Greyak and I had many arguments over this, back when I cared.
After several "fast" (and expensive)SOTs including my Shearwater that is 18'4" by 20" I just decided it didn't matter.
Real world observations:
No matter what boat I paddle, I just don't paddle as fast as TsunamiChuck, and he don't seem to mind waiting on me that much.
There is no sense in paddling an 18' boat when your wife paddles a Pungo 120
18' boats do not fit well into sea caves, or rock garden.
Pitch poling an 18' boat in a surf landing is pretty traumatic
You need something with a flat bottom to surf, and its going to make it slow no matter how long it is.
If you are paddling less than 5 miles, it don't matter much.
I pretty much just went back to paddling my 13' Ocean Kayak Mars most of the time.
If I want to go more than 5 miles, I'll break out the RTM Disco.
The only time I take the Shearwater off the rack is if its just Chuck and I, and that does not happen much because Kathy always wants to paddle, too, but it sure is a pretty boat!
Strength of paddler Longer is faster only if you have the strength to get the kayak moving and keep it moving at a fast clip over a long distance. A designer told me once that most people are in a kayak that’s too long for them, not realizing the effort it takes to move them. Intuitively it’s easy to see that a small, under-muscled person wouldn’t fare well in an 18’ kayak weighing 60 lbs.
A person who likes to meander around in coves will do better in a shorter kayak. At low speed a shorter kayak is faster than a longer one, because it takes less effort to get it moving and keep it going at a slow speed. This is why I love 15’ and don’t want to go to 16’ or more.
Getting caffeinated again for the morning hammerfest. Maiden run for a new jacket I bought. I'm shooting for some water time next week. I was up your way a few weeks back. Camped near the top of Mt Rogers in VA. Hope you and Nanci and family are all well.
Just to be clear "As to hull speed and why a boat has it (or doesn’t)"
Just to be clear, every boat has a theoretical hull speed, as it is just a quantity based on its waterline length. I presume what you mean is that some kayaks hit a more noticeable resistance ‘wall’ than others when approaching hull speed, which is undoubtedly correct.
It’s interesting in Phrancis’ post below that the resistance crossover point between the short and long hulls is between 4 and 4.5 knots, which is pretty fast.
hull speed Very few paddlers have the combined technique and strength to ever get close to hull speed in most boats, just too much drag to overcome. It’s fairly easy to feel when it happens though, the bow will rise up and the stern will fall into the trough between the waves and the boat will feel like you’re paddling up hill, which you are. A paddler doesn’t have anywhere near the power required to paddle up over the bow wave and make the boat plane, like most powerboats do.
I’ve done it, but only when I practice hard and often with the wing, otherwise can’t get enough power to get a long boat going fast enough to overcome the drag.
It’s fairly easy though with a shorter boat and specially with displacement WW boats. Their hull speeds are pretty low.
Btw, do yourself a favor, don’t try this. Once you realize there’s a wall you can’t get over the boat seems slow and you’ll want something faster. This can get expensive
LWL/Beam Aspect Ratio Okay, assuming constant waterline beam, I can understand why a 16’ boat is faster than a 12’ boat. But if the beam were reduced on the 12’ boat, such that the aspect ratio were the same, would the two boats be equivalently fast?
For argument’s sake, let’s say the 16’ boat has a 24" beam for a ratio of 8:1. If the 12’ boat has beam of 18", it would have the same 8:1 ratio. Notwithstanding surface area or other issues, would the theoretical hull speeds be the same, or would the 16’ still have an advantage?
