SHAPER'S HOTSEAT: Larry Allison aka ProBox Larry

Hans, Yes I do play with different foils depending on application. The Ninja fin is a perfect example. The Ninja Blade which is the G-10 with Red vertical fin below I designed in 1988, which is 7/16" thick for Windsurfing. The Ninja Weed from that same time frame I brought back in 2007 like in the pics below of the 3 colorful ones at 3/8" thick for Standup Paddling. 

The Windsurfing Pointer Blade at 7/16" thick with a 45 percent leading edge foil and 65 percent trailing edge foil tracked straight while pushing water at that thickness which is what you want at high speed to have control with very little tip deflection. In the Standup world taking the same Ninja shape going to a thinner foiler of 3/8" with the same foil break down had less resistance threw water at low speeds which went faster than the thicker foil of Windsurfing. Note Important: By changing the foil thickness it also changed the flex dynamics. Thicker foil in Windsurfing less deflection able to point and hold better. Thinner foil for Standup Paddling good hold with a deeper plan shape with more flex which reacted like having a smaller fin of 2" less on your Standup Board which carried high volume went faster.

As for moving the foiling section around I will explain that in answering gdady question about thicker foil from front to back.

Thanks Hans for the kind words. Always find your projects unreal my friend. 

Artz, Very clever question my friend.

Single fin would be a Sparkey, because of it’s large range of performance dynamics.

For multiple fin set-up GT style fins, due to hold and drive dynamics.

Hey Larry,

I was wondering if you could give some insight into how you are laying up your panels. Do you lam up all sheets at once? Do them in stages? Do put a release agent down on the surface you are working on? I am just beginning to play around with fins & would love to hear your process for making the panels. Thanks



Gdady, Not sure I understand the first part of this question about Rake or are you referring to plan shapes?

As for thicker foils, are more reactive on boards that have more momentum but slow on boards with less momentum. A thicker leading edge like this Joe Aaron fin (Hot Curl) outline is better for quick response and tightening up the fin from flexing laterally for projection, same like a Paul Gross fin foil on a narrower outline design.


We lay up the panel all at one time. Adding Harder to the resin at different stages of the lamination for working time to do this. Yes you do put down a releasing agent to pop the panel. 

Hey Larry,

Thanks for taking the time

and so freely givin’ advise.

The burning question for me would be

How or what do you do in hand foiling

to achieve consistant “inside foil”  fins.

Thanking you forward.

God Bless

If you are talking about Twin fins, scribe the template and flip it to duplicate your flat surface.

If you are talking about foiling a single fin center, read the fiber glas lines from each side and try holding the grinder at the same angle when foiling. This takes practice over time!

A short video of me working! Enjoy! Yes I still get in the sand pit!LOL

LA on the move rocking out while sanding Bill Stewart's 2 colo... | Larry fine sanding Bill Stewart 2 color fins for spray on a busy Monday after a morning at the Beach. | By Larry | Facebook


North Shore style ! 

Paper mask with facial hair filter .  ;-)

Hi Larry,

What kind of tool / pad are you using in that video?

Larry , love the Sparky and rarely use anything else on my 8 foot and up boards. I need you to make me a white glass on for a restoration. I have the template . Let me know when you are doing a white panel and I will make time to bring it by. Dont know if you heard but another one of our 70s surf crew has passed on. Probably have not talked to you since the last paddle out at TB.  

Larry, You have become very involved with Stand Up Paddleboarding.  Since I am now on the gulf coast of Florida. I do alot of flat water boarding in the gulf. Minor chop and wind.  My question is for the un-race boards what fins would improve the tracking of my board? 

What do you do to get all the glass dust off your body when you work in short sleeves and shorts?

Nice to hear from you Chris, the sanding Pad in the video is a Power Pad not a Flex Pad which is a Plastis Cheap imtation of a Power Pad that guys are selling for a cheaper price. The machine is Hitachi, but discontinued the model in the video!   

I have White coming thru this week for Arrow Surfboards. PM me and I will make it happen for you my friend.

Didn’t hear about another passing which is driving me crazy. I enjoy talking and spending time with you guys and my friends because our time is short here on this beautiful planet. Stay healthy my friend! 

What kind of Board are you touring on my friend!

Sharkcountry, I dont sweat alot so my pores dont get effected like some from fiber glass dust. I air myself off and take a cool not warm shower and you are good to go. Hot shower will allow your body to react with the dust and when putting on a polyester material shirt you will go crazy.

Mahalo Larry, I sweat a lot, so if I’m sanding glass I like to cover up. Even then the dust gets into areas where didn’t cover up good. I use a soft bathing brush when I shower and that seems to help quite a bit. Do the brush on the exposed areas first then shower as usual. Fins are not on my list of things I like doing, glad there are people like you who do it for us.

Hi Larry,

What kind of tool and pad are you using in this video?

One more thing, I don’t know why, but I’ve torn out Proboxes on several boards in the last year. They were all in EPS or XPS boards. In one board I don’t recall hitting anything and it broke loose from the foam. I’ve only lost one box, but that was because I fell right on the fins. I’ve had this happen to 4 boards total but 3 since last October. Going forward, I am going to add support in the foam under the glass.

Speaking of supporting the box…

One other thing I remember from talking with you is your comment that many box/plug failures are actually the results of the surrounding foam moving around as opposed to the box itself failing in isolation to the rest of the blank.  I’ve been using 4# PU foam inserts and collars for my installs because of that.  My question is where do you think the point of diminishing returns is for foam density around a box or plug?  At what point should I not bother to reinforce the blank for a plug or box install?  

Related to that question, I’ve also been doing rout-in fin installs:  install HD plug insert into the blank prior to shaping, then shape, glass and finish the board and do the rout-in install last.    It allows me to tie the fin install to the deck lam and use deeper and longer fin tabs that have more contact area with the foam.  

I would imgaine you have experience with that sort of thing so again, where do you think lies the point of diminishing returns for the foam inserts?  If I just skipped the insert and did the rout-in to a standard weight PU blank do you think that would be sufficient, or is that risky?