Man, that ITW video was disheartening. I guess those glue dispensers feel they're lucky just to have a job (or maybe they're Deltas and Epsilons). I imagine their days are numbered though, the corprocats will soon give those jobs to robots...
The most interesting thing about this picture;
in comparison with this picture;
is the difference in the size of the radii in the fillets. The fillet in the Plexus joint is easily twice that of the fillet in the tabbed one. Does this indicate a testers' bias, or inconsistent experimental controls, or designed joint criteria? It makes a huge difference.
Additionally, from what I know of Plexus's almost crystalline hardness (I'm aware that ITW makes at least dozens of products and that some of them should include flexibility), the use of a deformable core panel in the test leaves me with more questions than answers, as regards this particular application.
I prefer bonding, filleting and tabbing. Hope I'll be forgiven, the pictures below are from a 21 ft., 85 mile an hour bass boat, but the idea is the same, When does use
?, and seems in line with the general question about what makes a boat seaworthy
(dare I say bluewatery?)
The boat was rated for 200 hp, the owner put a 225 on it, which is not uncommon. He also added a 6 inch jack plate, which resulted in what you see in the pictures. The buttresses (for lack of a better word, knees maybe) were tabbed but not bonded and were still securely attached at the floor. The boat itself when getting on plane pulled severely to port and once on plane listed about four inches down to port while running, indicating an induced hull
twist under power.
The first picture is just an overview showing what is to me a basic design flaw, an unsupported transom.
2 and 3 are closeups of delaminated tabbing.
Picture 4 shows what is to me the correct way of installing bulkheads (although in this case they're actually stringers), that is; bonding the panel to the hull
, filleting as generously as possible and practical, and tabbing, in this case with a layer of 18 oz roving 5" wide, followed by a layer 8" wide followed by a layer of .5 oz mat 10" wide, all laid wet one after the other.
Picture 5 shows the overall substructure, the different fillet radii where the stringer meets the transom on the outboard
versus the inboard is the key point.
Picture 6 is just a vanity picture after gelcoating.
pictures 7 and 8 show the reason for the different radii of the fillets where the stringer meets the bulkhead. While I felt pretty sure the new reinforcements would be more than adequate, I also knew why the owner brought the boat in and therefore recommended the addition of the aluminum
plate, just to CMA.
Pictures 9 and 10 are also vanity pictures, but I always like to see the end result. It's interesting though, in picture 10, the "hand laid hull" logo doesn't say anything about how strong the boat was, or wasn't. Often times the owner, or the conditions, have more to say about that. (The manufacturer is no longer in business)
And by the way, the white putty shown in the fillets is just glass beads mixed a little wet, with a little silica added to control runny-ness. My seat of the pants tests show that this putty is stronger than PVC foam or wood and is much easier to sand than milled fibers or anything else. This yields the smoothest fillet, which allows the best tab layup
, which yields the most strength. It's the system, not the individual components, that give strength.
Which of course leads back to '(mass) production' boats. Many production boats cannot be assembled in any other way than using the glue in liner or modular approach, indeed, it appears that many boats are designed around the solution (a glue gun) rather than the other way around.
For a status symbol, no problem. To trust these boats in the Northern North Atlantic or South Polar Seas, I'd try to make damn sure the glue spreader was fat and happy....