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Old 10-01-2015, 08:46   #151
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Re: Breaking All the Rules ...

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There are some suggestions above to blast the hull to look for corrosion.

The only way to find all corrosion would be to rip everything out of the inside of the boat that touches the hull and completely rebuild which is not practical. .
Not quite true. We have been Metal boat owners for 20 years

To find corrosion in a metal boat from the outside you could, if the price is right, get the hull below the water line Non Destructively Tested (NDT). This is basically an ultra sounder survey and if the paint system is uniform the paint does not have to be removed.

We had a lot of filler scattered around on the hull so had to have the hull sandblasted first, which found a few thin places, then the NDT guy tested all of the rest, anything that was more than 16 percent corroded was replaced

You do not need a "marine" expert, you want the guys who tests pipelines, metal strictures and welds, we found our guy through yellow pages

On the Perkins 4236M, we have one as well and it is insulated earth return so NO DC current flows through the hull which is good news on a metal boat
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Old 10-01-2015, 09:12   #152
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Re: Breaking All the Rules ...

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... so am lucky it happened on land instead of at sea where I would have...
I'm glad things are getting sorted out.... Out on the water, luck in our favor is far less common than luck we want no part of...
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Old 10-01-2015, 09:57   #153
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Breaking All the Rules ...

An untrasound that is used to test for internal corrosion of aircraft tubing is not that expensive. The age old method of testing was with an ice pick, actually an awl, but the ultrasound is far better. It's operating principle is exactly the same as a depth sounder, thicker substrate takes longer for the reflected sound wave to return.
The machine is very easy to use and does not require a lot of training, assuming you can't find someone to do it for you.


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Old 10-01-2015, 10:06   #154
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Re: Breaking All the Rules ...

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An untrasound that is used to test for internal corrosion of aircraft tubing is not that expensive. The age old method of testing was with an ice pick, actually an awl, but the ultrasound is far better. It's operating principle is exactly the same as a depth sounder, thicker substrate takes longer for the reflected sound wave to return.
The machine is very easy to use and does not require a lot of training, assuming you can't find someone to do it for you.


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Would this work on chainplates? More to the point I suppose, would it be cost-effective?
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Old 10-01-2015, 10:13   #155
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Re: Breaking All the Rules ...

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Originally Posted by a64pilot View Post
An untrasound that is used to test for internal corrosion of aircraft tubing is not that expensive. The age old method of testing was with an ice pick, actually an awl, but the ultrasound is far better. It's operating principle is exactly the same as a depth sounder, thicker substrate takes longer for the reflected sound wave to return.
The machine is very easy to use and does not require a lot of training, assuming you can't find someone to do it for you.


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An excellent suggestion.
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Old 10-01-2015, 20:29   #156
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Re: Breaking All the Rules ...

One would think that a boatyard would have wifi so someone would not have to resort to 4G to upload photos to document a story as fantastic as this one. Just sayin'...
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Old 10-01-2015, 21:07   #157
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Re: Breaking All the Rules ...

Every time I have been down in the engine room over the last two months I removed a few bolts from the old Onan generator that died during the flooding, and have been throwing pieces out as they come off. Today I finally removed the block, so the engine room is now a lot cleaner, and there is more space to work and see problems.

Behind where the generator sat I can now see the inside bottom of the starboard fuel tank that corroded through on the hull. There is obvious corrosion on the inside also around ... what appears to be a bronze fuel tap. So just like the corrosion from the tank riser elbow at the top of the starboard tank, the corrosion at the bottom of the tank is also associated with dissimilar metals. On Monday I will be trying to source fuel taps and elbows that won't corrode my tanks, and will replace the fuel lines at the same time.

Think I will have a closer look at the water tank fittings also ....

I want to keep the bilges dry and clean to minimise corrosion and bad smells and have cleaned the bilges a number of times over the last few months, but continue to find more mud there, and have even seen some small crabs wandering about. Today I washed them out again and there was more mud so I did more investigation. The bottom of the chain locker has a drain connected to a hose ... that empties into the bilges. So if you anchor in mud, you haul in a muddy wet chain and that mud eventually ends up in the bilges. When single handing it is already a hard job running up and down the boat to control throttle and gear change and rudder from the cockpit and raise the anchor from the bow while potentially drifting through a crowded anchorage, so I guess now I also have to make sure no chain comes aboard with mud still on it, though not sure I can also run the deck wash at the same time as everything else.
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Old 10-01-2015, 22:06   #158
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Re: Breaking All the Rules ...

homeless, you might want to consider a couple of anchor locker drain holes, and discontinue the internal drain entirely. Even if you have to change the shape of the "floor" of the locker, you want it to be dry and clean in there, too.

Good luck with sourcing all the pinholes. What a job! Keep on truckin'.

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Old 11-01-2015, 01:02   #159
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Re: Breaking All the Rules ...

Go and buy a tube of Duralac and use it every time you put a fitting into aluminium, acts as an isolator and will prevent corrosion due to dissimilar mtals
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Old 11-01-2015, 03:12   #160
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Re: Breaking All the Rules ...

