Big boy Simmons-inspired design questions (help!)

General Discussion
1

Hi all,
First, I’m happy to see that Sway’s in still generally alive! I used to frequent here under an old account many many years ago, and got a TON of advice from the community. My dad and I are now 30+ boards in! I’ve been away from surfing after kids and life in general, but I’m able to get in the water a bit more frequently now, and I’m kicking a design around in my head and need some help.

I’m trying to design a board for San Onofre (or general smaller, rolling waves, maybe a clean Church day) that fricking flies in a straight line. My current idea is a 10ft-ish Simmons style outline with very little rocker (maybe 1.5" in the tail and 4" in the front), 23" wide point, 3.25" thick, and a tiny twin or quad setup so I can slide the rear into a wave if I want to. I like sharp, low volume rails, a pointy nose, a rounded tail, and very little bottom contours going on other than a slightly concave entry to mid. I’m thikning of placing the fins further up than usual (sort of like an oldschool fish, not quite Aussie kneeboard). For what it’s worth, I like to surf a 7" or smaller greenough style fin in my 9’8". I just love to stall and haul ass down the line. Love that feeling!

With that context, here are some questions I have…
-How do you think this board will work?
-What are some of the major advantages of a twin or quad setup?
-Am I just nuts?

Thanks, looking forward to your responses!

I attached a screenshot of my VERY QUICK sketch from BoardCAD–are you still using that???

Screenshot 2025-07-25 at 12.07.14 PM
Screenshot 2025-07-25 at 12.07.14 PM2846×894 335 KB

2

I will get things started with these:

image
image2160×1441 460 KB

image
image2160×1411 347 KB

2 Likes
3

Links to Simmons’ shaped boards:
(Scroll all the way down for top, bottom, and side views)

https://shacc.emuseum.com/objects/7216/simmons-sandwich-model-with-twin-fins?ctx=89240fd1be443dc2cf1efc8840b0b2c8241cef1b&idx=1

https://shacc.emuseum.com/objects/7954/1940s-wood-spoon-longboard?ctx=89240fd1be443dc2cf1efc8840b0b2c8241cef1b&idx=0

https://shacc.emuseum.com/objects/7222/spoonshaped-fiberglassed-balsa?ctx=89240fd1be443dc2cf1efc8840b0b2c8241cef1b&idx=3

https://shacc.emuseum.com/objects/7191/solid-balsa-simons-spoon?ctx=89240fd1be443dc2cf1efc8840b0b2c8241cef1b&idx=2

1 Like
4

If I had a nickle for every time someone wanted to design a board for San-O…I’d have 15 cents!

Look for the recent post from @haavard in the Announcements section for the latest developments related to BoardCAD.

Welcome back!

1 Like
5

Thanks for all this links so far!

6

I have been a diehard single fin/mid-length kinda guy for decades. Though my latest quest for the past 4 or 5 years has been finless. Regarding the nuances of building a Simmons Spoon twin, I don’t believe anybody here can credibly comment what Simmons envisioned. But I understand the desire to re-create and ride an historic classic.

Regarding Twin vs. Quad, I decided copying this Google AI summary was as good as anything I could offer personally. I got this Google AI response searching “twin vs quad surfboard fins.” I think it is a reasonable, “general summary.”

“Twin and quad fin setups offer distinct surfing experiences. Twin fins emphasize speed and a loose, flowing feel, often favored for smaller waves and point breaks. Quad fins, on the other hand, provide a balance of speed, drive, and hold, making them versatile for various wave conditions, including more powerful waves.

Twin Fins:

  • Feel:

Known for their speed, flow, and looser turning style.

  • Ideal Conditions:

Best suited for smaller waves, point breaks, and waves with a long, open face where you can link turns and maintain speed.

  • Considerations:

May not provide as much control as other setups in powerful or steeper waves.

Quad Fins:

  • Feel:

Offer a combination of speed, drive, and hold, making them versatile.

  • Ideal Conditions:

Suitable for a wider range of wave conditions, including more powerful waves and situations where more control is needed.

  • Performance Characteristics:

Provide a balance between the speed of twin fins and the control of thrusters, with the potential for down-the-line speed.

  • Considerations:

Fin placement (distance between rear fins and their position relative to the front fins) can affect how the board performs, with closer and further back placement influencing the board’s feel closer to a thruster or twin fin, respectively.”

7

This side view gives a better idea about Simmons’ rocker, foil, belly, and rail. (Click on image to enlarge.)

image
image356×1857 29.6 KB

8

Thanks Stoneburner.

I’m not looking to make a replica, but instead I’m aiming to borrow a few design elements such as:
-low rocker, especially out the tail
-a wide tail
-lots of planing area
-parallel rails

One the ways my design will diverge from the classic design is the bottom–I want a pretty flat bottom (maybe a bit of concave in the mid section), and generally hard, squirty rails that will release plenty of water.

All the info is very helpful!

9

At that length with parallel rails, I’m not sure knifey rails are going to help performance much.

10

You’ll be doing a lot of angling. They don’t exactly turn on a dime.

1 Like