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Thread: safe boat repair

  1. #26
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    Re: safe boat repair

    prcon - This repair has landed in my lap due to a variety of circumstances, not all under my control. I am paid hourly but this effort is low priority for me, I have other duties which allow a few hours per week on this. I originally put this out to bid with several local companies, funds available are inadequate based on estimates received. I had never welded aluminum before thinking about this job and it has taken me several years to consider patching this corrosion myself. My research into safety standards indicates specific steps to be taken so I proceed with an abundance of caution. Advice from this thread has me constantly re-evaluating my decisions. You are correct, this is a lot of whoopla, many I have spoken with have indicated it is time to connect the ground and get after it. That is usually my approach and I may have gotten away with it this time as well, just trying to avoid scaring myself spitless. My first thought was to rent a MIG system, HF in a TIG process wasn't a concern as much as feeding all that filler by hand. If you were local to me I would invite you for a look, maybe if I learn enough about this repair I can make a stronger case and the decision-makers will re-consider hiring a qualified contractor.
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  2. #27
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    Re: safe boat repair

    _Dom, Prcon'tn,

    here's what I'd do to weld (TIG) on the boat, rent a pump driven LEL and O2 combo area gas monitor with current calibration stickers- (run against cal gas within a few days or weeks) and put the want down the tank fill to the bottom of the tank. I'd get a current reading- the gas monitor is non-intermediary- or safe to monitor 'an occupied space' with LEL readings that are 'unsafe'- then purge the tank with argon until the reading was below the LEL with an O2 reading out of range of combustion (lower than 14%-13% usually )

    then I'd put some paper towels in the fill & vents coated with plain old axle grease (marine grade of course!) so that all passages to atmosphere were sealed with paper coated with grease- I usually put a peanut butter like cap on- inside the fill caps- then seal the entire show- argon in the tanks, (with whatever hydrocarbons remain) and call it "safe".

    I'm not discussing welding on the tank(s) or any part related to the tanks or any fittings and hoses. If the boat has filter lines to a set of filters aft near the engine mounts- I'd shut off the valves, and remove the filters just to make elimination of those fuel sources faster and easier than purging. Fuel draw lines are inert and usually (if rated for fuel) pretty immune to any arc and spark being they don't conduct.

    Then, preparing for lots of pain-in-the-stern welding reworks, go to it! MIG would be counter productive in my view because of the constant (expected) gas bubbling in the weld path due to the corrosion shown in the pics above. I would be tempted to make a back up plate of 1/4" or so, this plate would be 1-2" wider on all sides than the oval replacement plates for each cut out. I'd drill the replacement plate and the back up and using a flat bar on the front (three layers; one backing larger on all sides; two, the replacement plate fit and beveled to the dressed opening; three, a 1" x 1/4" bar wider than the replacement plate along the wide axis.) then using a 3/8" bolt through all three items I'd tack the replacement- around the perimeter- and then weld the entire replacement in- skipping the 1" wide strip at 3:00 O'clock and 9:00 O'clock.

    Let cool, and remove the backer, center stud and cross bar and finish the two vertical 1" strips covered by the compression bar outside the hull used to get the replacement patch piece into plane of the damaged topsides sheets.

    I'd have on hand a carbide burr on a die grinder- make sure you don't use a cross cut (steel bit) type and only use the fluted non-ferrous bits; this will allow you to excavate in short time when you've developed a gas expansion pocket in the weld path. Grinders are usually too big to use on edge (not always ) so a tear drop or pear shaped carbide burr is very handy for this type of TIG seam.

    I'd use a pair of flap sanders (4" grinder motor) one with a 40 girt to cut aggressively and the second with 80 or 100-120 grit to smooth the final weld areas. Once welded, if rubber of any kind is being replaced on the boat?

    THen, I'd use acid (or self-etching primer) to etch the areas of pitting, rinse with a water hose, then I'd spray Allodyne from a hand spray bottle, and let that dry; next, I'd trowel on body putty (fair it off with a fine grit power grinder/sander when dry) and finally use a coal tar epoxy (both primer and top coat) allowing all the above to dry adequately - and finally put the rubber back on?

    Still less work to me to just weld a 1/4" strip on!

