Bondo hull coating

I recently purchased a 50ft aluminum sailboat that was made in France in 1988 by a french boat builder by the name of Ferru. I haven't had much luck finding him to get more information. But anyway, I have it dry dock now and decided to sand blast the hull to get rid of many coatings of protective paint that was peeling, and at some locations bear to the aluminum. While sand blasting, we discovered that the entire hull below the water line was coated with a Bondo like substance that I never heard about before. Has anyone any knowledge about this process and why it was used?
We stopped short of removing the bondo and only removed the paint.

Any info on this will be greatly appreciated.

 

I've never seen Bondo on a big hull like this... usually it's applied to little aluminum cartoppers and skiffs that the owners were too lazy or stupid to fix properly.

It's possible though that your hull has been 'blueprinted'- filled and faired to exactly match the ideal lines, correcting all the imperfections inherent in the hull. If the entire hull is like this (and is smooth and regular) it's probably part of the design, meant to smooth it out and improve efficiency.

 

Bondo

One of the Australian boatbuilders I have talked with say they do apply Fairing compound to aluminum hulls. He said if the owner is paying hundreds of thousand dollars for the boat, they expect it to be mirror perfect.

I guess its really being practiced, there is no way you could get a "clean" surface on a welded metal.

 

I have not the slightest idea what Bondo means, but according to what I know from French aluminium builders, they often keep their alu hulls bare.
But in a number of cases, clients don't like the bare hull and then - before painting - the hull will be faired, till the wind-waterline or a little under and coated and painted.
This is standard procedure for the bigger and more expensive yachts.

If you can tell me where she is build, I may trace the builder - the name Ferru on itself doesn't sound bells, though I know most of the builders in France.
If it's clearly a fairing compound, don 't blast it away. Fairing a boat like yours is painstaking work, requires a lot of experience and is super expensive over here.
For such a job, a profi asks normally somewhere between 30/40.000 euros, say US 48.000,-- (fairing & painting) - just to give you an idea.

 

Bondo = polyester-based metal fairing compund

The stuff's easy to work when hard. Careful light sanding (not sandblasting) to bring it back to smooth condition is what's needed.

 

Fairing compound

Hi Mat,


Thanks for your reply. Further investigation has concluded that it is fairing compound, and like you said is probably blueprinted. I do feel that sandblasting was in order to rid the many layers of accumilated paint, and glad we stopped short of removing the fairing. Now comes the time to fill and sand to produce a mirror finish ready for paint. It won't be easy!


John

 

Bondo= fairing compound

Yes, you are correct. Further investigation has discovered it is what you say, fairing compound. Now I have to find out what materials are available for refilling what was removed through sandblasting. We stopped short after removing years of accumilated paint. I do feel this process was in order to see areas that were bear to the bone. I will be doing all the painstaking work to produce the mirror finish before painting. It WILL be done!

As far as the boatbuilder Ferru, all I know is that he built 4 or 5 vessels in the area of Antibes, France before retiring. The aluminum workmanship is remarkable. It is a custom built sailboat that was later finished in Kiel, Germany. There is a lot of components installed by German manufactures, wiring diagrams and the like. The sail number on the spinaker is 4561 which I believe came out of Kiel, Germany. Oh, and the reasons why all this is so mysterious is because this sailboat was seized by the DEA in Fort Lauderdale, Florida and put up for auction by the US government, and bought by the last owner before me.
Anything at all you can add to solve this mystery will be greatly appreciated.

Jean

 

About the builder, I can find out easily what happened, if he was located near Antibes, then certainly there are possibilities to find out more about this boat and/or building company.
What sounds a bit peculiar is the fact that she was finished in Germany but on the other hand, if she was bought as a casco, it is explainable. Antibes is not the cheapest place to fit out a boat and I would have done the same: bring it back to a place where you have very short logistic lines, which is absolutely not the case in France, save maybe for the La Rochelle area.

If you ever come to Europe, just be careful with the DEA story, keep that for yourself. Jurisdiction is here a bit different than in the US and your ownership could be contested in case there is any doubt about the legality of the DEA's actions.
As they have to finance themselves for a substantial part, impounded goods are used to be a basis of their financial resources, which is overhere regarded as illegal.

If the Bondo-like stuff is a polyester based fairing compound, it will suck up water like a sponge after a certain span of time. Admittedly, it may take years, but it will finally happen and than your coat of paint comes off. ou will notice it when the coating starts to blister.
Nowadays, certainly in fiberglass and steel boatbuilding one uses epoxybased fillers with added microballoons or fibers.
These materials are impermeable to water and don't have the flaws f the polyester fillers that are a lot cheaper and easier to apply.
In any case, only the the topsides are of importance - there is not a single reason why you should fair a hull below the waterline that is invisible to he eye.

 

Hello
I read the post D'Artois about the importance of using the proper fairing compound. I am moving toward fairing my own boat soon and had thought about using polyester base "bondo" but opted for epoxy based due to the same concerns. I know fairing to the water line is a common practice ...however I will fair to the chine. I think this makes for cleaner fairer hull. It really does not take that much more work to fair the little bit remaining to the chine. The fairing compound of choice for me is awl-fair by awl grip.... expensive, but does not shrink much so goes farther.

 

Easi,

Just take a bit of sandpaper and sand a little bit on the fairing compound, then sniff the sandpaper, that will tell you if it's epoxy or polyester based.

Yoke.

 

Yoke,

Should I be concerned applying epoxy over polyester fairing compund, assuming that the previous coating was dry?

 

Best to use epoxy over epoxy and polyester over polyester. I have seen polyester used over epoxy and never heard anyting about it failing but if I knew it was epoxy I would use epoxy over it...just my two cents worth

 

Fairing an Aluminum hull

I was researching fairing on a boat we are building in aluminum and ran across this site....(those of you who are aspiring metal boatbuilders prepare to be a bit overwhelmed) http://www.yachtsindustries.com/jeu%20cadre%20YI-US.htm the .mpeg on this page shows a brief scene of fairing being done by a French master.

Hmmm. a shop to aspire toward no?

hang5 (or 6 if you got 'em)

 

Fairing compounds for hull smoothness or are there other reasons for it's applications? I am curious to know about your researching and why.

I had my hull sandblasted recently just to remove old paint when this fairing was discovered. We stopped short and am contemplating on it's total removal or to top coat it off smoothly again. I'm not sure if it's epoxy or polyester, and if it is polyester will it be compatible epoxy. I do know it was done in France in 88. Any comments or interesting information you can pass on will help.

 

Mostly for smoothing out the lines to get better water flow along the hull. Thus increasing speed and efficiency. I would suggest sanding it smooth (250 grit, 400 grit, then wetsand with 800 grit), filling in any holes/gaps, and priming & painting over as per a brand-new hull.