Hi I wanted to get my new (used) ride a 10 foot Brown Dog slider wet yesterday but when I put the fin (that came with it) in and tried to tighten the retainer screw (that came with it), it just wouldn't tighten. Inspection showed the plate was flush to the base of the fin, but the plate slid up and down in the slot the plate slides along, which is wider than the thickness of the plate. Rummaged around and found a retainer set with a thicker plate (as thick as I've seen or used in any longboard finbox), tried that but same outcome... Is the solution a thicker plate (presumably so thick that it can just slide along the slot but is effectively flush when tightened)? Or are there fin boxes out there that need you to say use a washer above the fin box (extending over the gap in the fin box) to pull the plate up against. I probably haven't explained it very well! Surprised that I haven't came across this before. Looked at my other fin set ups and there isn't any overlap in the screw head over the finbox gap so the plate must be pretty much flush in the slot...

Maybe the depth of the tab on the fin is too deep??

Despite idiot status I explored a few fixes.... with no luck (reconfirming idiot status)! two of my thinnest plates on top of one another are just a tad too thick for the slot. And a "washer" won't work as the part of the fin (and every other fin I've got) which the screw goes through is actually thicker than the distance from the top of the fin box to the top of the slot, so you cannot get leverage from the washer to the pin.... Any other bright ideas? the box is branded Dion chemicals and says it has a patent pending, is there a proprietary type screw for this system? I've had Dion fins before and used them without problems in any other boards... Don't have any lying around now though (sold one with a board the other day!)

Thx Ricardo as per subsequent post (if it came thru) tried that all my fins have tabs same size.... And I have a heap! Including some smaller ones... That kills washer solution (smaller tab only helps if you fix it to the top of the fin box eg via a washer) and options i now see are trim down the tab to allow a washer, or create a thicker plate by attaching something else to the bottom of a plate, might have a tinker with that.
Does make me wonder about all my other fin boxes. There is nothing over the top of the fin box (like the washer I refer to) that they can pull up to, so they must work by the plate itself being almost flush with the slot??? or is the tab somehow angled to allow the plat to pull against it as you tighten??? Now I can't work out how my other fin set ups work!!!

Thx Ricardo as per subsequent post (if it came thru) tried that all my fins have tabs same size.... And I have a heap! Including some smaller ones... That kills washer solution (smaller tab only helps if you fix it to the top of the fin box eg via a washer) and options i now see are trim down the tab to allow a washer, or create a thicker plate by attaching something else to the bottom of a plate, might have a tinker with that.
Does make me wonder about all my other fin boxes. There is nothing over the top of the fin box (like the washer I refer to) that they can pull up to, so they must work by the plate itself being almost flush with the slot??? or is the tab somehow angled to allow the plat to pull against it as you tighten??? Now I can't work out how my other fin set ups work!!!

is there a difference in depth from bottom of tab to base of fin from this fin to others

I've had a problem before where the screw was too long to tighten the fin. Check the depth of the screw this may be the problem.

Cut it down with a hacksaw!

Had that before too and will check but think the plate is flush to the bottom of the fin tab... will check again!

I had an Island Fin Design fin that, from memory, was similar - I had to run the tab down on a sander, maybe 1/8" or so, before the whole thing would tighten up.
If you think the tab is too deep (and you could measure how deep the channel in the fin box is vs the depth of the fin tab), hit it with a sander or grinder or similar to take a bit of material off it.

Just put a shim between the plate and fin. Don't go grinding anything.

BTW I'll take payment in the way of alcohol.

Do you mean the fin once tightened is sliding forward and back in the box?

If that is the case try a few layers of packing tape on the sides of the fin base to make a tighter fit.

Sanders. Grinders .hacksaws. Hammer (macs personal favourite)Chisels. Blowtorch. Nailgun

Anything. Just get the bastard in there and stuck.

Perkins paste works but tastes like ****,
im here all day.

