Any interest in a build thread?

[Surfdad]

Hard eges don't cause pearling. Most skimmers have hard rails all the way around and folks that are proficient at riding them don't have pearling issues. They are also mostly really short boards, so length isn't a cause of pearling, of and by itself. I know there has been a TON of misinformation tossed out there so it makes it really hard to determine what's what.

Water will wrap curved surfaces, like a round or soft rail and will release off sharp or hard rails. So a round or soft rail tends to keep the rail from sliding out, but also increase drag and will slow a board down. Foregiving in the classic sense of being slower and less responsive.

Sometimes I think unique shapes and combinations of shapes just have to be tested to get a feel for how it reacts. If you pursue the asymmetrical, be sure to post up the build process.

[Surfdad]

Ok in the last set of posts we had used the electric planer to quickly take large sections of the foam down. It's not very precise, though. So we use it to QUICKLY remove a bunch of foam and then use hand tools to do the finish shaping.

You'll remember in the last pictures we had left the bottom concave with a sort of stair step rough shape now we want to smooth that into a continuous curve. Your design might be different, such a channel with right angles, but regardless we are smoothing and doing the final shaping after the elecric plane.

The first tool we'll use is a surfform. It looks like a cheese grater and for folks that have done any body work with bondo, you've most likely already used it. That tool will take down the squared grooves of the stair step and with it's narrow width allows us to "grate" away foam on an angle to make the smooth shape of a flowing concave.

After that, it's sanding blocks. I typically never start with anything below 80 grit. This polyurethane foam will shape down pretty easily. Also, remember that on polyurethane blanks, the further IN to the foam we go, the softer it will get, so typically a reduced amount of effort is needed to make the same depth of cut.

Work your way from the 80 up to around 150, the foam should no longer have any visible scratches on the surface. Also run your hand along the surface, feel for lumps, bumps or any irregularities. Pro shapers use a room with blue walls and waist high back lights that create shadows on the board if there is any weird undulation. You can usually feel this sort of things with your hands also. Use your level, a popscile stick, anything that will allow you to check for irregularities along the surface.

I also like to shape some and check and then leave it for a day or two and then come back to it with a fresh eye to see if there are any weird parts I missed.

Now, as you are shaping the foam, the wood stringer, being a much higher density than the foam, will not shape away as quickly as the surrounding foam. As you are shaping the foam and running your hands along the bottom, you'll eventually be able to feel the stringer "proud" or above the foam. When that happens, you'll need to hit the stringer with a hand plane. You don't want to take a LOT of the wood down. So adjust your plane to where you're just barely taking a thin strip off with each pass. LESS is better here. This picture gives you an idea.

[Surfdad]

This process is really slow, keep sanding, planing and checking. Look at the shape from as many different angles as you can and you can make light pencil marks if you find high spots. Keep working and checking until you are ok with the shape.

THIS process should also give you an idea as to why you don;t want to cut to your final dimensions with the electric planer, it won't give you any room for this final hand shaping.

When you are planning down the stringer you may find that you wind up tearing the foam around it, leaving gouges. Don't worry about that, you can use a lightweight spackle available at Home Depot to fill those in and it'll match the foam almost exactly.

So here it is again! More hand plane and sanding. I didn't get a picture, but as a final pass, I use a piece of sheetrock screen to give it a nice smooth surface. I put the screen on a section of 2 inch thick sponge foam and then hit the surface in long passes, making sure to run the full length of the surface. This screen is often called dragon skin by shapers.

[Surfdad]

I'm not quite satisfied with the shape of the concave, so I'm going to do some more work on it, and now you know how that works! Rough deep cuts, check, closer shallow cuts, check, sanding, check, plane the stringer, check, finish sand.

[Doomswell]

I have a few im making as well. We have some work to do. All the boards on the right are wake surfboard blanks. Dig It!

[Surfdad]

Nice.