    Cheers,
    Kevin Morin
    Kenai, AK

  3. #28
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    Re: safe boat repair

    should read: gas monitor is "non-incendiary", but.... for reasons not clear? the autocomplete changed that!

    cheers,
    Kevin Morin
    Kenai, AK

  4. #29
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    Re: safe boat repair

    Gotta love that auto-INcorrect!
    Thanks for breaking it down so completely, agree with everything you wrote.
    I like the idea of self-etching primer (except I may delete the body putty. It is a workboat after all

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    Here is what I was thinking about as you were posting;
    1) Fuel filler hose (circled in red) will be removed to allow camera inspection of tank internal surfaces and another attempt to remove residual fuels. Tank inlet will be capped before purging.
    2) Purge line will be connected directly to tank outlet (circled in green) which will flow inert gas from the lowest point in tank.
    3) Fuel tank vent (circled in blue) will be connected directly to my vertical stack, instead of relying on tape to secure stack external to vent outlet.
    4) Oxygen sensor probe dropped down the filler neck, squeeze bulb to take initial readings and battery driven continuous sampling if rental unit is available.
    5) Clip on style four gas monitor laying in void space between deck and hull bottom. (belt and suspenders kinda guy)

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    Very much appreciate your advice, had been over-thinking the purge a bit. Still debating removing the outboards completely, visual inspection is suspect due to fact the swiss cheese was not clearly evident until the rubber bumper was removed. I knew I had a problem, just didn't appreciate the extent of the damage. Would hate to ignore something like that in the transom, fingers crossed it won't be that bad. Fuel filter in the picture is new, not worried about residuals there.
    Last edited by _Dom; 03-14-2018 at 04:01 PM.
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  5. #30
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    Re: safe boat repair

    _Dom,
    pull the legs and look to see how they're actually attached? Takes an hour with an overhead and you know for sure!

    The pic of the topside repair is SO revealing. I hope Yofish doesn't see it or you'll get a sailor-language note of comparative work! What, for example, is the circumference of those ovals? let's say its in the neighborhood of 20"- so given their spacing- what is the difference in weld length between what you show and what a full 1/4" x 12" topside patch? Ummm.. that would be about zero!!!

    And the bottom of the pipe's wall and the lapped joint of the topsides to 'patch' weld could be stitched- so there is the real world possibility of a Saving Welding and doing it in MIG- much less time and heat sensitive!!!

    _Dom, beating a dead horse::::: but.... if costs are included in the consideration- just the labor to cut the ovals is great enough cost to buy the plate as full sized, continuous rectangles!!!

    Just sayin'

    Cheers,
    Kevin Morin
    Kenai, AK

  6. #31
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    Re: safe boat repair

    Oh man, this poor horse...!
    I have randomly cut these twelve with a hole saw and sawzall, call it 3" by 6" so your neighborhood is right in there. If this test works I will probably set a template and plasma cut the remaining, be more consistently sized patches that way.
    Only reason this makes any sense is it can sit here in the shop taking up floorspace and I work it NIB (non-interference basis) around my normal duties. Only cost the decision-makers are seeing is the bottle of helium I ordered specifically to assist with penetration on this job. Everything else is just normal maintenance. My biggest concern is handling the 28' sections of 1/4" plate, I anticipate warping to be far outside my ability to cope with. No doubt it has been a learning experience!
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  7. #32
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    Re: safe boat repair

    I only posted that top view for Yofish viewing pleasure, pretty sure I could match him for salty language but truly interested in all comments.
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  8. #33
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    Re: safe boat repair

    I think you are way overthinking the fuel tank. If it is not leaking and you are not welding on it, then it is safer full than empty. If you are that worried about it fill it with water and be done worrying about it. Yes it will take a marginal amount of effort to rid the system of water, nothing to write home about.

    Got any pics of the corrosion areas?

  9. #34
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    Re: safe boat repair

    Wow, I've never seen an aluminium boat that compromised in that short of a time! It looks like it was sunk for thirty years. I wonder if in part of its life it was spraying some sort of etching chemicals.

  10. #35
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    Re: safe boat repair

    Yofish, you recall that in the '90's (I think) there was a huge QA vs Alloy problem with lots of the mills in the PNW? I wasn't building regularly during that mess but do recall that many builders got stuck with aluminum with false labeling- the alloys used in the smelting/refining/milling was not really what was claimed.

    So, for example, an order of 5052 or 5086 might end being way off spec and therefore super-susceptible to corrosion? I'm wondering if this boat's hull is an example of some mis used "Boeing Surplus***", unlabeled sheet material?

