How to join Composite flat panels?

Good day,

How do you join flat panels (sandwich panels) together when constructing a boat? I am considering making flat panels using vacuum bagging. However, how do you join these panels, making sure that the joints are mechanically strong? I am thinking of making modular panels, that can be joined together (on the mould), rather than one big panel, if that is possible.

Is it possible to create a "tongue and groove" joint for composite panels, where one can make up an epoxy putty and bond the panels together?

Also, can one use gelcoat, especially for panels to be fitted below the waterline, when making flat panels? Will gelcoat be susceptible to osmosis?

Kind regards,
J

 

Google duflex z-joint for one method. But that is for a series of panels joined together before being installed.

 

You can use epoxy and cabosil to edge bond panels, then they are typically taped with biaxial or some other specified tape and epoxy.

You can also make reliefs or rebates like sheetrock so the seams are not proud of the panel for finishing.

These panels were bonded on the edges, then inside while in the female jig/mould, then bulkheads added and then exterior tapes were done. Then the deck was done as a shoe and not rebated because didn't require much compound. Here is a picture of other deck work and beam integration, but this shows the seams well.

 

I guess the inside of the boat is a lot easier in terms of finish considerations, the "sheetrock" analogy certainly seems a neat solution for the outside.

 

This looks great.

I assume you do not have gelcoat on the outside of the panels?

I searched for sheetrock, drywalling is not that common in South Africa. I notice the tapered ends on the sheetrock panels, which makes sense.

Do you have a write-up of your build? Do you vacuum bag the panels, or do you do a hand-lay-up? What do you do at the open ends of the panels that are not joined - again epoxy and carbosil, or do you use tape as well?

 

Panel ends are flycut and filled, but because it is such a pain; we allow it rarely. Foam ends are only allowed in places covered by components like doors, but very rarely.

The build blog is here.

https://www.community.boatbuildercentral.com/forum/viewtopic.php?t=62495&start=2100

Here is a small locker door made from foam. The edges are flycut with a router and filled and sanded.

 

You may want to rethink gelcoat. For a number of reasons. This build method, for one. For another, modern 2 part paints, while toxic to breathe while flashing, are really very good and offer exceptional looking hulls. This is Epifanes Polyurethane. I had trouble with fisheyes; likey related to silicone mould release on paint trays from the paint supplier. This hull was rolled and tipped, but we did not tip the other hull and it looks better untipped.

 

Wow Fallguy that paint job looks great. So you just rolled without tipping and it turned out looking better than the hull above?

 

yes...weeist bit of non-notable orange peel