Otterblog

A record of the renovation of a
Wooden Drascombe Longboat 'Otter'


28th November 2006. The Transom

Started in-depth study of transom area. Removed GRP sheathing to reveal rot.

 

The rot affects the outer two layers of ply. After that the wood appears sound.

The sheathing goes behind the outboard mounting pad but I can't see how to remove that.

On the inside everything appears to be sound. All the hardwood fillets are completely sound. It is only the ply that was rotted.

I noticed a crack in the ply. Strain from the outboard motor?

The sheathing is not the colour that I expected for glass cloth and resin. It has a colour approaching black. Here the resin is brown where it seems to have picked up the colour of the wood to which it is bonded. Perhaps there is a pigment in the resin

 

I am making steady progress sawing the keelson from the hog. You can see where there are brass screws which I have to cut through with a hacksaw blade.

I think I now understand how the rot progressed. It started with rainwater standing in the bilges. Eventually the bilges rotted and the water reached the GRP sheathing. It then made its way up the outer plies by capillary action. When it came to a corner, such as a chine or the transom it continued up the outer plies. The endgrain ply, which is vertical, was the main conduit.

So, from the inside the ply looked solid and from the outside the sheathing looked solid. But within....

See video at YouTube

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Unless stated otherwise, Colin Watt 2006, 2007

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Last updated: 2 January, 2007