STUMP said..
After dialling in my silver bullet 72 with a 40cm mfc slalom fin Im looking for advice from other SB 72 owners on there fin choice for this board.
Im 100 kg and using 7.5/8.6 free race sails, I feel I can go smaller and will be chasing the top speed of this board in choppy ocean conditions.
I didn't get the original fin when purchased but im believe it may have been 36/37cm?
Older threads on the SB's don't refer to experimenting with fin sized designs.

I use my WTs in lake chop.
I can't speak for the larger size you have but when I 1st got my WT64 ( 112ltres) I tried the 39cms pointer I usually used and the board actually foiled for 10m..
This was back in prefoiling days..
It came down and kept going ok but after that I went smaller.
WT64 - 35cms tectonics Weed Demon - expensive but works great!
For my WT57 I bought WT weedies and they are perfect!
I find the Wt's need smaller fins and for my weight ( 66kgs) I like the weedies to settle them.
24cm WT stealth weedy for 12 -20 kts - 7.2m - 6.5 - 6.2 - 5.7m then 20cms WT Stealth weedy for 20 - 25kts.5m - 4.5m
Once it's 24kts plus the chop is usually getting pretty big and the board too fast . I used to change to my 85ltre WT but I've got too heavy and it's now a sinker. It has a very narrow tail area.
I have never had any control issues using the WT weedies or the tectonic..
I blast upwind and they are fantastic for doing bearaways. Could be an issue getting hold of them now..

Hey stump ,I don't have the same board but also 100 ,kgs my 73 I use 2 fins .the 40 for 8,0 ,8,6

Then I go straight to the 37 carbon fin .6,5-7,5 ,if buying 1 more fin a 37 sounds about the right size .

The Silver Bulet 72 is a classic and unique board.

My 72 goes nicely with on of Neils 44 cm fins - I use that for my 8.6 and it balances beautifully.

I go down to a 38 for the 7.8. I am 95kg. I use the 44cm 90% of the time.

The Silver Bullet 72 is incredible in open ocean long rolling chop / swell. It does give away a touch of speed ,in less powered conditions, in flat water / short chop - due to its rocker. But in open ocean conditions the curves match and you become invincible.

I find on the 72 the mast base needs to go slightly forward of centre to balance/ trim the board. Anything back of centre and i cant plane out of gybes.
I also set my front straps all the way forward. My trim set up is about flat trim and control.

Some people set things back a bit for "less wetted area / less drag" - and i suspect this may work for lighter riders. but i personally find that if everything is flat / nuetral on the water then the control and confidence allow me to push hard and get more speed.Because it does have a bit of rocker and curve -

when gybing,
as well as pressing down with your back foot to carve the inside rail (as you would in any carve gybe) -

try also consciously lifting with your front foot (using the footstrap) to bring the outside rail up.
Something magical happens and the board finds a curve that lets you do a beautiful carving gybe that almost feels like the board accelerates through the turn- so you can come out with speed, do a rig flip and sail away on the plane. For all you 80s / 90s freestyler / freeriding crew - This front foot lift also lets you do carving 360s (on a 4 cam 8.6) Its a small thing that makes a huge difference!

Just out of interest, what sort of speeds have you been getting?
Reading Reflex's post makes me wish I was younger and could try mine in the ocean. They are fun in short lake chop but swells sound great!

Love the 72 (and smaller SBs) - I second Matt's feedback, tho I am not in his league of skills
At 95+kg I usually go 8.6 with 42 or 44 C3 Sting (very powerful G10 fins, feel about 2cm bigger than actual size) and play with flex levels depending on conditions and mood
Have never tried carbon fins in the Silver Bullets, maybe quicker??
With their beautiful length and shape, just feel in control no matter how rough, and even at your 34knots in the ocean which is fast
Maybe you are missing that OMG edge of disaster experience, rather than actually needing more speed ...

Searoamer said..
Love the 72 (and smaller SBs) - I second Matt's feedback, tho I am not in his league of skills
At 95+kg I usually go 8.6 with 42 or 44 C3 Sting (very powerful G10 fins, feel about 2cm bigger than actual size) and play with flex levels depending on conditions and mood
Have never tried carbon fins in the Silver Bullets, maybe quicker??
With their beautiful length and shape, just feel in control no matter how rough, and even at your 34knots in the ocean which is fast
Maybe you are missing that OMG edge of disaster experience, rather than actually needing more speed ...

Maybe you are missing that OMG edge of disaster experience, rather than actually needing more speed -
I get that at 26kts plus in chop. Not from the board, but the worry that I'm going to get flung over the front by the sail in a big gust I can't see coming as I do a deep overpowered bearaway..
Love the adrenaline..