I have a few boards that have been in use for a while and have accumulated their fair share of pressure dings on the bottom (longboards and shortboards). They are all water tight, but I’m wondering what is the effect of perfomance from this “swiss cheese” bottom. I couldn’t locate any info in the archives. I figure it must have a negative effect but I’ve never noticed a difference over the years, they still seem to ride the same to me. I’m guessing it wouldn’t be cheap to have them filled in (and it would add lots of weight?).
How 'bout the most basic sort of physics to look at the situation: Every time you make the water move, every time you make it change direction, it costs energy.
Thanks to Sir Isaac Newton, what, 150 years ago?
Thing is, you’ve gotten used to that board so over the time span, you don’t notice the difference. And on a 15-second wave, longer than many we ride, if it makes a one-second difference, you’ll never notice it. And that’s the key to a lot of the whack theory that’s floating around… you’ll never notice it.
Nuff of that, if the little dents bother you, sand them and fill with some qcell mix. Pour on only exactly as much as you need, then cover with a flat piece of stiff acetate like you may have used in school for report covers. The qcell/resin will cure with a very slick finish. Beware that you don’t trap bubbles under the sheet plastic.
What causes those pesky little dings on the bottom anyways?
I think the fix is worse then the disease. Leave them alone and surf it if they are not leaking. The dents on a golf ball make it travel further through the air. I seem to remember some one experimenting years ago with a golf ball (many indentations) type bottom. I dont remember what the results were, probably not good or everyone would be doing it by now. I think the weight of fixing them is going to effect the performance of the board more then the dents.
Yo,
Some surfers aren’t into maintaining the integrity of their board’s contours. I for one think that it’s the single thing that makes any given surfboard what it is. So here’s what I do.
If it’s a surftech I don’t have a clue, but if a board is of laminated construction you can very carefully apply heat to the dented area with a heat gun. You will want to broadcast the heat all over the depressed area evenly and bring the temperature up ever so gradually. If you do this you will find that for minor pressure dings the foam will expand and press out the depression. If you put excessive heat on the area it will delam so you have to very careful. Some areas simply will not return to their original contour. So don’t force things. For these areas tape off the area and sand with 80 grit exposing the weave around the depressed area. This will allow you to put a few layers of cloth on the area with sanding resin. You can then feather the area out. Then put a hot coat on and feather the area into the rest of the board. Epoxy laminated board can be managed the same way. It just takes a little longer for the resin to cure. The fix won’t be invisible but it will give the area some integrity and put the board back to it’s original shape. Some of my boards have many dark spots on them where I have done this several times on very low spots in order to keep the board’s contour and they still surf like they did when they first came out of the factory even though they are now 2 or 3 ounces heavier. If it’s just too too deep. I cut the section out and drop a foam plug in, reshape it feather the lamination back in.
In the end a 0.25% weight gain seems worth it to me.
Surf’s Up, Rich
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What causes those pesky little dings on the bottom anyways?
well i know the main reason for a huge one on my board and that would be my head (very windy day and dove off my board after a ride and came up and the board nailed me in the head not fun but it still rides fine)
This is all with my new sig in mind, mind you, and I’m a bit out on a limb, but I’ve taken on some very reinforcing reading today…
This issue as Halcyon states it speaks to how critical bottom contours are made by the boundary layer, and how difficult such critical flows/flow releases can make things. Criticality of this kind in a pure manifestation, given a glass-slick polished finish, would seem to make a board harder to surf well, therefore a worse surfboard (than it could be.) I explain.
If you could build the same surfboard in terms of foil, outline, everything else, but mitigate the criticality of the boundary layer movement over the bottom, specifically at the zone of the boundary layer’s separation and resultant turbulent drag behind (tailward of) any bottom curves, you would have a better surfboard, in the same way that the Ferrari F50 is a better sports car than a Ferrari F40, and the current Porsche Carreras are better than the old 911s, because they’re easier to control and drive well (the older cars were notorious for sudden catastrophic oversteer.) Easier to drive well today, and easier to rip tomorrow.
If you could mitigate this turbulent by inhibiting the suddenness of the release of the boundary layer, your boards would surf better, and so would you. To wit, if you roughen the surface very slightly, to keep the boundary layer incorporated with the mainstream, you keep the boundary layer from segregating itself so completely into a flow that can suck free as a turbulent mass after a bottom curve, given the mainstream’s turbulent above/below it, the whole a big zone of instability, where you could have had a flow/plane.
If you keep the boundary layer from adhering so laminarly/segregating from the mainstream, you keep the flow over the bottom more uniform overall, mitigate the mass separation turbulence behind the rocker curve and end up with a surfboard that works better–is more predictable, forgiving, and in fact, faster, with better plane.
Random dings aren’t going to do this uniformly though.
Greg
Wow, thanks for all the insight, I was afraid the question was so dumb no one would respond. The problem for me with fixing the dings, at least on my Old Faithful longboard is that there are just a ton of them, it’s approaching golf ball status! Good excuse to call the shaper and order a new one I suppose, and keep this as a back-up and to loan to beginners. Fixing it doesn’t seem economical. I too wonder where they all came from but I guess taking in that last wave to the beach when you think the water is deeper than it is, and you don’t feel the one cobblestone you went over. In fact, on my new longboard I have been hopping off well before shore and just wading in. After a few low tide sessions at my favorite spot I did notice more rocks than I had believed were there. Now on my favorite shortboard it only has a few so I should drop it off for repairs.
Who are you “gaucho”? Where are you from?? Why people insist on not to fill the profile up? Could you answer?
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I seem to remember some one experimenting years ago with a golf ball (many indentations) type bottom.
That was the Willis Bros, in Hawaii I think. Here’s a pic of one of their boards…
Ok, 11 YEARS! This is damn overdue a reply. So here goes…
Did the dents help?
Discuss 