extended bow thought experiment

Still thinking about plumb vs extended bows, I came up with the following thought experiment: Take a Nordkapp Low Volume, and/or a Current Designs Solstice or Nomad GTS, all very different designs. Bring them into the shop and remove 6 or 8 inches from the bows, faring it up smoothly.

Would a paddler even be able to tell that the boat was shortened? In what conditions? My guess would be no. I had a Solstice GTS for over 10 years and do not recall its extended bow ever in the water, except perhaps exiting a surf break. But it has been a while and my memory might be hazy.

Note that removing those 6 inches has zero effect on rocker. The Nordkapp LV has high rocker, and the Current Designs boats have low rocker, all completely unaffected by modifying the extended bows.

bow volume vs overhang
The overhanging bow when submerged in following seas, surfing or playing in standing waves seems to allow the boat to come up and get back under control quicker. However the bow on my Sterling reflection is fairly high volume compared to a Nordkapp or anas acuta.

In my plumb bow surfski, the bow and entire front half will submerge when surfing steep wind waves. It is pretty much locked on course until you lean way back and get he nose up and the rudder engaged.

There’s also some aesthetics there. Cut 6-8" off a Nordkapp and you will have a less pretty boat (and one very upset boat owner. )

you partly answered your own question.

– Last Updated: Apr-05-13 5:48 PM EST –

"except perhaps exiting a surf break". Any time you are going up OR down any wave that is sufficiently steep the bow will have an impact on performance.

paddling along the coast on a day with some decent wind waves the bow of my Valley Aquanaut has been quite wet much of the time. The real question on bow type is whether it's better to largely push through those waves or somewhat float over them. Plumb bows give a longer waterline for the same overall boat length can be a plus for speed.

At one time, naval vessels had plumb
bows, because it added speed and saved fuel.

But experience brought flared and extended bows. Ship control in storms with huge waves is a real issue.

I had a Squall

– Last Updated: Apr-05-13 5:10 PM EST –

Which is a Solstice series boat. I can assure you that bow had to punch thru a wave more than once, and in some open water rather than surf. That was on open ocean bays with good fetch, as well as in steep breaking lake waves where the lake was narrow and the fetch was long.

Not a good experiment
You are comparing extended bows to a design that does not exist and is not at all like a plumb bow.

I suspect the effect is small but the extended bow will catch more wind and possibly reduce weather cocking.

weather-cocking and bow

– Last Updated: Apr-06-13 12:31 PM EST –

weather-cocking is mainly the result of what happens *below* the waterline, not above it, so I doubt if this would make a real difference.

That said, since weather cocking is caused by the high pressure at the bow, when moving forward (visualize the bow of a tug-boat as it plows through the water), with wind from the side, one could speculate that a plumb bow or a Ulstein X-bow (inverted bow) might slightly increase weather-cocking because the bow is so solidly planted in the water (relative to the stern). Maybe a kayak designer will care to comment.

However, I can't say that I have noticed this to be true on the water, but, then again, all of my plumb bow kayaks have rudders.

Greg Stamer

I think the more interesting question is
About pinched vs. plumb bows (and sterns), not the amount of overhang (though the two may be related somewhat).

Having some sort of bulge in the front and rear I reason helps with edged turns. When you edge left you turn right. The more the bulge and the closer to the cockpit, the easier the bow and stern release and the boats turns faster (all else being equal). Coincidentally, pinched bows/sterns often go with more pronounced bulge compared to plumb ones. There are also effects on how the boat handles waves and surfing.

I don’t think one is better in absolute terms. But one is better in specific scenarios. Anyway, I don’t know enough so I find this discussion vey educational :wink:

Then there is the “figure 8” shaped kayaks - the Warren light craft designs, that are fat front and rear (above water) and skinny in the middle, then plumb and slender below water…

the pintail compared to nordkapp has a lower deck and bow and more volum in the front. For me as a quite light paddler, it will leecock less that a nordkapp, in strong wind.

yep NM