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Pirogue Component Relationships

oldbuffpilot

Well-Known Member
May 13, 2014
566
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Central Kansas and Central Texas
Pirogue Component Relationships, how they affect each other and boat handling characteristics.Length, width, depth, rocker, flare, stem angle and shape , bottom shape.

Length
Generally longer equals better tracking, faster, easier to paddle, more stable.If other components remain the same, any rocker increases with length.

Width
stability increases with width, in most water conditions.
Speed decreases and paddling become more difficult as width increases

Height of sides
wind signature increases with height above waterline
weight capacity increases with side height

Rocker
maneuvering (turning) easier as rocker increases
Tracking increases as rocker decreases
Paddling?

Flare
More flare equals more stability, more resistance to paddling, slower speed
an increased stem angle increases bottom length compared to overall length.
increase stem angle decreases flare at least a small degree

Bottom shape
flat bottom more initial stability, less secondary stability
slight V bottom more stability, more draft,
inverted V more stable, more drag?harder to get off of stumps and mud, angles add strength to fiberglassed boats.

Designing/ Building
Shape of sides: straight sides equal some rocker (Uncle Johns style) also simple
Curved (rainbow) chine, increasing side “cutback” increases flare?, decreases rocker
technique: use temporary center form and gradually increase "cut back" and change form shape to achieve the flare and rocker you want.
For asymmetrical boats i.e. widest point not in center. move form and high point of cutback to widest width. That will place the most flare,width, and pivot of the rocker to the widest point of the boat.

? for JD
Water moccasin rocker is mostly in the ends of the boat, ie the boat rocker is flat in the center and the up curve starts about 2 feet from the end. so how would I change the loft of the cut back to do this? My guess is to flatten out the ends of the cutback.

The above are some things I wrote a couple of years ago to organize my own thoughts about building. I’m not even sure it’s correct, but this is a good a time to share it and solicit comments, maybe some of you can help me correct it .






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beekeeper

Well-Known Member
Mar 4, 2009
1,849
52
"? for JD
Water moccasin rocker is mostly in the ends of the boat, ie the boat rocker is flat in the center and the up curve starts about 2 feet from the end. so how would I change the loft of the cut back to do this? My guess is to flatten out the ends of the cutback."

When I built some boats "upside down" on the strong back I shaped the rocker similar to this. If the floor was 12' overall, I would level the middle 4'' to 6' section and then bend each end to the rocker I wanted. Unfortunately I did not pay any attention to the side cutback. I believe your thinking is correct.

You might try tracing the sides of your Water Moccasin onto cardboard or thin ply to see what the cutback looks like.