Thank you all for the feed back I think I have gotten most of what I was looking for the basic concept behind doing this is to mimick the drive, control and pivot of the thruster but with some of looseness and speed (though turns) a quad set up. I think the last thing I need to decide on is the can’t of the back fin should I go vertical or a bit 2 or 3 degrees? What would be the benifits and draw backs to having a degree or none of can’t? As far as how close to the stringer think I’m gonna keep them close (1 1/2 max off stringer) with no toe
I strongly suggest getting boxes that will allow you to experiment. Probox allows for cant and fore-aft adjustments. 4-Way does all that and adds tow adjustments. Probox is designed to work with older FCS fins or probox style fins. 4-Way uses it's own fin tab design.
Using the 4-Way fin system would allow you to get the data you are asking for, plus you could fine tune the tow to suit you. The only thing you have to decide on is placing the box, the distance from tail and rail.
Every break has a unique aspect that would make it hard to say one thing is better or not. I surf a beach with 4 breaks in about a 1/2 mile stretch. Each one is a little different, and favors certain kinds of boards from longboards to high performance short boards.
...hello, please understand this right; I am not trying to be impertinent but seems that you did not read my previous comment, also the practical example that Hiloshaper posted.
What Sharkcountry mentions is very good in the reasearch department.
There s no magical measurement, that practical measurement depends on those questions. To answer those, you need to think about your previous boards etc
If you have a 5 8 x 18 x 2 1/4 HP quad and you want to move the board in a dime then search for the pocket on and on to gain speed and to have modern hardcore Surfing plus may be you are big, etc is not the same that if you are building a 6 8 x 21 x 3 low rockered quad and to want soul arcs or down the line and may be you are small etc
Then may be your standing position is TOO CLOSE or you are a front foot surfer.
I can write a lot but you have the point; so please, seat down and not ask for a magical number.
Too much theory and nothing concrete you can say, again Hiloshaper put a practical example.
I can add that if you have the complete quad experience and if you are a very good skilled surfer (so you always surf by the rails, carving) and surf consistent walls you better go not so small on the rears regarding the front ones.
I let you one example: if you have plenty of tail rocker the shape and position of the fin (regarding backwards or forward movements) should var depending on the intention of the board
Think about it.
Thank you reverb for your comments on this thread I did read your last post and although it may seam like I’m looking for some magic number I am not just seeing what people think or if they have experimented with no cant , no toe in and close to stringer quad sets and can give me some feed back based on there own experiences with that set up.
Reverb has a good point about stance too. I'm old and from the single fin generation. I tend to stand with my feet closer together than the kids today, and I tend to stand further up. Opening up my stance makes a world of difference for performance surfing, and having the rear foot on the right part of the tail makes a lot of difference too, doesn't matter if I ride a single fin, tri, quad or 5 fins. The further back you get your rear foot and the more you press with that foot, the more you can shorten the radius of your turn. That's probably the biggest reason today's surfers use a stomp pad, for rear foot placement. I don't use them.
That is a good point he made I guess I should have made it clear what kind of board I’m thinking of putting this on. It would be a hp board with a bit of a wider tail block. So yes the back foot placement is going to be over or behind the fin cluster Right up against the stomp pads kicker
Since you are shooting for a high-performance turn oriented board I think putting the fins 3 inches apart is to close. At that distance I'm not convinced you will get the benefits you seek of a quad. At 3 inches I think it will feel just like a thruster but possibly stiffer but lack the same thrust and instant acceleration of a quad. I'm not sure what you mean by pivot. On a single fin longboard you stand on the tail and pivot at slower speed. On a hpsb if you are really pivoting you are going slow. There are a number of things you can do to increase the tightness of your arc in turns so that it might feel more like a pivot but is really a tight radius carve. Increasing tail rocker, more curve in the tail, widening the tail in some designs or even those soft tail channels like are on a sci-fi will all make the board looser and tighter turning.
All other paramètres equal, More cant=more lift=over water feeling=more speed=less control. But 1° will not change face of world.
Thanks for your info lemat it’s been useful in understanding how it might feel
Stuff from a local shaper