Tuesday, 19 February 2013

In Again

Spray is back in the water again, resting comfortably in home port.  We got a good signal from the new depth transducer and there were no blub-blub-blub noises coming from the through-hull fitting seals, so we're declaring a victory.

New epoxy, paint, and wax.

Up...Out...Down.


Home, Sweet Home.
Yesterday, less than 24 hours before launch, was a good day to try out a number of desperate last-minute tricks, like trying to set gel-coat repairs with a hair dryer (12° C outside but dry), and touching up white scratches in blue gel-coat with a blue felt-tipped marker. Laugh if you will - it looks pretty good !  This morning, the gel coat was dry, if not hard, and the ink …well, I’ll let you know how that fares after she gets wet. 

The biggest novelty for us was a new way of mounting the anode on the propeller shaft. 

I learned the term “sacrificial anode” as a child in introductory science classes, but I’m beginning to suspect that, when applied to boats, this term implies that one must perform sacrificial rituals to get the damn things to work, or rather, to stay in place.

Last August, we dutifully clamped a new 25 mm anode on to the propeller shaft before we launched the boat.  We tightened the screws as hard as we could and put a liberal dose of sikaflex on them.  It couldn’t possibly move.

What we did not realize at the time is that when anodes corrode, they often corrode on the side touching the metal to be protected, which is to say, from the inside out.  That perfectly fitted 25mm hole of the anode clamped around the 25mm propeller shaft in August corroded away over 4 months, leaving the anode free to slide along the propeller shaft. 

If you’re lucky, this situation will simply lead to some strange noises and vibrations, but the anode will stay in the same general area.  If you’re unlucky (as we always seem to be), the anode will start moving up and down along the propeller shaft until it causes real problems.  Ours somehow defied gravity and got lodged at the upper end of the shaft and carved out a place for itself in the fibreglass when we put the motor in gear ! 

Bad anode mounting.
This time, armed with advice from several friends and forums, we tightened the anode screws, pounded the two anode halves together with a hammer and then retightened the screws.  We did this repeatedly until it wouldn’t budge anymore.  Next, we put some tie-wraps on the shaft on either side of the anode so that even if it got loose, it couldn’t slide.  To finish the job, we put sikaflex in the screw holes, along the edges of the two halves and around the shaft to prevent as much water from entering as possible.  We hope this will lead to an immobile anode that will corrode from the outside. 

Good anode mounting ... ?

0 comments: