|
|
Post by lollygagger on Dec 5, 2016 11:15:04 GMT
The trickling sound of water running through a corrosion hole ?  Maybe it doesn't work then, I sponged out 14 gallons the other day...  |
|
|
|
Post by JohnV on Dec 5, 2016 11:17:36 GMT
The trickling sound of water running through a corrosion hole ? On the subject of leaks .... the other day I was head down in one of the inspection hatches (beer and wine stores) on Sabina and as I peered round generally with the torch, I saw to my absolute horror what appeared to be a puddle of water shining in the torch light. ......At full stretch I could just get my finger tips to it and dabbed at it to see if it was fresh or salt. To my surprise when I drew my hand back, my fingers were dry. After a few moments thought I remembered that a couple of weeks ago I spilled some water based varnish when varnishing some woodwork in my new tool cupboard some of which had run through the gap in the plywood base into the bilge. The sense of relief was overwhelming  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2016 11:18:08 GMT
The trickling sound of water running through a corrosion hole ? Maybe it doesn't work then, I sponged out 14 gallons the other day... You need a CI - Condensation Isolator, also known as a dehumidifier. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2016 11:20:04 GMT
The trickling sound of water running through a corrosion hole ? On the subject of leaks .... the other day I was head down in one of the inspection hatches (beer and wine stores) on Sabina and as I peered round generally with the torch, I saw to my absolute horror what appeared to be a puddle of water shining in the torch light. ......At full stretch I could just get my finger tips to it and dabbed at it to see if it was fresh or salt. To my surprise when I drew my hand back, my fingers were dry. After a few moments thought I remembered that a couple of weeks ago I spilled some water based varnish when varnishing some woodwork in my new tool cupboard some of which had run through the gap in the plywood base into the bilge. The sense of relief was overwhelming It could of been worse, it might have been a bottle of Chateauneuf de pap |
|
|
|
Post by JohnV on Dec 5, 2016 11:21:14 GMT
Maybe it doesn't work then, I sponged out 14 gallons the other day... You need a CI - Condensation Isolator, also known as a dehumidifier. That would be a hell of a big dehumidifier much more than that you need the best bilge pump in the world ..... a terrified man and a bucket |
|
|
|
Post by smileypete on Dec 5, 2016 11:39:42 GMT
Sooooooo.... I have a galvanic isolator with lights to show AC or DC problem. I noticed when I blacked it had it blacked that there were a few bright slightly pitted areas which must be galvanic corrosion. They are all around the middle of the boat, as far from the sacrificial anodes as could be. I'm hooked up to ac mains in a marina. What could be the cause? Edit: I don't have a transformer, I have a galvanic isolator. Is it a newish boat? Can be caused by millscale on cheaper steel, especially with blacking that flakes off with it. I'd also check the GI is wired up OK, the mfr should give instructions. Disconnecting the shore line and connecting a PP3 batt between the big earth pin and hull should light one LED, up, turn the batt around to check the other LED does too. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2016 11:45:41 GMT
On the subject of leaks .... the other day I was head down in one of the inspection hatches (beer and wine stores) on Sabina and as I peered round generally with the torch, I saw to my absolute horror what appeared to be a puddle of water shining in the torch light. ......At full stretch I could just get my finger tips to it and dabbed at it to see if it was fresh or salt. To my surprise when I drew my hand back, my fingers were dry. After a few moments thought I remembered that a couple of weeks ago I spilled some water based varnish when varnishing some woodwork in my new tool cupboard some of which had run through the gap in the plywood base into the bilge. The sense of relief was overwhelming It could of been worse, it might have been a bottle of Chateauneuf de pap Actually a good wine is excellent for varnishing wood as well. You sit looking at the bit of wood. Open the wine. Pour into a glass. Start to drink it and after a while the wood no longer seems to need varnishing  job done !! |
|
|
|
Post by lollygagger on Dec 5, 2016 12:34:26 GMT
Sooooooo.... I have a galvanic isolator with lights to show AC or DC problem. I noticed when I blacked it had it blacked that there were a few bright slightly pitted areas which must be galvanic corrosion. They are all around the middle of the boat, as far from the sacrificial anodes as could be. I'm hooked up to ac mains in a marina. What could be the cause? Edit: I don't have a transformer, I have a galvanic isolator. Is it a newish boat? Can be caused by millscale on cheaper steel, especially with blacking that flakes off with it. I'd also check the GI is wired up OK, the mfr should give instructions. Disconnecting the shore line and connecting a PP3 batt between the big earth pin and hull should light one LED, up, turn the batt around to check the other LED does too. Thanks for that, can I use the unplugged end of the lead? It's 28 and the only pitting looks to be active. It's been blacked now of course and hopfully still is. I'll have to Google pp3... |
|
|
|
Post by tonyqj on Dec 5, 2016 12:48:40 GMT
|
|
|
|
Post by lollygagger on Dec 5, 2016 12:56:10 GMT
There might be one in my multimeter. |
|
|
|
Post by lollygagger on Dec 5, 2016 15:10:20 GMT
I've made myself read up a bit and it seems an isolating transformer might be a better bet than a galvanic isolator?
