Tuesday, May 26, 2009

Port Lights

The other big project I undertook this spring was to refurbish and reseal the portlights. This turned out to be a really big job. Had I known what a big job it would be I'd have tried to get it done over the winter instead of waiting till two weeks before launch.

Initially I wanted to remove all the aluminum frames, clean them, replace the plexiglass, and reseat them with new sealant. The first frame proved incredibly hard to remove. Even using a putty knife and hammer to cut around the flange, it didn't want to come out, so I gave up on that idea and just removed the plexiglass.

When the boat came out for knotmeter replacement, I found that four of the frames were installed with white butyl and came out very easily. Of course, they'd been leaking like crazy; white butyl isn't a good solution for portlights. They were also extremely gunked up. Two of the frames were very hard to remove and I ended up resorting to brute force with a putty knife and hammer to cut through the caulking under the edge of the frame. Finally they came out, no damage to the frames thankfully but the fibreglass was a bit worse for wear. I epoxied the small gouges I'd created; they're hidden by the frames when the portlights are installed anyway.


Cleaning up the frames took a couple of days. The white butyl cleaned off easily with Varsol, but the silicon / polyurethane caulking took hours of scrubbing. I used Marine Debonder and GooGone with a scrubbing pad and a razor blade. The thing that worked best was GooGone, a green scrub pad, and lots and lots of elbow grease. GooGone smells like oranges, too, a lot better than Marine Debonder.


This is something you want to wear eye protection for. I managed to get a speck of solvent-soaked gunk in my eye and took a sprint across the boatyard to wash out my burning eyeball under a faucet. All of this stuff is poisonous, toxic and caustic.

I went to the plastics store and asked about cutting new portlights. It was going to be 20 bucks a piece but the guy said the old ones looked like they'd clean up with some polish. He sold me a bottle of Novus number 2 fine scratch remover and it works like magic. With a little more elbow grease the lenses polished right up, almost like new. This polish is great. It will remove oxidation and scale that's acumulated on plastic, buff out the fine scraches, and give you a shiny clean new surface. I'm going to use it on my car headlight covers next. Incidentally I tried toothpaste and it didn't work.



The sponge went in first, and for good measure I put a bead of BoatSeal around the outside edge of the sponge. The lenses went in next and sealed up against the sponge and caulking. The idea is to seal the lense to the metal frame with caulking rather than relying purely on the sponge to make it watertight. There were also small gaps at the weld-points that I filled with caulking.

Next the rubber spline goes in. I had to trim a little divot to squeeze it in at the weld joints but in general it went in easily. Tanzer Boat Parts sent enough spline and sponge to do all the ports with several inches left oer. It ain't cheap though.

There was some delamination from the plywood core around a couple of the port lights. I epoxied the worst of it. I might have covered all the exposed wood with epoxy if there'd been time, but only did the areas that looked like they'd seen some water. In theory these should not be getting wet anyway; if they are you have other problems that need to e dealt with.

I filled the small seam at the ends of the spline with BoatSeal and installed the portlights with Sikaflex 291 and the original half-inch number six stanley head screws. They look pretty good.

Through with Thru-Hulls

The epoxy cast turned out great. A two-and-a-quarter inch hole turned into a two-inch hole. Just a few rough edges to sand down.
The new through hull looks good. Lots of LifeSeal (BoatSeal) polyurethane/silicon hybrid caulking around the through hull and up over the threads.
With the transducer in place it's ready for a coat of antifouling. Is it water tight? We'll soon find out.

The transducer is an interesting device; the small paddle wheel on the outside of the transducer spins and interacts with a magnetic sensor on the inside. The sensor is good enough to pick up the frequency of the wheel's rotation through the plastic plug and send it to a instrument panel for conversion into a digital readout. As a bonus there's a temperature reading to test the water on those days when you really feel like going for a swim.

Wednesday, May 13, 2009

knotmeter retrofit

This all started by trying to fix the old knotmeter. After some enthusiastic inspection and troubleshooting by my pal, who decided it was broken, the old thru-hull transducer fitting sprung a leak as soon as the boat splashed. I went to the chandlery and checked out my options. There weren't very many.

