Transducer Removal
I can't think of anything worse than sitting in your dinghy watching your boat sink and knowing the cause was something on your "someday" list. Well, maybe swimming in the water under the same circumstances would be worse.
When I first launched the boat back in 2005, I found the knotlog leaking under the backing block for the thru hull. Endeavour did a good job on all the thru hull backing blocks and it was clearly a previous owner's addition that was done very poorly. Re-installing the knotlog was a priority project for the first winter.
The unused depth sounder transducer seen on the far side here was done with the same type of backing block but it was tight and felt solid. Due more to it's nearly inaccessible location than to risk assessment, it went on the "someday" list. Fortunately, "someday" came while the boat was on dry land.
The transducer now in use on the right is the type that simply transmits through the hull and is just glued to the inside of the fiberglass.
I decided it was worth destroying and rebuilding the two drawer locker under the V-berth so I could get at this thru hull to remove it and glass up the hole.
I sawed through the plywood bottoms of the boxes that the drawers slide into and broke the pieces loose from the sides.
The drawers have unused grooves for side rails so I will reinstall them with these and eliminate the shelves that previously supported them.
I then took a chisel to the pathetic scrap of wood installed as a backing block.
You can get a sinking feeling on land. The backing block came apart easily because there was only a token amount of dry, brittle, bedding compound under it. Probably because the installer just smeared some compound on the block and set it in place, most of it had never even adhered to the hull.
Outside, inspection after pushing out the transducer revealed that the shoulder of hull laminate behind the flange was just a thin layer of un-reinforced resin. Only the bevel of the transducer head was providing any significant resistance to the whole fitting being punched in by striking a floating object.
The hull ground down to a feather edge at the hole. A long, itchy job.
I compromised a bit on the recommended 12:1 scarf slope because the location is one where I can build up a thicker section of epoxy and glass inside. The hull is also about twice as thick as it would be if built today so the scarf length is as long as it would be on a modern hull.
A small disk of glass cloth with a patch of partially cured resin in the center to stiffen it is epoxied over the hole on the inside. When fully cured, it will keep the inside layup from sagging through the hole.
The inside laminate patch in place.
I finally found the secret to working with fiberglass in tight spots like this. I stretched and taped a piece of clear plastic wrap to a smooth surface and built up the layers on that using a grooved roller to squeeze out excess resin and compact the cloth layers tightly. Next I put another piece of plastic wrap over the patch, untaped the bottom plastic sheet, and turned the whole thing over. The plastic wrap now on top was carefully peeled back and discarded. I could then carry the patch up the ladder into the boat on the palm of my hand protected by the wrap. The hull had been previously coated with epoxy and I simply plopped the patch into place. The wrap now on top let me roll it down tightly with the grooved roller without it becoming coated with resin and pulling up strands of glass. The wrap extending out to the side also made it easy to seal the edges of the patch, always troublesome, tightly down to the hull. Excess resin squeezed out of the patch was simply pushed out under the edge of the plastic wrap where it can be chipped and ground away after the epoxy set.
The inside patch worked so well, I used the same method on the outside.
This had unexpected advantages aside from working in a tight space. The plastic wrap keeps air out and prevents the epoxy from running and the cloth from sagging off the hull. The tape holds the edges down tightly. These are certainly the tightest and most glass rich layups I've ever done since the plastic wrap let me roll the laminate much tighter. Excess resin was worked out the the bottom edge and allowed to drip onto the floor before the edge was taped.
The drawers under the forward berths rebuilt:
Conversion to the side rail arrangement the drawers were originally intended for opens the whole space up for inspection or damage control when the drawers are removed. I ommitted the teak crossbars that edged the original shelves the drawers slid on as the slight gaps aren't as noticable when there isn't a light inside for photography. A little air circulation is always a good thing in such spaces anyway.
The whole space in way of the knotlog and transducer is now greatly cleaned up. I also installed valves on the fresh water tank connections in case of a piping leak.
