Earlier this week we were talking about sanding problems.

Few people understand how to choose a grit and how to use a power sander.

Here's the hornet's nest.

I think using a block plane to go over a stripper hull is not only a waste of time
but counter productive.

I know, I can here the hornets, but if you are a novice listen to my argument.

The genius of strip building is that if you align the edges of your strips and your strips stay in contact with the forms the resulting surface is fair and nearly perfect! I've not seen this simple statement anywhere. Just as the panels of a stitch-n-glue hull are perfect and fair, there is a small surface down the center of each strip that's perfect. The less you do to that surface the better. Only the joints of the strips are high.

This is why aligning the edges of your strip is your number one task. Nothing else is as important. Dry fit each strip, clamp it in place, make sure it will fit before applying glue.

And if you have strips that are not aligned go back and fix them before doing anything else.

This business of using a block plane started to simply take down high spots of misaligned strips. And it started because back in the 70's disc sanders were used to sand strippers. These were awful to use, dusty and difficult. The only other sanding option was a orbital sander which was a finish sander and not powerful enough. So some people who hated using these sanders started using a block plane to smooth the surface of their strippers.

The problem is, that if you remember that a stripper hull is nearly perfect, the fixed depth of cut, and flat blade of a plane will destroy that fair surface.

One cut across the center of a strip and you have a low spot. Try using a plane on a plywood panel of a stitch-n-glue boat. Yes, it would destroy the surface!

Try using a plane to smooth your glassed surface. Ouch! It's pretty obvious in those cases isn't it.

You do the same damage when you apply a plane the wood strips. You destroy the fair surface the strips naturally create.

Now when the random orbital sander came along the game changed. The speed of the disk and the random action has enough power to remove material aggressively. The whole disk surface is held flat against the wood and rides on the high spots. Disk speed and grit along with hand pressure give you tremendous control over the amount of cut. This is why you can comfortably use 60 grit on your fiberglassed surfaces.

Most of all the flat disk is large, rides on the high spots and, with a soft backing pad, even conforms to curved surfaces. The cutting surface is never less than 5" wide.It works very well across grain and excels at rounding surfaces perpendicular to the strip orientation.

Strip building includes a lot of sanding, there's no way around that. Many people who don't exactly know what they are doing find sanding awful because they start with too fine a grit and wonder why nothing's happening.

If you learn how to use a sander you will find it fast and satisfying.
Start with a course grit to level the surface. Course grits are 24, 36, 40, 50 and 60. Sanding grits of 80 and above are used to remove the cut makes of the courser grits.

On a ROS start with 60 grit. It will level the surface quickly without the need to "erase" a low spot or blemish. It will not sand right through your wood, I use only 3/16" strip, if you always hold the disk flat against the surface.

You will see results immediately. You must look carefully at the surface you are sanding to see when you have removed the high strip joints. Once you hit the fair centers of the strips, producing a uniformly sanded surface it's time to move on. The ROS is held with the disk ALWAYS flat against the wood. Constantly moving the sander back and forth or up and down work from the finished uniformly sanded surface to the rough surface. If you do this your surfaces will be fair without the need for a fairing board.

Wet the wood after rough sanding to raise the grain. Then you can jump to 120.

I do the same with glassing, but you must plan for this. I apply 3-4 rolled on fill coats to the wet-out glass, then rough sand with 60 grit. Then I apply two new coats of resin. This surface looks like it's varnished its so smooth. Then I sand with 120 and 220 and varnish.

I hope some of you novices will save yourself save time and mess and leave that pane for tasks it was meant for.

All the best,
Rob