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Old 16-07-2009, 22:00   #1
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Jedi Adventures in the Engine Room ;-)

Hi all,

If you've read some of my posts before, you know I'm not a mechanic so when I go down into the engine room to do some projects, it's an adventure as soon as I open the hatch!

So, this thread is for tips that are good for even seasoned mechanics:

- check the drain-screw on your waterlift mufflers. I have Centek and they use a rubber washer behind the head of the machine screw. After only 4 years the original washer crumbled away when I loosened the screw after seeing some evidence of a tiny leak. When did you last check that? ;-)

- we have two of those really big battery on/off switches to select either start-batteries or house-batteries for starting. I noticed some stress marks in the plastic housing around the knob and when I switched it over, the whole knob with a piece of the housing attached came off. The internal spring pressure was too much for this switch after 15 years. This failure isn't fatal because you end up with access to the normally internal copper plates that the rotary contact (that is now gone) moves over. The small separation between the plates is good for putting a flathead screwdriver in so you can still start the engine. I would advise to turn your switch roughly a couple of times or pull the knob a bit to see if this is still sturdy.

- Something very strange: the 3" exhaust hose for the main engine still looks great after 15 years (1500 hours on the engine), no need to replace. But other hoses (same exhaust type hose) between 2" and 3" diameter (like for cockpit drains etc) were close to total failure. The outside was severely cracked on the outside of bends and the inside was crumbling. The steel reinforcements were corroded up to a foot from the end. When I put them on the dock and forced them straight, they collapsed. I replaced them all with corrugated hose.

- We check the genset injection elbow every 600 hours or so. In fact, we replace it with a spare and later clean and check the old one. If it's still good, it becomes the spare. The problem here is not the elbow, it's the exhaust hose between the elbow and the waterlift muffler. It gets hard and tough to remove after just a year of use. I am not sure if my solution works (time will tell) but I replaced this (short) hose with that expensive blue silicone corrugated exhaust hose. I have high hopes that this stays good and easy to work with for much longer. I sure hope so because it's pricey stuff. This hose looks so great I'm tempted to hang it on the main bulkhead in the salon instead of installing it ;-) Shields Nautiflex Corrugated Silicone Water Exhaust Hose

- The SSB/HAM radio copper grounding foil. It was unprotected and after 15 years about half was left. I didn't anticipate this one so we got new foil flying in with FedEx and I will epoxy it to the hull and paint it. The old foil was much thicker than the stuff WM sells but I could only source the same quality in 100' lengths for over $250.- so the WM quality it is. If I protect this well it should be as good as the old one because for HF only the outside surface area counts.

- Floorboards: yes, I sometimes make a mess while changing oil... I can design micro-chips but I'm clumsy with oil ;-) So, we took all the floor boards out, put a gallon of degreaser to work, wet-sanded a couple of times and today they got their first coat of primer. We will finish them with "BilgeKote" from International paint who promises that this paint can withstand anything around an engine room like oil, coolant etc. Again, time will tell. We put a coat of this on a small (guinea pig) board today and it looks good so worth to use this paint instead of regular as it's not more expensive. yachtpaint.com - the website of International and Interlux paints

- My starter battery bank consisted of 4 gel batteries of that prevailer/seavolt/WM brand. They lasted for more than 7 years so I was tempted to replace with the same until I saw the price. After some research I am now installing 2 Odyssey 2150 batteries (military spec they say) which together have much more cranking power than the old bank of 4 batteries for 20% less $$$. If you're about to replace starter batteries, these are worth a look: Odyssey PC2150 series battery

- Lights. You don't want fancy light armatures in an engine room but the cheap ones I used all break down or the lamps fail (vibration?) I have two main lamps which are good (TL) but need more like near the watermaker because we tend to operate that until after dark. I found these cheap Sylvania LED lights that are battery powered and come with double-sided sticky tape, Velcro and even magnetic tape. You just pop 'm where you need them, no wiring etc. It's amazing how much light you get for a couple of dollars! Amazon.com: Sylvania 36051 Silver Linear Dot It Portable LED Light, Silver: Home Improvement

