so would i be a heathen for asking this

[bitofascallywag]

i am making the transition from steel yacht to wooden yachts so go easy on me,i slipped and cleaned my 35 foot steel bermudan yacht today and for the first time noticed small liquid filled blisters in certain patterns around below waterline,when blisters are burst with a pressure washer they create a foam type liquid,funny thing is that there is no rust beneath blisters and it tastes slightly acidic.a large blister would be around 1cm across.now a bit of history....i bought said yacht in 96,sand blasted and did the wattyl treatment from full zinc coat to tie coat then undercoat then antifoul,boat is moored in fresh water,has not been slipped in 3 1/2 years,last slipping saw new ss seacocks all through,4 wd type hf radio also fitted then.......so any help much appreciated

[ozwinner]

tastes slightly acidic.

Tastes???

Al :eek: :confused:

[bitingmidge]

oops!

The blisters can only be caused through water getting into microscopic pores in the paint surface, and osmotic action of the water under the skin, or through inadequate preparation (grease, silicone or something else) on the substrate.

That's it for me.

I'd suggest a cleaning back to bare metal in the areas they've occurred and re-doing the coating exactly to manufacturers recommendations.

Oh, and don't drink any more of the water from them eh? It may not be good for you!

P
:D

[echnidna]

Sounds like a dash of Morello Cherry would help the taste ....

[Auld Bassoon]

Sounds just like osmosis - but that doesn't normally occur with steel hulls :)

Something in the previous coatings allowing water in and there to fester?

[ozwinner]

Sounds just like osmosis -

Gee they were a great group, I can still hear their songs in me head....

Al :)

[bitofascallywag]

i was thinking electroloysis of some sort but zincs appear ok.another steel boat owner called in and he gets it similar everytime he slips,just not in patterns,another thought was that it appears or seems to near any heat affected aeras in its construction,fittings welded in place for seacocks would not of been galv??it was built in 65 in launceston by perc barren,a philps design by what i wastold,round bilge by welding foot lengths together on the 45 deg so i renamed her the hungry horse as her ribs show, and as for tasting it...gee i reckon i have drank much worse....

[bitingmidge]

i was thinking electroloysis of some sort but zincs appear ok.
Could be, but it's a bit hard without seeing her.

Zinc Coat is Zinc too of course....

P ;)

[bitofascallywag]

i had a large zinc on her from 96 about a 10/15 kg,it is 2/3 gone and appears to be working.the way i understood the first coat after sand was the zinc coat,i do not understand painting principles too well so just put the micron coating on that was required.another thing that is in my mind is about the king river that polluted the harbour for 150 years with tailings from a copper mine[mt lyell] there are massive amounts of tailings in the harbour but recently i believe they stopped neutralising the acidic mine water drainoff,i used to get 3 inch weed growing off her at times and there was none at all this time but a sewerage treatment plant has been moved as well.it all has probably nothing to do with it but makes you wonder........

[bitofascallywag]

one more thing as electroloysis makes metal leave your boat all blisters are clear and not pocked beneath the blister?

[Boatmik]

Hmmmm Scallywag. I am not a SUPER EXPERT in this - but I would suggest some questions to ask and who to ask.

AND YES IT IS A LONG POST - BUT IF THE WHINGERS CAN EDIT IT DOWN TO SMALLER AND KEEP THE RELEVANT INFORMATION - THEN WHY DIDN'T THEY ANSWER THIS SENSIBLE POST BY Brother Scallywag (who isn't being a mischiefmaker here!) AND SAVE ME THE BOTHER!!!

Actually it is not a bother scallywag.

Osmosis needs two things to be in place.

1/ A semi permeable membrane
2/ A concentrated solution on one side
3/ A less concentrated solution on the other.

(I thought that if I said there were only two things my post might LOOK SMALLER.)

The direction of the osmosis is to dilute the solution of higher concentration so it matches the less concentrated solution.

The Acid tasting water in the blisters is what the water is going through the membrane to dilute.

The blister IS the semi permeable membrane - the unaffected surface that you can see when the blister is removed is impermeable.

If you have used all Wattyl products have you contacted their help line?

I would be asking them what the source of the acidity is (ie which of their paint components) and why the paint over it is permeable.

If you a) used their materials and b) followed their instructions
they should be prepared to have a rep look at the problem for you - and they would bear some sort of responsibility.
_______________________________

Electrolysis has two forms
_______________________________

Normal sort of "natural" electrolysis caused by dissimilar metals (but can include other conducting materials). (sorry if my jargon is not up to speed)

There is also a "forced" type of electrolysis where there is an electrical current leakage into the water.

So the natural "unforced mode" first

YOu need both metals to be in contact with the seawater AS WELL as having an electrica connection through the hull to complete the electrical circuit.

The current that flows (made up of electrons) goes from the anode (least noble metal) to cathode (most noble metal). The electrons are stolen from the anode - as it dissolves/combines with ions in the seawater it happily dissolves away.

