SHAPER'S HOTSEAT: Larry Allison aka ProBox Larry

OK, you asked for him, and here he is.  Remember your manners.  You ask the questions, he, alone, answers them.  Keep it civil and relevent.  (This makes it easier to lure others into the hotseat.)

Larry, you are on!!!

Larry, how did you get your start in shaping fins?  Did you train under someone?  Or just invent yourself into a stellar fin designer/maker?

Hi Larry,

(just for starters)

4oz vs 6oz for fins?  

Resin rich or resin lean, and why?

Besides fiberglass cloth what other materials have you worked with for buildings fins and what did you like/hate about them?  



Hi Larry, thanks for stepping into the hot seat!  Do you have a website where people can purchase your fins?

If someone buys their fins from you, and gives you the details of the board they’re intended for, will you give a suggested layout of fin placement?

And do you also design fins?

Greg, I was actually hired to cut fins out with a jigsaw at 13 years old for a summer job at a surf shop that just opened in San Pedro. I picked up a grinder 6 months later to get the feel of foiling, My first attempts were hacking up pieces of fiberglass scraps. Mike Stavros who was my boss at the time and the guy that hired me was foiling Jeff Ho flex fins for Natural Progression Surfboards. I started out as a rough foiler to help Mike finish foiling the fins. In time I started finishing the fins completely myself. 

Gdaddy, 4 or 6 oz dosen’t matter with a plan shape like a Brewer type fin or Rudder type fin where twang (flex) isn’t important. I prefer 7 1/2 oz because it gives me the best ratio of resin to glass for lighter weight and twang in a fin. Moderate saturation of resin is the best for a fin I feel to achieve best flex and weight combination.

I have made fins with exotic woods in the 70’s. In the 80’s I made fins with Clark Foam sheets and fiberglass 1st half for the surfboard Industry. In the mid 80’s I started making fins with carbon and epoxy like G-10 for the Windsurf Industry. In the late 80’s into the early 90’s we started lightweight Honeycomb fins for Windsurf and Surfboard market.

I hated working with G-10 material after making Windsurfing fins in the late 80’s into the early 90’s. 

Huck, We sell mostly through online distributors like or or my Facebook pages: 1) Fibre Glas Fin 2) Sup Race Fins 3) Larry W. Allison 4) Probox Finsystems 5) Click it Fins.

Yes I do tweak and design fins for others and myself Huck. 

I have no problem helping people and companies with placement and designs Huck as you can see on my Facebook pages if you follow me.

Hope that helps my friend.

Hi Larry,
Thanks for volunteering your time to answer some questions. I am a big fan of looking at the fin designs you post on your blog.

Do you mind describing any part of the process on how you guys decide where to put fins, say a quad setup, when you are doing a new fin design?
Also how sensitive do you think the placement is , for instance how much would move the rear fins in from the rail to get the board to respond differently?
Or do I have it backwards, and you choose a fin position and then alter the fins you put in the box?

Feel free to answer any or none of the questions, just looking for some of your intuition on fin placement.


Larry-- so what’s happening with Pro -Box ??  Still going strong?? What’s the status. Also--  do you still make your 10.5 single box??? Lowel

Thanks for the reply Larry - I never go on facebook, so completely missed your presence there.  Didn’t you used to have a website or blog with updates on what you’re up to - is that still going?  I do buy from fiberglass supply dot com, and love that they carry your product.

(Along with Lowel’s question) Does ProBox make single fins and single fin boxes?

Also, can you post up some pics of your current stuff, we love pictures here on swaylocks!  Feel free to advertise your wares in this thread, its completely appropriate here.

I will be back to answer your questions my friends, had a house full yesterday.

Hi Larry,

I’m wondering if you’ve been experimenting with different foil profiles.

If so, to what extend and do you mind sharing some findings?

I’d imagine that you’ve been experimenting with the location of the tickest point along the chord?

Do you find any differences between foils for windsurfing and traditional surfing?

I really admire your work, thanks for being here!


 Larry if you were stranded on a Desert Island with one short board and One Longboard what fin set up and fins would you want on your boards?  

melikefish, This JC board came with Quad positions very similar to what people call the Mckee set-up, where the rear set of Twins are inset off the rail close to the center box. When the owner of this board was riding this board he was having problems with getting the board to respond quickly in a beach break surf condition. So I suggested to add another set of twins closer to the rail behind the front set of twins. In adding the outside boxes the board came to life and was quicker responding. With Probox finsystem we can also change the Cant of the fins in aiding the responding feel. This is very important in a Quad world to have this option for beach break to point break which would be different Cants for Drive and Turning. Placement is sensitive, I have learned this by retro fitting over 500 surfboards and now 300 Standup boards from their existing placements and getting rider feed back or by riding the before and after myself.


McDing, Probox Finsystem as become the Finsystem of choice in the Standup world. In the surfboard world when FCS Fusion hit the market in 2008 the Probox sales dropped because of Glass over option. But because of the structure change and process Probox became a easier install to the boards of today. People screw up when installing Probox, when they install it like the other finsystems in a foam structure with no glass support. And I dont mean using mill fiber. I mean using a glass sock like the pic below.

Yes McDing, I do also make a 10" fin box called Hi Surf.

Yes Huck, I do have Blogs that I probably should update but with Facebook and Instragram people follow there first it seems like. The Blogs I use mainly to date my designs and ideas especially in the which supports me with the companies who bought the riders I had earlier on to legitimate themselfs so they think, LOL!

Probox Finsystems is part of Fibre Glas Fin so no need to call our single fins Probox which is a Finsystem brand. Other companies piggy backed into the market with Finsystems then added single fins as a after thought to gain market share. But at the end of the day they are still a shipping system and not a fin company, perfect example is FCS changing their name to Surf Hardware.


Also, can you post up some pics of your current stuff, we love pictures here on swaylocks!  Feel free to advertise your wares in this thread, its completely appropriate here.


Here are some pics of what I am doing now Huck! I paddle alot for fun and in some Races!

Probox Twins for Sup Race Boards and Surfboards for Infinity Surfboards!

Huck, I also created a movement with understanding multiple fins on Raceboards using ProBox Finsystems like you see here on this Infinity Raceboard and with other companies.

Somemore goodies Huck!

Okay, here’s another question about fin design:

I visited your shop once a couple years back and we got to talking about fin designs, specifically about singlefins.  You commented about the evolution of the templates and specifically how the rake evolved through the 50s, 60s and 70s.  Could you expound a little one that?  

I’m also interested in your opinions about fat fins; like 1/2" thick bases; and about fins with the more forward foils.