Twin fin placement...... help please!!!!!

General Discussion
1

Hey Guys

Just finished shaping my first twin fin and looking for some advice on fin placement. The board is 6’2’’ and is 12 1/2’’ inches pin to pin. I’ve purchased a set of small Larry Gephart glass on’s and really want to get them in the correct location and do the fins justice

Any input would be excellent - Thanks in advance, Chaz

2

how long are the fins at their base?

3

Hi Kirk

The base of the fin is 7 1/2’’ and at it’s highest point is 5’’ high, double foiled

Take it easy, Chaz

4

Hi Chaz

As a rule - based on advice I got from swaylocks over time - I place my keel fins with their trailing edge in line with the butt crack - that’s asuming I have a crack that’s 6" deep - I then set them 1" in from the rail (again trailing edge) and then usually have 1/8" of toe-in at the leading edge - some purists would say however that they should be straight - parallel to the stringer (which makes the board very fast but not as easy to turn. I also set them without any cant - ie vertical or at 90 degrees to the underside of the board. Mine seem to work well - I guess I’m a novice on this too but all the guys I’ve made fish for seem happy with them. Good luck!!!

Cheers

Thirdshade

5

In general I would agree with the last post (albeight with limited experience). My twin had the keels set up so that the trailing edge was about an inch up from the crack. An inch in from the rail is a good bet, could go even a bit more ~1 1/4. The 1/8" toe in worked like a charm, very fast, gives some turning ability. BTW, this spec is typically given over a length of 4 1/2 “, so this will change if your fins are longer. My understanding was that double foiled fins are typically oriented straight up and down and straight forward on the board. Also made a 4 fin fish and had a set of smaller trailers that were double foiled with no cant. Didn’t work well with my fin box set up, being toed in 1/8”. Felt very ridgid and slow.

6

i’d say go 7" up on a 6’2". 1 1/4" off the rail and toe’d in at least an 1/8th with minimal cant.

7

Geppies? Your a smart one. I say in line with the top of the crack, lined up with the tips. Straight up, no cant. They’re Geppies for God’s sake! Mike