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When single handing it is already a hard job running up and down the boat to control throttle and gear change and rudder from the cockpit and raise the anchor from the bow while potentially drifting through a crowded anchorage
A solution is to get control of the windlass at the helm. I bought an off-road car winch wireless control and wired it up to the windlass contactor. Much easier than direct wires and inexpensive. Try Amazon, Ebay etc.

For your starter problems: there are a few suppliers in the UK selling refurbs a quarter the cost of new. I can call someone for you if you have the part numbers.
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Old 11-01-2015, 04:02   #161
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Re: Breaking All the Rules ...

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I bought an off-road car winch wireless control and wired it up to the windlass contactor.
Similarly, I bought a wirelesss anchor control on eBay. It is only cheap quality, but for less than $100 it is the best value tool for single handing I have bought. When the wind is strong you really need to see the anchor chain while retrieving. I can now stand close enough to the bow so I can see the angle of the chain, yet close enough to the helm to quickly get back there and change power or rudder settings without having to stop hauling the chain.

Warning. I only trust cheap stuff so far. I recommend installing a switch with warning light so it is only switched on and enabled when you want it to be. I would not enjoy the day if it decided to deploy the anchor on its own while I was sailing. Also, my anchor is currently not tethered to prevent such accidental deployment and this is high up on my to do list.
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Old 11-01-2015, 07:54   #162
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Re: Breaking All the Rules ...

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Originally Posted by Wanderlust View Post
Similarly, I bought a wirelesss anchor control on eBay. It is only cheap quality, but for less than $100 it is the best value tool for single handing I have bought. When the wind is strong you really need to see the anchor chain while retrieving. I can now stand close enough to the bow so I can see the angle of the chain, yet close enough to the helm to quickly get back there and change power or rudder settings without having to stop hauling the chain.

Warning. I only trust cheap stuff so far. I recommend installing a switch with warning light so it is only switched on and enabled when you want it to be. I would not enjoy the day if it decided to deploy the anchor on its own while I was sailing. Also, my anchor is currently not tethered to prevent such accidental deployment and this is high up on my to do list.
My father and I both bought a cheap Harbor Freight wireless winch controller. He used his for the windlass, I used mine for my primary electric winches. It was after we both installed them that the light bulb went off. How many frequencies does this cheap remote have? If I'm sailing next to my dad and I go to trim the sail, am I going to drop his anchor? And if we're racing each other, he has an unfair advantage of being able to make me over trimmed. Luckily they were different, which is good because there have been times where we were sailing close enough to be in range.

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Old 11-01-2015, 08:01   #163
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Re: Breaking All the Rules ...

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Would this work on chainplates? More to the point I suppose, would it be cost-effective?

I don't think so, all this device is is essentially a thickness gauge, like a depth finder that only shows depth as opposed to say a bottom machine that shows fish, bottom composition etc.

Ultrasound for NDT is usually not the preferred method for metal, usually for metals dye penetrant and eddy current , magnaflux etc is preferred. eddy current and dye pen require the flaw to exist at the surface of the metal, X-ray and magnaflux can detect inclusions or internal cracking etc.


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Old 11-01-2015, 15:19   #164
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Re: Breaking All the Rules ...

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Originally Posted by a64pilot View Post
I don't think so, all this device is is essentially a thickness gauge, like a depth finder that only shows depth as opposed to say a bottom machine that shows fish, bottom composition etc.

Ultrasound for NDT is usually not the preferred method for metal, usually for metals dye penetrant and eddy current , magnaflux etc is preferred. eddy current and dye pen require the flaw to exist at the surface of the metal, X-ray and magnaflux can detect inclusions or internal cracking etc.


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Thanks for this info, a64. Thus far I've only pulled one, easy to access chain plate and used a dye penetrant on it. It only showed some light pitting that could also be seen with the naked eye, but no surface cracks. It seems to me that a dye penetrant might be a good starting place, but not definitive. But then the cost of x-ray & magnaflux could easily exceed the cost of replacement it seems.

When it comes to SS crevice corrosion, would any unseen internal fracturing also manifest at the surface?
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Old 11-01-2015, 15:32   #165
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Breaking All the Rules ...

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Thanks for this info, a64. Thus far I've only pulled one, easy to access chain plate and used a dye penetrant on it. It only showed some light pitting that could also be seen with the naked eye, but no surface cracks. It seems to me that a dye penetrant might be a good starting place, but not definitive. But then the cost of x-ray & magnaflux could easily exceed the cost of replacement it seems.



When it comes to SS crevice corrosion, would any unseen internal fracturing also manifest at the surface?

Not sure about crevice corrosion, but if I understand it, then it begins at the surface and if this is true, then yes.
When the time comes to replace my chain plates I've considered Titanium.
But, I come to the conclusion that the original ones lasted 27 yrs so far, if the replacements last that long, then who cares?
I run into the same quandary with my tanks, I felt sure that when I replaced them I needed to go with something better than aluminum, but back to they are 27 yrs old. Maybe aluminum isn't that bad after all?

My chain plates are glassed in, and with all the work required to remove them, they won't be inspected except as a matter of curiosity. If they come out, new ones will go in.

If they are very old and they have to cone out for inspection, maybe just replace them, like standing rigging, do we wait until it fails inspection or replace on either inspection failure or a time interval whichever comes first? I'm asking because I don't know, but it would seem chainplates should be the same?


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