tweeking the T-V

[tx river rat]

My son in law is wanting to join me on some of my trip and wants to use the T-V aka Brazos queen ( plus I need some sawdust flying) so I have a few questions to ask. You always wonder what if
I made the T-V longer make the bottom panels a full 16 ft that would put the overal length at 17ft 6 inches I know two splices on the sides.
I haul on a rack that this want make any difference.
Pros and cons to this length?

Bottom of the T-V is 24 inches how much will it help to cut it to 23 inches
a wag on performance increase?

Does length affect stability

Come on you spurts help me out here
Ron

 

[bearridge]

Friend Ron,

If ya paddle on a river where ya mite have ta turn quick, the biggest problem with a very long canoe iz how long it takes ta turn. One year on the St. Mary, the water wuz up.....moving nice.....but we come round a bend 'n a big tree lay across the whole river. Some fellas had ta pull up thru the mud, unload, drag boats and gear along the bank, then reload. Some of us worked our way thru the limbs 'n branches. I dont recall nobody with a 16+' boat making it thru....dry. :wink:

The more gear ya fill a boat with, the harder it iz ta turn too.

regards
bearridge

My husband and I divorced over religious differences...he thought he was God, and I didn't. unknown

 

[oldsparkey]

Friend Ron,

If ya paddle on a river where ya mite have ta turn quick, the biggest problem with a very long canoe iz how long it takes ta turn. One year on the St. Mary, the water wuz up.....moving nice.....but we come round a bend 'n a big tree lay across the whole river. Some fellas had ta pull up thru the mud, unload, drag boats and gear along the bank, then reload. Some of us worked our way thru the limbs 'n branches. I dont recall nobody with a 16+' boat making it thru....dry. :wink:

The more gear ya fill a boat with, the harder it iz ta turn too.

regards
bearridge

That trip was Dec 05 , 2005 in the trips section. I had a 16 pirogue but not over that and made it threw both the dunking strainer and the tree across the river.

RON.. I made a pirogue at 18 feet and it was simple to do , just add more panels to it.
Cutting the width down to 23 you will have more of a kayak then what you have at this time ( Read tippy) , the width should be OK at 24 by stretching the boat out , more boat so it should draft less water.

Matt would be a better person to answer your question but for a longer boat I would keep the rocker in it so you can turn it when needed.

My one kayak at 17 1/2 and 23 wide is a sucker to turn really quick and it has good rocker in it. Well it does not turn or spin around like the pirogues do. On the straight away , none of them would even think of staying up with it , sacrificing turning /maneuverability for speed. It is a river/open water boat not a swamp boat.
( I have paddled it threw and around trees when needed)

Chuck.

 

[JEM]

Length does effect stability in that if you just stretch the length and keep everything else equal, it will be more stable.

FYI: My website hosting service is doing some sort of voodoo maintenance. So my forum and e-mail will probably be acting weird until tomorrow.

 

[bearridge]

That trip was Dec 05 , 2005 in the trips section. I had a 16 pirogue but not over that and made it threw both the dunking strainer and the tree across the river.

Ole Sparkey,

Yer messin' up my tale with facts. Shame on ya! I jest dont recall yer boat bein' that long. That wuz mitey fine paddlin' makin' it thru limbs 'n branches in fast movin' water over close ta the bank. I reckon we oughta have a drink ta that.

But try not ta mess up no more of my tales with facts. :mrgreen:

regards
bearridge
paddlin' geezer canoe clud

If there are no stupid questions, then what kind of questions do stupid people ask? Do they get smart just in time to ask questions? Scott Adams

 

[hairymick]

Ron,

Ya thinkin on makin a burner?

To get the inline speed, you need to sacrifice something, be it stability or maneuverability or both. Make the boat narrower it will be less initially stable - no question. It will also draw more water (float a little deeper) and be more inclined to part the water like a spear. (like a good kayak should)

Add extra length to this narrower boat and you increase the load capacity, water line length and displacement hull speed as well as hull glide when you stop paddling.

The throw - off to all these good things is that you also reduce the ability of the boat to turn in tight places.

Reading your trip reports of your Brazos, I am inclined to think that a longer and narrower boat may not be so suitable for your waters. Perhaps, a little longer only might suit?

