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#1
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Peggie Hall wrote:
Sometimes spelled "yacht." Hmmm...it sounds like she's going to hit the "general instruction mode"... ;-) There are a few tricks that make re-hosing a bit easier: 1. As is true of most jobs, planning and prep are 90% of a successful project. Told ya LOL So if the tank is in a completely inaccessible place, or the plumbing run is ridiculously convoluted, or the tank is much further than about 6' from the toilet, there is no law requiring you repeat the same errors. Take the time to investigate how to do it better...if necessary, cut hatches to create access (it's not hard to do, and worth the effort)...reroute the plumbing...even move the d'd tank! None were a concern...at this time. But were I going to the trouble to reorder & rearrange a whole system access, runs & config, I'd be better off to rearange it for piping. 2. Before you start, measure the OD (outer diameter) of the fittings....'cuz some nominal 1.5" fittings are actual 1 5/8"--or they're metric and slightly larger than 1.5", which can make putting toothpaste back into a tube a walk in the park compared to trying to get a 1.5" hose onto 'em. Avoid gray PVC 1.5" tank fittings...use marelon or nylon fittings. Btw, this anomaly only seems to apply to 1.5"...other sizes are likely to be true. Ya think...? But when you start changing out bronze seacocks afloat because their (decades-standard & perfectly correct) hose fitting OD is on the fat side for the new vinyl sadistic hose, lemme know. 3. Removing the old hose and running the new hose can often be made easier by doing both at the same time: cut the ends of the old and the new hose as cleanly as possible. Put 'em together on a male-male connector, butting the ends as tightly as possible...you want the smoothest unbroken surface possible...Use PVC cement to make sure both hoses STAY on the connector...do NOT use duct tape--it won't hold if you hit a snag...hose clamps will get caught on something. When you've got all the hose pulled through, cut the new hose off behind the connector. Great tip! 4. Don't try to make any hose bend tighter than it wants to bend willingly...heating a hose to bend it will damage the hose, resulting in a kink or even a tear. ....drumming fingers... Instead, break it and insert an inline radius fitting. Putting two ends onto a fitting is also a LOT easier than wrestling a hose around a "corner." Wasn't an issue, but that inserts a major obstruction to smooth flow, & is beginning to negate the seemingly sole advantage of hose over a good piping job... 5. When you're finally ready to start putting hoses onto fittings, it'll go a lot easier if you warm the hose a bit. ....coulda sworn I went there... A lot of owners like to put the end of the hose in hot water for a couple of minutes...I've always found it easier to use a blow dryer. Use a heat gun ONLY if you know what you're doing with one...'cuz overheating the hose will damage it. Lubricating both the hose and the fitting with a little dishwashing liquid--or better yet, K-Y surgical jelly--will help the hose go onto any fitting that isn't bigger than it's supposed to be. The water trick's unworkable in tight spaces & the other 2 require hi-watt 120vac, which is why the heatlamp gets useful - anything worth doing takes watchfullness... 6. Double clamp all connections, putting the screws on opposite sides of the hose--or at least offset a minimum of 90 degrees. SOP 1) How may anyone effect a voyage repair aboard a small craft at sea with this stuff? Do it as PREVENTIVE maintenance before you leave the dock, and you won't have to do it at sea unless you turn into the "Man Without a Country," unable to make landfall anywhere ever again. I feel this is copout reasoning (not in the personal sense please). 2) Does this material become irreparable with age due to changes in properties? No...but sea water minerals can build up in it if allowed to (it can be prevented), and sooner or later it will become permeated with odor. I referred to a section of hose which responded oppositely to warming & could no longer be made to accommodate a fitting it had been fitted correctly to 27 years ago. 3) Is there some compelling reason why reinforced rubber hose with a suitable polymer barrier - which requires no heating or dubbing around & clamps better besides - isn't in general use? Any hose that would slide onto a fitting without any effort would slide off almost as easily...and prob'ly would leak too. You're getting a little creative - "without any effort" wasn't there, consider the hoses in your vehicle - if it isn't electric or sail powered. :-) 4) Beyond the obvious end treatments, is there some method of making larger sizes of this "interesting" but uncooperative & pricy product more easily routed in tighter spaces/radii? See 1-5 above. IOW, "no" - I can accept that. 5) Is there some compelling reason why yacht waste piping doesn't more commonly employ rigid sched 40 DWV? Several reasons: 1. unless every connection to any fixed component in the system (toilet, tank, thru-hull, y-valve, etc) is "soft coupled" with enough hose to cushion shock and protect from flexing, SOP - many decades... hard PVC is likely to crack, especially in cold weather. Not. (incompetently piped?) And then there's the need for unions in anything but a long straight run. Making all those connections is so labor intensive that the cost of it compared to just running hose is too high. Have you never worked with PVC fittings & layout? It is very fast & easy. (yes we know about sweeps & expansion joints) In the case of blackwater wouldn't it last far longer & be more vapor-impermeable? (not to mention that you could *work* on it, pitch it so it'd drain & clean it if/when needed) I'm not seeing an advantage to a very pricy hose that has R/R issues, offers no timesavings in fitup, seems dicey to have to deal with at sea & often (I am told) lasts only 2-3 years. That's not true...white PVC or black rubber hose can last decades with no deterioration, provided it hasn't been overheated, bent too tightly or hasn't been chafed through by poor installation. The only reason most hose is replaced is because it becomes permeated with odor and stinks. Which is exactly what I was talking about. The hose is otherwise fine. As a general rule, the stiffer the hose, the less likely it is to become permeated with odor...the softer it is, the more likely. Many owners don't realize that not all white PVC hose is created equal or rated for sanitation...so they use hot tub hose from the hardware store because it's considerably cheaper than sanitation hose. I tried to caption the matter "marine sanitation hose"... What am I missing here? ;-) Nothing that most boat owners aren't also missing. So, far, I am thinking even moreso that most boat owners are missing all the benefits of simple, properly properly piped, inexpensive, never-stinks, long-lived, easily maintained PVC. Bonus Q for the jaded: is there a implicit, international agreement among those plan & specify such things, that the macerator pump shall be mysteriously concealed within an inaccesible void locatable by occultic divination, x-ray services or systematic disassembly of the head compartment & foreship? No...in fact, just the opposite SHOULD be true. It--and all seacocks--should be readily accessible for use and servicing. I didn't realize a macerator pump was called a seacock by boating peopleg. But I've seen a lot of USCG people call whole piping systems & tanks things they totally aren't during compliance inspections on larger vessels, so I'm used to it. :-) If yours isn't, and you left it where it was, re-read #1 above. Mine? Not on your life. If you mean the macerator pump, it is unreasonable to disassemble a significant portion of the guy's interior in the middle of his season without any other cause. ISTM you may be doing a better job of making my case (which began as a question) than I am. I haven't noted any general advantage of this hose product over piping. |
#2
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PVC, as you say, is, indeed, easy to work with.
I did that in the space I thought I'd never get to use it in, the forward head, for all the reasons you're aware of. That the directions changed frequently merely required me to make more sweep joints, not prevented me from putting it in. Actually, it likely went in easier than a single length of that hard white hose. Meanwhile, I believe Peggie is referring to paid labor costs vs hose cost; if you discount your time value, and it's feasible, the PVC is a drop in the bucket in boat costs. I supported it/fixed it tightly with clamps any place which could (possibly - it was pretty tight just sitting there) move, so I *believe* I have it safely put. You can see pix of the adventure in the section of my gallery on repairs at http://justpickone.org/skip/gallery/...=64 0&start=0 and click on 405 and 4267, both April folders. The first page on both shows the PVC stuff. Anyone interested is welcome to wander around the other folders (get to them by clicking on the highlights at the top of the page) to see what I've been up to in the last couple of months aboard. I'm currently waiting for the finishing of the electrical in the engine room, and the bilge pump relocation under the aft head, to see if I can hard pipe that one. Originally I thought that one would be a piece of cake, but it turned out most likely to be impractical, so I have the appropriate length of the expensive (but nearly half the cost of the other supplier!) aussieglobe.com sanitation hose. FWIW, the PVC discussion comes up fairly often; a search of the archives will give you lots of food for thought if you have a second head to deal with, later... L8R Skip, refitting as fast as I can Morgan 461 #2 SV Flying Pig http://tinyurl.com/384p2 - The vessel as Tehamana, as we bought her "Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." - Mark Twain |
#4
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In article , Peggie Hall