Where was I? I know that folks have some questions about rail shape and which is better or why. Lots of theory about what and why, but hydrodynamically speaking water will wrap around curved surfaces, creating more hold. In an oversimplification, round or soft rails are more foregiving in the slower and less responsive sense of that phrase. Sharper or harder rails make it harder for water to wrap and so tend to be associated with more responsiveness. There are any number of variations and all have their followers. We can generally associate skimmers have hard rails all the way around and they have almost zero hold. Softening from that will increase hold. On this board, knowing it's designed to be a cruiser I went with a rather traditional, soft forward blending to harder at the back. However, I am going to shape a small bevel at the nose as we might see on a longboard/noserider that will allow Fastfive to manuever some when he is further up the board, possibly riding tandem with the kids!

Sharp at the back!

I should mention shaping stands. I have a back injury and can't work with a board on taller shaping stands, so I use saw horses. But the surface is covered in a low density Polyurethane foam like you would find in a matress topper. As you are working with the blank at this stage, any significant pressure on the top will transfer to a dent in the foam on the bottom, unless your stands are properly padded. Handle with care is the watch word at this stage.

[Surfdad]

It's inevitable working in your garage that you'll get a ding in the foam from rough handling. Something falls on it in the garage or you drop it while moving it to the shaping stands. There's no need to try and shape the ding out, if it's not structural or won't compromise your shape. Your friend will be a super low weight spackle, like DAP's Fast N' Final. It's a spackle with microballooons, to make it really light and most are a bright white which will match Polyurethane foam or EPS foam. In fact, it's used frequently to seal EPS board before glassing.

A small dent can be quickly filled with a dollop of the spackle. Some before and after pictures. Allow the spackle to dry and then sand it off, being sure to not take too much of the surrounding foam off. Also, if you plan to do artwork on the blank, test with your paint before hand, it can create different shades with some water based paints.

[konajay]

OK, I'm all caught up on this thread and can't wait for the next post.

[IDBoating]

...can't wait for the next post.

Same here. I am crazy busy and have no experience at all and I still want to order a blank and start shaping. It's like drugs or something!

[Surfdad]

Thanks for following along guys. It really is fun and gives you an appreciation for how the board works with your wake.

I wanted to show one last thing regarding blanks, before moving on to the art and lamination on this build.

Buying a blank and having it shipped can get expensive if you are away from the coasts. It is possible to pour your own Polyurethane blank, with a mold made from common wood and plastic.

It's not the best foam, but if you're just playing around, it's more than adequate. You may have seen the two part pour foam at places like West Marine. The upside to this method, is that YOU can make the mold and the blank then is just like you want it, not some 8' long blank that you have to cut down.

Polyurethane is amazing stuff, it will stick to anything and everything except polyethelene. Like those cheap drop cloths you get at the big box stores. I line my wooden mold with that stuff and the blank just pops out.

This gives you an idea of what my mold looks like.

[Surfdad]

Just to be doubly sure I also dust the PE with some spray on mold release. This is overkill, but better safe than sorry.

[Surfdad]

The manufacturers normally give an expansion rate, like 30 times. Lower density foams willl expand more and ambient air temps impact the expansion also.

The working time is very short, like 40 seconds or something, so I have everything ready and I always use extra mix. You only have to ruin one blank by under mixing and you'll opt to waste some on all the others.

[Surfdad]

In order to get uniform expansion and get rid of the air bubbles that come from the exotherm during the cure cycle, you need to cover the mold. I always leave spots for the foam to vent thru. The expansion is really significant and will easily break the 1/4" plywood sides.

I always screw the top down to the 2 x 4 frame.

[Surfdad]

Like I said, I use excess

[Surfdad]

As I mentioned, Polyurethane is an amazing glue, you can form different rail with a higher density foam. It can be dyed any color, I used black here to color the rail material and also polyurethane is very heat stable. The exotherm associated with polyu would easily melt EPS, but an existing polyu mold is verty tolerant.

Also, you can see I've used the mold in a secondary bonding operation. The black rails are a 4 pound density foam and the core is a 2 pound density foam.

So it's pretty handy stuff.