Dools111 afternoon mate, how old is your board, I also have a Dion brand fin box in my new NMC board and unlike other boxes the slot where the fin goes in is straight up and down so no tab for the screw will go down and then slide along. There is a recess however towards the front of the finbox which means the tab is on an angle and the slotted up into the tab groove. (If this makes sense????)

thx all esp crusty solution was padding out the base of the fin tab so the screw is effectively pulling the fin base down to the bottom of the box.

seems this fin box has a relatively wide slot, smallish upper face and longish lower face (ie above and below the slot) and overall a larger depth, so base of fin tab wasn't pressing against bottom of box. top of fin tab now sitting above top of fin box, a bit ugly and could be solved with some grinding of the top of the fin tab,. but on a 10 footer i doubt it will affect hydronomics (??) and i'm too lazy to tidy up. Same problem with every fin and screw i tried so must have been a weird box... perhaps some dion fins have a different set up...

Yep books thinking I have had the same problem in 3 old boards - if you had the same issue as mine basically the fin tab was wider then the width from the top of the fin box to the slot - did my head in the 1 st time - tried about 20 different screws / washers . have found 2 fixes - 1 is to grind down the tab so is less then the width from top of box to slot , works well and have not snapped any fins as yet ( might just be lucky )
other - Sounds like what you have done fit a washer so basically you are making the tab wider - have heard there is a commercial kit you can get made just for this problem - I just have a pack of rubber washes

I wouldn't grind the fin just adjust the shim thickness, FCS Once supplied shims with single fins.

What do you mean by shim thickness - tab thickness ? We had this topic on one of the surfing Facebook forums ( backyard board shapers )few months back - about half went for washers half went for grinding - 3 boards I am using at the moment -2 old 80s thrusters and one of my own backyard jobs ( probably sanded the box down to far ) all have the same issue - found the fins I sanded the tab down on much more stable ( less movement ) - sanded 5 so far
have to admit would be pissed though if the tab on a brand new fin snapped after thinning it down .
Was told jamming news paper down the side of the fin was the way of fixing the problem back in the day . Apparently gets wet and sets like paper mache - probably not the best look though

Yep FCS had about 3 long plastic shims you could fold them or add one, I've never needed more than 2.

Thanks for the explanation mate - are they still available ,made from hard plastic?I find the soft rubber washes I use easy to put in but still give a couple of mm play when tightened , just fold them over the screw .

With thinning the tab - its not so much grinding the fin tab , it's only taking off a couple of mm off the bottom of the tab . From memory the fin tabs measure about 12 mm , my home made board fin box depth to slot is 10 mm so taken off 2 mm . The old hot buttered boards slots are thinner again - 8 mm - which I think is pushing my luck - but so far all good . Being older boards the side fin boxes are the old longboard style as well as the centre .Must admit did get a bit nervous sanding away at the tab on my last lot of new Hanalei fins - great fins

I've used thin bits of plastic from old ice cream containers just depends what you need. Remember sometimes you need to pack/shim under the fin to bring the tab down. Doing this has a see saw affect.
did they ever talk about that in the other forums? Some people have bludgeoned fins with grinding but sometimes it's probably needed like when the fin is to wide for a box .....I don't know.

80 grit on a gyprock join sanding pad is my go to.

I shave them down to fit my narrowest fin box I am going to use them in and then use masking tapes to pack them out if I need to. Straws work good too. Usually can find one on the ground in the car park.

Match under the front of the fin to fill the gap in the bottom of the box.

And a rubber o ring under the head of the screw.

While talking about loose fins what are you blokes using to pack fins that wobble side to side , once again hot buttered side boxes - fin tab is tight so no up and down but both have a bit of play side to side - probably worse from a fin performance point of view

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Tassiedevel said..
While talking about loose fins what are you blokes using to pack fins that wobble side to side , once again hot buttered side boxes - fin tab is tight so no up and down but both have a bit of play side to side - probably worse from a fin performance point of view

Masking tape down the side of the fin, it kinda swells and wedges them in tight.

Thanks SP will give that a go - swell forecast here towards the end of the week . You blokes still surfing up there or is the beach ban statewide

Na ban isn't state wide, they closed the beaches at a few popular swimming beaches around here but no ban on surfing yet.