i’m using jensen’s method of building a hollow wooden 9’2" longboard, and i was hoping somebody could help me with a glassing schedule.
the wood is 1/4 balsa and redwood, and i was thinking of doing 6 under and 4+6 over for the top, along with 4 under and 6 over for the bottom. would this be strong enough for a 140 lb person like me? i’d rather not ding it, but i would like to save some weight as well… i also can’t decide b/w poly and RR epoxy, so comments on that are more than welcome. thanks in advance
I have not worked with wood yet, but Bert (I think) uses 2oz over and under his balsa skinned boards. His skins are not as thick as 1/4". Now is not building hollows, but the lightweight EPS provides little if any strangth and is really just and interrior mold. With the hollow you’ll want more under the skin I’d think so that the pannel does not flex between the ribs, but you should not need much glass on the outside of the skins.
I think that’s lot of glass. I would do it 4 oz inside 4 oz outside for the top and bottom. That’s the way I glassed my 7’2’’ HWS, using poly resin. I’m 170 lbs, and after 1 year of using the board, it’s as strong as the first day (no delams, blistering or something). If you are using epoxy it will give you more strenght.
Maybe you can only glass the outside of the bottom to save weight (what I’ll do in my next board) since bottom doesn’t take your load. Remember strenght in hollows is in the rails.
I read about some people who built their HWS glassing only the outside. Maybe Paul can give us more advice.
This is a shot or two of how I did my latest board. Apologies if you are ahead of me here. This is my 2nd hollow, the first wasn’t glassed at all on the inside and seems pretty solid but there are only 3 pieces of wood making up the deck rather than the 40,000 or so that go into a board like P. Jensen’s.
The join in the woods is covered in carbon fibre, wrapping up onto the stringer and ribs. The bottom has patches of c.f. between where the stringer and ribs will be to reinforce the joints. The whole thing feels really solid already and I haven’t even glassed the outside yet.
jack, what were your top/bottom skins made of? do you know which is stronger; doing all of the little pieces of wood vs. one slab of ply? also, if there is a slight imperfection or flat spot in the bending frame, how does it end up affecting you later on? is the plywood forgiving because it naturally makes a good arc? thanks
Top and bottom skins are one piece, I built the entire board using only hand tools, and was too lazy to cut several pieces to build up the skins.
I think skins built from several pieces must be reinforced inside and outside.
Little imperfections in the frame doesn’t show in the final product. And I think any mistake made in the frame can get fixed before gluing the skins to it.
Do you have any pics of your board? I’m interested in building one like yours, but I’m afraid of the final weight of the thing.
that’s a nice looking board, i remember studying it a few days ago and having questions but not bothering to ask. i’ll post pics of my project once there’s something to take pictures of… i’ve just been resawing balsa lumber, cutting out frame pieces, templating, etc… should have something to show for it by tuesday though. if you have any tips or anecdotes that you feel would help, please send them my way. thanks for all the help, it looks like i won’t be needing near as much glass as predicted… i think i’ll make some test pieces and see if jensen’s willing to share his .02 cents.
I’ve attached the original plan for the board, it is pretty much true to the plan but I did lower the rocker by 20mm nose and about 12mm in tne tail. I’m a novice here and this is just a made up by me shape, have no idea how it will perform. The blocks inside are just either pieces of ply in the nose for a bit more rigidity and blocks of pine in the nose and tail, again to add a bit off strength and to fit the leash plug into. I didn’t bother with blocks for fin boxes but probably will next board. I’m still working on this board but my last one surfs OK. (attached)
that’s nice lookin. would you recommend RR or poly? i think i’ve almost convinced myself on the RR, but is is an extra 100 bucks or so. i just got finished bending the inner rails and making the final ribs and rocker template. i’m wishing i had two boards to work on becuase i figured out how to do all of the little steps. i’d save so much time by not having to figure things out and redo mistakes several times over…
Regarding Poly or RR: I glassed with poly my first board because: 1. I was a student back then, and money was scarce. 2. after doing a little research I found that there is no epoxy resin in Mexico. 3. After doing another research in internet about poly resin and wood, I found that years ago, before epoxy was invented, all boats were made using poly resin, and they worked ok. So why not a surfboard?
Now, if you think your work is worth a hundred bucks of epoxy, go ahead. I’m not a student anymore, finally found a epoxy supplier, and I glassed the inside of my fish with epoxy and cotton fabric (see attached pic). I didn’t like the resin, it doesn’t flow and wet the fabric as poly does, so I’ll glass the outside with poly.
w.r.t. RR epoxy, it will wet out better than poly. Older epoxies did not wet out as well but the newer stuff is great. As for cost, it looks more expensive but use uswe/waste so little that it really is not. You can mix as you go without harm so it is OK to underestimate (i.e. no need to leave it in the pot when your done).
that said both will work; I just like the benefits of epoxy.
I’ve only used poly resin so far, I can’t really justify the extra expense of epoxy to the missus. I think that the epoxy would be more resistant to dings but you can always repair anyway.
The stuff I used first was Seabase x7 poly from Seabase in England, I found that even in a cold garage (and I do mean cold, this is England) and putting less catalist in, the resin was kicking far too fast for me, as I was totally lacking in experience with glassing. The stuff that I’m using this time (I’ve done some fins already with it) wets out better and holds off for about 40-60 mins which is plenty of time for me to get it on and flat it out, it’s also not as thick as the other stuff and so levels itself better, oh and it was 1/2 the price at £3.00 kg and with no delivery charge as I can pick it up on my way to work. RESULT!
I personally am going to stick with poly until I really get the hang of this board building thing. Though the lack of toxic fumes from RR epoxy that I’ve heard about is appealing.
All the best and don’t forget to post some shots of your progress.
Okay, so I have a question then. If you use 6oz carbon fiber on the stringer of the HWS, and 6oz reinforcing the decking material on both the top and BOTTOM, and you were say 260LBs, what would you glass the top and bottom of the board with. Granted, the top and bottom decks are Fir w/ Purpleheart for a stringer. They seem pretty darned strong to me just from the carbon fiber. The rails are 1/4" balsa strips, 6 of them, glued together.
Would a 6oz S cloth work for the top? We’re using only epoxy resin on the the board.
I used 5oz top and bottom on my 3 HWS using epoxy, free lapped from one side to the other covering the rails and onto the flats, I’m around the 200lb mark, nothing moves, no leaks, no nothing.
I didn’t use any glass or epoxy on the insides, just liquid nails and a whole heap of bricks…
I would go with what Paul Jensen suggest on his site (or lighter) especially if you have carbon under the skins. I went totally overboard with double 6 top and single 6oz bottom. It still rides good, but it’s heavy to the point where I try to avoid surfing it near other surfer because it will damn near kill them if it hits them. I think most of the strength is in the wooden framework anyway, the glass is just there to seal it all and prevent it from dinging.
I try to avoid surfing it near other surfer because it will damn near kill them if it hits them
Whole heartedly agree with that statement, I was standing next to my board in the water last summer, 1’ slop and looked away for a second and the damn thing flipped up over a wave (if you can call it that) and smacked me in the side of the head, saw stars, numb face, wife said don’t ever surf again etc… (yeah right!!!)
