round are hard chined hulls.

[tx river rat]

Some one needs to educate me here. I have heard the statement that a round bottom , soft chined boat has less initial stability and better secondary stability than a hard chined boat.
I can see the less stability because in rounding the corners you really narrow the bottom of the boat, secondary stability would seem to be the same deal, you really have less hul in the water as you lean over. Now I can see it being a smoother transition ,
To me the shape of the sides would be the determining factor in secondary stability
Lets hear from the choir on this one.
Ron

 

[woodchips]

I've heard it the other way. A flat bottom with hard chine had less initial stability, because it doesn't stiffen up until the chine is forced down and the flare in the side creates a greater amount of volume at the water line. And a round bottom sits deeper but with almost plumb sides it is stiff a first but never really creates any more volume to resist the roll. Unless the volume becomes greater as you move up the waterlines on the way to the gunnel rails. :?
Maybe Matt will tell us.

 

[tx river rat]

Somebody is full of it .

Initial stability , MY OPION My flat bottoms are the most stable, then v bottom then round bottom.
Ron

PS I am not talking about you ,just two opions that are 180 degrees from each other somebody has to be wrong

 

[woodchips]

I checked the canoecraft book and he says, flat bottom has the greatest initial stability when you sit still in flat water due to the greater wetted surface, BUT he only recommended using it for cargo purposes not recreation use. Try telling that to a bunch of piroguers. :twisted:
But it stiffens up on the chine. Next was the round bottom, figure it as a middle of the road shape. The V bottom had a low inital stability with the highest usage stability.
But there ya go ... options. I've swamped a canoe but never flipped a pirogue in a chop.

 

[Kayak Jack]

The conversion from initial to secondary is a feel sort of thing. When I leaned flat bottomed boats, they would have more and more resistance - up to a point. Then BANG I was in the water. Once it started to go, it seemed to go so quickly that there was no reversing it. Kind of like holding a pane of glass and trying to bend it so it would crack only part way down. Once it starts, it's going all the way.

A semi-round bottom seems more predictable in a lean. It stiffens, and then finally starts to dip water, then goes further. The break is not as sharp as a hard chined boat. That's been my experience.

Also, a flat bottomed boat will follow the contour of waves more than a semi-round bottomed boat does. A flat bottom will tend to roll left and right as needed to match the angles of an oncoming, then retreating wave. A semi-round bottom always has a curve to match the varying angles as a wave passes underneath; so it mostly just rises and falls with very little to no roll.

 

[JEM]

Depending on shape, a round chine hull can have great initial stability that has little secondary stability. Same is true for hard chined.

If one wanted to compare, you'd have to have a very specific set of parameters. Beyond that, these are generalizations like "women are bad drivers".

 

[Kayak Jack]

"women are bad drivers".

Whether they're semi-round bottom or hard chined.

 

[oldsparkey]

Personally I think it all depends on the person and what there thoughts are about the different shapes of a boat. You might call it ..... What you are use to.
Some folks like flat bottom boats and feel really secure in them while others would tend to panic. The same for the round bottom boat or even the semi V bottom. I can look at a flat bottom boat and feel really secure with it in any type of water or weather. The same time I see a round bottom boat and instantly feel like it is going to be tippy and want to rock an roll with me. It is nothing more then mental since both of them float and do what I want them to do when paddling them.

Only thing I am sure of is that when the flat bottom boat is beached it is rock solid on the sand bar while that Dang round bottom boat wants to roll out from under me when I stand up. :roll:

 

[shikeswithcanoe]

Take a pirogue with slanted sides. Take a canoe that has a mostly flat bottom but rounded sides. Make them the same size.

It seems to me the canoe almost HAS to have better secondary stability. When tilted far enough, the canoes rounded sides are going to provide more bouyancy further from the center of the boat than the straight slanted sides.

Now, I guess if the slant is low to non existent (ie vertical sides) then the opposite may be true, but arent most pirogues NOT built that way?

I have a 12 foot Bell Bucktail. Its bottom is not particularly flat and is definitely well rounded at the outer thirds. I'd say it has very little initial stability. When floating down the river, I often like to lean it back and forth just to play with it. It really "locks up" once you tilt it a good bit. For that matter it just locks up more and more until you actually have water poor over the gunnels.

 

[WDfrmTN]

"women are bad drivers".

Whether they're semi-round bottom or hard chined.

:lol: :lol: :lol: :lol: :lol:

 

[tx river rat]

I think Matt answered my question, the hull shape has more to do with it than being hard chined or rounded.
I built the crusier to play with several questions I had about flat bottom boats, my findings were it wasnt the flat bottom that made as much difference in side waves as it was the angle of the sides, the less angle the less the side waves effected it ,the more angle the more it pitched with the waves.
Ron

 

[Oyster]

You really need to also know the ratios, beam to length too. A flat bottom hard chined pram in the neighborhood of three to four feet in beam versus eight foot long compared to even a 16 foot dory type boat has incredible differences in regards to stability with the narrower beamed bottom versus the wider flat bottom pram. Now take an eight foot round bilge pram of the same beam as the flat bottom pram and step into the boat at rest. :shock: Like its been said, generalizations are in full swing without knowing the actual specifics in these discussions.

 

[tx river rat]

I was talking identical length and width boats.
Ron