I have a weed speed 34. Not sure if it is EQCM size or other so a bit confused about which size of BP weedspeed to buy. I have discarded the delta idea as my shallow water is not exactly smooth and not super shallow, so want to just get a weedspeed that is larger than my current one
www.blackprojectwindsurfing.com/windsurfing-racing-slalom-fin-size-guide-including-options-for-weed-shallow-water/
Most other manufacturers that I can think of use actual depth for sizing of weed fins.
BP weed fins use "equivalent" sizing, meaning your "34" weed fin is equivalent to a "34" upright fin, even though its actual depth is considerably less. So in theory, you'd just need to take the size of your current upright fin for that board/sail size combo and choose that same number on the weed fin. In practice and with the current fin (45 degrees vs. the 40 degrees rake you have) you could go one size up.
Hope this is helpful.
I own the 34 and 38 in this model of Black Project weed speed. The numbers represent the length of the fin and as WindFlyer suggests represent the approximate equivalent length of pointer fin. I use the 38 with my Falcon 115 and 7m2 sail and the 34 with my Falcon 97 and 6.2m2 sail. I use 36 - 38 and 32 - 34 pointers with the same combos.
I don't know why Black Project insist on being different to every body else it's most confusing.
Rake and depth is what's needed, then you have a chance of working out what size you need. length of fin doesn't give equivalent size.
Wasn't a bad system & relatively easy for newcomers of raked fins to understand.
& they did provide those numbers originally somewhere including area. I dislike length measurement, measured from where to where- when I put tape on the ws34 I would've said initially it was 35 with some uncertainty but it is 28.2 deep. In a sport where some nutters have fins every 1cm there shouldn't be uncertainty.
It'd be nice for some consistency with weedspeeds bp, atomic & tribal all different.
What about the ride?
I've been really happy with the atomic weed weapons in the chop for grip (plus they aren't as deep for equivalent size to bp) but a bit harder ride as not lifting board so much.
Select to expand quotethedoor said..
I have a weed speed 34. Not sure if it is EQCM size or other so a bit confused about which size of BP weedspeed to buy. I have discarded the delta idea as my shallow water is not exactly smooth and not super shallow, so want to just get a weedspeed that is larger than my current one
www.blackprojectwindsurfing.com/windsurfing-racing-slalom-fin-size-guide-including-options-for-weed-shallow-water/
This was BP weedspeed chart from about 7 years ago, probably still relavant although the sail sizes were a bit ambitious
They were not too bad as far as weed fins go
BUT
IMHO you can't go past a Tribal Weedspeed for that upright fin feel and performance
Select to expand quoteducati said..>>>>but IMHO you can't go past a Tribal weedspeed for that upright fin feel and performance
Spot on, designed by WA's fastest sailor. If I had to buy a fin, that is what I'd get.
^^^
Trying to get one of slowie's weedies.they look good. Need one for my Perth trip at the end of the year. Then l meeting up with Phil aka Tardy for our Shark bay trip in early Jan next year. NEED ONE 