One was to glass over the whole thing. There were no plugs or other devices for a temporary fix. The best option was to put a brand new transducer in the hole, so I ordered a new Raymarine ST40 Speed by priority post.

Things were looking grand as I drove to the yard with my new knotmeter, but when I tested the thru-hull fitting in the cutout, it rattled around with about 1/8" of space around the whole device. The cutout was too large by about a quarter-inch.

I decided to do an in-situ epoxy cast. My mold consisted of a flat base, pressed up against the outside of the hull, and a 2-inch outer diameter central vacuum PVC tube sitting in the old hole from inside the boat and resting on the flat base. Central vac pipes are the only PVC pipes I could find with a precise 2 inch outer diameter. I covered the flat base with a sheet of waxed paper. I cut a piece of the PVC pipe about 1.5" long and wrapped that in waxed paper also. To "glue" the edge of the waxed paper flat against the pipe I used some cross-country skiing liquid glide wax. This gets between the layers of waxed paper that I'd rolled around the pipe and makes them stick together.

I propped up the base against the hull with tape and pieces of foam on a box. From inside I inserted my home-made plug. With a syringe I put epoxy into the gap between the plug and the old cut-out. Some gentle turning of the plug ensured that the epoxy went all the way around the outside of the plug filling in the gap.

I won't know till tomorrow how this turns out. I'm hoping that if there's too much epoxy in the gap it can be sanded off, or if there are voids they can be filled in with more epoxy by hand and then sanded smooth. With luck it'll be a smooth cast with only a few burrs to clean off. The new transducer should be nice and snug in the new opening.

Foam blocks propping up the base of my mold for an epoxy cast.


My home-made plug, 2" outer diameter with epoxy filling the gap in the old cutout.

Sunday, May 10, 2009

The Close of the Day


© 2009 Darren De Ridder

Launch Weekend

Preparation of the keel joint nearing completion mid-week.

Interprotect 2000 and Sikaflex 291 polyurethane caulking have been applied.



A final layer of Interprotect. I had thought of leaving the polyurethane expsed, since the Interprotect is more brittle, but I painted over the joint after all, to provide a base for the antifouling.

VC-17m antifouling always looks great after it has been freshly applied.

Ready for launch day; fellow Tanzer 22 owners take a break from preparations.


Aura splashes! Cranes and crews had all boats in the water by mid-day.

The first thing a skipper looks for when his yacht splashes in the spring is any water coming into the bilge or around the through-hulls and keel bolts. One of my crew had been working on the knotmeter. Within minutes of launch, water was slowly collecting in the bilge and we were able to trace it to the knotmeter thru-hull fitting. I'm happy that it was discovered immediately rather than springing unexpectedly while nobody was around to manage the problem. As I discussed my problem with John, an old salt and fellow T22 owner, a wry smile spread across his lips as he realized I'd probably be laid up for the start of the racing season. "Well," he said with a prim British lilt, "you're f***ed!", and cackled gleefully.

At the other end of the system, the instrument gauge itself, which had also been opened, filled with rainwater, so repairing it is out of the question. A knotmeter is a valuable piece of equipment for a good racing crew, so I would like to replace it. The through-hull may be replaced with a temporary dummy plug for the time being. There is now a new rule on my boat, however: don't unscrew anything without supervision of the skipper!

Aura back on the hard to repair a thru-hull fitting.

After some hours the fitting is removed. The right tool for the job couldn't be found at first. Finally I discovered an oil filter wrench at Home Depot. It's three narrow grips are designed for large-diameter threaded fittings like shower-heads, etc. The inside lock-nut came away with some delicate yet firm negotiation. Note the thickness of the fiberglass lay-up; the toughness of Tanzers is legendary.

Saturday, May 2, 2009

More Keel Joint

Progress! Chemical warfare on the hull-keel joint...

Keel Boy™

A gelcoat crack, ground out for patching.

Gelcoat patch and POR-15

Prep was Metal-Ready, containing phosphoric acid and zinc. Residue is zinc phosphate. POR-15 inevitably got on both sides of the joint, but with a topcoat of Interprotect 2000, I expect good adhesion from Sikaflex 291 polyurethane adhesive sealant.

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