Thursday 15 December 2011

Stripping and Bare Bottoms

DIY Bottom Blacking part 2
November 2011

Having hauled Wand'ring Bark out of the water we were faced with the prospect of cleaning down the hull, ready to accept the new coats of protective bitumen. 

A first blast with the pressure washer

The first and most important element of this process is the availability of friends, especially on these short winter days. I was very fortunate to have Martin and Adam available to help, our two man recovery crew who have picked the boat up from the four corners of the inland waterways over the years.

 Capt Ahab Roto Blasting

Stafford Boat Club have a good industrial strength pressure washer available which made light work of the accumulated slime and weed, together with acres of loose bitumen, taking the sides down to bare metal in many places. Adam proved to be very good at this task, methodically working his way round the boat with plumes of spray erupting from under the hull from time to time. Martin set to with wire brush, scraper and sandpaper hacking away at the stubborn corners whilst I wielded the Tercoo Rotating Blaster which made short work of all the large areas.

The cleaned sides

About three hours concerted effort resulted in a clean hull, which we left for an hour or so to dry out, ready for the application of the first coat of Sealex.

 Close up of the Roto Blasted sides

They say that 80% of effort in decorating should go into the peparation and the same could be said of cleaning the boat's bottom. Our end result wasn't perfect and with hindsight maybe we should have spent more time on it. But the underside of the boat is the working end of things and its more important that the sealing is effective than beautiful.

An annode having reached its half life

The extensive use of the rotating blaster seemed to provide a good key, so hopefully the future bumps against the bank will result in scratches in the bitumen rather then the flaking off of big patches of black - which has been the case to date.

Martin applies a final rinse

As for the state of the hull? It is nearing 10 years old, so some deterioration is to be expected. In the event the pitting such that there is appears to be very minor and shallow, worse in the centre away from the protective annodes, as you would expect. The sections below the waterline were stripped back quite thoroughly and the general consensus among the assembled members was that it was looking good for its age. They put this down to the use of decent quality steel during its construction and informed me that they have seen much worse on three year old boats built cheaply abroad.

A rather grimy shot of Capt Ahab - post Roto Blaster!

I did consider blacking the bottom of the base plate but a quick inspection revealed very little deterioration in the 10mm of steel, certainly not enough to justify the horrible task of squeezing under and working in such cramped conditions.

More about the blacking process next time.

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