I built a boat lighter than Pogo

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bowgarguide
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I built a boat lighter than Pogo

Post by bowgarguide »

Got ya Pogo

A guy on another forum and I have been kicking this around for a while and couldn't agree. Now I am a lot better with my hands than talking so I built a model about 1/4 scale of the bottom of the T-V asymetrical.

Image

I just glue a couple strips down the center to stiffen it

Image

I then marked a line 5 inches in front and rear of center this is pretty close to where my rear sits behind the center of the T-V and also a line parallel with the center line



Image


I commandeered Magoos swimming pool for the test. My black lab
Break here
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Re: I built a boat lighter than Pogo

Post by bowgarguide »

The line to the rear will simulate me sitting in an asymetrical boat,the line to the front will do the same but in a symetrical boat ,ok here goes.

I did some playing with some weights
Image

I used half a brick 2 7/8 nuts and a 7/8 socket, the water is just below the top of the foam
now this is asymetrical

next pick I put the brick on the line in front,simulating symmetrical seating arrangement.

Put the brick on the line the same distance from the center

Image

now this is what happened


Image

Image

Just the brick turned it over didnt have the 7/8 nutts are socket on it.
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Re: I built a boat lighter than Pogo

Post by bowgarguide »

Summary
Testing done by the Smith redneck institute
An asymetrical Swede form boat is more stable than a symetrical boat with the same length and width measurements.
Ron
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Re: I built a boat lighter than Pogo

Post by gerald »

I......am...............flabergasted..........



Science and technology. It's what boats are all about....
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Re: I built a boat lighter than Pogo

Post by Pogo »

I'll have to say this: Ron's enthusiasm for homemade boats comes down on you like a ton of bricks.... 8)
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Re: I built a boat lighter than Pogo

Post by Light Keeper's Kid »

This is what happens to builders when it rains :lol: :lol: :lol:

Mike
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Re: I built a boat lighter than Pogo

Post by barditch »

Light Keeper's Kid wrote:This is what happens to builders when it rains :lol: :lol: :lol:

Mike
:lol: :lol: :clap:
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Re: I built a boat lighter than Pogo

Post by preacher »

Seriously . . . . . . . . Ron . . . . . . . you need to go fishing.
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Re: I built a boat lighter than Pogo

Post by Dogpaddlin »

preacher wrote:Seriously . . . . . . . . Ron . . . . . . . you need to go fishing.
X2
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Re: I built a boat lighter than Pogo

Post by Pogo »

Image

The comments are a hoot and I'm LMAO, but in all seriousness........ I LOVE seeing people doing tests to find definite, BS-free answers for themselves. Ron exhibits a remarkably acute brand of savvy, in my opinion, just from the fact that he keeps a pool for the black lab, a breed specifically developed to make water go splash. And now he's endeavoring to side-step the universe of opinion and theory and get real answers in real time for hisself. I say ---> :clap:

Now I'm wondering how accurate the test and results are. Being as flat-bottomed boats are being represented by flat slabs of foam, I'm thinking it's pretty good. I worry a little about the lack of sides, and what role flare in those sides might have. So now that we've had our laugh at Ron's expense, an amusement I never get tired of, how 'bout some real discussion now?
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Re: I built a boat lighter than Pogo

Post by Light Keeper's Kid »

I think it has more to do with the hydro physics of the hull than the actual shape of the hull(what did I just say :roll: )like an airplane wing that loses it's lift in a stall :wink: Because there's less hull in the front arangement,right :?: Ron,your the Man :dance:And yes Sir Sargent Pogo :lol:

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Re: I built a boat lighter than Pogo

Post by bowgarguide »

Pogo
The weights were set in the swede form to just come to the top of the foam,less weight flipped the boat in the symetrical test,so this is basicaly a test on initial stablity.
also I cut the foam to a true symetrical shape and the boat would flip faster .
Maybe thats why you dont see many fish form boats.
Ron
Boy some of these folks would give Leno a run for his money :D :D :D
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Re: I built a boat lighter than Pogo

Post by gerald »

I always appreciate the scientific approach. I go way back with scientific testing. I once built a hang glider out of 2X2 pine and visqueen (clear plastic). Me being the engineer/designer with the scientific approach I got my little brother to test it. The wind was blowing about 25 mph. I conviced my brother that this was a good thing. It would provide more lift when he jumped off the roof.

Well...there he was perched on the roof fighting the hang glider in the wind. He peered out over the horizon, gathered himself...and said, "....oh hell no!"

Damn...he backed out.

Another brother refused to try it out but we all decided we could get the one who was only 1 year younger than me to try it. He's the smart one--black sheep of the family--now rich and successful. The rest of us are total no accounts. Anyway--there he was up on the roof. He set the hang glider in position, took 3 or 4 running steps, and launched himself out in the high winds. Unfortunately we quickly learned that when you angle the wing down--the wind pushes you down even faster than you can fall. He hurt his ankle and was off work for 6 weeks. I think he glided....a foot away from the house.

So...there you go. The scientific method showed me all kinds of way I could improve the design.

Then I needed to find another test pilot.....
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Re: I built a boat lighter than Pogo

Post by Pogo »

I never did get the fish form shape. Why would it be attractive, anyone know or care to guess?

