Inline Single Fin

General Discussion
1

I’ve been exploring shapes that would suit my local beach, which is a shifty beach break, usually onshore head high slop. Now I have a full quiver from fish to logs and a host of shortboards. None of them seem to fit the bill just right in the marginal conditions on this local beach. There all great on perfect waves! The Flat Rockered boards that trim well don’t handle the situation when the wave suddenly turns from fat to an air drop in 1 yard. And those with the kicked nose seem to be pushing water once your’e up.

I’m thinking a 6’10" - 7ft Single fin with a similar template to the CI MSF2. about 4" Nose Rocker 2" Tail the recommended bottom from CI is Spiral Vee. I presume this dies out in the last 18". What I’m not sure about is the rails and their transition. What kind of volume should they have? I was thinking soft rails up to the last third and then a progressive tucked to about 1/8" of an inch in the tail. What do you think are the correct rails for a modern single fin.

I’ve never seen a in-line single fin and I’d be mighty grateful if someone could describe the setup or post a pic.

Thanks

My APS3000 plan is attached, to view it you will need to download it and open it up in APS3000

2

Hey there Burnsie, I can’t open your attachment so I’ve got no idea what your board design looks like. But an in-line or single would be a good addition to your quiver, especially in the conditions you describe. They go even better in good waves, my avatar is me on an in-line.

Personally I’d go a bit shorter, as the stability of the setup allows for it. Depends a lot on your ability and experience too I guess.

Although technically a single should be designed slightly different, I would choose something along the lines of a board you already know and like. The main thing I found helped my singles and in-lines was to bring the wide point back from centre a bit. And if you want to loosen it up a bit more, make the tail a little wider. The vee concave thing is personal choice depending again on your liking.

All this depends a lot on you actually, your weight, height, experience and style. Although if you ride something like this it should improve your style, as they will only do what you limit yourself to doing. Push harder, go harder.

I’ll try and attach some things I’ve been playing with, and would like to make in the near future.

Edit: couldn’t get it happening, sorry. do you know how to attach aps3000 files?

3

A couple thoughts…

I think you’re trying too hard. You have how many boards already, and none of them “work”? This is like the guy who comes to me for a board that will catch waves real easy (a longboard) but will rip and shred at the instant he wants it. Same guy, probably, wants his car to have all the power, speed and handling of, say, a Ferrari, but with AC, a back seat big enough to make out with three chicks, and so on. They ain’t made that way, friend!

Ditto your board: it has to surf head-high slop that suddenly turns into airshow stuff? You’re taking your Caddy to a racetrack. It can’t be all things at once.

Going a little further, we don’t know how well you surf… could be a hodad, could be a ripper, or anything between.

Only YOU can build a board for YOU. Keep asking though, any response could be significant.

4

hiya Greg !

as you’re one person who has actually RIDDEN an inline for many years , can you please tell me …

What sort of ‘gap’ /spacing do you have between the two inline fins ?

What size and rake are each fin ? similar , or not ?

For head high beach break like Burnsie has described , what size fins have you found to work best ?

I’m interested to give this a go in one of my long boxed single fins one day …

cheers !

ben

sorry … just one more …do you prefer stiff , or a bit flexy, single fins in this type of setup ?

5

I used to ride inline singles in windsurf boards, and all configs worked well. Really hard pivots snaps maybe get drawn out a little, but otherwise more solid and better hold.

ANY config, from tiny forefin and regular 8.5" trailer to two equal 7’ers shoved closer together by cutting the base. Seems anything closer than 4" works always.

I’m surprised big wave guns don’t use that fin setup, as there are few losses and many gains.

Seems a board with a curvy tail outline, and lots of tailrocker would suit your needs.

6

Isn’t it really an inline twin fin?

7

You could be right, but seems twins cannotes both fins the same sized, which CAN happen with inlines, but mostly front is bigger and trailer is smaller.

But most of my windsurf boards inline was the opposite!

Hecka day today…worked early, watched AMEX with comp ChampClub card (free lunch and drinks, we had doubles), surfed Cabrillo me first out, caught buncha OK lefts, then got swamped with 10 guys sitting within 30’ of me! I’m such a weak paddler I couldn’t paddle away, so got skunked instead and went in after 3 closeouts.

Naturally, then stuck in traffic for 1.5 hours…

8

thanks Lee , I’ll try those setups you suggested !

ben

9

THanks for you observations Honolulu. I take your point. I didnt explain myself properly. All my boards work in the appropriate situations. Any yes for slop, my epoxy longboard is probably the best but I work in the city and surf on the way home most evenings I dont want to look like a fool driving around every day with a log on the roof.

My 6’7 swallow tail thruster probably works the best in those situations, but It needs a touch more volume. I dont like the snappy turns of thrusters in waves where you can loose speed easily. Plus I like to build something that I’ve never tried before. This brings me to the single fin option. I just want to catch as many waves as possible in my 45 mins after work. The waves would probably let me pull of 1/2 moves.

