: So, that's it! I thought the paddles were the same except that one of them
: was 3 oz lighter - my mistake. Anyway, as nice as shoulders are on GP nr
: 1, who needs them anymore after the tilted stroke has been mastered? A
: well-shaped loom will be enough, especially if it is just the right
: thickness for my hand! And nixing the shoulders means nixing that much
: solid wood. And weight.

For myself, Ive taken a liking to the shoulderless paddles. Sliding strokes are easier. It does remove quite a bit of solid wood, which I think is where most of the weight savings is.

: I wonder if the pine you are using is even in the same family of trees as the
: one we have here in Finland - my experience has been that pine is very
: heavy, even 50 % heavier than spruce. Anyways, you have so many more
: species of trees in North America, even the pine family seems to contain
: at least half a dozen, although they probably are close relatives.

This particular pine is the 'cheap Home Depot' species. I am not sure exactly what it really is. Probably poplar or some such, but it's lighter than poplar usually is. I cut the knots out of a 1x10 to get the blade laminations.

: Hmmm... when I read your first account of the hollow core or
: "truss" my first reaction was "that's great! how simple and
: elegant" and the second one was "but why does he put the thicker
: strips front and back, and not top and bottom?".

: After all, to get max stiffness and strength one should have the long side of
: the thicker strip horizontally, so that it resists the bending stresses on
: the paddle, which are mostly in one plain only. The front and back strips,
: that run all the way to the tips full width, can be quite thin - they
: don't really carry much load.

: And on the other hand, the cap strips are cut down along the blade tapers,
: and also their corners along the loom as this is ovalled, while the core
: strips are hardly cut at all, if they are thin enough to begin with.

: Now it seems that you are doing the same thing, having switched the places of
: the thick resp. thin strips? And gone thinner still, for each strip.

Actually, thinning the cap strips adds more volume to the hollow than does thinning the core strips. The other reasons to use thicker core strips are simplicity - dividing the desired thickness by 4 gives a nice easy way to lay the core up using scrap strip to block the center and the ends, so it comes off the jig true. Thinner core strips would require a custom set of blocks, and if the thickness tolerance was not quite perfect you'd get a paddle curved more on one face, and flatter on the other. Finally, out at the blade tips, thinner core strips will give a flatter blade profile. I like the flat profile, but many people have commented to me that a thicker ridge up the middle of the blade adds lift to it. Lastly there is a matter of practicality - one little slip with the block plane and Ive ruined several hours work. I like to have a little fudge factor in there... More than once it's paid off. Someday I'll be perfect, but not today. The best I can do is a little better than yesterday

Youre absolutely correct that the cap strips are where the paddle stiffness comes into play though. I'm thinking a little glass will make a huge difference in stiffness, but I could be wrong. I'm hoping for a smidge more stiffness, and no weight gain.

: Have you considered making some loom sections (3 feet long) without any
: blades, for testing with the classic sand bucket method? That would soon
: settle the question of how thick the strips need to be, and how oval the
: corners can be before the strength is lost. Weighing them would also give
: some basic data.

I havent done that yet, that is also an interesting thought. It's kind of like boat testing - how strong is strong enough? Or does it matter? Or is it relative strength between one or another technique that I'm after? I do have a paddle with what I thought was a fatal flaw in it - but I let Steve try it Monday and he couldnt feel it. I was tempted to break it, but now I'm not so sure. I could give it away at R2K2, and not tell the recipient what the flaw is - they'd probably never figure it out. But I know it's there, so I can feel it. Tough dilemma - after I told Steve what it was, he tried to talk me into giving the paddle to the store for thier classes...

: Glassing the inside is an idea that leaves me scrathing my head - I just dont
: see the point, or how it could be done? If you glass at all, why not just
: on the outside?

: Anyway, I dimly remember an argument about a year back, where the idea of
: glassing paddle shafts was decidedly bashed, and labelled useless at best.
: Could have been all hog-wash though.

Actually, glassing the inside is quite easy - I cut the material for the core strips, and glass it. Let it go off, and then machine the core strips and lay up the core. At the same time, I take the cap strips and glue the blade laminations to them. Finally, lay the cap strips out side by side, glass them, and assemble the whole affair while the cap stip glass is still wet.

In any beam structure, the further out toward the outside the fibers are, the more strength those fibers impart. In the paddle, adding glass to the inside should significantly increase the strength. Not as much as adding to the outside would, but still significant.
One of my main concerns using this technique is the slight possibility of water somehow wicking its way into the core - either through a pinhole in the cap strip glue joint, which is polyurethane, or through the wood fibers themselves. Ive been coating with thin epoxy to address the pinhole issue, which then requires a varnish finish. Varnishing, sanding, recoating, repeat, repeat, and buffing with 0000 steel wool gives an acceptable finish, but it is a PITA. By having glass on the inner surfaces of the core, I will be able to save that time spent varnishing by instead soaking the paddle in a standard oil/turp/varnish brew. I have a couple paddles which are soaked, and I like the finish better. It's the classic oiled feel, and it is infinitely easier to apply. The only downside to soaking is that it takes at least a week in the oven for the paddle to dry. But the oil penetrates better than the epoxy. So, I'm hoping to keep the total production time to what it currently is, and get a stronger paddle with a better finish by using glass on the inner surface. Of course, the jury is still out on this, I'll lay up the first two tonight.

Thanks for your input Risto - I really value this.