Fast unique assembly method !

BTW, isn't this thread better placed on Boatbuilding or Wooden Boat Building and Restoration as this isn't specific about Multihulls but about plywood boatbuilding in general..?

Cheers,
Angel

 

I have been on that boat pictured. Structurally it is just like any other FRP over plywood, similar to stitch-n-glue, but without the stitching. Most of the strength comes from the FRP skin and the glued joints, so how it is temporaily held together I think is irrelevant. It seems to me that cutting off temp tabs, made from costly marine plywood, is a expensive temp assembly. It is possible to do something similar with low cost wood.

It is a cleaver design, I wanted one like that as a sailboat and limited to 16 ft. In our state if it has no motor and is less than 16 feet, no licensing is required.

 

That looks very similar to the Duncanson effort (my god that was 21 years ago now!). They covered the panels in epoxy prior to them being cut by the high pressure water cutter. With the kitsys method the hull deck and internals of a 43' yacht could be assembled in around 3 days by 2 men.

 

The idea was computer cut, mm perfect, rapid assembly, low cost, idiot proof construction. It achieved that, wasted material was not an issue, if anything it saves material by nesting the cuts perfectly. The costly part was the high pressure water cutting, back in 89 the machine was massive! The main issue, as I recall, was that no one in Australia seemed to want to build a plywood boat because the resale was shockingly low. If they did want plywood it was more from budget constraints and then they didn't want to fork out for the kit.

The Duncanson's had some nice designs, they where light and stiff when build using this method. It was a well thought out system but ultimately a failure in the market.

 

(thread moved to the wooden boatbuilding forum)

 

For starters:
It's easy way to have hull formed, but from there starts the real job (as said allready in some responses here). A lot of gluing cutting sanding filleting etc. Is there a need for gf over the seams and joints (I think so). The hull is filled with stucture preventing pretty much anything to be done inside (not sure but it looks like in cat that it intended to stay in place?), and if the "backbone" stucture is removed it must be then replaced with smth.
A free advice.. CNC cut only the side panels with tooths pattern on the sides matching the next panel, with a couple of "stithes" on the full length, some bulkheads at right places and forget that T rex skeleton.. IMHO

 

Agreed Teddy, CNC can be handy, but this is just plan over thinking and over engineering. It's the British Jag of CNC kits. Lovely to look at, but way over thought in application. It just adds to setup time, machine time, convolution, complication and extra parts to fiddle with.

A few well placed jogs in a seam, to insure alignment, some duct tape (or stitches if you prefer) over one or two temporary station forms and bingo, you're ready to smear goo. The point isn't to make it idiot proof. The idea should be keep it cost effective, easy, a minimum of parts and contrivance, so you can get to the meaningful aspects of taped seam construction, which is taping the damn seams, so that you finally have a fairly rigid structure to play with, instead of the floppy un-glued one you start with.

 

Thanks Teddy and PAR, that gives a lot of insight . . :idea:

Thanks!
Angel

 

Here's that picture...



Both sides glassed I think, but it still looks weak to me if it's not backed by a strip of skin ply. But if it's backed then a simpler traditional butt joint will do as well. However scarf joints would be neater (smooth interior) and lighter and maybe even stronger..?

Cheers,
Angel

 

You need to understand that the only reason for this method is to provide a kitset for newbie builders who percieve even stitch and tape by the existing methods as too difficult,and scarfing the panel joints falls into that catagory. A scarf joint is easy and plenty strong but a lot of newbs fear them for some reason, i have no doubt that the puzzle joint with a strip of glass tape over the inside and the outside glass skin will be every bit as strong. This is not a better(or worse) method than existing methods,it just makes a good kitset that minimizes the need for measuring. Im with Par on keeping it simple myself,i like to assemble over or in a simple jig and skipping the stitch part,you can use the occaisional dab of hot melt to keep things in line, unfortunatly this usually only works with my own designs.
Steve.

 

The puzzle inserts are very narrow in the middle. So if only glassed the strenght would be near the same as just a plain butt joint with only glass on both sides.

pic attached so it will stay with the thread for discusion matters...

Cheers,
Angel

 

I like the dogbone, puzzle joint . To cut and glue a normal slash scarph requires a good work bench and a big workshop. Everytime I scarph two sheets of ply, the whole workshop is unusable for 24 hrs while the joint cures.
Those dog bones need no work bench and no work shop space to glue up and cure. Perfect for a kit boat built in your living room or out back.

 

The point is this method brings additional difficulties to that novice builder. It just looks simple bcs the form of the boat is achieved so easily.
The scarf joint could be prefabricated too and thus be as simple to glue as the jigsaw joint..

Not saying this technique isn't clever.. for a doghouse

 

It figures you'd like the dog bone joint Michael. Again, lets take a simple joint and make it much more complex then it needs to be and while we're at it, lets toss some more pieces into the mix too. What a good idea. In the case of those topside panels they've taken a normally two pieces joint and made it a 5 piece. The garboards are 6 pieces! Yea, that'll fix it! The dog bone joint is a joke.

A Payson butt joint or a taped seam scarf can be cut out with a hatchet and a pen knife and still work well and doesn't add a bunch of non-radius conforming pieces to the mix either. What's to be scared of there. There's no precision in taped seam construction, just hack it together, any 'ol way you can, fairing compound hides all sins.

 

Yeah,i dont see a reason for the dogbone either,why not just a puzzle joint if you must?unless he needed every bit of the sheets length on this particular boat. He could certainly machine actual scarfs but they are pretty vulnable in a kit until glued up. Without actually seeing the designers drawings im not going to speculate on if there are extra components in this construction vs the original as designed construction.
Steve.