My Pirogue

[beekeeper]

I wanted a boat that would paddle easier/faster than my skiff. I hope all the changes work.

Length =15'-2" on top / 14' in the bottom / 25" wide bottom / 36" beam / 11" sides, flared 30 degrees / rocker = 1.5" at bow, 1" at stern

Thanks to seedtick and Keith for their lessons and help. Thanks to Joey for your practical thoughts and insights on design features.


beekeeper

 

[Coal]

Beekeeper, another fine looking boat. Looks like you really have a handle on the rocker. Well done.

 

[mike]

That's a mighty fine lookin' boat!

Why the 1/2" difference in rocker? It doesn't seem 1/2" would make much difference...

Mike

 

[beekeeper]

Thanks Coal and mike for the compliments. I learned a lot with this build, mostly how little I knew about boat design and building. When researching and asking about rocker, I found the subject to be evasive. "More rocker helps you turn." "Less rocker tracks better." "The more arc you cut in the sides, the less rocker." "You probably won't see any practical differences between small changes." :
My questions were of this nature: How much do I need to turn easily enough?, If I reduce the rocker from 6" to 2", will it track better?, How much difference does it take to see a difference? etc. My conclusions were, as imprecise.
I wanted a boat that paddled easier than my skiff, and tracked better in the wind. I looked to tradition (what has been working) for answers. Touring kayaks plans said 1" of rocker. An expert pirogue builder said traditional pirogues have less rocker in the rear. I decided to try 1.5"/1". The sides were flaired more to compensate for the difference in the bottoms footprint. It also lowered the sides, hopefully reducing the area the wind can contact, and aid in reaching the water with the paddle. It is longer and not as wide. The pointed stern should be more efficient than the transom. Same for the inside chines vs the outside ones.
I hope it works. Only the paddling will tell. "You got to go to know,"

beekeeper

 

[Kayak Jack]

<SNIP> An expert pirogue builder said traditional pirogues have less rocker in the rear.<SNIP>

I've seen this before, asymmetrical rocker. At face value it sounds ridiculous. Put more rocker in one end of a boat, and that end will merely settle a bit lower into the water, and the other end will raise a bit. VOILA'! Symmetry is reestablished. Or, balance for trim and the asymmetrical part disappears. Or, a paddler can balance a symmetrical boat into asymmetry - canoes are trimmed nose high almost all the time.

I could be wrong, but, in my observations, asymmetrical rocker exists only in the mind of someone who talks about it. On the water, it will disappear.

 

[oldsparkey]

Beekeeper......

An off hand observation from me..... It sure looks like you need a few more boats since you have so few. :wink: No never mind , I like to think no one can have to many but just don't ask my wife about her thoughts on that. :roll:

Looking at this last one I will bet you will be really happy with the way it handles , should sit shallower in the water which offers less resistance and with the standard stern , no drag or turbulence when paddling it. It should just slip threw the water and offer you everything you are looking for.

Chuck........

 

[beekeeper]

Thanks Chuck.

Kayak your post is an example of the elusive nature of the subject to me. Too many variables for all theories to to be true all the time. That is why I chose to use tradition( it has been working, wright or wrong) to guide my choices. The builder that told me the stern rocker is generally less than the bow rocker also mentioned today the load and it's position factor.
Are you saying trimming the load can counter act the effects of the rocker? Does the amount of rocker or the difference between bow and stern rocker disappear just because it is deeper in the water column?
I suspect that after some paddle time in this boat all I will know is how it compares to my other boats.

beekeeper

 

[tx river rat]

Oh boy ,I am going to really cloud this up. most of my boats are asymmetrical in shape and also have less rocker in back than in the bow.
Lets take the stern first . With a boat that is wider in the rear ,it sinks less in the water because of displacing more water ,so you need less.
Rocker in the bow depends on what you want to get out of the boat,if turning easy and running up on banks is important the a high rocker is what you want. If tracking and speed are the things you desire the less rocker is the best. Less rocker gives you a longer water line ,that increases speed,a smooth transition from boat to water on the stern also gives you speed. the longer water line also helps in the tracking department a bunch.
Now its time to pick on Jack in theory what he says holds some water, in real life with a boat that is trimed for its hull shape will hold close to the measurement you start with.
In my asymmetrical boats ,if you get nose down it paddles like a dog,nose up the wind effects it a lot trimmed where my weight needs to be she paddles like a dream.
Boats are very job and location sensitive .
Length gives you speed,tracking,stability
Rocker needs to be tuned to how you use the boat
And the list can go on and on ,you just have to compromise and get as close as you can.
Ron

 

[oldsparkey]

Going with the old Cajun idea which was told to me......

