#1
IP: 24.97.227.132
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Thru Hull
I'm not sure this is the right Thread Topic, if not I appologize.
My question is in regards to the 'proper' or 'approved' method of installing a thru hull. I've done a bunch of research and was planning on using a Tri-Flange Adapter. I was recently at a local marine store and someone there told me that this method was not Coast Guard Approved? He said the Seacock method was the only approved method for a thru hull. It seems like the Flange Adapter is a much more versatile installation with benefits such as allowing you to change the valve without replacing/removing the entire thru hull. I've contacted a Vessel Saftey Check inspector associated with the US Coast Guard Auxiliary and he said it was a question outside of an inspectors resposibilities. The gentlemen at the Marine store said if we got boarded by the USCG the Flange Adapters would be an immediate red flag? Can I use the Flange Adapters, or not? Anyone have any experience with them? Thanks, |
#2
IP: 38.102.16.210
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If anyone tells you something is not "Coast Guard approved" ask them to cite a chapter and paragraph from CFRs or provide a link. The flange adapter is a splendid idea and solves a serious issue regarding the mixing of straight and tapered NPT.
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#3
IP: 70.91.159.33
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here's a helpful link
__________________
Mike, Slower-Lower Eastern shore, MD 1973 Pearson 33 1967 Bristol 27 |
#4
IP: 74.101.167.216
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"Mainesail"'s richly photographed monograph is the best coverage of this general topic that I've seen anywhere:
http://www.pbase.com/mainecruising/replacing_thruhulls Actually all of his stuff is top-notch. http://www.pbase.com/mainecruising/boat_projects |
#5
IP: 75.62.248.28
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Yeah, if you do it like that it ain't goin anywhere. Wish mine were all like that.
dvd |
#6
IP: 24.97.227.132
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Those Compass Marine links are where I've been getting most of my information and is exactly what I was planning on doing (probably the Alternate method). Sadly, the flange and the seacock don't have the same bolt pattern (I checked yesterday). Since they're different, I really don't want to go to all the trouble of making and installing the backing plates only to have the tri-flange be a problem with inspections/surveys..
Any suggestions on where to get a definitive approval on the tri-flange? |
#7
IP: 70.91.159.33
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I can't guarantee it but,,,
You might try contacting either of the provided links. Possibly Niel Dutton or another member may be of help.
Do you know any local marine surveyors?
__________________
Mike, Slower-Lower Eastern shore, MD 1973 Pearson 33 1967 Bristol 27 |
#8
IP: 24.224.206.117
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I think Hanley and Neil are excellent sources of information as well. When I did mine I put a standard thru-hulls (2007). I had not heard of these flange adaptors at the time. Actually, this is the first I've heard of them.
__________________
Mo "Odyssey" 1976 C&C 30 MKI The pessimist complains about the wind. The optimist expects it to change. The realist adjusts the sails. ...Sir William Arthur Ward. |
#9
IP: 74.101.167.216
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Those flange adapters, simple as they are, are new in the last five years or so and are I think patented by Groco.
Any marine surveyor who prefers the wrong way (mismatched threads and wooden backing blocks) over those robust slabs of bronze should be escorted out of the boatyard. I would personally rather have sealed through-bolts in my through-hulls rather than the threaded-in-G10 alternate method of Mainesail's. The alternate method seems like a lot more work too. |
#10
IP: 24.152.131.155
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I didn't do too much digging but what I did find was at least a portion of the ABYC requirements.
As for installation specifics, I found none. What was specified was that the thru-hull installation shall be capable of withstanding a static 500# side load on the assembly tailpiece (where the hose attaches). That pretty much eliminates everything except a through bolted seacock I think. I'm not saying a thru-hull, wood doughnut and ball valve won't comply but it too has to withstand the 500# load to meet the standard. Mention was made also about the mismatch of straight thru-hull threads and tapered valve threads. The problem cited was only three or four threads engage before binding and it is assumed the fit will never meet the 500# standard. Regarding bolted seacocks, those with cored hulls need to take special care. You cannot effectively bolt through the core.
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 05-05-2012 at 12:52 PM. |
#11
IP: 75.74.178.214
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Thanks for the links.
I want to replace my thru hulls this summer when I have the bottom job done. I like the idea of the tri-flange for extra strength. My big question is marelon better than bronze? I think my existing are original and bronze but have turned green. Also they have round knob valves like a water spigot so im afraid to even try and turn them in case they break off. Will marelon last 30 years? Im looking for the longest lasting material possible so I only have to do this job once.