So if passive electrolysis then some part of the boat will have had the electrons stolen from it and have significant pitting or other damage.

Thats where the zinc coating or zinc anode comes in - it provides the electrons for the current so disappears first.

But your anode is still there - but maybe the zinc coat on the hull is the same "nobility" and was relying on being protected from the water by the paint over the top. The paint hasn't protected as well as expected.

So I would also ask the Wattyl people that if water was getting through to contact the zinc coat whether it would become the anode to the SAME DEGREE AS THE SACRIFICIAL ANODE.
___________________________

Forced electrolysis

Usually the culprit is leaking current from a shore supply - if current leaks from a battery it goes flat.

I once did some work polishing the stainless steel staunchions and lifelines on a 39ft racing yacht. The owner rang back a day later to tell us that all the metal looked tarnished and the acid we had used to clean the stanchions hadn't been rinsed off and had eaten into all the metalwork.

This was impossible.

We used hydrochloric to do the cleaning (while running fresh water over the decks so spillage wouldn't change the colour of the decks or make streaks down the topside. You then have to follow up with phosphoric acid to passivate the surface (otherwise it gets light rusting within a few days). We then had rinsed off and hand polished using a light abrasive polish with silicone to protect the metal further.

So there was no way that there had been any acid left anywhere - it had all been dried and hand polished.

We went to check the boat and the owner's description was correct (but we werent the cause.)

All the metal was tarnished and where the dew had condensed on the wire and dropped to the deck the acid that had been formed from the seasalt that had been deposited had been transformed by the current to hydrochloric acid that was strong enough to eat through the fastenings in the stanchion bases over a 24 hour period.

The culprit was a cable led from shore power and an electrician that had installed a navigation light to one of the stanchions a bit carelessly.

So could be that but you would need shore power and I suspect there would be some pretty serious pitting or corrosion somewhere.
_____________________________

The only other thing that might be a possibility is whether the Micron antifoul is compatible with the coatings underneath. ( I would ask this question of boat Wattyl and International (who make the Micron I think).
_____________________________

I would also make some enquiries of the radio manufacturer tech line to see that the beestie is grounded properly etc.
_____________________________

So in short I don't know what the cause of the problem IS but I hope that some of the information above is informative - and maybe something will twig. Though I wouldn't jump to conclusions too readily.

Best Regards
Michael

[Bodgy]

I had a 'similar' problem with my steel 36 ft sloop. Different paint regime to yours, but similar symptons, ie blisters around waterline.

Culprit was a current leakage into the hull from the electrics. This caused the forced electrolysis as detailed above. Once I re-wired, it never re-occured.

Just out of interest, would you get another steel boat? I never would. I bought mine for a long cruise around the reef, thought that I'd have some close encounters with coral and steel gave me the best chance, and was easily fixed.

Problem was the constant maintenence, Drop the anchor on the deck, and immediately out comes the chipper and paint. Just drove me crazy, tiniest spot would leave orange streaks down the hull. This despite an AUS10 steel hull. Also, the weight made us a bit slow.

I do remember tho 2 weeks of rain, tied up alongside. Most of the glass and wood boats leaked around the deck and hull/deck join. The steel boats never did.

Good luck with yr problem.

[Boatmik]

Howdy Bodgy - it is good that a well put together epoxy timber boat has no place for the water to get in either! No joins that can move or leak.!

But back to the prob of blisters.

I did a bit of search on google and there are a few mentions of stray current causing blisters in metal boats.

The best references I found were to do with Aluminium boats on ...
http://www.fishsniffer.com/cgi-bin/forumsyabb/YaBB.pl?num=1117771557;start=all

It is a huge thread so the relevant bits are below the line ...

(by the way - it does not necessarily mean that it is the problem on YOUR boat - but I would certainly look into the wiring.)

The thread sorta started with a manufacturer of fishing boats saying that they "electrically balance" their boats so the current generated won't scare off the fish. This is a lot of marketing hooey - the electrical field will be tiny and quickly dissipate as you move even small distances away from the boat. Maybe the fish might get the s***s as you pull it closer to the boat - but I just slightly suspect it might be a bit distracted by the hook in its jaw.

But the thread quickly moves to more scientific areas - electrolysis.
____________________________________________

heres a question for boat builders. Are your hulls electronically balanced? Heres a quote from the motion marine webpage. Just curious.


Motion Marine hulls are electrically balanced to catch more fish. (How can that be?!)

The electrical charge of a boat can be measured. We found that when dissimilar metals touch, it sends a current through the hull. Also when the electrical system is grounded to the hull, it sends a current through the hull. It has been shown to be true that fish are repelled by these currents.

Another problem with hulls that are not electrically balanced is electrolysis which corrodes hulls and bubbles paint.