- Genset exhaust reducing diameter. Our exhaust system was increased in diameter from 1.5 to 2" which solved problems with carbon build-up. However, the genset still has that 1.5" elbow to connect to. For years we used a reducer fitting which I really hated because it doesn't really fit. Finally I decided to tackle this and I modified the waterlift input (see attached photo). I bough a piece of fiberglass pipe, 1.5" O.D. (Centek) and epoxied it into the waterlift. The pipe is much smaller than the muffler input so I decided to use some fiberglass. I wrapped about 3-4 feet of 2" wide fiberglass tape around the piece of pipe while wetting it out with epoxy. This went surprisingly easy and clean. I inserted it into the muffler (don't put on too much tape or it will start sliding) until the tape was about 1/2" inside the muffler and supported the pipe with some bamboo skewers until the epoxy started gelling and holding the pipe in place without support. I turned the muffler with the input facing up and injected some thickened epoxy around the pipe to fill up the cavity. I used some microfiber (to make it tough) and colloidal silica (non sagging) filler to make it ketchup consistency, and a syringe to inject it. The result looks like it came from a mold and I am confident it will cope with the heat (I never found temperature specs for West System epoxy, if you know more, let me know!) That temperature aspect is scary for not being on the West System product sheet while even JB weld lists it. I planned on using JB weld but decided it was too thick for this job.

cheers,
Nick.
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Old 17-07-2009, 02:46   #2
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Quote:
Originally Posted by s/v Jedi View Post
- The SSB/HAM radio copper grounding foil. It was unprotected and after 15 years about half was left.
FWIW, I like to tin the copper foil with solder before fitting it. Don't really know if it helps, never put it to the test with tinned and untinned side by side in the same enviroment; but it looks like it is "better".
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....I never found temperature specs for West System epoxy, if you know more, let me know!) That temperature aspect is scary for not being on the West System product sheet ...
OK I AM guessing here but somewhere 70 C rings a bell for slight softening while 100 C has definite softening.
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Old 17-07-2009, 08:33   #3
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FWIW, I like to tin the copper foil with solder before fitting it. Don't really know if it helps, never put it to the test with tinned and untinned side by side in the same enviroment; but it looks like it is "better".
I am sure it will be better for protecting it against the environment, like like tinned wire, but I see two problems with it:

- When you put a torch to that WM stuff it'll burn up, it is that thin (0.002" if I'm not mistaken)

- At the radio frequencies you have what is called the skin effect. This means that the current will travel at the skin of the conductor, not through the core. I have no details at hand but am almost sure that tin has more resistance than copper, so you make it a worse conductor by tinning it. For coils, silver over copper is used (oh yeah, I made those myself once, incl. the silvering) so that the energy travels through the silver.

Quote:
OK I AM guessing here but somewhere 70 C rings a bell for slight softening while 100 C has definite softening.
Which sounds like temperatures common for an exhaust. Well, under 100 C but 70 is there I think?

cheers,
Nick.
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Old 17-07-2009, 22:03   #4
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Can't comment on the WM stuff as I have never used it but I usually tin with a hot air gun and I wouldn't have thought any foil would be melted by that.

I understand what you say about skin effect but would counter that with the higher resistance of copper oxide on the surface of the untinned foil cf the lead/tin surface of tinned copper.
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Old 17-07-2009, 22:20   #5
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Hmm... I had to check Wikipedia on that ;-) Copper Oxide is actually a semi-conductor and was used in electronics before silicon came around.

So, that's why I plan to paint it. I am confident that the paint will be an insulator ;-)

cheers,
Nick.
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Old 17-07-2009, 22:25   #6
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And if you fold it a bit after it has had time to corrode a bit, you might get a diode or even an AM detector - just kidding (a bit) .
Good luck with the engine room makeover.
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