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Stem Angle

beekeeper

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Mar 4, 2009
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Some boats have more angle "rake" to their stems than others. Why?
Where I paddle, some rake makes it easier to "beach" the boat or paddle over a log or vegetation. A curved stem helps when backing off objects.
I would think rake would help deflect waves but could reduce capacity and footprint.
 

Kayak Jack

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Aug 26, 2003
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Okemos / East Lansing Michigan
You’re correct about a raked stem cutting the waves better. It also provides a slight assist in raising the bow in a wave.

And, I believe, the Titanic had a bowline that was pretty straight up and down. Lesson learned.
 

beekeeper

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Mar 4, 2009
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Titanic vs iceberg = pirogue vs cypress knee.:confused: I thought the Titanic side swiped the iceberg? Unless the bow angle restricted the maneuverability I don't see the correlation.
Most vintage pirogues I have seen, seem to have more vertical stems than the newer designs. Not as much as canoes but more than a kayak. May be because of building procedures or use of plans.
A marsh pirogue has more flare and volume in the bow area than a swamp pirogue. Probably to provide lift to the bow when meeting a wave.
 

beekeeper

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Mar 4, 2009
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I understand now. I had to research the accident and then became confused. Lot about icebergs a south Louisiana fellow might get wrong.
Are canoes and pirogues raked on both ends so they can be paddled in either direction? If so why are kayaks? Are they ever paddled in either direction? I had assumed not.
 

Kayak Jack

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Aug 26, 2003
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Okemos / East Lansing Michigan
A sharp stem on both ends presents less drag. The water is parted cleanly, and put back together cleanly. It’s known as “hydrodynamically clean”. The opposite of that is a boat with square ends. They don’t cut the water; they plow it and push it. The gurgling sound at the stern is water changing directions all across the stern.

Moving the water like that takes energy. That energy was furnished by the paddler. The energy was used to move water instead of moving the boat. That is called drag, caused by a boat that is “hydrodynamically dirty”.

A goal in boat design is to have as little drag as you can. Compromising with other performance and design considerations.
 

beekeeper

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Mar 4, 2009
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I understand having narrow stems reduce drag. They also reduce capacity, stability, and lift. Every feature of a boat is a compromise. As you stated paddle efficiency is not the only goal, maybe not even the most important one.
All that said, I was trying to ask about the angle off vertical, not the angle (thickness) where the sides meet.
Seems the more vertical the ends are the more foot print, longer water line, and capacity the boat can have for the same overall length.
Are there any building issues, advantages/disadvantages, of one style (vertical vs leaning) over the other?
 

jdupre'

Well-Known Member
Sep 9, 2007
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South Louisiana
Not so obvious reason for a verticle bow and stern.........more waterline length for a given boat length. BUT, not so handy at going over obstacles and pushing up on shore. Not a concern for big, ocean-going vessels. In displacement craft, length is a big determining factor in speed. Most any boat is a compromise for it's given location and use.

Take a Cajun rowing skiff. It's got a a flat bottom that rises above the water at the bow. A big no-no for speed. It took me a while to figure it out, but here's my conclusion. The skiff was never meant for speed or big waves. It was a bayou pick-up truck and family hauler. You could put a big load in it and still paddle at about the same leisurely pace. When you got to your destination, you just ran it up on the bank and stepped out on dry land and unloaded your family and groceries.