Bell Rockstar

[Guest]

I'm developing a strong preference for symmetrical canoes with the same rocker for and aft.

Oh god, don't say that! They'll call you a Luddite!

Next thing you know you'll be tossing away that bent shaft for an otter tail...

 

[charlie wilson]

The above two pages include several "inoperative" statements as Nixon described one of his office's claims in 1973. Way more hopes than facts.

Kee 15 is narrower than Osprey, hence a smaller boat. Nomad is narrower than the Kee 15, not larger, and no sentient individual would "tweek" a Nomad to resemble Peregrine, which was splashed from Nomad. Pheonix has differential rocker. It is not a larger version of WildFire which is symmetrically rockered and much loosed in the stern.

Vacuum formed hulls are sucked into female molds with lots of vacuum pipe running around the outside to vent holes; generally upwards ever since a MRC guy dropped his Zippo into a downsuck mold.

Quantification often helps. When we start measuring items it clarifies our thinking, we can discern differences, so....

Colden DragonFly 14.5'l X 28.5"w, 25.5" wl, 2/2" rocker
Hemlock SRT 15' l X28.5"w, 26" wl, 2.5/1.5" rocker
Colden Nomad 15'4" l X28.5"w, 26" wl, 1.5/1" rocker
Hemlock Peregrine 15'9" l X28.5"w, 26.5" wl, 1.8/1/3" rocker
Swift Keewaydin 15 15' l X29.5"w, 26.5" wl, 2/1" rocker
Swift Osprey 15' l X 29.5"w, 27.5"wl 1.5/1" rocker
NthStar NthStar Solo 15.5" l X 30" w, 26.5"wl 2/1" rocker
NorthStar Phoenix 14.5' l X30"w, 26.5" wl, 2.5/1" rocker
WeNoNah Wilderness 15' 4"l X30.5"w, 30"wl, 1.3/1.3" rocker
Bell RockStar 15.5' l X 31"w 28" wl, 2.5/1.5" rocker
Swift ShearWater 16'2" l X 31"w, 28" wl, 1.5/1" rocker
Swift Raven 15' 3" l X 32" w, 29"wl, 3/2.5" rocker

Notes:
1. excessive stem layout increases overall length w/o changing waterline length, [Peregrine, Wilderness.] For most hulls figure wl L is 9" less than overall.
2. rocker doesn't compare between manufacturers or designers. Peregrine and Wilderness have almost none. Osprey by Winters has more than Kee 15 [Yost]. RockStar and ShearWater have similar rocker although the numbers differ???
3. For stability, look at waterline width.
4. Seakindlyness is approximated by the difference between max beam and waterline width, more being better.
5. The narrowness of SRT and DragonFly, combined with their rounder bottoms make them questionable for larger guys looking for a stable platform.

At 5' 8.5", 170 lbs, I need to move my offside knee to cross heel Osprey, ShearWater, RockStar or Wilderness. They seem huge to me, but I'm a compact guy. Larger folks with wider shoulders and knee spread will find them a better fit than the several 28.5"/29" hulls with ~26.5 waterlines. So it goes.

 

[Guest]

Well Charles... either you're lying, Swift is lying, or your figures don't give the whole picture.

Despite the waterline width Swift rates the Kee 15 (140-290) for a full 20-30lbs more than the Osprey (120-260). I'd say there must be some difference in total volume to accomplish that. Or those numbers are worthless. I of course don't have the actual displacement load tables but assume those numbers are derived from a similar load/displacement.

As far as my statement regarding Colden's Nomad, I'll take the quote right from the website as I believe I may have misinterpreted something:

"Nomad/ Peregrine/ Heron/Merlin II are variants of DY's concept of the Solo Tripper. Slightly Swede form, quite happy with kneeling paddlers with a straight shaft; equally pleased with sitting paddlers with bents. The Nomad has a more pinched and skegged tail to improve tracking." - CEW

I had thought that last statement somehow meant the latest Nomad had been modified in the tail. Now I'm guessing that was referring to the original? If so referring to the Peregrine, it has that same tail and straight tracking I'd assume - so that entire statement makes little sense to me.

 

[charlie wilson]

Dear Mike;

My mother is the sole living individual who ever called me Charles, and then only when I was in trouble. I scattered her ashes in '09. Lying? Those are strong and tortable words for a learning amateur to throw at an industry guy with a reputation to maintain. I suppose mom will haunt you for that. She was a neat lady with quite an edge to her and didn't suffer fools gladly; enjoy!

My chart, above, was directed at finding wider hulls that would compare with RockStar in stability, maneuverability and tracking. Obviously, 28.5" hulls with 26" waterlines are not going to that very well and neither do rounder bottoms. I remain amazed that so few wider, say 31-32 in max beam, ~ 28" waterline exist, because the market suggests they should.....

As the discussion concerned Dave Kruger's excellent RockStar and comparables, I didn't do into detail on DY's solo trippers as they are all narrower at waterline than Osprey, so otiose to the discussion. The Nomad, lofted ~87, was and remains a little pinched in the stern compared to other Yost solo trippers. Colden has flanged the mold to infuse hulls, improving lamination quality and lowering weight but otherwise not changed the hull one iota. There is a discernible size step between Nomad and the Kee 15. There is also a noticable performance difference between those two and your Peregrine; it's flattened bottom improving stability somewhat at the cost of secondary stability/seakindlyness; it's decreased rocker problematical to both tracking and maneuverability.

I can discuss DY's and others solo trippers with real, not published, dimensions for hours, but none have requested that intensity. Doesn't make much difference anyway, most tend to get what's locally available anyway.

Swifts capacity measurements? Osprey came on line ~ '91 in syntactic cored glass and Kee 15 ~'11. infused with foam core and rails, so there's twenty pounds. Measurement process and measurer might change in 20 years too. We intend to redo capacities for the entire line this fall, knee deep in OxTongue Lake with four humans, a 5 gallon bucket, a level and tape measure. Sorry for any inconvenience caused, but no one is intentionally misrepresenting data. I would think it embarrassing to parse multiple and disparate presentations in a forlorn attempt to catch someone out, even me, what with Mom's ghost protecting me and all.

 

[Guest]

I wasn't actually accusing you of lying... it was a bit a poke if you will that the data I see doesn't necessarily coincide with what you are saying. So someone must be wrong.

Charlie,

I'm an engineer. I go through reams of the most advanced analysis and test data you could ever imagine. My job is not just to sift through this crap. I do it. I design the parts, analyze them, design the tests, and carry out the tests. This is rare in a big company but times are lean and I like to be able to touch what I've created. I'll be at my computer for months and in the lab for months at a time. I'm very careful about understanding how to calculate things and how they actually measure in real life. I'm a professional as well.

My only gripe about the canoe industry is isn't based on hard data, it is really almost all subjective. And when numbers are given, there is little consistency. So you can see where I might not put much faith in the number you have posted and take your assessments the same as I would any other qualitative one. I very rarely talk 'engineer' in terms of boats. I don't have the information to do so. I don't think the people that build them do either. It's fine, it's a cottage industry. But let's not put to the ultimate test. I've read some John Winters. If you want to get technical, the level of engineering there is Freshman level at best, no disrespect. The actual fluid mechanics involved cannot be summed up that easily. The interactions that are involved are difficult to understand for even the foremost minds in computational fluid dynamics.

I'm glad you are trying to bring a level of math based engineering to this industry, but you are bashing the wrong guy and merely pointing out the inconsistencies in the industry.

And from the buyers standpoint, at least mine, I'll tell you exactly what is important to me. Load capability, tracking, handling, efficiency and fit (Then of course comes weight, which is easy to measure) Fit should be the easiest but it doesn't always line up with exactly what one might infer from dimensions - this is rather obvious from an engineering standpoint because the shape of the cross section of these boats varies wildly. Rarely is the load vs. displacement given and if it is the consumer doesn't know where the boat remains efficient as the designer intended. There is no table of load vs motive force and velocity. And as far as tracking and handling, there is no standard test for how a canoe turns or tracks, much like the skidpad in the automotive world.

If it were a car we could easily turn to Road and Track or Car and Driver and look up all the specs for standard tests. And even so, that wouldn't give us the entire picture. There is a reason that people write words instead of just providing the data.

Alas, I hate to say, but I think you are too late anyway. It seems our OP has decided to go old school and shun all this hard work in design and engineering in the canoe industry as of late. Despite the handling and acceleration of the modern Corvette ZR1, sometimes the '69 Camaro is all you want.

 

[Guest]

This discussion is so entertaining. As a longtime financial analyst I have to chuckle at incomplete data being used to make conclusions about different boats' comparative stability and load-carrying capacity. What's missing is any indication of fullness in the quarters. My Peregrine, at 15'8" is the same LOA as my old Mad River Independence, but it's far less stable due to narrower WL width and tracks a whole lot better due in part to having less rocker and in part to having less volume in the quarters. I.e., it's more streamlined. It would be nice to see a measure of streamlined-ness in addition to all those other data.
And yes, I said the Peregrine is 15'8". My steel tape measure, measuring from stem to stem at the outside ends of the deckplates, showed that it's 15' 8-1/8" long. I didn't use a chalkline because of possible stretching.

 

[charlie wilson]

Yeah, but.....

Overall length, as measured above, is useless. The WaterLine Length is one of the key determinants of forward speed and tracking. Peregrine has pretty heroic layout at both stems as do several WeNoNah designs; waterline length is, thereby, a significantly smaller number. Stretch a tape to figure waterline length. Waterline length is another key number that helps get a handle on fit, capacity and wavemaking or residual friction.

Converting the two to similar units and dividing the width into the larger length gives us Length to Width ratio, a prime approximation of tracking, but it doesn't compensate for hull form. Tracking is even more accurately described by Block Co-efficient, the block being the waterline length, width and depth of a given hull. The less of the block the hull displaces the better it tracks. In short, finer lined hulls track better than full figured ones. I guess we knew that.

WHile block co-efficient is difficult to compute, prismatic co-efficient is even harder, the prism being the in water cross section of the hull at max beam. Interestingly, numbers ~.62 indicate highest efficiency with numbers ~ .58 indicating highest maximum forward speed.

L/W ratio is the beginning on tracking. Most of us induce yaw with our forward strokes. Decreasing stern rocker counters that yaw somewhat, hence the movement towards differentially rockered recreational hulls. It turns out bow rocker has little effect on tracking but it does aid forward maneuverability and speed, so, within limits, say, 2" for Winters, 3" for Yost, 4" for WeNoNah, [~all the same amount it seems], the more the better. Rocker is a drafting comvention that varies with the designer.

MRC lists Indy at 30" max beam, 29" wl; Hemlock prints Peregrine at 28.5" max beam, 26.5" waterline. Jim Henry's V does improve tracking; contemplate the Block Co-Efficient described above. The MRC has a deeper block but fills less of it. But it's excess width reduces L/W ratio to closer to 6.3. Peregrine benefits from DY's magical control of elliptical bottom and sift chines, even if somewhat flattened in mold making, and it's higher L/W number, 6.8, indicates better tracking. It is the finer lined hull.

The best design/function primer for interested solo canoeists remains John Winters the Shape of the Canoe, available from RedWing Designs. There are other texts that have proven useful, but they always include data on electrical systems, power plants and rudders, so require more wading. I'll be glad to provide a bibliography for any interested parties. I also kinda maintain a semi complete listing of solo canoes past and present which I will also gladly forward. Email charliewilson77@gmail for electronic copies.

 

[memaquay]

Charlie, thanks for the list, it confirmed many of my sus[icions. For over 10 years I paddled an Osprey. I was 170 pounds at the time, but even at that fly-weight, when I was loaded heavily, with chainsaws, etc, the Osprey became a beast. The differential rocker combined with the heavy load made it somewhat difficult to do basic eddy turns in river travelling. As I moved up in personal weight (think it's called fat), the Osprey was even more untenable for my style of tripping. Moving up to the Raven was quite an improvement, although I still face the problem of the asymmetrical rocker in the white water department….it simply doesn't eddy out as nicely as a symmetrical boat. I've never had a problem making a canoe go straight, and I want the ability to move around easier in white water, so I'm going to a symmetrically rocketed canoe.

That's my theory, and I may or may not stick to it. Plus I like the looks of old school canoes more.

 

[pblanc]

This discussion is so entertaining. As a longtime financial analyst I have to chuckle at incomplete data being used to make conclusions about different boats' comparative stability and load-carrying capacity. What's missing is any indication of fullness in the quarters. My Peregrine, at 15'8" is the same LOA as my old Mad River Independence, but it's far less stable due to narrower WL width and tracks a whole lot better due in part to having less rocker and in part to having less volume in the quarters. I.e., it's more streamlined. It would be nice to see a measure of streamlined-ness in addition to all those other data.
And yes, I said the Peregrine is 15'8". My steel tape measure, measuring from stem to stem at the outside ends of the deckplates, showed that it's 15' 8-1/8" long. I didn't use a chalkline because of possible stretching.

The prismatic coefficient is more or less a relative measure of fullness of the hull ends below the waterline:

http://www.oneoceankayaks.com/smhydro/hydro.htm

Of course, most makers do not provide prismatic coefficient data for their hulls.

 

[Guest]

Here I go again. Feel-I also paddles a SRT and beautiful,lite, new (Colden) dragonfly back to back sunday. The feel radically different. The SRT feels bigger,fuller,more sluggish,safer in big water, higher. The Dragon-feels more responsive,faster,narrower, more fun. Obviously I preferred the Dragon,but that's me. I seriously considered a Dragon before buying my Kee 14,but the high freeboard was a deal breaker for me. It's behavior when the wind came up confirmed my decision.
Turtle

 

[pblanc]

Yeah, I agree with Turtle.

While the SRT and Dragonfly are certainly both good boats for river tripping, I prefer the Dragonfly for the type of paddling I do, and I certainly prefer it to the SRT for paddling unloaded. Although both boats have considerable depth, the SRT is significantly deeper, especially at the stems. I prefer the symmetrical rocker of the Dragonfly for paddling in whitewater. Although the SRT might have a tad more initial stability, I found the fall off of secondary stability to be a little abrupt for the SRT whereas the Dragonfly can be predictably heeled to the gunwale.

I should add that I have only paddled the SRT about 4 times, twice in current, and always unloaded. It is quite possible that with more experience the SRT would become more comfortable to heel. I can see that for expedition tripping in which it was anticipated that the boat would need to be run with a heavy load through sizable wave trains, the SRT might be the better choice, but IMO for general usage including Class II whitewater day trips and multi-day trips the Dragonfly is the better choice.

 

[Guest]

To me, I think the obvious difference is that one was targeted as a whitewater racer that was tripping capable and the other was designed as a tripper that was whitewater capable.

Pretty sure the design priorities got flipped there.

Harold could probably paddle a log and be better than the majority of us, but from what I have heard the SRT was meant to be numbed down a little bit to appease a wider majority of paddling skills.

 

[Guest]

Charlie,

Thanks for the more in-depth discussion. It reflects the big difference between someone who knows what he's talking about and the rest of us who can at best guess at the effects of various design elements. Yet, I remain undeterred from my general perspective that boat design - i.e., naval engineering - is as much magic as anything else.

 

[Guest]

Magic - possibly a bit of a strong word, friend. Not well understood. Yes.

Anything that involves Navier-Stokes' equations is bound to be shrouded in mystery.

I could give a you a lengthy story about the difficulties of designing something as simple as a dynamic pressure limiting valve but I'm bound by non-disclosure and it makes a lot of smart people look really stupid.

All I can say is I've yet to see the real part act like the model.

 

[yellowcanoe]

Well Mem likes his Raven and where he lives maybe trying to use the heavy pine Raven for a mold for an experimental Kevlar (don't forget the external glass!) version is a possibility. He is amenable to playing with chemicals and the winter in Geraldton aint short.

 

[memaquay]

Ha ha, I laugh at chemicals! You off Gitche Gumi yet Kim? I'll see what kind of time I have this winter, but I'm pretty sure I will be building a boat of some kind!

 

[Odyssey]

[No message]

 

[Guest]

I really did enjoy paddling the Dragonfly. It made me have 2nd thoughts about buying my new Kee until the wind picked up. Thank you wind god. I do think if I planned to haul heavy loads so it would stay stuck, it would be a great tripper for me. I don't do any serious whitewater so the extra freeboard is not important to me. Now if you could saw 2" off the height and keep the tumblehome. Silly idea.

Turtle

 

[Guest]

Magic - possibly a bit of a strong word, friend. Not well understood. Yes.

Anything that involves Navier-Stokes' equations is bound to be shrouded in mystery.

I could give a you a lengthy story about the difficulties of designing something as simple as a dynamic pressure limiting valve but I'm bound by non-disclosure and it makes a lot of smart people look really stupid.

All I can say is I've yet to see the real part act like the model.

In 1972 I was working as an inside salesman in a small industrial sales office. We sold air and hydraulic equipment and I was a recent political science graduate. That's right - absolutely no connection with fluid power. That year I designed an all-pneumatic two-hand-no-tie-down safety circuit to prevent people like punch press operators from losing fingers and hands. The engineers said it couldn't be done; I thought their expertise acted as blinders, and I was right. I don't know how many of those things I put together (they used Clippard mini-valves and went into a rather crowded 8x12 steel box). I should have patented it. Anyway, I meant that naval engineers seem to think that normal, educated people can't understand technical stuff so they don't talk about it.

So, does your imaginary valve have to respond to varying input pressures, produce varying output pressures, or something else?

 

[yellowcanoe]

Ha ha, I laugh at chemicals! You off Gitche Gumi yet Kim? I'll see what kind of time I have this winter, but I'm pretty sure I will be building a boat of some kind!

you promised good weather.. Typical weatherman. The ride down the Goldfields road was nice. Then all the weather turned foul. The first day paddling was fine then followed by three days of ick.. We had a weather radio which promised another seven days of ick with highs of 9-12. We did turn sissy and bailed. The constant fog and drizzle was demoralizing. We did have a GPS but navigating three mile crossings with no frame of reference now makes me ill literally. We are going to the Aposlte Islands ISO better weather with a little stop in Thunder Bay for laundry and visiting. If the weather is still foul, we will continue east back through the Soo and put in at Lake Superior Provincial Park. Its got to get better sometime.

Now this has nothing to do with the RockStar..or maybe that refers to Gitchee Gumees reflecting waves which were kind of fun yesterday.

Turtle.. the DF could really benefit from a sliding seat for the reasons you describe. It is wind sensitive so for tripping is less than ideal. Great river boat though!