__________________
1978 Catalina Yachts C27 1993 Bayliner Classic 2250 1986 South Seas 16 - sold 2012 Suzuki GSXR 1000 - The Commuter 2007 Suzuki GSXR 750 - 31k miles, sold 2006 Suzuki GSXR 600 - 9k miles, sold "Therefore I say unto you, what things soever ye desire, when ye pray, believe that ye receive, and ye shall have. And when ye stand praying, forgive, if ye have ought against any: That your Father also which is in heaven may forgive you your trespasses." Mark 11:24 |
#12
IP: 96.244.238.12
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I hate the marelon valves because I've had the handle snap off in my hand. Think 30 years from now (or next year) when the valve is a little sticky that the plastic handle is going to hold up? These are not nearly robust enough to handle the abuse that boat owners throw at them. Nobody greases the vavles every year, as well intentioned as we may be. Also, no matter how green your bronze gets, you can always clean that off with a wire brush or a little weak acid.
I agree, replace the gate valves that you have, but replace them with bronze if you want them to last. |
#13
IP: 76.118.149.176
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I have 2 marelon thruhulls and valves with no issues. I find them very easy operate vs my bronze ones, which I do grease every year.
When you replace the thruhull make sure you use the correct valve threads, IF I remember correctly, most valves are npt and the thruhull is a straight Steve Last edited by smosher; 05-06-2012 at 05:49 PM. |
#14
IP: 108.4.61.32
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I followed the Compass Marine article and I can't imagine how I would ever have a problem with it or how any subsequent buyer or marine surveyor would either. The surveyor I hired didn't say word one about the extremely sketchy through-hull that was in there when I bought the boat. I'm surprised it kept the boat afloat, actually.
Neil can tell you all about marine surveyors... Just one man's opinion, but I would use the three-bolt flange adapter without hesitation. In fact - I did!!
__________________
- Bill T. - Richmond, VA Relentless pursuer of lost causes |
#15
IP: 151.200.29.202
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Keys, like Micah, I went to Marelon & have been very satisfied.
I have epoxy coated wood or PVC (plastic) backing plate (depending on the thickness I needed) in my Catalina 30. I 5200'ed the thru-hull to the hull & backing plate (used the nut from the thru-hull fitting to clamp) and then removed the nut and screwed on the marelon seacock. I cheated just a little bit and instead of thru-bolting the seacock flange, I used 1" sheet metal screws and screwed the seacocks to the wood/PVC that was previously bedded with 5200. I think the keel is more likely to fall off than for these fittings to fail. YMMV of course, but I have not had any problems with mine.
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-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#16
IP: 70.91.159.33
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Fantastic Plastic
I also had a hardware store variety non marine ball valve on my raw water intake. NPT threads onto straight threads. Marelon was the only 1/2" NPS valve I could find. No issues with mine.
__________________
Mike, Slower-Lower Eastern shore, MD 1973 Pearson 33 1967 Bristol 27 |
#17
IP: 69.248.49.55
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I am intrigued by this requirement of withstanding a 500 # side load on a thru hull. Is there anyone out there who would consider allowing anyone, surveyor, coastie or other do that to a thru hull on their boat? Consider what even your own weight so applied could do!
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#18
IP: 108.4.61.32
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The previous installation on my boat? No way - 500 lbs side load would have snapped it right off.
The current one that I installed? It would handle it no problem.
__________________
- Bill T. - Richmond, VA Relentless pursuer of lost causes |
#19
IP: 75.74.178.214
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Quote:
BTW how much did the install run you?
__________________
1978 Catalina Yachts C27 1993 Bayliner Classic 2250 1986 South Seas 16 - sold 2012 Suzuki GSXR 1000 - The Commuter 2007 Suzuki GSXR 750 - 31k miles, sold 2006 Suzuki GSXR 600 - 9k miles, sold "Therefore I say unto you, what things soever ye desire, when ye pray, believe that ye receive, and ye shall have. And when ye stand praying, forgive, if ye have ought against any: That your Father also which is in heaven may forgive you your trespasses." Mark 11:24 |
#20
IP: 108.4.61.32
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Aside from the cost of the Groco bronze through-hull mushroom, the Groco bronze ball valve, the Groco bronze flange adapter, the three bronze machine screws, nuts and washers, and the tube of Sikaflex, the install cost me about 45 minutes of my time (with my wife helping).
__________________
- Bill T. - Richmond, VA Relentless pursuer of lost causes |
Tags |
flange adapter, seacock, thru hull |
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