Crunch time is near for getting the SkipperLiner back in the water. What little time I've had to work on the thing, especially the bottom proper, has been an exercise in frustration; I've got at least one of every kind of 'disc' known to man for my angle grinders, all of them have one or two strengths but many weaknesses- 40 grit disks really chew thru the rust on FLAT steel but do zilch in the pitted areas, fiberglass wheels remove paint nicely, but not heavy rust, wire wheels get into the pits but aren't aggressive enough. Sandblasting works well, but it is SO frickin messy, and since I'm using actual sand I have to wear a respirator so I don't kill myself, and even running a 60 gallon and a 30 gallon compressor inline, I can work for about 3 minutes before I'm out of air. I could keep griping, but nuff said...

Last year I tried to get a dustless sandblasting service to take care of it in one fell swoop. There's 3 locally, 2 didn't answer back, the one who did hemmed and hawed and finally said in so many words he didn't want to do it, but he'd call someone who'd call me back- who never did. I had $6 grand to spend and nobody wanted it. Buncha sissy's...

SO, I've been doing some research on acids and have come to the conclusion that I need something like the big steam cleaner I borrowed 11 years ago and used on the bottom. That thing was wonderful for finding rust hiding under the bottom paint. It was rated at 4200 psi @ 4.5 gpm, and would get water to 210°. It had enough power that when seeing how well it might wash my truck, it actually peeled the clearcoat off!

-One of my questions is, since I didn't, and won't be, removing any grease or oil, did the hot water help, or is the brute force of the water pressure doing most of the work?

Ok, so I've checked around all the rental places anywhere nearby, and nobody rents power washers, other than ONE place that rents a 5000psi cold water machine for $300 per day. No.

So I guess I'll be buying one. And as for affordable machines, that stops at 4400psi. Above that is basically 5000 psi and more, and the cheapest 5000 I've found is 3x the price of a decent 4400 machine. And then there's 4000 psi machines, which I can get for $200 or more less than the cost of a 4400...

Next question, is there a reasonable difference between a 4000 and a 4400 psi machine? An extra couple bills won't hurt much, but at the same time if there's not much difference why not save the money...? But my take is, there IS a noticeable difference between 2600 and 3000 psi machines in my experience, so...

Any advice on this is welcomed

So here's my plan and why acids are involved...
First up is would be fully blasting the bottom to unearth any more rust, large pits and more holes if any. Large pits and holes will be sandblasted and filled with MarineTex, then sanded level when cured.
Next- any bottom paint remaining will be quickly rough-sanded to provide grab for the coal tar epoxy. I don't have the time or resources to go full bare-metal, and if 4400 psi won't remove the paint, it doesn't need removing. And since my bottom paint is a 'modified epoxy' and the boat was originally primed with coal tar epoxy, it's all compatible with fresh coal tar epoxy...
Next- injecting hydrochloric (muriatic) acid into the pressured water stream at a rate of about 6% strength, specifically hitting all the bare metal. Between the pressure and the acid eating the rust, I should have clean bare metal in short order. The hydrochloric acid will also etch the metal, which is good, and bad- good because etching provides grab for the coal tar epoxy, bad because flash rust can occur quickly, so I have act quickly--
-- Enter phosphoric acid, which will be injected into the water stream of my 2700 psi washer, which is plenty for this part of the job. The phosphoric acid essentially rust-proofs the steel, and neutralizes any flash rust that may have started.
After the phosphoric acid has had time to work and dry, then the whole bottom gets a final pressure wash with plain water. Once dry, the coal tar epoxy can go on...

I'm no chemist... Is dumping that acid on the ground a good idea?

I'm exhausted just thinking about the amount of work you have ahead of you. Good luck with the project

I'd be curious about needing to neutralize the acid before bottom paint is applied. Is there a plan for that or is it not necessary?

I am not sure how it will work on your application, but 99.6% PURE OXALIC ACID Powder might be a relatively safe acid to use and easy on the environment--pressure washing and the potentially hazardous spray that comes with it is not necessary. It will definitely remove the rust. So will vinegar, but it would be slow.

