Professional BoatBuilder Magazine

General Composites Discussions Composites Talk
#1

Professional Boat Builder has an informative article on some of the processes Genmar uses to produce boats. Although likely on a much larger scale than any of us do, you can still pick up some good hints on how the big fellas do it.

To view it go to <http://www.proboat-digital.com/proboat/200606/> which should bring up the June 2006 issue.

Click on “Pages”. The article starts on page 62. Or you could click on “Contents” and then on “VEC”.

If you go to page 66, the last paragraph (starts with “For tooling”) has a short discussion about “floating molds” which I found most interesting.

It is NOT necessary to subscribe but if you wish to there is usually no charge for a subscription.

No doubt you could pick up a lot of information by looking through the archives.

#2

A form of RTM. At one point I believe they (Genmar) were trying to do away with gelcoat by putting a layer of polyethylene in the tool instead, are they still doing that? Whatever happened with their lawsuit with Bayliner? I’ve not gotten the next issue in the mail yet but look forward to checking it out. Professional Boatbuilder always seems to have informative articles on composites and its processes that other industries could benefit from.

#3

[QUOTE=Glenn]A form of RTM. At one point I believe they (Genmar) were trying to do away with gelcoat by putting a layer of polyethylene in the tool instead, are they still doing that?

The layer of polyethylene in the tooling is addressed in the article. It appears that they are not satisfied with the results of doing that yet.

#4

The “vec sheild” is basically vacuum formed acrylic sheets that are then laid with fiberglass. This is how they make acrylic showers and spas. I hope they have better luck with the system than Bricklin did when they used the process to build cars. Early on they had adhesion problems but finally worked it out thru chemistry. for the adhesion test they would hit a part with a 3# hammer, if it didn’t delminate it passed.
the next issue was uneven thickness, as the parts were vacuum formed thin spots would develop as the sheet stretched, This problem didn’t show itself until years later whem the thin spots cracked. The stresses left in the acrylic sheets by forming often led to micro cracks on parts that never even made to assembly. I have several new old stock panels that have never been outside of warehouses and they all have stress cracks in them. The next issue was the acrylic and fiberglass expanded and contracted at different rates leaving panels with corners that either curled up or down depending on temperature. The acrylic panels were also very wavey once the fiberglass was laid up. The acrylic was also very brittle, a stone would put a star in it with ease, the only proper repair is to replace the panel, I can be painted but then it is a painted part not an acrylic part any more it just a painted one. I think the constant flex of waves beating on the hull would lead to many stress fractures in a few years. Bricklin claimmed his process would revolutionise the auto indusrty at the time, but in the end it put him out of business.

#5

Polyethylene (PE) does not allow PER to stick to it. You could make a mold (THICK SHEETING) of that stuff and make parts from it but it can distort with the heat generated. In my class, we vacuum form small PE casting molds to be used with PER.