Steel sailboat and corrosion should detection and prevention.

[Lucas1983]

It looks as though I may be buying a beautiful steel sailboat, but I am not an expert by any means on detecting corrosion and handling it, or which sort of paint and chemicals are the absolute best to use and so on. I also wanted to find out more about how your engine can corrode and how best to prevent that, also i ant man to confirm if changing to fresh water cooling will fix this issue or if it still happens and if there are any other things on a steel boat that can be effected by this.

[wingless]

The rusty steel parts on my boat was stripped down to bare metal, coated with Pettit 6455/044 Metal Primer, then Interlux 2000E Barrier Coat Primer, then Rustoleum Professional High Performance Aerosol Spray Paint.

Those old rusty looking steel parts have retained a glossy plastic finish for well over a decade.

Here are some examples. It has worked great on all the parts I have finished using this process, all for over a decade.

[MicHughV]

I built and sailed a steel boat for nigh on 15 years. Now 40 years old, that boat is still around on it's 3rd owner. Still going strong !!

You can expect to do some maintenance work on the outside, should you drop something or otherwise chip the paint, but these days there are a plethora of paint options available to deal with these things and these paints are remarkably tough. See above.

The inside of the boat is the boogeyman as far as rust is concerned as this is often out of sight. Here again, many options available. I have gone so far as cleaning rusty spots with a wire brush and coating with WEST system epoxy with excellent results.

I've never had the slightest issue with engine corrosion, other than normal maintenance, but you would get the same in a fiberglass boat.

Steel is remarkably tough, and a simple rule of thumb is that a 1" thick steel plate can throw of 10" of rust before rusting thru'.

You can purchase a steel thickness measuring gauge that fits in the palm of your hand, that you can place against any steel surface and it will give very accurate readings to how thick the plate is.

At the end of the day, having a steel hull under me, gave me a feeling of confidence that no fiberglass boat ever could.

[tkeithlu]

If you keep sufficient aluminum anodes on the hull etc. you will have no rust below the waterline. Get yourself a silver test anode to check that you have one volt of protection (drop the test electrode in the water, connect your voltmeter between it and your hull).

https://www.boatzincs.com/corrosion-...electrode.html

Windless has got wisdom on paint. The only thing I will add is finish bare steel with sandpaper before you apply primer. A wire brush can leave too smooth a surface for good adhesion. I learned that here on the forum.

Ever seen a fiberglass boat burn? It isn't pretty.

[MicHughV]

I had a big 6" x 12" x 1" thick sacrificial zinc bolted to my hull, near the back of the keel.
This would provide protection for around 3 years before I needed to replace it. You can tell it's getting worn by diving on it and looking at it and feeling it. If the edges crumble easily in your hand, it's time to replace it, even though it looks like it has some service life left.

I've seen some steel hulls that had several sacrificial zincs on the bottom of the hull, but I only ever had the one as described above and never had any issues with my boat whatsoever.

I also had the zincs on my prop shaft, but they rarely lasted more than about 6 months.

Since then I have taken to hanging a zinc fish over the side of my fiberglass boats, which is hooked by cable to the boats grounding system. I only do this at marina's as one never knows what a neighboring boat is up too.

I could have done this with my steel hull, but did not think to do it at the time, as it's a simple way to tell if the zinc is being eaten up by simply pulling the fish up and out of the water and looking at it.

[Mike Banks]

If you have a steel boat I would rig a keel engine cooling fresh water system. It is what most small commercial vessels use.

[oceanshoretiga]

Originally Posted by tkeithlu

If you keep sufficient aluminum anodes on the hull etc. you will have no rust below the waterline. Get yourself a silver test anode to check that you have one volt of protection (drop the test electrode in the water, connect your voltmeter between it and your hull).

https://www.boatzincs.com/corrosion-...electrode.html

Windless has got wisdom on paint. The only thing I will add is finish bare steel with sandpaper before you apply primer. A wire brush can leave too smooth a surface for good adhesion. I learned that here on the forum.

Ever seen a fiberglass boat burn? It isn't pretty.

