: Polyurethane glue requires perfect mating surfaces to develop its
: full strength. If it foams it will fill voids, but the foam has
: no strength.

Hence the need for tight joints and firm clamping, as I stated. However, the surfaces don't need to be "perfect", which I'll explain below.

: In testing by Fine Woodworking PVA glue like
: Titebond III had the best gap-filling properties and lost no
: strength to any other glues. I can't remember exactly, but I'm
: quite sure that it came out ahead of epoxy, although as many
: people have noted in the past the way they used the epoxy was
: different from the way most people on the forum here use it.

If epoxy isn't thickened, it doesn't fill gaps well, but regular participants here all know that.

: Here is an article about polyurethane glues that you may find
: interesting:
: http://www.popularwoodworking.com/article/The_Truth_About_Polyurethane_Glue/

Yeah, that's the straight scoop. Polyurethane glue works really well for certain applications, but it's not a "miracle" adhesive. The same can be said for any of the glues we commonly use.

: If you have a well-tuned table saw and a sharp blade, you will have
: little to no saw marks, and can just glue it up if you have the
: right glue because the tiny saw marks will be insignificant.

Of course.

: If you want to be sure you have the strongest bond with
: polyurethane you'll need to plane off the saw marks.

That depends on how significant they are, but for argument's sake, let's assume you need to clean them up.

: If you have a thickness planer, just run 'r through and you're set.

In theory, yes. However, the surface that results is often far from perfect. It depends on how sharp the knives are and whether they're set up properly. Otherwise, the surface may be more consistent (no swirling marks or burning), but it may not be any smoother.

: No hand plane.

Sorry Mike, but this is where we part ways.

: Using a hand plane can be a problem because it assumes
: the ability to create a very sharp edge...

Well, that's pretty much a given with ANY edged tool, whether it's a plane, spokeshave, chisel, scraper or knife. For that matter, a thickness planer needs sharp knives to produce a smooth surface. Even when both are properly sharpened and tuned, a hand plane can produce a smoother surface than any thickness planer.

: proper plane tuning

It ain't rocket science and again, it's just part of owning and using hand tools. Plane adjustments are quite simple and information on adjusting/tuning them is widely available. By comparison, properly setting up the three rotating knives on a thickness planer is a considerably more complex process. Sharpening them is a whole bucket full o' fun!

: in fact even owning the right type of plane

For the type of work we're talking about when making paddles - taking a very small amount of wood off an otherwise flat surface - anything from an apron plane, to a block plane, smoothing plane, jack plane, scraper plane or a jointer plane would work. About the only planing tool I wouldn't use would be a spokeshave. Since the OP indicated that he has a plane, I think he should be encouraged to use it. I'm not going to just assume that it's dull or improperly adjusted, though I did emphasize the need for it to be sharp.

: a way to secure the workpiece

Mike, we're talking about people who are building boats and/or paddles. Having a sawhorse or a bench and a clamp or two can pretty much be assumed. For that matter, you can use the table of a table saw.

: and a really good feel for keeping the plane flat so
: you don't plane a taper.

We're talking about planing off saw marks, removing a few thousandths of an inch of wood. We're starting with a basically flat/square part, not hewing a board from a downed tree. It's not difficult to control a plane when you're not removing much material. Also, bear in mind that the parts we're talking about in paddle making are relatively long and flexible, and they're being laminated on the long surfaces. The mating surfaces don't have to mate absolutely perfectly, they just need to be a close fit with smooth surfaces. Clamping will close any tiny gaps and the firm clamping that poly' glues require pretty much ensures a tight joint.

: Those are a lot of ifs, and a lot of
: people spend a long time learning how to do those things. If you
: want to start learning with this project, cool. Read up on how
: to use a plane for this task, and read up on sharpening, and go
: to work. It's the only way to learn.

While this is all true, you make it sound like some onerous chore. Again, we're dealing with people who WANT to make boats and/or paddles. If they weren't willing to invest the time to learn how to do so, they'd just buy them instead.

: If you want to make paddle
: blanks, build some pretty good paddles, and start paddling, go
: with PVA glue and just a table saw.

Not everyone wants a "quick and dirty" approach and I certainly wouldn't encourage it, as it's not wise to RELY on the gap filling properties of adhesives to make strong joints in wood. I don't leave surfaces rough regardless of the type of glue I'm using, as I take more pride in my workmanship than that. If the parts are smooth enough off the saw, fine, but if they're aren't I'll touch them up. If it's faster and easier to grab a hand plane than to set up my thickness planer, that's the tool I'd choose for the job.