" If a boat looks good , then it will paddle good " . Beekeepers looks really good so draw your own conclusions about the paddling.

Chuck.

 

[Kayak Jack]

What I'm getting at is this - no matter where the rocker occurs, front or back, it's likely the TOTAL amount of rocker (front plus rear) that matters more than where it's located. Trimming with weight distribution then locates some rocker fore, and the rest aft.

If you have four boats, and they all have four inches total rocker - 0/4, 2/2, 4/0, and 3/1 - you can greatly alter handling characteristics with trimming. If the hulls are identical except for rocker distribution, I would expect to be able to get identical handling from all four boats by trimming them differently with weight distribution. IE: pretty much no matter what rocker is built in to start, you can overcome or imitate it with trimming.

Now, when you start having asymmetrical hulls, or other design differences, that will be mitigated to some extent. But, it will never go away.

 

[tx river rat]

2and 2 and 4 and 0 will never paddle the same because of waterline length, or track the same ,with the same load I dont care how you trim them
Ron
Boy I like to pick on Jack.
Ron

 

[Kayak Jack]

<SNIP> Boy I like to pick on Jack.

Go right ahead, Ron.

 

[tx river rat]

Jack
You know I will . lol
Back to the rocker ,a friend and boat designer builds and races, he builds several different models of three panel boats (perows) I have been lucky enough to paddle several of them and there is no comparison in the handling with different rockers.
Ron

 

[beekeeper]

A couple more pictures:

My new assistant: :lol:

I made the stem pieces to curve. They don't curve as much as I thought they would. The pictures don't show the curve very well either:

beekeeper

 

[seedtick]

you need another pair of hands to help you out

i'd loan you friend Keith for a couple of days but the extra food bill wouldn't be worth the benefit

 

[keith]

Nice boat bee, on my rails I start in the middle and work out to the ends. I'll have about a foot extra on each end that i will cut later, I put a c-clamp on the ends and a bungy cord to help pull it around. some times people try and use to big of a rail. on my rails,I use 5/8 x 1-1/4 ( outside= a foot longer than each end ) it will also be beveled on the bottom edge. a outside chine will be beveled on the top side and be 5/8 x 1-1/2. if you dont have a note pad, buy the book. later keith

 

[beekeeper]

Jack
You know I will . lol
Back to the rocker ,a friend and boat designer builds and races, he builds several different models of three panel boats (perows) I have been lucky enough to paddle several of them and there is no comparison in the handling with different rockers.
Ron

Did/would moving the load to adjust the trim make the effects of differences in rocker go away? I'm trying to ask,(I think) two boats with the same dimensions except different rocker. 1st. boat rocker = 2"/1", 2ed. = 5"/4" , but both are trimmed to the same amount of bottom out of the water at the bow. Will they paddle the same?

beekeeper

 

[beekeeper]

Thanks Keith.
The written book probably wouldn't help me much :roll: , and I didn't think you were selling the secret one
with all the pictures. :lol:

beekeeper

 

[tx river rat]

Beekeeper
No they want, the 2-1 boat will paddle easier and carry more weight with a shallower draft. More square inches displaced with that hull. the 5-4 will turn much better but paddle worse as far as speed and tracking ,the reason for this is is the middle will be much deeper in the water,more drag.
I think we are talking about sinking the boat to a point the bow and stern is the same depth in the water, draw you a straight line the draw a 2-1 rocker boat with it sticking where the bow and stern are under water an inch the do the same with the 5-4 you will be able to see how much more drag the high rocker boat will have. Now that is a theory in real life with the same amount of weight in a boat your bow and stern on the 5-4 will be out of the water on the 2-1 they want be.
You want to know about tracking and speed just go look at touring are racing kayaks are canoes they dont have much rocker
Ron

 

[beekeeper]

Ron I was not building for speed, just wanted improved paddling in the boat I use for my style of fishing and the type of water we paddle. Thanks to you and all who share your experience and ideas. When I get to use my boat I will know if it works for me. I may not know how much rocker is needed, but I now know how to build a boat to a specific amount of rocker.viewtopic.php?f=11&t=7810

beekeeper