Wednesday 7 August 2019

Sanding Inside The Hull

I have read many times that building PocketShip is 90% sanding, and sometimes it really does feel like that.

So before I started the rather large task of sanding the first coat of epoxy on the recently applied fibreglass in the bottom of the hull, I had a serious think about how to do it efficiently.

There a quite a few tight places in the hull which are difficult to get to, such as around the floors.

I suspected that the Festool Rotex 90 would be too big and clumsy to do the job. It seemed to me that a small, cordless detail sander would be very useful.

Research, however, failed to find anything suitable. The detail sanders were all aimed at the occasional DIY user. They all had the same size pad as the 90; none of them had effective dust capture; and the grits for all of them were expensive and not easy to source in bulk.

So I abandoned that idea and went ahead with the Festool. It worked just fine!

The geared rotary sanding mode was ideal for aggressively feathering the edges of the fibreglass and roughing the surface, and the delta attachment was ideal for getting into awkward corners and doing the faces of the floors, bulkheads and the centre board case.

Here is the sander.

As mentioned in a previous post there are nine bays in the bottom of the hull, each with a port and a starboard panel. Each would receive two more coats of clear epoxy, sanded after each coat. It would be really easy to forget the status of each panel, so I drew up a spreadsheet when I 'glassed out the hull, to keep track. Like this.

This proved invaluable. There are still two more coats to apply and sand at this stage.

As an example of what they looked like afterwards here is bay 9, feather edged and sanded to a matt finish ready for the next coat.

And here is bay 8, starboard panel.

Note that there is now no unsightly raised edge on the fibreglass. It will look great when finished!

It took a total of 19 hours to sand all of the bottom interior and chines.

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