I need a pirogue to play with, since I can't really see them as having any usable secondary stability at all. I mean, I tried a Michalak Piragua, a 14-foot 3-panel job with prettily flared sides, in a pond back in 2003, and as I recall it was all primary stability. I could stand up in it, and paddle a rather heavy friend around in it, although just barely (it was a really hot day :lol: ). But leans were all resistance to overturning until suddenly breaking into a flip without warning. Which is exactly what I'd expect a simple flat-bottom hull shape to do.

But I can't use flat bottomed boats down here; they're just too uncomfortable in chop, and I'm surrounded by bays, not rivers.
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Re: I built a boat lighter than Pogo

Post by gerald »

I prefer the swede form because I like the way it looks. Symetrical is also fine for me. There have been many fine example of fish form boats. All forms have their positives and negatives. Boats are a compromise.

Contrary to poplular belief, a widely flared 3 panel is going to be a little tippy. You want the ratio of the flare between the bottom and top to be such that secondary stability is just slightly stronger than initial stability. Otherwise the lean angles will be unpredictable. With a properly designed 3 panel--or any other boat--you should be able to easily predict when you are going over...and when you're not. I shouldn't say "properly" designed because sometimes you may want different performances from different boats. All boats are a compromise--they may be "proper" for any given situation.

I've also had several 3 panel boats that handled choppy waves and white capping waves quite well--from the side no less. Old Blue was one good example.

The Conquista is not one of the boats that handle side waves well--but the Challenger should be. They look almost the same....
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Re: I built a boat lighter than Pogo

Post by Pogo »

The question remains. Symmetrical is easy to design and build, and swede form places max beam aft of the paddler for stability, and skinnier beam ahead of him for easier reach; those advantages are fairly easy to discern. But where could a fish form possibly be preferred? Why would you want the volume ahead of you?

I didn't mean to imply that 3-panel boats cannot negotiate chop safely; I said 3-panel are not comfortable. My first wood boat had a flat bottom, and almost instantly I was wishing for a vee bottom, rounded bottom, or any shape other than flat. The boat was plenty safe and seaworthy, but it wasn't comfortable (in chop).

I want to see somebody demonstrate a 3-panel boat accepting aggressive lean technique .... or loan me their boat to try myself. I can't imagine secondary being astronger than primary. Heck, I'm still wondering if they have ANY secondary, and now you're saying secondary should actually be stronger? Not trying to be contrary, it's an honest question asked in good faith.
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Re: I built a boat lighter than Pogo

Post by DSmithla »

I thought fish form was supposed to be fastest (most efficient) although, I'm not sure that would be realized at kayak speeds. Isn't the basic shape of our modern (nuclear) submarines fish form, modeled on high speed fish like the Dolphin? (again, since our reactors aren't nuclear, not sure we can take advantage of the design).

Personally I like the way Swede form looks, and I mean, really, if you're going to go to the time and effort of building a boat, shouldn't it look good to you when you finish.

(cue Billy Crystal) You look mahhhvelous.


eta:

Just found a reference that makes a case for Fish form being faster UNDERWATER (i.e. submarines) but not on the surface where wave action and other characteristics at the boundary layer make Swede form more efficient, so I dunno. I still think Swede forms are prettiest.
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Re: I built a boat lighter than Pogo

Post by bowgarguide »

Pogo
This is fudging a little I guess my last boats are four panels ,maybe a 3/4 inch v in the bottom and I can heel that boat over till water is coming in the cockpit,Gerald saw me doing it on the Trinity in the blowdowns.I dont think the flat bottom would make that much difference.
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Re: I built a boat lighter than Pogo

Post by Pogo »

Thanks Ron, that's helpful .... as is DSmithla reminding me about submarines, even if it doesn't translate directly to kayaks. About heeling the boat over, maybe I can see what you're talking about for myself in about a week....? 8)

What's a 'blowdown'?

I don't pretend to know a lot about hull design, but I know what I've seen with my own two eyes -- and felt with my butt. Even the very shallowest vee is a distinct improvement over a flat bottom somehow, and how much deadrise there is doesn't seem to affect stability. I once built two identical 4-panel jobs, except that one had maybe 3/4" deadrise and the other had more like 2 1/2", and this was in 22" wide boats. The deep-vee was tippy as all hell, and that's why I built the second with a shallow vee, for my then-girlfriend. I'm tellin' ya, in a blindfold test you'd never be able to tell the two boats apart. They behaved exactly the same in every last regard.

A friend down by Powderhorn built a B&B Birder, almost identical to my CLC Mill Creek, except for a very, very, shallow vee to it. Dang near flat, but just a little teensy bit of vee to it. And it was comfortable in chop, where the Mill Creek just ain't.

Seems to me that all kayaks ought to be swede form for the reasons I mentioned above. Solo canoes, too. The racing boats all are, just about.
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Re: I built a boat lighter than Pogo

Post by bowgarguide »

Pogo
Sorry a little terminology from hunting , blow down trees falling down are across a river.
Ron
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Re: I built a boat lighter than Pogo

Post by gerald »

I could lean Old Blue over until water was lapping 2" up on the deck at the side. Now that's a predictable lean. It was actually hard to turn over. I was practicing turning over and re-entry one day at the gravel bar near Winkler's Campground on Belton Lake. It was hard, but I was determined to sit it out all the way over. Big mistake. I was too shallow and hit the bottom with my head. Damn near knocked me out.
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Re: I built a boat lighter than Pogo

Post by DSmithla »

Pogo wrote: .... as is DSmithla reminding me about submarines, even if it doesn't translate directly to kayaks.

True enough, unless we're doing something way wrong.
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