    I've never seen such widespread surface deterioration except in one of the boats caught in the 90's alloy problem? I agree that it seems to have been etched and not rinsed- leaving the etching solution to dry and then continue to re-activate periodically from rain, spray or as little wetting as the dew condensing in a fog in the evening as the boat cooled?

    It will be interesting to see what happens if the boat gets etched with Zep- and then rinsed? will the surface clean up?

    _Dom, you sure got you hands full!

    Cheers,
    Kevin Morin
    Kenai, AK

    **** One Puget Sound builder, in the 1980's bought some sheets from a Boeing Surplus sales agency - unlabeled and two of the resulting boats (very low cost of materials) ended up in Cook Inlet. I was able to see them during a stage of deterioration- they were later the subject of law suits and bankruptcies as all concerned pointed the finger to the next person in line of supply and building. Nice designed, well made by skilled people - the material wasn't marine grade and the boats suffered massive corrosion failures.

  11. #36
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    Re: safe boat repair

    Haven't spent much time looking around inside the hull, all extrusions labeled 6061-T6 that I can see. No markings visible on the plate, I suppose it is possible a marine grade alloy was specified and bought on the cheap as you say. Before the 2018 server meltdown I had exchanged posts with Zapster about a boat he was reworking, he was convinced 6061 was his alloy of choice, even below the waterline. His was a freshwater if my memory is correct, it often is not. I am going to stick with my story of a combination of crevice corrosion and galvanic due to contact with the rubber. This is an explanation I understand, will attempt to slow the damage with proper repair process and continue to observe over time.
    One thing for sure, I am going to have spend some time in that confined space between deck and hull to remove the outboards, bottom four bolts are through-hull below deck surface. Outfall for the bilge pump needs attention while I am back there. Will be good practice for the etching/alodine treatment. I can't see myself painting in there, thinking a supplied air respirator would be too bulky for my comfort.
    Last edited by _Dom; 03-15-2018 at 06:37 PM. Reason: added detail
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  12. #37
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    Re: safe boat repair

    Quote Originally Posted by _Dom View Post
    Haven't spent much time looking around inside the hull, all extrusions labeled 6061-T6 that I can see. No markings visible on the plate, I suppose it is possible a marine grade alloy was specified and bought on the cheap as you say. Before the 2018 server meltdown I had exchanged posts with Zapster about a boat he was reworking, he was convinced 6061 was his alloy of choice, even below the waterline. His was a freshwater if my memory is correct, it often is not. I am going to stick with my story of a combination of crevice corrosion and galvanic due to contact with the rubber. This is an explanation I understand, will attempt to slow the damage with proper repair process and continue to observe over time.
    One thing for sure, I am going to have spend some time in that confined space between deck and hull to remove the outboards, bottom four bolts are through-hull below deck surface. Outfall for the bilge pump needs attention while I am back there. Will be good practice for the etching/alodine treatment. I can't see myself painting in there, thinking a supplied air respirator would be too bulky for my comfort.
    You may have accidentally come to the answer: it IS possible that the whole thing is made of 6061, which, in salt would be bad. How do I know? When I first started welding in the mid 70's, I worked for a guy that built many seine skiffs and all of their bottoms were of 6061 tread plate. Just recently a friend bought one of those old skiffs and wanted be to do some mods/repair. It was impossible to weld AT ALL on the water-side of the hull and the always wet bilge as well as the sheer pipes that were covered with rubber hose. The rest of the hull was 5086 and presented little problem. If yours is made of 6061, then it's toast unless it's coated with 235 and zinced up the ying...By toast I mean that its life is limited as nothing stops that interior (with-inside the plate) corrosion that happens with 6061 that has not been anodically or barrier protected. I know of several other of the described skiffs that had holes blown through them when blasting/painting was employed to try and save what was left of them.

  13. #38
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    Re: safe boat repair

    No accident, I have been wondering about the alloy since I first recognized the problem. No help that original builder, local to us, seems to be out of business. I like hearing about 6061 that has been in service recently since construction in the seventies. No doubt a seine skiff sees a much rougher life than our boat. Maybe there is hope for me yet. I am picturing a skiff hauled out on the back of a purse seiner unless it is in the water tending the nets, maybe I misunderstand. Do the commercial fishing boats fresh water wash regularly? I know that lack of "normal maintenance" is a contributing factor to this condition.
    When you mentioned 235 I wondered if that was etch, chromate conversion (alodine), or paint. Looking online I found Devoe Bar-Rust 235 Multi-Purpose Epoxy Coating which sounds promising.
    Other options include zinc chromate primer, Jotun coatings or some other system. Considering Jotun for bottom paint since we have a good relationship with the distributor, coal tar for bedding the rubber bumper. Topside anti-skid is in good shape on the deck and as I mentioned will leave the void space unpainted.

