Powder coat/anodize new mast step?

[00X]

Thanks everyone for all the good suggestions. I was considering using G-10 as a backing plate between the keel bolts and the top of the mast step. It has a compression strength of 60,000ish psi. I wasnt sure if that would handle the torque/compression of the bolts/nuts, but it sounds like after reading the replies i might be able to get away with it.

I have enough space for a piece thats at least 0.375" thick. Once i know where the keel bolts will sit in the slots, i could easily machine the slots around the bolt to accommodate a plastic sleeve of some sort, thats not a problem.

Looks like i'll go with the anodizing.

[00X]

Originally Posted by s/v Jedi

Around the bolts you can use nylon bushings to isolate, but the slots need to allow the room for those. You can also wrap with good quality gaffers tape.

Then there is an antiseize that works really good around aluminum. Most on CF only use Tefgel but Loctite LB 8023 is better https://www.amazon.com/gp/product/B00B74AB5C

Thanks, i'll look into that. That was going to be another question that i was thinking about last night.

[00X]

Originally Posted by neilpride

I see a huge beautiful mast step keel bolts backing plate there, aluminium in this case , wrong material of choice in my opinion.

He can make a sacrificial washer with aluminium to, or like Jedi point out, FG, but nylon, delrin, or any kind of plastic used there can compromise keel bolts in the long run, i would have made the foot of the mast in stainless steel, more expensive but easier to isolate the foot of the mast from the mast step in stainless steel than the keel bolts from the aluminium.

The plastic tends to crush leaving a gap between the nut and the plate, it could appear that the bolts are tight when in fact they are loose.

Thank you. I wanted to make it in Stainless , but couldn't find any fabricators to make it for me. Most of them wouldn't even return my calls/emails. The couple that did quoted stupidly expensive prices ($2000). The original step was aluminum so out of frustration i decided to machine it myself on a desktop CnC at work. Cost me about $500 all in.

[neilpride]

Out of curiosity, i have seen many mast steps, but never one like this, what boat is it?

[RaymondR]

Beg to differ on the SS option.

Assuming the mast is aluminium, by using aluminium for the base you have avoided a potential dissimilar metals problem at the mast to base interface.

So now the only problem is with the keel bolts which are easy to electrically isolate.

What you are trying to achieve with the electrical isolation is to break the electrical circuit between the poles of the voltaic pile which might form with dissimilar metals in the presence of an electrolyte oe. a battery. It is the current flow which causes the corrosion and current flow always requires a connection between positive and negative poles.

In your case the aluminium would be the anode and the keel bolts the cathode and the current would flow in the direction to cause dissolution of the aluminium.

[dfelsent]

Originally Posted by 00X

Thanks everyone for all the good suggestions. I was considering using G-10 as a backing plate between the keel bolts and the top of the mast step. It has a compression strength of 60,000ish psi. I wasnt sure if that would handle the torque/compression of the bolts/nuts, but it sounds like after reading the replies i might be able to get away with it.

I have enough space for a piece thats at least 0.375" thick. Once i know where the keel bolts will sit in the slots, i could easily machine the slots around the bolt to accommodate a plastic sleeve of some sort, thats not a problem.

Looks like i'll go with the anodizing.

I should have mentioned that mil spec hardcoat anodizing type III is significantly more durable than most other anodize coatings. Make sure you talk with the shop and explain that you are looking for salt water corrosion resistance. They should recommend a seal step post anodizing. This is important. If they don’t, talk to another shop.
We used to use a hot water DI water seal to improve resistance to corrosion from fluorine plasmas. Big improvement for short money. There are other anti corrosion seal processes available. Ptfe seal is not what you want afaik.

A good shop will also work with you on surface finish, preparation, and cleaning.

20 years ago I used these folks:

https://platingforelectronics.com/

You may have a close by shop that does great work too.

[CarinaPDX]

It should be clear by now that a high quality anodizing is the way to go. I consider powder coating the devil's spawn. Eventually it will start to peel off, but the remaining coating will be quite tenacious and difficult to sand off. So I would just remove the loose coating and paint the bare aluminum, then wait for more of the powder coating to come loose. When there is little left I just put the effort into sanding the rest off. It is a PITA.

Greg

[00X]

Originally Posted by neilpride

Out of curiosity, i have seen many mast steps, but never one like this, what boat is it?

Mariner Yacht.

[00X]

Originally Posted by RaymondR

Beg to differ on the SS option.

Assuming the mast is aluminium, by using aluminium for the base you have avoided a potential dissimilar metals problem at the mast to base interface.

So now the only problem is with the keel bolts which are easy to electrically isolate.

What you are trying to achieve with the electrical isolation is to break the electrical circuit between the poles of the voltaic pile which might form with dissimilar metals in the presence of an electrolyte oe. a battery. It is the current flow which causes the corrosion and current flow always requires a connection between positive and negative poles.

In your case the aluminium would be the anode and the keel bolts the cathode and the current would flow in the direction to cause dissolution of the aluminium.

