A more precise method for measuring zinc erosion ?

[baz]

So far I've been eye-balling my zincs to determine just how much has eroded. I'm thinking the more precise method would be to weigh the eroded zinc and compare it with its original weight.

Of course, visual inspection of a zinc will still be needed to determine the necessity for replacing it.

...and then of course, some zincs simply need replacing because they may be in danger of falling off or being so loose that they are ineffective -- example would be the prop zinc.

No matter, do others agree that a weight comparison is a reasonable approach for determining a more accurate measure of the extent a zinc has eroded ?

 

[GulfSailor]

No matter, do others agree that a weight comparison is a reasonable approach for determining a more accurate measure of the extent a zinc has eroded ?

More accurate than a visual check certainly, but to what end? If it was important that a zinc had to be replaced when 50% eroded, or 65%, or any specific figure, then a weight comparison would be as good a method as any, although you could also easily measure its volume by water displacement.

However, the figure is not specific and either of those methods would entail removal of the zinc, so unless the percentage of erosion is needed for another reason I'd say a visual inspection is adequate for the purpose of estimating when renewal is due.

However, there's no denying that a weight or volume comparison is likely to be more accurate than even the most careful eyeballing! 😉

 

[Bruce Moore]

We trust the dive service, and I'm pretty sure they makes their decision based on visual inspection. They always leaves the old zincs for my review. Never had a reason to question their judgement.

Cheers,

Bruce

 

[baz]

I've made several changes to my boat to hopefully reduce the frequency of zinc replacements. I have records of my zinc replacements for past year and wish to evaluate the effectiveness of my changes. This is why I want to precisely record the zinc conditions as they get replaced.

 

[sleepyboat]

I attempted to change the zincs on the Side Power thrusters yesterday. They came from my dealer and were the Side Power product. I put them in wrist tight which felt very snug only to discover the zincs still spun on the screw. I had heard there was a screw length problem, with the wrong ones being shipped in the package. Upon compairson the new and old screws are the same length BUT the shoulder that it sits in the new zinc is deeper. This makes that screw too long. And yes, after three and one half month in the water they were more than ready to be replaced. has anyone else run into this issue?
Being in the Neuburyport Ma area moored on a river in brackish water, three months seems to be the limit of my zincs but the other boats you are around and marina electrical conditions seem to be the big variable.
John
Sallison R-27

 

[walldog]

I've made several changes to my boat to hopefully reduce the frequency of zinc replacements. I have records of my zinc replacements for past year and wish to evaluate the effectiveness of my changes. This is why I want to precisely record the zinc conditions as they get replaced.

Good Morning Barry,

I know that you will keep excellent records. Those of us with inquiring minds want you to let us know when the Net Present Value of just replacing the zincs being sacrificed will equal the cost and maintenance of the modifications.

Big Grins from Herb,

PS, Please do not take offense, I am just fondly picking on you.

 

[baz]

Walldog: Fair enough and yes enquiring minds are kindred spirits indeed.... 🙂

The benefits... well it's kind of like trading in a paid for auto that gets 30 mpg for a new Prius getting 60 mpg. It takes several years to break even financially as you have to regain the initial capital cost of the new auto while saving on gasoline expenses. If the cars were driven 15,000 miles per year and gasoline cost $4/gallon then the Prius would be saving you $1000 per year. Thus is would take quite a few years to reach a point where the Prius is actually saving you money. However, the immediate benefit is of course that you are reducing your gasoline consumption by 50% and hence being 'greener' as they say.

Reducing zinc erosion will help with the boat's immediate operational expense but it will take time to recover the initial capital expense.

Reducing consumption is a worthy goal, right ?

The other benefit is that attacking some of these problems provides intellectual challenges and keeps the gray cells multiplying or avoids them from eroding too quickly... 😉 :lol:

 

[walldog]

Walldog: Fair enough and yes enquiring minds are kindred spirits indeed.... 🙂

The other benefit is that attacking some of these problems provides intellectual challenges and keeps the gray cells multiplying or avoids them from eroding too quickly... 😉 :lol:

So True......and getting truer.

 

[captainmike]

If your zincs are going away quickly and you are plugged in to shore power a galvanic isolator will help and making sure your bonding system is intact along with seeing how the other boats near by are doing as one of them may be the problem.

Capt. Mike

 

[GulfSailor]

I've made several changes to my boat to hopefully reduce the frequency of zinc replacements. I have records of my zinc replacements for past year and wish to evaluate the effectiveness of my changes. This is why I want to precisely record the zinc conditions as they get replaced.

Ok, I can understand that. However, there are some variables to take into account also, such as water salinity and temp, and maybe a 'rogue' boat that appears in the vicinity, all of which could affect the rate of erosion, and all of which I'm sure you're aware of. 😉

 

[jroyle]

Being in the Neuburyport Ma area moored on a river in brackish water, three months seems to be the limit of my zincs but the other boats you are around and marina electrical conditions seem to be the big variable.
John
Sallison R-27

John, I am moored 12 months a year in Huntington Harbor Ca. and I had a "hot" boat in the next slip to mine. I was burning thru all zincs every 2-3 months. The "hot" boat has since left and my zincs look close to new after 3 months...our neighbors boats can be our worst enemy.
Jeff

 

[Bruce Moore]

The other benefit is that attacking some of these problems provides intellectual challenges and keeps the gray cells multiplying or avoids them from eroding too quickly... 😉 :lol:

Hmmmm. Good point. Maybe I should have the divers put my brain on the schedule! 😀