 

[tx river rat]

the 23 inch bottom is still widder than the Laker bye an inch do you think that would be unstable at 16 ft plus
Ron

 

[digr57]

I am a newbie on here but i'd like to put my 2 cents in for what it worth. Lenghtening the plans would be easy.Narrowing a litlle bit harder. that being said.Mick has some excelleny points as usual.

Pros:
Higher theoretical hull speed
Better strait line tracking for long water crossings.
Long boats look really cool.


Cons:
Higher hull speed only needed when racing, outrunning weather on open water like getting to shore off of large lake or bay Paddling flat out hard
Longer boat will weigh more and may be awkward to load on rack.
Harder to manuever on river and creeks

The difference in hull speed of say a 15 foot boat and a 17 having the same hull design is probably only relized by strong paddlers and the 15 foot boat may actually be easier to paddle at a comfitable cruising speed of 3 or 3.5 miles per hour. Matt can probably explain this much better.
I have some personal expereince with this when i paddled 12 miles along the coast with a friend of mine. I was paddling my 16 foot x 24 inch sea kayak and he was paddling a 17 foot 6 inch x 22 1/2 wide sea kayak. Paddling as hard as we could ( both in 50s and average shape ) he could just barelly beat me. Paddling at a normal cruising pace I was constantlly having to stop and wait for him. WE were paddling side by side at one point and i was doing one stroke to his two to maintain the same speed. Hope some others chime in with better knowledge than me.

Russ

 

[Kayak Jack]

We're speaking in generalities here, and all generalities are false - including this one.

Generally, longer, thinner boats are faster and track better than shorter fatter boats. Shorter boats turn easier and track worser than longer boats.

Rocker will enter into this, depth of water the boat is drawing, wind signature and wind direction, currents present against various parts of the hull, etc. Hull crossection also enters into it.

Another thought is this. You may want two boats, one shorter for close in work, and one longer for moving across long reaches of water.

 

[jdupre']

I've been doing a lot of reading on this subject. Longer boats have higher hull speeds and normally are more efficient at those higher speeds. What people don't think about is it takes a LOT more effort to paddle at those speeds. Sure you can cover more feet per stroke with a longer boat, but that stroke will cost you dearly with the effort it takes. It does you no good to paddle fast if you can't paddle but a half mile before you have to stop and rest. Longer boats also pay the price of more wetted surface that creates drag, and drag is the primary resistance at cruising speeds.

I've read that the "best" compromise of paddling effort and speed is about 15.5 feet long. Go up in length for a little higher "potential" speed and a little shorter for easier slow speed cruising and manuverability. As for width, go as narrow as you can comfortably handle. Some people might need over 30" if they want to stand and flyfish. Someone with good balance might prefer 21" for a light duty day tripper.

 

[digr57]

Yes no perfect boat just the best boat for the paddling situation.

 

[tx river rat]

Jack what was the overal width of your boat and length.
Ron

 

[Kayak Jack]

15' 9" X 24"

(That's on a 70 degree day, and at normal air pressure of 30" Hg.)

 

[hairymick]

G'day Ron,

the 23 inch bottom is still widder than the Laker bye an inch do you think that would be unstable at 16 ft plus
Ron

Mate, I believe stability is a relative thing. I find my Laker very stable yet others have found the same hull to feel a little "tippy" I am no expert in these things so I bow to the judgement of those who are, and who may say otherwise. My thoughts are that i really cant see how added length can add to the stability of a boat. Stability, as i understand it, means a boats resistance to tipping - sideways. Shot of overloading the weight capacity of the shorter boat, I can't see how extra length alone can make a boat more stable.

Jack speaks of generalities being false and this is, in a large part true, but that statement is in and of itself, a generality and needs to be viewed with a degree of caution.

Kayaks, in general are displacement hulls. There are exceptions to this generality in the surf and white water kayaks which have planing hulls.

For the purposes of the argument/discussion here, I will address "displacement" hulls only. A displacement hull has a designed hull speed. By that, I mean the most efficient speed that that hull can displace the volume of water that equals its displacement weight as it passes through it. This designed displacement speed is governed by a set of rulls. Roughly, those rules are that the longer and narrower a boat is the faster its designed displacment speed should be.