Motion Marine hulls are wired with a 2-wire system rather than a 1-wire system ground to the hull. All of the electrical is routed in plastic pipe. We also isolate all dissimilar metals so any ambient current is neutralized.
______________________________
payne, that’s a great question. Here is what I do know on this subject:

1. Never ground anything to the hull on an aluminum boat or you will have major problems with corrosion, paint blistering and it will repel fish. Ground everything back to the battery as stated.

2. Stainless steel cleats, handrails, etc. should be insulated from the hull to keep the electrical charge at a minimum.

3. The current can be measured with a good voltmeter. If you want to do that let me know and I can tell you how.

4. We also route our wires in a plastic pipe also to keep the wires dry, protected and out of the way. I have never considered that it will allow you to catch more fish.

5. I am not really sure what a two wire system is and have not heard that term. If anyone knows please let us know.

As long as the boat is wired correctly you should have no concern of catching fish. I have seen many different brand boats catch fish and win Kokanee Tournaments. From the description it sounds like Motion Marine is doing an excellent job in their wiring and are taking the time to make sure it is right. One of the added benefits of doing it right is that less electrical current is put into the water and that is a good thing. They are promoting that and in the world of sales and marketing there is nothing wrong with that.

(though there might be in the world of science and logic - drang and sturm!!! - worried about electrons going into the water - where to they think the electrons came from? In other words I regard marketing bumph not very highly - MIK)
_________________________________

Hey guys. Even if you insulate everything and use double wires, most all aluminum boat hulls are grounded anyway. If you have an outboard with an electric starter mounted to the transom, the mounting bolts will make an electrical connection between the motor and the metal hull of the boat. Outboard motors are grounded to the negative terminal of the starter battery. This means the hull is also grounded to the negative terminal of the starter battery.. Larry

(wait for the reply below this line - quite a different approach - MIK)
________________________________

Motion Marine might be referring to their large hulls where a common ground strip is used for all of the electronics. Making an effort to get ride of stray electrical currents at the design stage is a very good thing. But as David_Neff has stated, almost all of the wiring on higher end aluminum boats is pretty good. But it pays to look at the fuse boards and see that they are mounted on insulating blocks. The wiring should all be tinned marine grade stuff (if you see the name Ancor on the wire, you'll know it's the right stuff). All terminal connections should be sealed with shrink wrap or coated with liquid electrical tape. Good manufacturers run the wire through plastic conduit to prevent contact with the hull. Everything should be well above the waterline and be protected from spray. Finally, the connector on the wire to the bilge pump and switch should be mounted as high as possible. This is the source of a lot of stray electrical discharge in my own experience.
________________________________

Lots of tips and things to look for there - but I would still talk to the paint and radio people too - don't mention the electrolysis to the paint people and see if they get to it themselves (play dumb and ask them to explain - you will probably learn heaps that I just don't know.

MIK

[bitofascallywag]

thanks very much to all,learnt a lot,knew some but i am going to go with osmosis as i did change paint brands from wattyl to sigma a few years back,and a hf radio will only add to electrolysis whilst transmitting if wired right,as it uses water,hull as a ground...........

[Boatmik]

Hi Scallywag,

I wouldn't discount the forced electrolysis through current leaking. The more I looked the more it seemed to add up. Particularly the acidity in the blisters and the position (from the posts I dug up above)

But I wouldn't discount the possibility that it could be osmosis.

I don't know if you can but it might be interesting to see if there was a closed electric circuit between the hull and the battery terminals. But at this point my electrical engineering all falls to bits. Limits of knowledge.

It could be as simple as a bilge pump wire being in contact with the hull.

MIK

[bitofascallywag]

i think not but it is a possibility,as i mostly am particular about wiring and shall recheck it all...

[bitofascallywag]

pics of said yacht

[Boatmik]

i think not but it is a possibility,as i mostly am particular about wiring and shall recheck it all...

Sure you are - but worth checking as the symptoms seemed to line up pretty well. And it doesn't need to cost you much either.

MIK

[Bodgy]

Nice looking yacht, Bito, for a steel 30 odd footer. They're usually sort of 'stumpy'

Do prefer the long keel over the fin. Broad reaching in a big swell with self steering on, in 20 knots - you'll soon see why!

[viking]

i am making the transition from steel yacht to wooden yachts so go easy on me,i slipped and cleaned my 35 foot steel bermudan yacht today and for the first time noticed small liquid filled blisters in certain patterns around below waterline,when blisters are burst with a pressure washer they create a foam type liquid,funny thing is that there is no rust beneath blisters and it tastes slightly acidic.a large blister would be around 1cm across.now a bit of history....i bought said yacht in 96,sand blasted and did the wattyl treatment from full zinc coat to tie coat then undercoat then antifoul,boat is moored in fresh water,has not been slipped in 3 1/2 years,last slipping saw new ss seacocks all through,4 wd type hf radio also fitted then.......so any help much appreciatedwhat 3.5 years thats your prob

[bitofascallywag]

you may be right i may be crazy...long periods never hurt the paint before but she did a fair amount of salt water cruising in the years before[3]...the top 3to9 feet in the harbour are mostly always fresh only...