Capac

[PascalG]

can you guys shed some light on the Capac system ?

my boat has one which has always been reading low. Recently, the reading has gone up a little, to 0.4 whcih is still on the low side. not sure why it went up...

I read the manual last night, and i'm still a little confused... if i get this right, current is emitted outside the boat in order to protect its submerged metal parts.

how useful is this system, how common is it? I guess it extends zinc life?

pascal
miami, fl
70 53 MY

 

[jim rosenthal]

Capac system...

Pascal, I had one of these on my 44 Striker SF, years ago. I am surprised it would be on a FBG boat- on the Striker it was essential as they have an aluminum hull...I don't see the rationale for having one on a glass boat.
Basically what these systems are supposed to do is measure the potential difference between the underwater hardware and a reference electrode in the water, and tell you whether the hardware is protected or not. I think basically is that it is telling you whether your zincs are doing the job or not. This assumes, of course, that the reference electrode can "see" the water, that the wiring is intact throughout, etc.
This is not the same at all as an impressed current system wherein DC current is used to actively reverse the process of electrolysis and corrosion of underwater hardware. Large metal boats benefit from this, because as expensive as it is in terms of electric power to reverse the potential for that much hardware, it costs a lot more in dollars and safety issues to replace said hardware. The only small-boat impressed current system I know of is the MerCathode unit which Mercruiser puts on some of their outdrives. This will be made obsolete by composite outdrive units in the next decade or so, I suspect.
You may be able to get a manual from Capac as to how to "read" the system. Meanwhile, check that the wiring is sound, and that the platinum reference electrode isn't painted over. Honestly, though, you could probably achieve the same ends by just keeping your eye on the zincs via a diver.
FWIW, I think the most important thing on boats like hours in regards to preventing corrosion is either blocking diodes on the incoing AC ground legs, or better yet, isolation transformers so that there is no direct connection. All new Hatteras yachts have them, and if they didn't weigh so much, I would too.

 

[PascalG]

Capac system

Jim,

yes, i have a diver cleaning the hull every month and replacing zincs as needed.

from what i read in the manual last night, it is using DC to reverse electrolysis which, I agree, seems an overkill on a fiberglass boat... at first I thought it was just a monitoring system but it seems that it does more than that...

pascal

 

[jim rosenthal]

OK, here goes....

..I think you have an impressed current system. It is using DC to reverse electrolysis. How fast do you use up your zincs?
Good reference on this: Metal Corrosion In Boats, by Nigel Warren, from International Marine Pub Co. They are distributed by McGraw-Hill I think. See if you can find that. Also, if you live near a Coast Guard yard, and can find a Coast Guard marine electrician who moonlights a bit, they know quite a bit about impressed current systems and how to troubleshoot them.
Interesting that it is on a Hatteras, I have never seen that before (which says nothing, out of 7500 boats they have made I have maybe seen twenty or thirty)

 

[pirtae1960]

capac

My 58' MY had the Capac system on it. It always read low and I hardly EVER had electrolysis or zinc problems. I would assume that the system was working properly.

 

[PascalG]

Capac system

jim,

zincs last about a year I think... looking into it last night, I noticed that... well... it's actaully disconnected!

the 12v + lead was buried in a bundle of wire and cut.. . not sure why the display shows any reading at all, I'll reconect it tonight and see what happens...

pascal

 

[Trojan]

Capac system and ZINCS

Longevity of a zinc is in direct relationship to the amount of - DC. current flowing through it.Every boat and slip is deferent.Zincs are the softest conducting element on your boat when they are in salt water.In fresh water you use magnesium.The positive charge of your boat from the Capac device through the zincs reverses or equalizes the voltage or the process.Its not AC. leakage that is bad,it's the leaking DC.that eats the zincs and metals.The leaking voltage varies from slip to slip,boat to boat.You can measure it without to much trouble.Ask the guys in the Marionette's.They have the measuring device built right into there boats to measure it 24-7 or there boats just might disappear.Bill

 

[Nonchalant1]

Freshwater and ZINCS

In freshwater you use magnesium?? I have zincs. I thought that if zinc was more easily electrolyzed than all other metals in contact with the water, that it would go first. If so, salt water just increases the process many fold, but zinc should still do the same thing in freshwater?

Gee, I guess I'll never get "mag wheels" for my boat!

Doug Shuman

 

[Trojan]

Salt water zinc

If your in fresh water,get rid of the Zinc.Zinc in salt water and magnesium in fresh water.The salt water reacts deferent to the metal zinc.Zinc is also cheaper to purchase.I found out the hard way.I had zinc on my 32 footer and both rudders had to be replaced $1000.bucks.It ate the bronze rudders instead of the zincs.You can use magnesium in salt.But the life span of the electrode will quite short.Some people don't use anything on there boat.You could use mag wheels on your boat.There just a pain when its time to rotate.The biggest offender on a boat is a cheap battery charger left on.Causing stray current flow.Check out the metal on the guys with the out-drives.Bill You should really detach the trailer!

 

[PascalG]

Capac system

i reconnected the Capac a couple of days ago and the reading on the monitor went up to just around 1.0 which is where it's supposed to be...

i'll see if it makes any difference in zincs... although according to the protection scale, it's set to protect bronze and steel, but no aluminium (obviously doens't matter on a hatt.) so since zinc would need even higher protection, I don't see how the Capac can protect the zincs...

pascal
miami, fl
70 53my