I recently shaped a small Bonzer with a thin tail, I used the FCS system to install all the fins, inc the rear fin. I thought every thing was going well until I went to put the rear fin in and found that I had ground too much off the fin box and the fin base was sticking up proud. Aggg.
I knew that it was gona be tight as I had such a thin tail and routed it out as deep as I could go without going through to the deck.
The only post I could find in the archives suggested going through to the otherside, (which caused abit of a slanging match between a couple of members!), or just make the board thicker in the tail.
For future boards yes making it thicker in the tail is def a good idea, or does anyone know of a rear fin system designed for thinner tailed boards, as alot of guys must be using reglar longboard boxes on small bonzers.
For this board however, I have a couple of options none of which sound great, but I’m resigned to the idea I will probably have to route out the fin box and start again.
Should I
Go through to the deck.
Modyfy the box, I was thinking, - grind the base right out, and put a thin bit of glass over the base so I can install as normal.
Modify the fin, - I really don’t fancy this at all.
How short are you? If it’s only a mm or so, modify the tab on the fin. If it’s much more than that, grind off the plug base so it fits, then modify the fin tab if you have to.
Hey NJ, The board is a 5’11’’ round tail and is just 3/4’’ thick where the box starts from so the fin tab is pretty proud, maybe 5-6mm. Modifying the base seams to be the way to go. It just seams a bit crazy if this is a common problem that there are no thinned boxes for these types of boards, or maybe its just not such a common problem?
I think I’d just knock off however much from the bottom of your fin tabs until they set flush. Make sure you don’t have any resin drips down inside the plugs from installation - that could keep the fin from dropping in, Don’t ask me how I figured that out.
Any routing out of the plugs now is liable to become a slippery slope… I.E. can you do it without chunking it all up? You plan to open the slot from the bottom of the plug and cap with glass? There may still be clearance issues with the fin tabs if I understand correctly.
Just grind the fin tabs. A glass fin should handle it OK.
If I’m picturing this right… the board’s only 3/4 inch thick at the back plug, and the plug depth is about an inch, so you have to grind off more than 1/4 inch of the plug for it to fit in the board. If you take it off the top, the tabs wont sit on the board’s bottom when yo do the install, and you run the risk of grinding down too much material over the grub screw, leaving not enough structural integrity to the plug - if you (somehow) hit the fin from the back, I’m afraid that grub screw could pull right through the thinned out top of the plug. I think the problem is better solved if you bore out your hole a little shallower than it should be, leaving a thin bit of foam between the plug bottom and the deck glass, and grind off the bottom of the plug so it fits the hole, and the tabs still sit on the bottom of the board when you install them. If you have to shorten the fin tabs then, to make the fin base sit flat, do it. But I think grinding too much off the top of the plug is sketchy.
Sounds like you screwed the pooch on this one? I’d do a glass on fin and call it a day. fin box modification is asking for trouble. Also next time leave your tail area at least 1 1/2" thick? theres no reason to make a tail area 3/4" thin… it’s the rail area that needs to be thin, not the entire deck area. Dome that puppy.
Install the plug(s) as deep as you can ( through to the deck) with the screws on the wrong side of the fin, take out the grub screws, grind that sucker down. Now drill and tap threads for new grub screws in the correct side of the plug (only works with the old solid plugs , Euro plugs and scarfini plugs) Fit the fin and grind a little off the tabs if required.
You can do the same just the grub screws will be on the other side. No biggie!
If the grub screws are still solid then as others have said, just modify the fin!
The only problem I see with that is… if you have a plug that has been exposed through the deck, one shot with your heel straight down on that plug could send it poppin right out of the bottom of the board… or at least crack it around the perimeter. It’a my understanding that the foam between the plug and deck is key.
Future uses a ‘‘half-depth’’ trailer box that fits well in thin tails. FCS Fusion also goes in thin ones well, but width might be an issue on your concave peak.