wrote: hard PVC is likely to crack, especially in cold weather. Not. (incompetently piped?) Incompetently piped is only one cause. Schedule 40 gets very brittle below 40F. Even a sharp rap against a dock can crack it. The kinds of stresses a boat can be subjected to in a storm at sea can crack sch 40 even in warm temps. PVC glue can crack, resulting in a leak. I really wonder about this. First, not all yachts have hulls that are all that flexible - steel boats in particular. Second, PVC *is* used on commercial fishing boats all the time, and it works well. Third, there are low temp plastics available. Fourth, PVC glue *can* crack, but rarely does if the joint is done properly - cleaned, primed then glued. It's a solvent cement rather than a glue. There are also other plastic products. I'm thinking of pressure rated black plastic pipe widely used on farms worldwide. The fittings are a bit on the bulky side but work very well. Some pipework on my country place has been exposed to UV and heat/cold cycles for 20 years now, under 10 metres of water head pressure. No leaks. Have you never worked with PVC fittings & layout? It is very fast & easy. You've obviously never had to pay for labor. 5 extra minutes per union on your own boat is one thing...multiply that by several hundred or even several thousand boats, and the cost to builders becomes prohibitive. Yeah, but that's a different argument. We all know builders of anything need to look at costings, esp when any potential problem is going to happen far enough in the future to be not theirs. In the case of blackwater wouldn't it last far longer & be more vapor-impermeable? More impermeable, yes. But the stresses on the glue in unions results in more maintenance (or repairs at sea). I really doubt this is true, if the hull is rigid enough and the pipework is well supported. Personally I think the whole business of running flex hose everywhere is plain crazy and a throwback to a time where the choices were flex hose or metal pipework. Put it this way - I spend some months of every year on an icebreaker bashing about in sea ice. It's COLD, the hull is cold, there's a hell of a lot of vibration, shuddering and shock loads that the average boat NEVER sees. There's a hell of a lot of PVC piping for the toilet systems, potable water systems etc etc on that ship. Sure, the final runs are all welded steel pipe, but the point is, we *don't* have massive and continual failures of the PVC pipework, despite cold and vibration. Haven't decided what I'll use, but flex hose will be considered only when I can't use something better. If the flex hose is better structurally than rigid pipework, why don't commercial vessels use it? PDW |
#5
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One more time: it's YOUR boat. Pipe it any way you want to and live the
with consequences. If you're lucky--and also more competent and knowledgable than the "average bear," you won't have any negative consequences...but I've learned from experience that it's hard to go wrong tailoring advice to the lowest common denominator. The real question is: how far removed from the lowest common denomator are you? These days, a lot of boat owners aren't as far as they'd like to think they are. Otoh, those who are smart enough to find their way here are usually are smarter than "the average bear.' At least the questions I see about sanitation systems seem to indicated that they are. Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
#6
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In article , Peggie Hall
wrote: One more time: it's YOUR boat. Pipe it any way you want to and live the with consequences. If you're lucky--and also more competent and knowledgable than the "average bear," you won't have any negative consequences...but I've learned from experience that it's hard to go wrong tailoring advice to the lowest common denominator. The real question is: how far removed from the lowest common denomator are you? These days, a lot of boat owners aren't as far as they'd like to think they are. Otoh, those who are smart enough to find their way here are usually are smarter than "the average bear.' At least the questions I see about sanitation systems seem to indicated that they are. When it comes to engineering stuff, I'm a long way from the LCD. My work group builds marine gear that's pressure rated to in excess of 2000m pressure, for example. Specifics of marine sanitation systems, pretty ignorant. Personally, I think the engineering of marine heads is ridiculously primitive. The Lavac is about the only one I've read about that makes sense. My point is, there's nothing that's real rocket science about low pressure plumbing runs. You need acess to the seacock no matter what, and anything below WL needs to be reasonably secure against leaks. Engineered flex hose with 2 connection points (sea cock & toilet) has a lot less points of failure - provided it doesn't get abraded - than anything with many joints, regardless of material. However it does have its downsides. I just can't accept that worrying about vibration cracking PVC pipes is a realistic issue in practice provided the pipe is properly supported. It's just as likely that a flex hose will abrade through and you don't seem to think that's a concern. PDW |
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