Thank you. I should have plenty of room to isolate the keel bolts from the step. I will end up wrapping them with something or putting a spacer/tube around them. I also machined a drainage system into the step inside and underneath it, so that there is no standing water in or around the step, assuming i mop it up. The panting rod may be a bit more difficult to isolate though.

[00X]

Originally Posted by dfelsent

I should have mentioned that mil spec hardcoat anodizing type III is significantly more durable than most other anodize coatings. Make sure you talk with the shop and explain that you are looking for salt water corrosion resistance. They should recommend a seal step post anodizing. This is important. If they don’t, talk to another shop.
We used to use a hot water DI water seal to improve resistance to corrosion from fluorine plasmas. Big improvement for short money. There are other anti corrosion seal processes available. Ptfe seal is not what you want afaik.

A good shop will also work with you on surface finish, preparation, and cleaning.

20 years ago I used these folks:

https://platingforelectronics.com/

You may have a close by shop that does great work too.

Thank you. Good info to be aware of.

[00X]

Originally Posted by CarinaPDX

It should be clear by now that a high quality anodizing is the way to go. I consider powder coating the devil's spawn. Eventually it will start to peel off, but the remaining coating will be quite tenacious and difficult to sand off. So I would just remove the loose coating and paint the bare aluminum, then wait for more of the powder coating to come loose. When there is little left I just put the effort into sanding the rest off. It is a PITA.

Greg

I had to laugh. You perfectly described my relationship with my old (horrendous) Cetol varnish coating.

I did end up powder coating some of my pedestal bits. We have some local shops that do really ice work and are affordable. My boats powder coating has faired pretty well. The builder did a decent job. Most of the problems are from previous owner inflicted damage. I found out the coating can be lightly sanded and buffed to restore it a bit. That being said, my mast coating is about 80% gone like you describe.

[ShoreFun]

About the coatings.

Paint, epoxy, and what have you are coatings. Powder coat is paint and often has the same chemical reactions to form the coating, just no solvents. Not always, but it will work for my next comment.

As a coating you must have the surface properly prepaired for adhesion of the coating and for any type of corrosion prevention. In actual use, if water can get in then it will spread under the coating. I have seen whole coatings pop off like a mold with significant corrosion underneath. Obviously, the coating was able to hold the moisture close to the surface for a long time.

Annodizing is essentially corroding the surface. This locks the free side of the aluminum from bonding to oxygen preventing further corrosion.

The issue with all cases would be the interface between 2 items. Clearly the mast will be rubbing against the block which will allow new free aluminum to be exposed to corrode.

Just all basic science. Keeping boats in good condition is about slowing down these processes as best you can. Part of that is to understand what might happen with each prevention technique.

My experience is from the car restoration side of the table. When you are at car shows look at corners with door and trunks meet on the older cars. You can tell where they failed to do proper paint work by which layer is showing.

[00X]

Originally Posted by ShoreFun

About the coatings.

Paint, epoxy, and what have you are coatings. Powder coat is paint and often has the same chemical reactions to form the coating, just no solvents. Not always, but it will work for my next comment.

As a coating you must have the surface properly prepaired for adhesion of the coating and for any type of corrosion prevention. In actual use, if water can get in then it will spread under the coating. I have seen whole coatings pop off like a mold with significant corrosion underneath. Obviously, the coating was able to hold the moisture close to the surface for a long time.

Annodizing is essentially corroding the surface. This locks the free side of the aluminum from bonding to oxygen preventing further corrosion.

The issue with all cases would be the interface between 2 items. Clearly the mast will be rubbing against the block which will allow new free aluminum to be exposed to corrode.

Just all basic science. Keeping boats in good condition is about slowing down these processes as best you can. Part of that is to understand what might happen with each prevention technique.

My experience is from the car restoration side of the table. When you are at car shows look at corners with door and trunks meet on the older cars. You can tell where they failed to do proper paint work by which layer is showing.

Interesting, thank you. Yes i agree. Sooner or later the elements and normal wear and tear will take their tole. I guess there is only so much we can do. My thinking is, that since im in control of the process this time, it makes sense to do what i can to make my restorations as good as reasonably possible. If i can get five more years out of it by anodizing it, i'll take it.

[RaymondR]

When I built my steel boat there was a very acute place where the hull plating met the stem bar. I knew I would have problems with it so I cleaned it out and thickly painted it with hot pitch.

During a hull refit twenty five years later I tried to scrape some of the pitch out to check the underlying steel and found that the pitch had very effectively wet the steel and very effectively excluded any water and was very difficult to remove.

Consequently I just used a hot air paint removal gun to remelt the pitch and brushed it out to re cover the part I had scraped away. If you cannot find pitch one of the wireline dressing products would do the same job.

[Searles]

Having double anodised and then powder coated , cast alu anchor winch cases a number of times for high use yachts and have the coatings work fine ,some over 20 yrs ago even with fresh water wash downs these are on high use offshore vsls in salt water ,plus I would be verry surprised if the keel bolts were 304 ,316l maybe or 2205 maybe closer ,must use non metal bushes for bolting in the high corrosive areas.