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 Post subject: Mattawa or Freedom 15
PostPosted: June 23rd, 2005, 1:59 am 
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Hi All,
curious if anyone out there may have had an opportunity to compare these two designs and what their opinions of each were.

Thinking I might build an asym hull but was looking for a small tandem that still solo'ed well.


Thanx......


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PostPosted: June 23rd, 2005, 1:14 pm 
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Here are links to the specs that I'm comparing:

Freedom 15' http://www.bearmountainboats.com/15-0Freedom.htm

Mattawa http://www.greenval.com/mattawa.html

They have a similar waterline width but the Mattawa is wider at the gunwales and longer both at the waterline and overall. Despite the apparent larger volume of the Mattawa they had similar recommended load limits. I suspect that the Mattawa will handle larger loads better, but that is only expected to be relevant above the optimum/recommended load limit.

The extra 8" in the Mattawa will contribute to leg room and/or gear room for example letting gear lie flat instead of sticking up.

The rocker numbers for the Freedom aren't given but it is described as having "less rocker and deeper aft sections", so I'll assume it has less rocker than the Mattawa.

The Freedom has a lower bow height, so it may be easier to handle solo in a wind on the other hand it probably won't handle waves as well.

OK enough of the details, the Freedom designs have always seemed narrow and low volume to me relative to others, personal taste perhaps but they don't appeal to me as tripping canoes. You don't mention what your intended use is, if it is day tripping, then either design should be fine and the Freedom may save a bit in materials. If it is weekend or longer then I would prefer the Mattawa, I think the extra 8" in length will be greatly appreciated when travelling tandem. I also prefer a little more rocker, so not knowing the actual rocker on the Freedom then I would again lean to the Mattawa.

All that said, if you think you may use it as a solo more often than not, then lots of folks like the Bob's Special and Huron Cruiser. Not sure if you have a particular reason to want an assymetrical hull.

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 Post subject:
PostPosted: June 23rd, 2005, 2:45 pm 
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Two more differences from looking at the cross sections on the drawings (not actual boats)...

The Freedom seems to have an element of shallow-vee in the hull cross section amidships, while the Mattawa is a shallow arch. Maybe the slight amount of vee was designed in to aid straight tracking or to improve secondary stability... the Freedom 15's one of the most stable in the Bear Mountain flotilla.

Tumblehome in the Freedom amidships, while the Mattawa has some flare... you might be able to heel the Mattawa over further or all the way to the gunnel without flipping. OTOH, the Freedom's tumblehome is structurally stronger and probably can be built more lightly (ie. less need for heavy gunnels). The Freedom's shorter length also means lighter weight.


The Mattawa appears to have more rocker, which might make it the more stable boat when paddled in waves or rough water.

M2CFWIW

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PostPosted: June 23rd, 2005, 3:16 pm 
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I have built a Freedom 15 as a solo tripping boat. Basically, the main difference you will notice from a Mattawa is that it will track better due to the straighter keel line. This may or may not be what you are looking for. However, being only 15 ft, it is not that hard to manuevre either. I also have a Ranger that I built (15ft prospector) and I have not noticed significant differences between the two when it comes handling waves and paddling heeled over. The Freedom catches less wind and with it's straight keel, seems easier to handle in windy situations. But as an all round tripping, tandem, solo boat, I do prefer the Ranger, mainly for it's responsiveness when heeled over.

As far as the actual building process; With the Freedom I found that because of the assymetrical hull, it was very difficult to get the 1/4 x 3/4 strips to lay down properly against the station molds in the stern of the canoe. Being a short, assym boat, the strips have to bend in to the stem more sharply and it takes more buttons than usual to get them to lay down true to the mold. This is something you won't find on the spec sheet. If you want more info on this you can contact me at jveira@linvatec.com


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 Post subject: Input.........
PostPosted: June 24th, 2005, 10:32 am 
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Hi Guys,
thanks for the input on my question.

I've never had an opportunity to paddle an asym design but from what I've read figured it might better suit my needs. My wife is a little new to paddling and not a very big woman ( [u]just[/u] over 5' ) so the narrower bow would be an asset as would a sliding seat. Thought since I would be doing a lot of the work initially a design that worked fairly well as a solo would come in handy.

We'll take a look at the other designs mentioned for comparison and make up our minds from there.

Thanks again,


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PostPosted: June 24th, 2005, 5:25 pm 
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frozentripper wrote:
The Mattawa appears to have more rocker, which might make it the more stable boat when paddled in waves or rough water.


I can't comment on the Freedom 15... but I like the Mattawa. Good in multiple types of water... one could run some whitewater and moderate flatwater. But it's not really big enough to do much more than weekend or very light week tripping.

Now why would rocker add to stability in waves or rough water? The only purpose of rocker is to aid in turning. It allows the bow and stern to be freed from the water when heeled slightly. This maneuverability might allow you to avoid the most nasty stuff in whitewater, that might swamp a less maneuverable hull. But rocker does nothing to increase stability.

PK


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 Post subject:
PostPosted: June 25th, 2005, 7:42 am 
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PK,

Quote:
Now why would rocker add to stability in waves or rough water?


I first heard about this in a discussion about why a Prospector was so good at handling rough water - eg. seeing Bill Mason's films with him bobbing around like a cork while the waves were crashing on the shores of the lake.

The most obvious thing is that a heavily rockered boat lowers the center of gravity relative to the overall flotation of the hull, especially when most of the load is amidships, when going solo... if a Prospector has four inches of rocker, then the weight being carried is that much lower relative to the flotation at the ends than if the hull were unrockered. It probably goes without saying that the higher the center of gravity, the more unstable things are likely to get when the canoe's pitching about in the waves.

The other thing has to do with the way the rockered hull "fits" into the troughs of waves when wavelength more or less matches hull length. When the canoe passes through waves, at times a wave crest will float and support the canoe amidships and things are stable, and at other times, crests are more towards either end. When the canoe just happens to be supported by wave crests at the bow and stern, the widest area of the hull (which offers the most stability in terms of flotation) might be lifted out of the trough, or close to it. This can be unstable because the lateral flotation isn't there to provide side-to-side stability if a paddler accidentally leans to the right or left. This might only happen when the distance between crests is just right, but not a good thing in freezing cold water if attention wanders from the possibility of hypothermia for some reason or another.

The rockered canoe should be less prone to this, because the curvature in the bottom fits into the trough more deeply and offers more lateral flotation and stability. I've paddled the Trailhead Prospector solo in rough water and it does seem to be fairly stable and more seaworthy, when compared to unrockered high-volume aluminum types which seem to pitch and roll alarmingly... besides differences in rocker, hull cross-section differences also probably had something to do with that, with flatter vs. rounder bottoms compounding the problem. Difficult to isolate the cause of instability because of that.

Anyway, I haven't paddled either the Freedom 15 or the Mattawa, so this is all in theory FWIW... still, I could see the reasons for preferring the more heavily rockered hull for paddling rough water, especially when going solo.

Rick

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 Post subject: Rocker and waves
PostPosted: June 25th, 2005, 10:51 am 
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Hey Rick,

Knew what you were getting at with the "rocker adding stability" comment ......

My sea kayak is considered to be fairly highly rocked and it's a great sea boat well known for surfing and playing in rock gardens.

When conditions get a little "lumpy" I feel far more at home in it than the larger touring kayaks that are the norm here in BC. Found the same was true ( for me at least ) with canoe's in choppy conditions as well.

On the other hand most folks who try my kayak find it very UN stable..... :o

With regards to which design might serve me better I've opted to go with a design I know and build it instead of an asym.

Thanks for all the input though folks....... very helpful.


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 Post subject:
PostPosted: June 27th, 2005, 9:58 am 
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The discussion about the stability of rockered versus straight keel boats is interesting because it is so hard to pin down why one boat is more stable than another. Stability is affected by lots of factors and not all are under the designer's control. Out of curiosity I took my Mattawa design and converted it to a straight keel and then compared it with the original.

This is pretty crude stuff because I didn't run a full stability study but I think it is interesting.

I used 300 pounds of displacement and set the CG at 1 foot above the bottom of the boat. I used a 15 foot long wave that was 2 feet high (pretty close to the maximum before the wave breaks).

At 5 degrees of heel the straight keel boat had -1.2223 pounds of righting moment and at 20 degreees it had -5.59 pounds of righting moment.

The rockered boat had 1.666 pounds of righting moment at 20 degrees of heel and 0.4785 pounds at 20 degrees of heel.

This, of course, means nothing when comparing two different boats. For example, the Freedom 15 has a harder turn of bilge than the Mattawa which could easily make up for the difference caused by profile. The reports I have heard on the Freedom 15 are flattering and I sure would not embarrass me to say I had designed it.

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 Post subject:
PostPosted: June 27th, 2005, 12:48 pm 
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Jwinters wrote:
.........I used 300 pounds of displacement and set the CG at 1 foot above the bottom of the boat. I used a 15 foot long wave that was 2 feet high (pretty close to the maximum before the wave breaks).


I can relate to this criteria and these conditions completely. This situation would be about at the limit of my comfort level while paddling solo. The effort to propel and maintain a safe course would be at the limit of my strength. I am, of course referring to paddling into these conditions. As is often the case it is not the design of the canoe that determines its limits, but the skill, conditioning and comfort of the paddler.

Jwinters wrote:
......At 5 degrees of heel the straight keel boat had -1.2223 pounds of righting moment and at 20 degreees it had -5.59 pounds of righting moment.

The rockered boat had 1.666 pounds of righting moment at 20 degrees of heel and 0.4785 pounds at 20 degrees of heel.


This part I don't understand. Would you be so kind as to explain (in novice paddling langauge) what this means. The postive and negative numbers have me confused.

Thanks in advance.

BTW, if I had to guess how many days I have spent paddling my beloved Mattawa (which I saddly sold this spring) I would say between 350 and 400 - and I never feel out once.


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 Post subject:
PostPosted: June 28th, 2005, 6:55 am 
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Rick wrote:


Quote:
This part I don't understand. Would you be so kind as to explain (in novice paddling langauge) what this means. The postive and negative numbers have me confused.


Positive numbers indicate that there is some force acting to return the boat to an upright condition. Negative numbers indicate a force acting to capsize the boat. If the numbers are positive the paddler doesn't have to do anything to stay upright but if they are negative the paddlers have to shift their weight to avoid capsize. The magnitude of the numbers tell how much the paddler has to shift weight or (in the case of positive numbers) how quickly the boat will right itself.

When stability calculations are made the assumption is that the center of gravity does not move (we can calculate for a shifting weight but it is rarely necessary). Of course, paddlers do move but the stability calculations still reveal how stable the boat will feel. Even if a boat has negative stability the paddler can still keep it upright by subtle shifts of his weight so negative numbers do not mean the boat will just flop over. For exaple, sprint racing canoes are extremely unstable because they are both narrow (less than 18" on the waterline) and the paddler paddles from a high kneel position. Nevertheless, the paddlers develop the skill to remain upright even while applying maximum power.

Hope that helps. It is a complicated topic.[/quote]

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