google-site-verification: googleffe3ebaef4e4b443.html Oztayls-Restoring and sailing a vintage scow Moth: Scope of work to be done to hull

28 April 2013

Scope of work to be done to hull

Max's condition is not up to sailing and there are a number of reasons for this assessment. On close inspection, Max has arrived at a good home, in the nick of time.

Hull: While the hull is sound and doesn't need any structural work, the finish is considerably deteriorated. The reason for the deterioration in the finish is probably a lesson in itself of how NOT to look after a wooden boat. There are 3 deadly sins that have been committed, which I'll detail below.

Deadly sin #1: The last time this boat was sailed, probably more than a year or more ago, it was not washed down with fresh water. As a result, the hull was covered in salt crystals. What happens is that salt, being hydrophilic, causes globules of moisture to attach themselves to the finish on humid days. This means that the boat's surface never dries. This then sets up a process called osmosis, and the moisture migrates through the varnish and into the timber below. In this case, very thin plywood. At best, this causes discoloration in the timber (dark or black streaks). At worst, rot can set in. Luckily, Max has just one small matchbox sized patch of rot, which is quite easily repaired.

Normally with a boat that has had proper care, the finish can simply be given a light rub down and then a couple of fresh coats of varnish. Unfortunately, Max does not offer me this simple route. The problem is that the osmosis has also caused salt to migrate through the finish. There are blisters all over the hull containing pure salt! Popping these blisters reveals the stored salt between the finish and the wood, so I have no option but to completely remove the finish down to bare wood. This is indeed a pity, because the lovely old patina that the boat has acquired will be lost. A painted finish may be an option.

Deadly sin #2: At some stage in Max's life, someone has seen fit to slap on a coat of two-pack finish over the original one-pot varnish. Mostly, it is the deck that has been affected. The problem with this is that whatever this 2-pack finish was, has made things worse. Two pack finishes do not bond to single pot varnishes! Also, Max's deck and cockpit area flexes quite a bit, cracking the hard finish and allowing water to get in and under, and be trapped there. Because it doesn't easily dry out, and the boat wasn't washed down after sailing, moisture has been ever present and discolouration has occurred. Luckily, there is no rot, but it means that if I decide to retain a bright (varnished) look, the discolouration will be evident. Another year of sitting may well have seen Max's demise.

Deadly sin #3: The dished cockpit area has been treated with surfboard wax. I know the reason was to provide a grippy surface for the helm, but there are much better solutions available for wooden boats. Surfboard wax is a bad idea for wooden boats. This wax has been applied over the top of the 2-pack stuff which was over the top of single pot varnish. Removal to allow refurbishment of the deck will be difficult at best.

These 2 pics clearly show the discoloration and the salt crystals under the varnish.


At Monday, 29 April, 2013 , Anonymous Anonymous said...

Poor boat. Hopefully there is no need to use paint and you can keep the beautiful varnished plywood look. The slight discolouration just adds a little more character.

At Tuesday, 04 September, 2018 , Blogger john said...

agree with the previous but as it's been painted, it doesn't matter... the design is the same an that's what is important.................jc


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