aluminum hulls+marine filler=issues

[gforcepdx]

i am looking at a 41' Eichenlaub Holland Design Sloop...built in 79... the problem with this boat.. well one problem... is that the hull compound used as fill, seems to have a mind to pop off here and there at times... i have never had an Aluminum hulled boat and they are a bit rare compared to there fiberglass counterparts... i don't know why it was used in the first place...[the hull compound i mean]... one reason may simply may be that it was used at seam points and the like ... another may be that the skin is a bit too thin and suffers deflection here and there on occasion... hopefully this not the case but this manufacture was a limited production one and so i am having trouble finding a forum of owners with intimate knowledge of the boats various quirks... the builder [41' Eichenlaub Holland Design Sloop] has a very good reputation for building fast, lite sailboats.... but its hard to find info as to how there designs hold up over time... the last boat i was looking into was a Morgan where there are hundreds of pages of info concerning all of there strengths and weakness's... and so concerning the Aluminum hull and the delamination of the marine compound, can someone tell me if this delamination issue is common ??? once started does it creep under the marine compound to break the bond of adjacent areas of filler ???...

[Jimbo1490]

This is no different than the problem of the paint popping off of aluminum hulls. Same problem, same cause; bad surface prep. Aluminum requires special attention to get paint or filler to stick to it properly. Awl-Grip's application guide will give you all the details.

Jimbo

[gforcepdx]

yes... i figured it had much to do with prep... i am guessing roughing the surface and removing any contaminates to get a good bond... thats true with most things... but if the prep is done right... will flex in the aluminem cause it to shed off... like bondo ??? or is hull compound somewhat flexible to withstand this sort of thing... also... if the proper care has been done during the repairs but for some reason [perhaps new injury... dock dings...] a bit of the hull filler is knocked off... does water wick along behind the surrounding repairs and cause further delamination ??? thank you..... j

[Jimbo1490]

Roughing does not mean much with aluminum. You or whoever re-fairs and paints the thing will have to study up on the prep process. Minor flexing of the hull poses no problem with a proper marine grade epoxy filler and proper surface prep which MUST include acid etching followed immediately by passivation/chromate conversion. As I said, the Awl-Grip application guide explains all. There is no other way to get lasting adhesion on aluminum.

Jimbo