Here is a PDF of the proposed board

10

I’d add an inch front rocker, move the rail fins up another 3 inches, and only ride it in mushy surf shoulder high or smaller.

11

Hey Ben,

Multiple questions deserve multiple answers, so of course all the measurements I used could vary from wave to wave, person to person.

My initial setup was roughly the same as a thruster, with the back of the fins at 11 1/2" and 3 1/2". The front fin had a base of around 5", depth around 8", the rear fin half of that. So to answer your first question, the gap would be around 5 1/2". After a few boards the measurements evened out to 12" forward and 3" rear.

Quite a few of the first ones I made were boxed, but with no adjustment due to the knock-out sytem I had. That would be next on the to-do list.

So immediately you have differences from a thruster because the leading edge of the front fin is further forward, the leading edge of the rear further back. The rake would end up being around 7", and I was mainly using straight edge fins. I started with curved rakey ones, but after a while I realised that there wasn’t the critical need for curvy rake because of the stability of the in-line.

The hold and manouvrability was balanced by the combination of fin sizes and placements. And although trying different size fins occasionally, the ones I liked the most suited most conditions. You could say they were stiff fins, because they definitely weren’t floppy, all moulded with foam inserts, but what I would call progressive flex. Stiffer at the base due to thickness (12%) but flexing slightly toward the tip. Pretty stiff though, no distortion.

I’m just a big fan of in-line fins, as you know Ben, the way they feel, the way they hold, the way they turn, the speed I could generate. But, apart from manouvrabilty, it was mostly the control. And that was in perfect barrells and onshore slop.

Give it a go, you might like it. Catch a wave for me.

12

thanks a lot for that info Greg !

I’ll let you know when I give that setup a go one day.

ben

13

Interesting-- I’ve been wondering about inline fins, uh, twins, singles, doubles, I guess, “single-double”? I wonder if there are pics of any of these kinds of boards and fin setups?

Also wondered about the straight-edged fin templates

Also wondered how that PDF has fins showing–could never get APS to show fins, although it has an option, “SHOW FINS”…

thanks

14

" I wonder if there are pics of any of these kinds of boards and fin setups? ’

hi janks !

I’m still waiting for the “right” day to try this out , but , as stated above (and waves permitting !) , I hope to be able to write down my findings , once I have ridden it .

[I also want to make a few BIGGER back fins for that setup , too]

I would figure , with a long enough finbox [say , 12"] in a normal single fin , people could easily try out this setup …I wonder why more people / I don’t ?? …maybe the fear of being laughed at ? Or , thinking "the second fin won’t make any / much difference ? " Because it’s not “cool” ? …I’m not sure why , really …

 ben



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15

…oops !

After just re-reading Greg’s ['Wildy’s] excellent , informative post above …

I realised I could do with moving the boxed single forward by 5 1/2 " from the position in the photos above , to make the back base edge of it at 12" from the tail tip , as he preferred .

[I will definately take a screwdriver to the beach with me though , so I can play around with different positions . And mark them on the finbox]

cheers,

ben

16

i read in an old mag. byrne surfboards made the same sort of thing for a pro guy named doug silva, i think in the late 90’s. apparently they’re good in the pocket and pivot, rather than draw a line. i’m looking at the mag. in question now. the info was in surfer magazine, april '96. the dimensions were; 6’1" x 11.5"(n)x18.5"(c) x 14.75"(t). looks like standard outline for the time. fins seem to be more forward than yours. the consensus from the ‘test’ rider (rob machado) says it rode like a single fin (which at the time he didn’t like). he also says it’s better to surf it standing right on the tail,

anyway, i hope this is of some use to you

17

" I realised I could do with moving the boxed single forward by 5 1/2 " from the position in the photo , to make the back base edge of it at 12" from the tail tip , as HE preferred ."

…which would look like this …

My question , Greg , is …

would this be too far forward on a wide fish tailed 5’8 in hollowish head high and bigger winter surf , or do you think it would hold fine ??

cheers !

ben



18

I’m also going to try an inline setup with a 6" front fin and 4" back in one fin box eventually.

19

…which board will that be in , Josh ?

do you have one with a 10" or bigger finbox ?

please take photos , and give us a report how it rides , when you do that , eh mate ?

cheers

ben
20

chip, if you start with the lead fin in a normal single position, and add a trailer, you need to move the main fin forward. How far forward will depend on the size of the rear fin. If you used a rear thruster fin you would want to shrink the front fin a bit and move it forward at least 2 inches. The front edges of thruster fins are three inches further forward than the front edge of a single would be on a comparable board. If you use a real small trailer, as shown in the pics, you will not be able to move it as far forward.

hth