Welcome to the Maunie of Ardwall blog

This is the blog of Maunie of Ardwall. After a six-year adventure sailing from Dartmouth to Australia, we are now back in Britain.

Monday, 15 July 2019

What we really hoped we wouldn't find

With Graham's new favourite toy, the Draper Expert SDS chisel drill, helping us get the last of the teak off the deck, the next process was to use a multi-tool blade and then an orbital sander to clean any remaining wood off the fibreglass. Slow and tiring work for us both but out $60NZ Chinese vacuum cleaner has worked wonders to keep away any harmful dust.

Di working wonders with the multi-tool
Our back-of-mind worry with this project was always that the fibreglass deck below the teak planking might be damaged. The challenge is that it's actually a sandwich: two layers of fibreglass (each about 6mm thick) encase a middle of end-grain balsa wood (the grain pointing upwards). The advantages of this construction are that the balsa gives good compression strength, it delivers excellent thermal insulation and, of course, it is very lightweight. The disadvantage is that if water gets into the sandwich, the balsa quickly rots and turns to mush. Knowing this, we always fixed any deck leaks as soon as we found them by renewing the caulking. Oh, what fun in the sun!

In the Aussie sunshine 3 years ago

Our biggest concern is that when the teak was laid, back in 1997, it was held in place with pins drilled into the fibreglass at roughly 6" intervals until the glue had set. The pins were then removed and the system left several hundred 4mm holes in the fibreglass, relying on the caulking to keep them covered. A fairly poor system but perhaps better than the alternative of using permanent wood-screws.

Finding the holes during re-caulking - we made sure we injected sealant into each one
So we hoped that our diligent maintenance would have paid off and now, with the teak gone, we used a counter-sink bit on the drill on every hole so that we could fill them all with a permanent cap of epoxy.

This process had a further use - by applying considerable pressure in the drill to countersink the hard fibreglass, we could confirm that the sandwich deck was in good order. The tell-tale sign of a damaged balsa core is that the top layer flexes under pressure. All good, we thought, congratulating ourselves on our effective deck maintenance. Until, that is, we reached the port side deck above our cabin. Did that area flex a bit just then? No, surely not! But yes, it definitely did. Bugger!

We drilled a couple of 25mm test holes and, rather than finding dry white balsa, we found black mush and a very unpleasant smell of rot. Bugger. Nothing for it but to cut open a section of the top fibreglass..

The sight and smell made us feel very sick. Nothing for it but to cut a bigger section in the hope of finding balsa that didn't ooze foul liquid when pressed. Alas, the next section was even worse:

The four holes are for the main shroud chain plate - a high-stress part of the hull, so it was definitely a worry to find this here. Nothing for it but to cut more deck open.

And now we had a real worry. The builders had sensibly used a pad of high-strength marine plywood, rather than balsa, around the chain plate but had obviously got their measurements badly wrong! The plywood was about 15cm too far forward, so two of the bolts went through strong ply and two went through soft balsa - all to a stainless steel bracket bolted to the hull. As a result, we are guessing, there'd be some differential compression and movement of the deck, enough to allow a slow but significant leak to invade the core.

In all we cut away about a 1.2m of deck until we found sound, dry balsa core and we also chiselled away two pads of wet plywood. It wasn't our happiest moment but it had to be done.

Di's hair-dryer used to ensure that we got everything dry

Back to clean, dry balsa
On reflection, after a long day and a glass or two of wine, we feel good that we found the problem and, like dentists drilling cavities, we'd cut out all the rot. The next challenge of course, is to repair the decks. Modern closed cell foam will be used to replace the balsa, high-tech epoxy will seal it and layers of fibreglass will be laid to make the new top of the sandwich. Not by us, this is beyond our comfort zone, so David, the hugely capable proprietor of Baltic Wharf Repairs will step in to do the fix over then next few days. More £££'s of course so we are talking to our insurers to see if this might be covered under the 'Latent Defects' clause.

Talking of hugely competent people, we managed to get help with the removal of our anchor windlass which, despite the treatment of penetrating oil and a large hammer, refused to come apart. Steve, who runs New Wave Marine (engine specialists) here, is hugely overworked but Graham managed to get him to accept the challenge and the two of them worked through lots of options and eventually used a 10-tonne hydraulic hub-puller to persuade the gearbox to part company with the shaft to which it has been attached for 21 years. Steve went beyond the call of duty on this, climbing into Maunie's cramped anchor locker but, after about an hour, the gearbox was finally off and we could remove the shaft from the deck to allow the last few shards of teak to be chiselled away. Phew!

No comments:

Post a Comment