550 def/rotf 240 def archimdouble /centerx 469 def/centery 835.7884 def/rotf 0 def archimdouble grestore showpage %EOF