On anodes, be careful to not have too many. I’ve had my current steel Herreshoff for 36 years and early on I thought more anodes was a good thing. It is not. As the quote above says, test for appropriate voltage for sure. Originally I though more anodes was good but the paint kept blowing off underwater with plenty of protection visible (ie anode material doing its job). A catholic protection specialist said my problem was too many anodes and recommended a maximum of two, saying one may be enough. I put two large anodes at the bottom of the keel, did the test, and left both on. Those anodes have been there for over 20 years. I weigh them each haul out to be sure there is still enough protection.

On deck rust, my boat was built about 1978 before stainless was used for all deck fittings. Yes, some key fittings but not all. If buying a new steel boat I want to lots of stainless deck fittings and protection strips to avoid rust and later welding. As already commented, the inside is the ‘Sleeper’.

I love the offshore security of steel but also the comfortable ride of a heavy, steady boat. She is no slug but I don’t speed to windward; as I virtually never sail in protected waters (the nature of the West Australian coast), I don’t want to go to windward anyway.

Jim

[Oceanride007]

In my experience, corrosion occurs inside hull consistent with inadequate limber holes below wet aria, surprised just weeks ago found Fore peak badly corroded. taken weaks to get right as angles not good for chipping hammer or chisel, or grit blasting or needle gun, combination worked, I hope. I use oxalic acid to clean rust then Carboline Altralock 576.

[oceanshoretiga]

I didn’t mention in my last post how I deal with rust. Acid solution don’t do it for me, except for cleaning stainless steel and brightening up the deck paint. I use an Australia product called Xtrol, which is a penetrating system but, as with all systems, preparation of the surface is the key issue. Penetrating is very important as it is almost impossible to remove all rust.

Cheers, Jim

[Lucas1983]

Originally Posted by oceanshoretiga

I didn’t mention in my last post how I deal with rust. Acid solution don’t do it for me, except for cleaning stainless steel and brightening up the deck paint. I use an Australia product called Xtrol, which is a penetrating system but, as with all systems, preparation of the surface is the key issue. Penetrating is very important as it is almost impossible to remove all rust.

Cheers, Jim

Thank you for the excellent advice,everyone. yeah I read a little bit about acid not a whole lot so far us lyric I think is what you're supposed to use oh, there's so many products out there I got a lot to learn yet as we all know but that's part of the job owning a sailboat.

Yeah it sure sucks that corrosion is more likely to start on the inside and that means taking off panelling cupboards and insulation etc. Can only hope that he took the coating as seriously as he did the welding and everything else which I'm 98% sure he did, I found out today the guy he had welding on his boat and counselling him we're certified 2 weld in nuclear reactor plants in probably vessels which is what they are usually mean so they're taking it above what we call a b pressure welder here in the oil field in Canada meaning of high pressure pipelines and vessels containing very volatile product Oh, so I have very high face in the boat structurally and pretty much in every other area really just as I get to know this poor deceased fella and his work. Unfortunately took a different approach to his medical condition or cancer due to being into Scientology and he opted out of chemo when the time was right to do it and that bit him in the ass later obviously.

[Lucas1983]

Originally Posted by Mike Banks

If you have a steel boat I would rig a keel engine cooling fresh water system. It is what most small commercial vessels use.

How do you like the keel cooling system I'm not very familiar with these, the builder of this boat swap the fuel tanks for water and but the diesel which is 200 gallons according to the specs in the keel, normally I would be worried a bit because some of the time your engine is on top of the heel making the tank hard to get at and clean or inspect at all but with the way this guy seems to go about everything being very meticulous and thorough I'm pretty sure it's set up very professionally or convenient or cleaning at least that's definitely not a tank where I want any sort of problems but I wouldn't be surprised if he has some sort of all Gage weather wave guided radar or float who knows but he doesn't really cheap out on important stuff I noticed.

[Lucas1983]

Originally Posted by oceanshoretiga

On anodes, be careful to not have too many. I’ve had my current steel Herreshoff for 36 years and early on I thought more anodes was a good thing. It is not. As the quote above says, test for appropriate voltage for sure. Originally I though more anodes was good but the paint kept blowing off underwater with plenty of protection visible (ie anode material doing its job). A catholic protection specialist said my problem was too many anodes and recommended a maximum of two, saying one may be enough. I put two large anodes at the bottom of the keel, did the test, and left both on. Those anodes have been there for over 20 years. I weigh them each haul out to be sure there is still enough protection.

