Determining Paddle Length

Not being able to try out a bunch of different paddles before buying, I was wondering about a more accurate way of determining length than those that I’m familiar with already. Playing around, here is what I came up with: Place the canoe on the ground. Next to it stack books where your paddle would be placed in the water at the end of your forward stroke (next to the hip). This will approximate the water level as the boat sits in the water. For example on my boat I approximated the 3" waterline (3" of books). Now resting one end of a broom stick (paddle or whatever) imitate the correct paddling position at the end of your forward stroke. Measure the distance from where your top hand is grasping the broomstick to the end which was resting on the books. Add to this number the length of the blade and you should have the over length of the paddle needed. Any comments would be appreciated as to problems with this method or ways to refine it would be appreciated. In particular I’m not sure where the placement of the top had should be at this point in the stroke. I’m guessing shoulder level. I’m also curious about measuring blade length. Some blades are so narrow for a significant length at the top that it doesn’t seem right to include that portion as part of the blade length. Do manufacturers when then write the specs? Also does type of paddle or type of water being paddled have an impact?

Do above on the water for more
accuracy, calm still water slow motion paddle all the strokes you wish to use but only ‘measure’ the ones you will actively use >80% of the time… mention a similar approach for folks to use all the time if they are not sure where to start or really want to fine tune things. Blade length will have some influence but not as much if using the shaft length first approach.