Quad fin schools of thought

So as I am marking fin placement for a quad the other day I started thinking… Way too much. About fin placement of the quad cluster. It seems there are a few different approaches to this. Some folks just put them close to the rail and call it a day with 1/4 and 3/8 toe in respectively. Others go a little more rogue and use the Mckee placement. But others I have notice, like Stretch in particular do not put the rears on rail. They put them roughly 2 inches in from the rail and slightly more distance between the rears and fronts. I understand the reasoning behind this, as it helps the board act more like a thruster or whatever. I thought it would be utilized more on his wide tailed boards, but he seems to use it on all quads. Can anyone weigh in on this? I’d like to know how he calculates it or similarly how someone else who does it marks out the fins. Also, are they at the same toe in angle or different angles? Just looking for some insight. I know there has been multiple quad placement threads but this one is more specific to Stretch style quad fin placement and why and how it is marked and used.

I’d add that the McKee placement, in my limited experience with one board, was terrible. Slower than any other quad, not as loose as a thruster. Trailers shouldn’t be that close together.

Ron,
Thanks for that piece of info. I was just waiting to hear something like that so I can decide not to use the Mckee method. I am however interested in doing both on the rail quads and some with the rears set in about 2 inches like Stretch does. I just need to know what toe angles are being used and distance from leading edge of rears to trailing edge of front. I guess I can measure a Stretch I have here, but I hate taking the 2 minutes to do that.

Measure the Stretch.

I’ve always been rather fond of the classic on rail placement of the quad clusters. When done well, they are great. I did a McKee last year on a 6.4 fish and the thing feels a little stiff but rock solid in bigger surf.

There are quite a few approaches to quads. I am no expert, just an occasional builder who thinks about this stuff way too much. Besides McKee’s approach, at other end of the spectrum is the Robin Mair method (sorry Robin, I think it’s just gonna be called that forever). If you go to the Gearbox Fins website, there is gobs of info.
A common approach is simply halving the distance of the front fins from the tail. Very few put 1/4" of toe in their rears. Depending on the design, you’ll see anything from no toe to 3/16". It’s hard to say “as a rule” because you’re balancing so many things it’s hard to make any rules.
Another approach is Rusty’s, which he explained in his Surfline design blog (a wealth of solid info in that blog).
I’ve wondered about Stretch’s approach as well because it looks different from just about everyone else’s and he’s been doing it longer than most folks.

I’ve done robin’s version on a few semi normal squash tails, they were 5’6" and I found that by moving the entire cluster back to the tail by 1/4 inch. but I also think I may have stuffed up and made the front and rear pair a little closer than they should have been. But I have used a variation I picked up from Grant Newby, for wider tail simmonds style tails.
I have to say the Newby cluster are epic.

I would be willing to share the Newby ones but maybe by PM not open forum.
http://www.swaylocks.com/forums/2015-bc-thread-my-version-blendingcurvescom-nug-b-50-x-215
pretty sure its on here somwhere.

Robin Mair’s quads are designed to be loose like a twin or speed dialer. That’s why he keeps them closer to the rail. I copied a Stretch Fletcher 4 and I liked it. His rear fins are moved in more, then rears have less tow. I also like the Alexander Gemini quad layout. Those rear fins are even closer to center and they are straight up and no tow.
I often take the rears and space them out about half way from the center line and the rail. Use about 1/8 tow or no tow, and very little cant. You’ll get more of a thruster feel. I use probox fins, so I get some fore/aft movement and I can switch out the inserts to change cant. Then there’s Greg Griffin’s 5 fin layout which I really like. They are about 1" from the rail, and the rear fins are lined up 3 across the board.
You have a stretch to take measurements from… you should do that. I’ve taken measurements of all the boards I like and use those as my guides. With the proboxes, you have lots of adjustment, so fine tuning it can be done. I don’t mess with that much. Maybe spread them apart more or less, and change cant on the rears. I prefer boards that seem slightly stiffer than too loose.

The further towards the stringer the rear fins are set, the steeper the wave needs to be.

That’s one way of looking at it.

Also the quartet by neal purchase Jr. Both fins have the same toe.

http://nealpurchasedesigns.blogspot.com/2011/06/quartet.html