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Jan 31

Creating a skimmer rocker bed

We’ve been talking about building some skim projects and that entails making up an entire new set of tools. One of the things we use frequently in our build process is a rocker bed. It maintains the bottom rocker and for our Flyboy Wakesurf surf style board it also maintains the bottom concave. So each test board has the same rocker and concave and that allows us to isolate the effect of changes to whatever we are working on in that test board. It’s not nuclear medicine where we have to worry about properly choosing between a myocardial perfusion scan or a parathyroid scan :) We can pretty readily isolate segments of the wakesurf board and their effects on performance. But having rather static rocker and concave’s makes changes in the smaller details much easier to differentiate.

So we want to do the same with our skim board projects, although we aren’t, at this time, doing any bottom contours, so the skimmers will all have a flat bottom. Also, the rocker on our skimmer is very VERY shallow. About 1.5 inches and most of that is in the nose. So from the apex back, the resultant wakesurf boards will be almost flat. That’s definately NOT what our surf style boards rocker bed looks like, so our skimmer rocker bed will wind up being significantly different.

So the very first thing we do is draw up a rocker template and transfer that to piece of melamine. It can be just about any substance that won’t readily melt with heat. The template is a reference of the selected rocker and as we are building boards, should we need to hotwire any foam, we’ll attach the template to the foam and hotwire the shape. This includes the 2 pound density EPS foam that will serve as the skimmer rocker bed.

Here is a picture of the fiished rocker bed, so that you get a visual of what we are trying to build. We think it will make the rest of the steps easier to understand.

Skimmer rocker bed 001

Now back to the first template, this is after we have transfer the general shape and then cut it out with a jig saw.

skim rocker 002

We then use the first template to cut the second and we attach them together and sand them down to the same curve.

skim rocker 004

Once we have a set of the templates we can attach those to either side of a block of EPS foam, in this case 2 pound density, and hotwire the rocker into it, which creates the basic structure of our skimmer rocker bed.

Just for completeness, we’ll post that first picture again. Now, this is one step further along in the process. After we hotwire the rocker, we laminated a piece of 6 oz eglass on the top.

Skimmer rocker bed 001

You’ll note the slight amber color to the deck lamination, it’s a rather cheap but stiff industrial grade epoxy. Epoxy is often touted as stiff and that’s a lie, it’s the most flexible of the three basic resin types used in wakesurf board manufacturing. It’s tough, like a rubber band and about as stiff. :) This particular grade of epoxy is pretty stiff, but not so clear. We really should say that there are formulations of epoxy that can rival polyester and vinyl ester for stiffness, but they aren’t clear so typically aren’t available from shaping retailers.

Once we have the rocker bed laminated and that has cured, we clean up the edges and then draw a centerline own the middle of the skimmer rocker bed. This will give us a quick visual when we are aligning our skim style projects on the bed. We also draw an outline using our preferred shape. We won’t always align with that shape, but we will always align on teh centerline so that we don’t end up with any twist on the rails.

Skimmer rocker bed 002

One last finishing touch is a surface treatment of mylar. Mylar is actually a polyester and has a very smooth and shiny surface. We’ll wax that up before any construction and the result will be smooth bottom surfaces that won’t stick to our skimmer rocker bed!

Skimmer rocker bed 004

Thanks so much for following along, hopefully we’ll start posting pictures of some skim builds here shortly and we’ll show the use of our selected divinycell wakesurf board core foam.

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