Then that chap gibbo spoiled it by pointing out that modern "things" with 3 core leads deliberately leak off high frequencies to earth. The only things I have are the washing machine and some power tools, nothing that's on a lot unless ah-ha I need to switch the machine off after it's done it's cycle?
Confused? I am.
|
|
|
|
Post by tonyqj on Dec 5, 2016 15:24:25 GMT
I've made myself read up a bit and it seems an isolating transformer might be a better bet than a galvanic isolator? Then that chap gibbo spoiled it by pointing out that modern "things" with 3 core leads deliberately leak off high frequencies to earth. The only things I have are the washing machine and some power tools, nothing that's on a lot unless ah-ha I need to switch the machine off after it's done it's cycle? Confused? I am. Yes, an IT is arguably better than a GI simply because the boat is completely isolated. Gibbo's article about 'things' was an argument in favour of ITs however modern CE regs mean that there is an awful lot less taken down to earth than there used to be. Note that he wrote those articles a few years ago. |
|
|
|
Post by smileypete on Dec 5, 2016 15:24:56 GMT
Thanks for that, can I use the unplugged end of the lead? It's 28 and the only pitting looks to be active. It's been blacked now of course and hopfully still is. I'll have to Google pp3... Yes, you could use the end of the lead, with the other end still connected to the boat (NOT the bollard of course!) Is it a safeshore one? They have some testing instructions on their site: www.safeshoremarine.com/testing%20an%20isolatorIf it's a faff to hold wires onto the PP3 and to the connections, a couple of croc clips leads could help: www.ebay.co.uk/itm/Crocodile-Clip-Test-Leads-Black-Red-Yellow-White-Green-0-5m-hook-up-croc-set-/111976496719I've made myself read up a bit and it seems an isolating transformer might be a better bet than a galvanic isolator? Then that chap gibbo spoiled it by pointing out that modern "things" with 3 core leads deliberately leak off high frequencies to earth. The only things I have are the washing machine and some power tools, nothing that's on a lot unless ah-ha I need to switch the machine off after it's done it's cycle? Confused? I am. Unfortunately it's a load of bollox with not a shred of real world testing or evidence to back it up. Y'know what they say in the army - bullshit baffles brains.  Pitting can also be caused by stray current in the water from other boats, or stagnant water. Best thing is to have the hull grit blasted back to 'white metal' and a 2 part epoxy zinc coating applied. You could fit an iso transformer if you really want but it only stops corrosion due to stray DC current in the shoreline earth, not all the other causes. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 5, 2016 15:25:57 GMT
I've made myself read up a bit and it seems an isolating transformer might be a better bet than a galvanic isolator? Then that chap gibbo spoiled it by pointing out that modern "things" with 3 core leads deliberately leak off high frequencies to earth. The only things I have are the washing machine and some power tools, nothing that's on a lot unless ah-ha I need to switch the machine off after it's done it's cycle? Confused? I am. I reckon johnV wasn't far off when he described it as black magic. I think all you can do is protect your boat as best as possible. From what I've read an IT gives superior protection, but is more difficult to correctly install onboard, and indeed is more effective if not actually on the boat. There was a chap on the other site recently that has had extensive problems with hull corrosion even though a GI was fitted. |
|
|
|
Post by smileypete on Dec 5, 2016 15:29:20 GMT
There was a chap on the other site recently that has had extensive problems with hull corrosion even though a GI was fitted. Yeah I read about this but the make and model was never given.  I doubt it was one with an LED status monitor, which is what I would recommend, as they also have a higher blocking voltage. Even so it could have been due to faulty wiring on a nearby boat, but an LED status monitor would likely have picked this up. If people want to fit an IT instead of a GI that's fine by me... Problem is with GIs is that you do need to choose a decent one and fit it correctly which doesn't always happen evidently. Should that be a basis for making a blanket recommendation to fit an isolation transformer? Maybe so... |
|
job done !! 
