oxidation questions

[wacdlw]

wondering about the severity of this oxidation

[wacdlw]

hello, I looked at another boat today and it look good. only had 196 hours. engine looked good, paint good interior very good..... This boat has been out of the water for almost three years. The owner said it was stored indoors and it did look clean. The pictures show the bottom and the amount of corrosion. The owner said he painted the boat three years ago used it for a season and put it on its aluminum trailer and it sat for about two years. So my questions are.

Does this look like a enough corrosion that I should be worried? the pics are in the preceding post.
The guy said he owned the boat for 10 years but when I asked him if the (don't know the proper name)meter was reading about .9 he said what meter? I showed him the meter and he said that he never knew what that thing was. Is this possible?
Is it a bad thing for a Marinette to be on an aluminum trailer?
Also the boat is a 1970 28' express and it has no undercoating inside the hull except on the sides of the inside. the entire bottom that I could see was completely clean aluminum. did they come with undercoating on the inside bottom of the hull in 1970?

Thank you for the help.
Bill.

[barkleydave]

Without stripping to bare aluminum one can not access the extent of the damage.

It is obvious that something is going on..... and YES I would be concerned. Since it is so wide spread it appears that the hull has not been properly prepped and painted. No barrier coats and possible wrong bottom paint will cause this. And Yes this is a problem. To have the boat completely stripped etched 5 coats of epoxy barrier coat and then a couple coats of proper bottom paint is going to be expensive. (Yard estimate could go as high as 4K.)

First I noticed the anode on the rudder. It was doing its job but needs to be replaced.

Are there other anodes on the hull? Should be a couple on the keel.

Looks like the Prop has not been hit at all which is good.

Again I have no way of knowing but from the pictures I would be suspect of paint was used. The wrong bottom paint with copper oxide in it would do what I see in your pictures. I see they did put on a different Red indicator coat. Must use ONLY antifouling paints designed for aluminum hulls.
Trilux 33 is one example and probably the most widely used.

Nothing wrong with having bare aluminum in hull if fact I prefer it. The " Goop" they put on them was very common in the industry then in Chris Crafts and Marinettes for Sound reduction.

Take a couple of picts of the struts, the edge of the chines and of the bow stem. Are they corroded or still clean edges?

* No problem having a Big M on an aluminum trailer. What you want to avoid is bare aluminum sitting on carpet bunks. If wet they can lead to corrosion of the aluminum due to salts etc; (this is a common problem with pontoon boats sitting on wet bunks)

safe boating,

dave

[wacdlw]

Hi Dave,

Thanks for the information. I was also very concerned with the fact that the guy said he knew nothing about the meter. I am thinking of going back over with some sand paper and asking the guy if I can remove the bottom paint from the area that looks the worst and see how much pitting I find. If he says no sanding I will walk. If the pitting is very minor I may go for a test run. The owner said he is fine with taking it out. The topside and interior is really nice. best I have seen in the 10 boats I have looked at.

Do you think removing the paint from the worst looking say 1 sqft area will give me a good idea of whats going on?

Bill.

[barkleydave]

You will see pitting.
Only remove paint to bate hull with stainless steel brush or aluminum oxide paper.

Exposed aluminum needs to be etched shortly after inspection.

[tundrarules]

Bill please add a signature so we know a little about your location etc.
She needs an extensive bottom job. The corrosion doesn't look too deep. Take a screwdriver and see how deep it is. Looks like you will need bead blast and filler to smooth out bottom. Price must be right so you can fix it up. If the top side and motors are as good as you say and the trailer comes with it.... May be worth $13k