Hull form and shape also play very important roles in this as do the paddlers strength, power and endurance. In paddle craft, other factors come into play as has been mentioned ie water line length verses resistance through it. I have been led to believe that around 17 feet is the optimal length. longer than that, (generally) and the resistance or drag, overcomes the benefiets of the added length.

I own a tandem expedition sea kayak that is 20 feet long. Its designed hull displacement speed is greater than any of my solo kayaks but on my own, I cannot paddle it as fast as any of them. I don't have the power to achieve the speed. Add the second paddler into the equation with all that extra power and it is an entirely different matter.

 

[JEM]

adding length will provide SOME additional stability. But it's a very small amount as compared to adding additonal beam.

 

[Kayak Jack]

Mick,

If you can get a copy of an Sea Kayaker Magazine, you will see some interesting numbers about boats. they have standard weight placements and then measure how many pounds of force it takes to roll a boat to various degrees. They also calculate (using two different methods that produce very similar results) pounds of force required to propel the hull, with various loads, at various speeds.

It occurs to me, that if a paddler could sit in a test boat and paddle at his "comfortable speed", it would register ass so many pounds of force produced by his paddling at that rate. If it was, say 2.5 pounds, then you take any hull, load it as he would for fishing, camping, day tripping, etc. and see how fast the hull goes at 2.5 pounds of force.

THIS is a more useful number, I think, than theoretical hull speeds etc. "If I paddle as I normally prefer, how fast will this boat go?

When I am planning a trip, I plan to proceed at either 2.5 mph or 3 mph according to which boat I take. I then add in (or subtract) estimated current and wind effect.

 

[tx river rat]

Ok I have a couple more questions
The ideal length is that overal are water line length
second ya'll talk about a 24 inch boat are we talking the widest point of the hull are the bottom
My thinking on paddling speed is the paddler probably has a lot to do with the speed bye how efficient he is .
II guess I should rephrase my question instead of fast to the most efficient hull
Ron

 

[hairymick]

G'day Jack,

I subscribe to Sea Kayaker magazine and am familiar with their Speed Vs Resistance tests as well as the prismatic coefficients.

I agree with your point about theoretical hull speeds. Just because a particular boat may have a theoretical or maximum displacement hull speed doesn't necessarily mean that a paddler will be able to maintain, or even achieve that speed.

The force required to propell a boat at a required speed is far more relevant. I think we might be slightly hijacking Rons thread here and being a little pedantic in the process mate

The point is that most kayaks would seem to have their effecient cruising speed, that is the comfortable, and best speed that can be achieved with the minimum amount of effort, relative to achieving that speed at somewhere between 3 and 4 knots.

For me, I would consider acceptable as being able to achieve 3.5 knots with around 3.5 pounds of thrust.

I have no way of measuring this however and suspect that I may be using much more effort in my paddle strokes

Ron,

My thoughts on kayak design are evolving as are the boats that we paddle.

For me, an ideal rec boat length to beam ratio would be pretty much anywhere between 14 and 16 feet with a beam of around 24 to 26 inches.

If I were to build a purely performance, as in go fast boat, I would be looking in the vicinity of 17 feet length with a max beam of no more than 22". Minimal volume, long, very fine entry in the bow with a heavily assymetrical hull and semi-planing hull under and to the rear of the paddler.

I have no desire to build such a boat but that is what I would be looking for.

I think 24" is very close to the ideal bottom width in pretty much any general purpose rec boat. Some might prefer a little wide for stability. Boat length is a matter of choice. A little longer might equal a little faster

 

[Kayak Jack]

Pedantic? My god the Aussie can speak English! Good on ya, mate. We did get a bit off the subject. (WTH was the subject, anyway?)

"Ideal" has many ways of being measured, and expressed. If the environment is a only straight ahead shot in a lightly loaded boat in no-waves condition, then "ideal" will differ from that wanted for a heavily loaded boat in waves and wind and rain with waves coming from a quartering rear location.

I have the feeling that we design (or, yearn) for our next boat to meet the conditions we met on our last trip. IE: we are often designing behind ourselves.

This is one of the advantages of having input from so many points of view, form so many types of countryside, and from so many types of paddling situations. We get more opportunity to listen to a paddler who is currently in a paddling environment that we may get into next, and can then draw from his experience.

 

[JEM]

Racing hulls usually want about 7:1 ratio for the faster top end speeds. That ratio is a general rule. Hull shape plays a lot into that.