    I remember high school welding class during the mid-seventies, lots of talk about heading up to Alaska to work the pipeline. Never did stay focused enough to be vey consistent, my grandfather joked about always keeping a grinder ready at hand, not much has changed...
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  14. #39
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    Re: safe boat repair

    Quote Originally Posted by _Dom View Post
    No accident, I have been wondering about the alloy since I first recognized the problem. No help that original builder, local to us, seems to be out of business. I like hearing about 6061 that has been in service recently since construction in the seventies. No doubt a seine skiff sees a much rougher life than our boat. Maybe there is hope for me yet. I am picturing a skiff hauled out on the back of a purse seiner unless it is in the water tending the nets, maybe I misunderstand. Do the commercial fishing boats fresh water wash regularly? I know that lack of "normal maintenance" is a contributing factor to this condition.
    When you mentioned 235 I wondered if that was etch, chromate conversion (alodine), or paint. Looking online I found Devoe Bar-Rust 235 Multi-Purpose Epoxy Coating which sounds promising.
    Other options include zinc chromate primer, Jotun coatings or some other system. Considering Jotun for bottom paint since we have a good relationship with the distributor, coal tar for bedding the rubber bumper. Topside anti-skid is in good shape on the deck and as I mentioned will leave the void space unpainted.

    I remember high school welding class during the mid-seventies, lots of talk about heading up to Alaska to work the pipeline. Never did stay focused enough to be vey consistent, my grandfather joked about always keeping a grinder ready at hand, not much has changed...
    Yes, Devoe (and others) make a popular and durable coating used extensively for hulls both ferrous and non.

    Usually these small skiffs are towed behind the mother boat and many of them stayed in the water year round as run-about for those that lived on the water. There are those who religiously replaced zincs AND bottom paint and they are still solid though the bilges usually show pitting. At that time (70's) 5052-86 tread plate was unheard of. The same thing happens to strakes etc., that are external to the hull made of 6XXXX applied to 5XXXX - I've seen them rotten and the hull more or less fine. Its all about protection.

    Here's a pic of said skiff. The transom had to be replaced because it was stiffened with a 2x12 board and the corrosion between the two was so bad that the AL had holes completely through. Notice the two large zincs on the stern, the only place they would stick. The owner had it blasted and coated, even the bilge which can't be seen in pic.

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  15. #40
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    Re: safe boat repair

    _Dom,
    maybe the gray deck non-skid coating is what gives the appearance of such deteriorated plate!! ?

    I think you're on the road to recovery from your remarks? Yes a coal tar and correct surface prep is the best way to bed the future rubber - but you don't have to put the topsides repair strips on in full length strips.

    (I'd put them on in 1/4" thick pieces that were give or take 4' long - at the most. They'd form easily and cover the Swiss-cheese sections.)

    The TAPS system was welded exclusively by the members of the 798 Pipeliners Union out of Tulsa, OK, if I recall correctly? " The best pipe welders on the face of the Earth. " But there were lots of other welding jobs in that era that didn't require a pipe cert or a 798 book to work!

    your boat may well see a tougher life than a snag skiff on a seiner? Boom tending may involve banging around and getting drenched with fluids that may be more corrosive than just salt water?

    Yofish, it was a treat to see one of Cliff's skiffs! thanks. I was forced (the owner is always RIGHT!!) to put 6061 tread plate bottoms in a couple of boats and always regretted not being able to afford to tell that owner -before the build- that I'd declined to build with that alloy underwater. I did it, but it was a poor choice and worse than pitting is the rate those hard, brittle alloys (compared to 50-series) will "sand off" when tractor towed on a beach!!

    I got one (6061 tread plate bottom skiff) back after a decade of pulling on the sand- and the entire bottom was 0.060" or thinner!!! (I) Lit up a TIG torch on a crack and got the shock of the day when the bottom opened up a 1" hole around the arc!!! talk about poor choice of materials!!

    _Dom, we're way off track on your thread, so feel free to redirect or ignore us "thread pirates' remarks" ?

