For smaller people I might agree, that the shorter boat is fine, but one of the criteria mentioned was the wish for stability. For a short boat to be as stable it needs to be wider, and that equals drag in a way that the same wetted area in a longer narrower boat might not.

I agree that at sedate touring speeds the shorter boat won't be at a disadvantage, but neither will the guy in the longer boat, and if you are on your own you probably won't notice it, but paddle in a group of fairly fit regular paddlers in 17 ft boats, and you will find you will be holding up the party, maybe not much, but enough to notice that you are having to work harder to remain at the back of the pack, and over long distances this gets frustrating fast.

When you add the dynamics of long downwind passages, where wave action and wind is adding to your power, then the potential hull speed of the longer boat starts to really become noticeable. It is like two bicycles coasting down a hill, one with a long wheelbase and one with a short wheelbase. With no input from the rider, the shorter wheelbase will rapidly pull away. There is nothing more annoying than to be continuously aborting downwind surfing in order to wait for a slower boat.

Of course all this is general, and depends somewhat on the style of boat, long overhangs, or plumb ends, hull section, etc.

I know that folks have done computer models and tank tests of drag over effort comparisons between all kinds of boat lengths, shapes, weights etc, to achieve optimum hull speeds, but subjective experience on the water, over decades, of thousands of active paddlers, has thinned out the style of kayak that the vast majority of experienced sea kayakers end up using, and the larger paddler, especially distance paddlers, end up in seventeen ft boats, and longer.

I also remember that the James is a novice and may not need all that potential performance, but he may not be a novice for long, so why not have the extra horse power tucked away for the future? As his ambitions and kayaking stamina grow he will have some length and hull speed to grow into.

All this is just my amateur opinion. Subjective, and based on my experience of paddling in sometimes roughish waters in groups, where many of the paddlers are younger and fitter than me. In such situations I don't want to be at a disadvantage, and I will instinctively reach for the longer boat. This's tells me something about my subliminal experience on the water.

I hope I am not being contentious here. It is not my intention, but I feel the OP leaning toward the shorter boat, and possibly for the wrong reasons... ie: convenience of build and materials etc, rather than convenience on the water, where it really matters. I just feel that I need to weigh in behind the longer boat in this instance.

Et