Fooling the boat gods?

[jdupre']

Well, maybe not REAL serious boat building stuff.

Something else from the somewhat twisted minds at Roll The Dice Fabricators. Quite crude and thrown together but it's a proof of concept.

Longer boats, on average, paddle faster and easier than shorter boats. BUT, shorter boats boats are lighter, turn better and are easier to load and unload. What if you could have the advantages of a 3 ft. longer waterline on a 13-14ft boat?

Voila! The boat extender.

Don't laugh......it seems to work. I took it out for a trial run and it seems to cruise a bit better and glide a bit farther. One other not-so-obvious advantage . When you paddle with a single or double paddle, the boat yaws back and forth .....some more than others. It might not be much in a 16-17 ft boat, but it's there. Now , when the stern swings out even an inch, it creates turbulence and eddies in it's wake. I have a feeling that this addition will help absorb some of that turbulence and turn loose of the water more gently because it gives to any side pressure. Fish tails work like this. To work properly, this addition would have to be faired into the hull.


OK, Fire away. :mrgreen:

Joey

 

[Kayak Jack]

I approve of both the duct tape, and the ice-berg-fender-offer-thingy-doo.

 

[john the pom]

I was being a bit tongue in cheek with the protrusion on the front of large boats and admit to playing with words also. This device effectively changes the waterline length of a boat, and is considered to be a streamlined method to "Part or break" the water ahead of the boat

The idea at the time being about altering the length of a short kayak to make it behave more like a longer kayak... and for all the reasons you reckon it achieves. I recall designers of the big boats believe it affects secondary waves that ocurr along the length of a boat.
Hmm Joey when I posted this about six months or so ago. The lounge wizards in here effectively turned the idea into a Trireme... also known as one them things that Romans used to ram other folks ships with. Anyways I do recall taking a patent out on the idea (really glad to see it seems to be of value by the way) Don't worry about the infringement though, next time you see me just buy me a beer :mrgreen:
Cheers John

 

[Kayak Jack]

John, on second thought, I don't think it would serve effectively as a ram. Joey just doesn't like to paddle that fast. Unless, maybe, the enemy boats were made out of Styrofoam? Or, whipped cream? :wink:

 

[jdupre']

Ok, a little carification is in order. Should have mentioned it. This thing attaches to the stern of the boat. It trails out behind it , half in and half out of the water. It gives the water 3 more feet to come together at a less abrupt angle, and absorbs any side thrust that could slow the boat.

I paddled the pirogue up and down the bayou (approx. 1 mph current) and it got up to speed and cruised noticeably better. It tracked straighter too. It still turns like a 13' boat. After putting it through it's paces for 20 minutes, I took it off and re-tested. Definitely a difference.

I don't know how practical it is, but it sure bares more experimentation. Adding 3 feet of waterline at the cost of a quarter pound of material is a pretty good feat in itself.

Joey

 

[Wannabe]

Joey,
I think that there was a thread on here several years ago about an underwater extension on some type of kayak or some other type of Eskimo boat. It was onthe bow of the boat and I cannot remember what it's purpose was.
Bob

 

[jdupre']

Bob, you're probably talking about the lower bow extension on an Inuit baidarka. There are many theories for the design, but I don't think increased speed is one of them. The best explanation I've seen is simple mechanics. You can't sew seal skins into a concave shape at the bow like in most other V type hulls. The thin lower extension helps to part the water better and the top extension is wider to keep the bow up when going through waves.

Joey

 

[Kayak Jack]

Joey, now that I realize the extension is on the back, I have a question. Would this streamlining aspect also serve as a rudder? With a hinge, it could both reduce turbulence and thus drag, and also provide directional control. Maybe.

 

[jdupre']

Jack, it probably could. But , I'm thinking that some of the improvement comes from it's flexiblity, which you might lose with some kind of steering mechanism.

I'll get my wife to take some video of me going by so I can see it's effect on turbulence.

On a related note: Most kayaks and pirogues have a longer waterline when fairly heavily loaded. A longer waterline tracks better and a heavier boat resists changes in direction better (yaw). So, it is entirely possible that a heavier boat might travel further in day of paddling because of slightly longer waterline and less veering off of a straight course. The paddling effort might be microscopically more, but the straight line distance might just be shorter.......less strokes.......less total effort.

 

[Kayak Jack]

Well, as a hull sits deeper in the water, resistance increases. Matt may have some formulae that will shed light here?

 

[jdupre']

Yes, resistance increases, but by how much? At 3 -4 lbs of resistance, would a few ounces of effort really make a difference? Maybe for a world class athelete. Don't know about most of the paddlers out there, but I'll bet not many really paddle for 8 hours at a stretch where 3 ounces of added resistance would show up. As for me, I'm going to take a break ever hour or so to take a picture, drink some water, look at wildlife, eat a snack or water a tree. A couple of ounces per stroke really wouldn't bother me much.

Joey

 

[oldsparkey]

On a related note: Most kayaks and pirogues have a longer waterline when fairly heavily loaded. A longer waterline tracks better and a heavier boat resists changes in direction better (yaw). So, it is entirely possible that a heavier boat might travel further in day of paddling because of slightly longer waterline and less veering off of a straight course. The paddling effort might be microscopically more, but the straight line distance might just be shorter.......less strokes.......less total effort.

When Vince and I would go down to the glades and use the boats they were loaded with the camping gear and food along with one gallon of water for each day. If it was a 12 day paddle we would have 14 gallons of water ( in each canoe ) which equals out to a lot of weight.
( At 8.34 pounds per gallon 14 gallons = 116.76 pounds )
After we got paddling the canoes seamed to go along a lot easier then when they were loaded lighter. It boiled down to the fact that after they were going the weight in the canoes tended to keep them moving due to that extra weight. Grant you it took more effort to get going but the going was a lot easier after we got up to speed.
You have the weight and when it is moving it tends to want to keep moving , some law about inertia or something about anything moving wants to keep moving. :roll: :roll:

By the way , when the water jugs were about half full and as you paddled along the water would slop from the front of the container to the back of it and actually make the canoe move that direction when paddling. If you would give a good hard stroke you can feel the canoe move forward and when relaxing the water would move forward giving the canoe a slight tug forward and then the water would move back you could feel it in the canoe.
When we got to the speed we wanted towards the end of the trip then we paddled really easy so the water would not slop around in the container which still had water but was not full.

 

[Kayak Jack]

If it's only a few ounces, you have a good point. Might be more than a few ounces. Adding capacity to a canoe with length is preferable to adding with depth. Maybe Matt can help out.