Moving from the colour thread, I chatted with my powder coating buddy yesterday, and epoxies are not recomended for outside use as they are not as UV stable as the polyesters. 60 mil thickness may be chip prone and he recommends 30 mil

OTHO he said that marine paints are pretty good and perhaps it is a prep issue with the aluminium. In any case a properly prepped polyester powder coat might be a bit better.

With reported problems with corrosion and pin/hinge issues I am interested on the ongoing development and addressing these issues for new builds.

Epoxies are not reccomended as the final coat where UV exposure exists. They bond VERY well to properly prepared steel and prevent the transmission of oxygen. What is done in general, and on the Duck, is that a coat, or two, of linear poly-urethane is put on top of the epoxy primer. Linear poly-urethane is very stable, physically bonds very well to the epoxy undercoat and blocks out the UV. It also looks very good.

This is standard industry practice. The key is that the surface is sandblasted to "white metal" and the epoxy primer is applied immediately.

Hugh

Wether powder or paint, prep is the key, and sand/shot/bead blasting to white metal seems to be the method of choice.

SeaDuctress experienced extensive aluminium corrosion and hinge problems. Her owner, Geerlofs reports that the castings do not have hinge bushings, and hinge pin material is not described. Oceaneer owner McCutcheon reports problems with his portholes but does not describe the problem.

I, like countless others have had aluminium hatches without problems so it must be something specific to the Seahorse design, materials, or process. I would be very interested in hearing Bills side of this story, and what is being done in current production to address this issue.

Robert,

I agree completely. I know that he is stripping the ports and hatches now and using the same protocol to paint them as the hull. However, aluminum is usually acid stripped prior to priming. I don't know how Bill handles this and would also like to know.

I don't know if anything has been done to the disimilar metal corrosion that SeaDuctress suffered from with improper pin and bushing materials, and/or improper preparation.

Hugh

Maybe Neal on Makena can weigh in on this issue. I believe his boat would be one of the next oldest discussed. He would be in a position to let us know if the hatch problem is still a problem.
John

I spoke with Neil on this some time ago. I hope that he can chime in as well. If I remember correctly what he told me, he didn't have as severe a problem but did have problems with improper selection of pin and bushing materials but less of an issue with loosing paint from the hatches and ports.


Hugh

Hugh,
Would you please e-mail me or post your address? I have a few questions that don't need to be on the list.
Thanks!
John Howland
jdhowland45@hotmail.com

h.palmer@acquamedtech.com


Hugh

Hello All;

I too am interested in this issue of the hatch and window aluminum corrosion. What about the idea of switching to another metal of less dissimilarity; eg stainless or bronze?
Bolting aluminum to steel needs a bimetal plate in between, right?

Still hoping for a sedan,
John.

I'm in California now and just had my second eye lens replacement at Kaiser. I'll return to the factory on the 17th.

Regarding ports. We now completely disassemble the ports and strip each piece and re-coat with the same system used on the hull exterior. I have a picture but I'm not at my home computer. I think I sent it to Hugh sometime back, maybe he can share it.

The ports are mounted inside the boats, not outside, and are isolated from the steel hull by two coating systems plus a neoprene gasket. Attachment bolts are stainless. Based on the pin problems on SeaduckTress we now drill a lubricating hole so the pins can be kept oiled. But we are always looking for a improvements and will approach the port factory about a stainless liner. However a stainless pin in a stainless liner still needs lubrication.

Another port problem is occasional misalignment of the glass part and/or the storm cover with the frame.

I have the photo on my office computer and will be able to post in on Monday.

I will post some photos of hull 4, or 5 which shows the hatches that have been sandblasted and then primed before installation.


Hugh

Bill - thanks for the update.

Wonder what Townsend Marine did about the pins and bushings. Perhaps SeaDucktress could comment.

Would a 316L pin in a bronze or Delron bushing c/w zerk fitting be better than stainless on stainless?

Assume that the hatches are given the same treatment as the portholes.

Robert

I posted the photo Bill sent me (in hull preparation album in the Album forum) that shows the ports that have been stripped and painted before being installed.

He confirmed that they are using SS pins and expects that in combination with the better paint application and improved bedding good progress will have been made to minimize problems that have occured in this area.


Hugh