On deck rust, my boat was built about 1978 before stainless was used for all deck fittings. Yes, some key fittings but not all. If buying a new steel boat I want to lots of stainless deck fittings and protection strips to avoid rust and later welding. As already commented, the inside is the ‘Sleeper’.

I love the offshore security of steel but also the comfortable ride of a heavy, steady boat. She is no slug but I don’t speed to windward; as I virtually never sail in protected waters (the nature of the West Australian coast), I don’t want to go to windward anyway.

Jim

I am glad you mentioned that, I did catch a article saying that more anodes is not a good thing as one could assume early on or just end up being a waste but your saying it makes thing worse so that's good to know for sure as I suspected that could be the case sometimes.
What about one on your prop? I noticed some guys do that in the cxxenter over the locking nut, but I am sure it's only applicable.to the boat and prop material which I think was stainless that I seen. The boat I hope to buys has a 3 blade feathering prop, a max prop, 16". Which was a better than average result when looking into the drive.

So you dont need to spread the anodes out either by what I am hearing if you had both on each side of the keel right? What do you do to protect you engine? Just insulated fr the hull and grounded to the keel?
What's your technique for testing the voltage? I can't recall the specifics on this at the moment but one guy was using a silver spoon beside his multimeter and put it in the water beside the hull when he was taking his reading, does that sound familiar to what you do? I'm curious to find out all what a cathodic protection specialist does as a while.inspection and testing, I used to have those guys out all the time at the remote oil and gas facilitiys for maintenance and to keep up with the cathode protection schedule on out lardge and small pipelines and various other things equipment, obviously a completely different ball of wax for the most part.

[Lucas1983]

Originally Posted by Oceanride007

In my experience, corrosion occurs inside hull consistent with inadequate limber holes below wet aria, surprised just weeks ago found Fore peak badly corroded. taken weaks to get right as angles not good for chipping hammer or chisel, or grit blasting or needle gun, combination worked, I hope. I use oxalic acid to clean rust then Carboline Altralock 576.

Is that a rust remover or coating and protection?. Pretty pricey stuff by the gallon I assume.

[Lucas1983]

Originally Posted by Lucas1983

How do you like the keel cooling system I'm not very familiar with these, the builder of this boat swap the fuel tanks for water and but the diesel which is 200 gallons according to the specs in the keel, normally I would be worried a bit because some of the time your engine is on top of the heel making the tank hard to get at and clean or inspect at all but with the way this guy seems to go about everything being very meticulous and thorough I'm pretty sure it's set up very professionally or convenient or cleaning at least that's definitely not a tank where I want any sort of problems but I wouldn't be surprised if he has some sort of all Gage weather wave guided radar or float who knows but he doesn't really cheap out on important stuff I noticed.

I forgot the ask, so why specifically in your opinion do you recommend the keel cooler as opposed to a exchanger? I have experience with exchangers of all types makes designs and sizes not that these especially are complicated or anything but from what I'm thinking at least they are very easy to access and work on but I have a feeling you'll be changing my mind. Too late for me anyways I think at least until I see the design just cuz my keel is full of diesel above the ballast.

[Lucas1983]

Originally Posted by MicHughV

I had a big 6" x 12" x 1" thick sacrificial zinc bolted to my hull, near the back of the keel.
This would provide protection for around 3 years before I needed to replace it. You can tell it's getting worn by diving on it and looking at it and feeling it. If the edges crumble easily in your hand, it's time to replace it, even though it looks like it has some service life left.

I've seen some steel hulls that had several sacrificial zincs on the bottom of the hull, but I only ever had the one as described above and never had any issues with my boat whatsoever.

I also had the zincs on my prop shaft, but they rarely lasted more than about 6 months.

Since then I have taken to hanging a zinc fish over the side of my fiberglass boats, which is hooked by cable to the boats grounding system. I only do this at marina's as one never knows what a neighboring boat is up too.

I could have done this with my steel hull, but did not think to do it at the time, as it's a simple way to tell if the zinc is being eaten up by simply pulling the fish up and out of the water and looking at it.

Your zinc fish thing you do sounds interesting, definately gonna look into that to