Hi Blue Crab,
I am in the process of upgrading from 24" to 30" stanchions as well as the pushpit and pulpit.
I have also sailed a fair amount on boats with both the shorter and longer versions, so here are a few observations FWIW.
First, any solid setup is good to have and much better than nothing at all. If you are sailing in flat water
you might be standing straight up and yes the top height of the stanchion could catch you under the knee and facilitate your unscheduled exit from the boat. But, if you are that close to the edge you will probably fall over anyway if you do not have toe rails and lifelines!
I do not see that as a terribly likely scenario, but it's a boat, anything can happen.
Keep in mind that 30", which is the often cited solution to the short stanchion problem is still only 6" higher. In the above flat water example, it will catch you above the knee, but your center of mass is still significantly higher than that and you are still likely to take a swim if forced against the lines or stanchions.
So, the previous posters remark about one hand for you and one for the ship is always important here.
I have boats without toerails and lifelines and I only use them for bay sailing.
work, which is what I am preparing for now, I want the tallest lifeline and the tallest (and strongest) stanchions, toerail or bulwarks I can get. For my Cartwright 36, 30 inches is about the best I can do before the height interferes with other things like headsails. If I could, I would use 36 or 40 inch, but that is really only practical on big ships or at least ships bigger than my means.
I am limited in time and money
for new toerails, so I will not change the 2" version I have now, but I would not go to sea without them.
Regarding actual usage, I find that at the times I really want the backup of the lifelines, and I do stress backup here, are times when the boat is heeled, it is frisky out, and usually wet on the deck. I am not as concerned about being flipped over the lifelines as slipping and falling and sliding/tumbling over the side. That is why I always want the toerails as well. In these conditions I usually run port and starboard jacklines
and tether in, but up on the pointy end it would still be easy to go over the side even with a short tether.
Now all I have to do is choose the best combination of quality and price
from a supplier.