    Cheers,
    Kevin Morin
    Kenai, AK

  16. #41
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    Re: safe boat repair

    Kevin, (now that we geezers have completely bar-roomed the conversation) it is a testimony of sorts of how even badly planed AL projects last. Yes, I helped Cliff build that skiff ca.1977. It lived in Halibut Cove as a runabout after I built its owner a larger end skiff. For many years it NEVER came out of the salt. In the late 80's I put a console (removed during this mod) in it and the bottom was still weldable inside. That pic was taken in Little Jakalof, where it will end its days with the Hopkins'.

    It really is amazing what happens to this alloy over time in an electrolyte: MIG reacts like you are trying to weld Al to steel; bouncing off, awful stubbing with little ball bearings scattering everywhere. It's like it isn't even metal any longer. The ONLY luck I've had is with TIG, but then again, I've had your exact same experience, too. The only reason I took this on was because of a long-time friendship.

    EDIT: Oh! to add a salty tale, I was skiffman in this very skiff in 1980 when I had my second near death maritime experience, so, I did have a little other tenderness in me for taking the job....
    Last edited by Yofish; 03-18-2018 at 12:28 AM.

  17. #42
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    Re: safe boat repair

    So how did this messy thing come out? I just now read this and change my mind about aluminum being the end all be all for boat manufacture. I always thought it was weight and manufacturing costs that made Al fade out. I’m glad my boat is is made of fiberglass. What year is that thing anyways and what in the world they do to it to get it completely covered and corrosion like that? One thing for sure I will never look at fiberglass the way I used to when it comes to Marine use. I go deep sea fishing on a 40’ boat the skipper built himself in 1960. Looks a bit roughish and there’s not much gloss on the hull and light pitting but it looks brand new by comparison. What year is that skiff anyways .

  18. #43
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    Re: safe boat repair

    Many thanks Yofish and Kevin, got my plan approved and started welding in patches today. Plenty ugly considering the rotten base metal but it should add a few years to the life of the boat. Watch for pictures in the other thread as this project moves forward. Can keep this thread open for discussing safety aspects if anyone is interested.
    driz - built in 2004, my records show it hasn't been out of the water much since then. Crevice corrosion is the common name, this rubber bumper trapped water between aluminum hull resulting in the damage. Anodes looked OK and the corrosion was not visible until dis-assembly, in my ignorance I did not realize it got so bad. Fiberglass, roto-molded poly, wood, steel and aluminum all have their place on the water, no shortcuts for proper maintenance on anything afloat.
    I am learning a lot.
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  19. #44
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    Re: safe boat repair

    Quote Originally Posted by _Dom View Post
    Many thanks Yofish and Kevin, got my plan approved and started welding in patches today. Plenty ugly considering the rotten base metal but it should add a few years to the life of the boat. Watch for pictures in the other thread as this project moves forward. Can keep this thread open for discussing safety aspects if anyone is interested.
    driz - built in 2004, my records show it hasn't been out of the water much since then. Crevice corrosion is the common name, this rubber bumper trapped water between aluminum hull resulting in the damage. Anodes looked OK and the corrosion was not visible until dis-assembly, in my ignorance I did not realize it got so bad. Fiberglass, roto-molded poly, wood, steel and aluminum all have their place on the water, no shortcuts for proper maintenance on anything afloat.
    I am learning a lot.
    Wow, 2004 is almost new for an AL boat. That is, an AL boat that was cared for. My own is 30 years old. Just today I shook hands on a new skiff for a client that I built for 29 years ago. The original still just fine, he's well off and wants my new version. As Kevin has said many times, it's all about care and original thoughtfulness as a builder. I'm glad that you seem to grok that with which you are dealing with and I'm pleased that you have found some value in the communications - best of luck!

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    Re: safe boat repair

    The only substance I ever trusted with my life was 1,1,1, trichloroethylene. It only takes a small amount to destroy the gasoline and fill the tank with a nonflammable gas. The only drawback is that it creates phosgene gas if heated or passed through flame. But welding does not cause any problems as long as you are not breathing the outgas.

    Perchloroethylene acts similarly. You could also flush it with RX-11 from NU Calgon, that will get rid of the gasoline. It is an expensive substance, but also highly effective and very non-flammable. It removes oxygen as well.
    Even 410-A refrigerant will keep the tank from popping if you purge with it. You will have your refrigerant license revoked if you use it though, hahaha. But is better than having the tank slap the family jules.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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