I used to use Slimy Grimy which is mostly oxalic acid, but but very expensive. I bought some pure oxalic acid this past summer to clean the bottom of the boat after sitting in the water all summer. It actually worked better than Slimy Grimy. You might want to read up on it. I got it from Factory Direct Chemicals, but surely, there are suppliers in your neck of the woods that also sell it. Here is FDC's website.

https://www.factorydirectchemicals....5lLGg4QIV5B6tBh1sTggAEAAYAiAAEgLjKvD_BwE

From their website:
Oxalic acid is an essential household chemical that can be used, like many acids, as a cleaner. For example, use 99.6% Pure Oxalic Acid as a rust remover, cleaning agent, wood stain lifter, bleaching agent, etc. Oxalic acid is a natural component of plants and vegetables (such as buckwheat and rhubarb) and is available for purchase in powdered form. Oxalic powder should be mixed with water to turn into Oxalic acid. Oxalic Acid can become dangerous if used in high doses. Use moderately to ensure safe and effective application.

Hydrochloric/muriatic acid is nasty, but about the only thing it's hazardous to in the concentrations I'll be using is metal. Cola drinks contain phosphoric acid, oxalic acid is naturally occuring in some vegetables, and muriatic acid is what digests the food we eat. I've used gallons of muriatic acid cleaning hulls parked over lawns, cement and asphalt, never any side effects, just rinse everything frequently. Basically, as long as I'm using watered down acid, keep it contained (8 mil visqueen tent will work), wear my respirator, and nobody buried a Cadillac under the boat, everything should be fine.

And as for the muriatic acid, I really won't need to pressure spray it, I can just use a garden sprayer like I always use to apply the acids, muriatic first, rinse with high pressure after it's worked for a few minutes, repeat, that'll neutralize the acid and remove any loose rust flakes. Then spray the phosphoric acid mix on, brush it into the metal good, 2 or 3 helpers can make that a quick job... after letting it work a for the recommended time, power-rinse, and done. The phosphoric acid will darken the metal and stop any new rust, and any flash rust - iron oxide- will now be neutralized and converted to inert and paintable iron phosphate...

OK, so no acid sprayed at high pressure and lots of rinse water, does that make everyone feel better?

So-- pressure washers?

First things first- The formula for determining HP for an electric motor is GPM x PSI/ 1460. For a gas engine it's GPM x PSI/ 1100. I'm in the hydro jetting business and it's a little known fact that manufacturers over state the specs on their machines. They also overstate the HP of the power supply. Do the math and make sure it's even possible to get the specs they claim.

Second- Pressure loss. Hose length and size have a huge impact on pressure loss. If you have a 5GPM @ 4K PSI then you put 150' of hose plus a wand, you won't be close to those specs. Keep the hose as big as possible and and as short as possible. My machine does 18 GPM @ 4K PSI but still, I can't get that at the end of 400' of 1/2" hose. It's just not possible.

HOT vs. Cold- I think Hot is overrated. But I suppose it depends on the application.

4000 vs. 4400 is not that big of a deal to me. My concern is can your hull take it?

One other thing- hook a hose up to wherever you'll be using this thing and time it into a 5-gallon bucket to check your supply GPM. Make sure you've got enough to run it. I've found around 5GPM is what you'll get out of a hose. But I have seen it both way higher than that and way lower.

Thanks 'Suns-- I found a website 'All Pressure Washers' that sells mostly Simpson washers, depending on which they come with their own motors, or Kohler or Honda motors. There's a good variety of 4000 to 4400 machines for $999 or less.

This one is on Amazon for $919, best deal I can find on a 4400 unit... https://www.amazon.com/Simpson-Clea...1553712639&s=lawn-garden&sr=1-23

Are Simpsons any good? One thing I notice about the high pressure washers in general is the not-so-stellar reviews, but when reading thru them, a big percentage of gripes is they're hard to start.. LOL.. I have a 357cc Cub Cadet snowblower which is not easy so I wouldn't expect yank starting a 420cc motor will get easier - a lot of other complaints focus on shipping issues-- throw those out and it's hard to find many 'doesn't work well' reviews. Anyway, any suggestions?
===============

As to my previous foray with this boat back in 2008--

This was the steam cleaner I got to use---




This is my starting point- that rust spot was pretty bad when the boat came out-




Looking MUCH better--




Note the surface rust, this is what I liked about this washer, where there was rust
it uncovered it, where the paint was holding firm, the washer didn't budge it-
Notice the lower rear corner, that's proof my electric problem was going on for
quite awhile, as it got much worse...



