So when I first started doing BalsaComps a few years ago it was suggested to me to add an 1/8" piece of wood on either side to support the fin box or it may pull out with that first hard bottom turn (this is with no center stringer).
This is the way I’ve done it since the very first and haven’t had any problems:
Then last night I posted this info on the ‘another balsa egg…’ thread. This morning I recieve this message from SuperFatPat
Hi Tridrles,
Didn’t want to take over the balsa egg thread, although perhaps this is relevant. When you add those supports in for the finbox, does it stiffen up the tail too much? I would think it would lock the deck and bottom skin together and kill your flex. I was thinking of putting a high density foam insert in, the way I do with my trifin boxes. Perhaps a bit wider than usual, to spread the load over more of the bottom skin, but try to avoid locking it to the top skin. Have you tried this approach with negative results?
So that made me start thinking…
I don’t know! I haven’t tried anything else but I’m thinking… I know SharkCountry (?) and his brother put the supports in lateral…left to right at the front and back of the fin box so that the board will flex more.
Here’s the question…
How can we make our balsacomp fin boxes strong enough so we don't rip'em out and can keep the flex? Lighter weight
wood? Denser foam? Let us know what you do ar what you've been dreaming about.
My boards are 8’ to 10’, I’ll be at the Swayloholics next month. Bring your boards and lets see if we can tell the difference in flex or is the flex infront of the fin box? OR is…?
I had always dismissed that the support would make much of a difference. I did the wood when I did longboard fin boxes and solid corecell inserts (covering both plugs with one piece) on the fcs installs. On my last couple boards I followed the recommended round inserts and I feel the difference is noticeable.
I was just thinking, didn’t you post a bunch or broken longboard photos a while back. If I am remembering correctly some of the breaks where just in front of the fin boxes (but it might have been Laravat - I never can keep track of you N.Cal guys )
Dan! How’s it? Can you show us a pic or diagram of how you did it? I mostly use Futures 10" boxes and lately FCS little side boxes also.
Yes, I’m at least one of the people posting broken boards, actually it was my 2nd or 3rd balsacomp. It had balsa rails and broke in the middle and 2’ back from the nose it was narrow (for me…21.5"x10’x2.5) and thin . About board 13 I bent (slightly) the nose again about 2’ back. No problems with the rear half of any of the boards.
I’ve been routing my fin hole (Lokbox, 4Ways, Single Fin Boxes, Vents, Leash Plugs) and filling it with 8# pour foam. Here’s a pic of the foam half way through the expanding process. I dig out 1/2 inch or so extra diameter, and dig down to the deck/bottom skin for the tie.
Did it before the bottom was on before too. Maybe easier at the hot coat stage.
Not sure about the long term performance of this method, I’m pretty new to compsands.
Pour foam for 3 fins= +/- $4.00 US
How much do the HD biscuts vs. the “stringers” vs. pour foam vs. other ways?
Try making a few longboards and you’ll learn a thing or two about breaking them Where I normally surf there is about a 2:1 ratio of shortboarders to longboarders. Sometimes it hard to fit all that nose into a small pocket.
Tridries - I haven’t worked out a perfect method for the longboard boxes. I’m not fully sure that these boxes belong on compsands. However, I’m just getting started with a new single fin. The only reason I’m making it composite is because I want to leave it in my van so I want the vent on it. I plan on making it pretty stiff (doing things like rapping the top and the bottom of the rail with skin) so I’m not too worried about tail stiffness. I plan on using the O’fishl longboard box. They make really good things for boards with skins since its possible to place the bulk of the box below the skin. I think I’ll also use a corecell insert.
The only one that actually broke, three pieces!, was under 2 1/2" thick with pinched balsa rails, no stringer/springer. It had 1/16" skin top and bottom with 4oz. S glass under and over the balsa. I was on an overhead wave that began to close out and I bailed out the back shoving my board right into the impact zone.
The other two boards bucked slightly (in the nose area) in the same type of wave. They were both 1/16" balsa except the rails were Redwood.
The last long board I made is a 10’er, wider 24", and thinner 2.5" with cherrywood perimeter stringers (1" from the edge of the rail) and, about 1/2" balsa outside of that. I put 3/32" balsa on this one to see if it would help the strength with the cherry stringers. Haven’t been in too big a surf with it yet, 6’ at second reef Spanish Bay, but looking forward too it this winter. It’s holding up just fine.
Next experiment/board I’ll add a springer, I’m thinking of using 3/32" thick bamboo just under the deck from the edge of the perimeter stringer towards the center, about 2" wide.
)
Where I normally surf there is about a 2:1 ratio of shortboarders to longboarders. Sometimes it hard to fit all that nose into a small pocket.