I already have two posts on how Unangan paddlers held their paddles. To read them, type paddle orientation into the blogger search box on the upper left side of your screen.
Most recently, I have been having conversations with Rob Macks of Laughing Loon Kayaks and he graciously gave me access to some pictures he took of Unangan paddles when he last visited the Smithsonian Institution. Unfortunately I can't post them without the permission of the Smithsonian so I will resort to photos I have posted before.
I haven't seen any Unangan paddles in person, nor handled them. Rob has. What he pointed out to me is that the Unangan paddles have looms that are roughly triangular with one of the corners of the triangle lining up with the ridge that runs down the center of one side of the paddle. The looms are also quite deep, commonly about 1-3/4 inches. The base of the loom's triangle lines up with the flat side of the blades. What Rob pointed out is that trying to hold the loom with the ridge of the blades facing backwards is uncomfortable because trying to paddle that way has the ridge digging into your palms.
To test the idea of the uncomfortable loom, I carved a loom section out of a piece of two by four with a dimension of 1-3/4 inch deep and 1-1/4 inch wide and roughly triangular with rounded edges so it became more egg-like than triangular in cross section.
Well, the loom seems a little more comfortable held as shown in the photo below, but not all that uncomfortable the other way around either. What might be more of an issue, and I have noticed this with one paddle that I made is that a loom with a 1-3/4 inch by 1-1/4 inch cross section is that a loom with these proportions limits how far you can rotate it in your hands to get the right blade angle for efficient paddling.
I will be making a paddle with a loom that is an accurate replica of the Smithsonian type paddles to test this hypothesis. The idea is that the triangular loom shape will orient the paddle in a favorable way when held flat side back and an unfavorable way when held ridge side back.
None of this is conclusive of course, but I suspect that a lot of the dispute about how Unangan paddlers held their paddles has to do with opinions based on Unangan style paddles that aren't very close replicas of the originals. How you hold a paddle has a lot to do with what is comfortable for you and that has a lot to do with how the paddle was carved and also with how the blades were carved. Some fairly subtle variations in construction of both loom and blade can easily bias use of the paddle either ridge or flat side towards the back. And as I noticed with my own Unangan style paddles is that I can use them either flat or ridged side back and both ways work although flat side back typically generates more thrust.
Another thing I noticed while looking at Rob Macks' photos of paddles is that on some of them the ridge on the blade was not sharp but rather about a half inch wide and flat. This type of paddle looked like the basis for the one with the groove down the spine.
One of the paddles in the Smithsonian was also quite long, 8' 6" according to Rob. It falls into the category of extra long paddles that Jeffrey Dickrell, historian of Unangan kayaks has reported seeing in some historical photos.
So there you have it. All in all, I suspect that Unangan paddles varied a bit from place to place and from paddler to paddler. I also suspect that once Russians pressed Unangan paddlers into hunting sea otters for them, paddle and kayak styles became more homogenized than they were before the arrival of the Russians.