--and all that surface rust, I just 'converted' with 'Rust Killer', and there's still no apparent rust going
on there, but that's for the new pressure washer to find out!

I don’t know anything about Simpson power washers.



C’mon.

Anything in that price range is gonna have a light duty pump. A top on the line AR, Giant, Cat, Udor, etc will set you back some coin. Probably half of what those units cost. It’s up to you if that matters. If this is a one off thing for its use, buy it. If you want to keep it around and expect a long life get a better pump.

Also look into getting a properly sized turbo nozzle. Thy will cut tree roots at 3k psi.

You have a refinery in town and they use contractors like K&M Industrial, Ancon to steam clean various equipment. Try them or whomever they use.

There's actually 5 refineries in town - and honestly, anything those guys are using would likely be WAY out of my budget!

'Suns, after doing some checking, the Simpson I linked to supposedly uses an AR pump...I figure for my needs, it should be plenty enough machine..

And- I just found the same machine on ebay for $729-- 10 year frame, 3 year motor, 5 year pump warranty... It'll be here in a week or two

So the thing was on backorder a few days, but showed up this morning- Was a snap to get together: change the pump's shipping oil plug to the vented plug, attach the handles, add oil, put in some gas, attach the hellacious hose to the pump, assemble the wand and attach to the hose, add water, flush the air out of the line (do this or lose an arm!), full choke, 2 pulls and the 420cc mill fired right up. Put the 40° tip on and started messing- the 40 tip immediately left me with a false sense of 'doesn't FEEL like 4400psi'- but once I started with the narrower tips the force became more noticeable. With the 5° tip I could sign the driveway, and could probably trim the small branches off the maple tree

-One thing I noticed right off was, aside from the larger frame, motor & pump, it's virtually identical to my 2700 Generac washer- EXACTLY the same gas, choke, throttle levers and On/Off switch, in the same place. Obvious they came from the same builder, or same engineer at least. And I've had zero issues with the Generac so I'm hoping to get the same service out of this Simpson.

--I'm thinking of trading the muriatic acid I was planning on using for an add-on sandblast kit for this thing. Was thinking of doing that before but the Generac didn't have the oomph needed, this thing sure does! If the sandblaster works, that'll save on a whole lotta power-tool sanding...

Like many others, I've acid washed the calcium off my boats for years using muriatic acid, at roughly 6% strength. It's water soluble so just keep rinsing as you go. Calcium neutralizes it, and what isn't neutralized gets diluted to where it won't hurt anything. Hasn't affected any grass or asphalt at the harbor or at home, BUT, it will etch concrete in high doses so have to be careful. I acid washed the old 26' Chaparral 3 times on my driveway, no ill effects.

And speaking of acid, after some research I've changed my tack, moving from muriatic to phosphoric acid. Muriatic acid will remove rust, but makes bare steel after the fact flash-rust in lightning time. Phosphoric acid on the other hand, will dissolve rust and leave an iron phosphate coating on the steel to prevent further rusting. It's water soluble also, plus they put the stuff in Coke and Pepsi so...

As to the power washer, the original subject of this thread-- all I have to say is holy crap! The thing literally wears me out to use it. Because the wand is like 3' long and that's about all the farther the boat is off the ground, I use an adapter on the trigger handle to eliminate the wand, so it's like using a very sawed off shotgun. Using it for an hour makes my arm more sore than 5 hours of using an angle grinder. Amazing pressure. I did get the sandblast attachment, but the extra hose is a bit cumbersome. I've only used it once, but spraying uphill, I should have held the sand hose above the nozzle, but didn't, and ended up with water in the sand tube. And wet sand doesn't move so not the best test. My pressure pot blaster has been working well for me so no big deal. My next test with it will be to see how well sandblast tube draws water. There's an air valve to regulate the sand draw, I assume it'll regulate water draw also. My plan is to pressure spray the entire hull with a 20% solution of water/phosphoric acid, followed by a clear water rinse an hour or so later. This is the best way I can think of to acid treat any rust I may have missed.

Nothing helpful to add re: powerwashers other than MY Generac is about to head to the dump. I've had multiple issues with it, fuel leaks, water leaks, and have only used it a few times over the years. Anyone have a consumer ELECTRIC pressure washer to recommend? Doesn't have to be a beast performance wise, but would like one that is well built.