Question for Osprey/Kite builders

[Cookannapurna]

I'm looking to build a new solo, mainly for 3-5 day trips in the Adirondacks. I love the design of the Osprey/Kite but...

I'm 6'7" and 300#'s, 340-360 with gear. I don't think the Osprey/Kite has the volume. What is the opinion on lengthening it to 16' to handle my size/weight?

 

[stripperguy]

I wouldn't lengthen it, I would scale it!
As it is, the Kite has a design load of 283 lbs, another 10% and you're there. If all you do is make it longer while keeping the same sections, surely that would change the character of the boat. But scale up all of the dimensions, and you'll likely have a boat that performs much like the original design, just a little more of it.
One of my virtual boat buddies (actually, we've paddled together once) is nearly 7 ft tall, but very thin. He built his Kite as a sit on the bottom pack boat, and uses a double ended paddle. His CG is so much higher than most folks, that he decided to keep his weight down as low as possible. It definitely works for him, and he goes quite fast with that kayak paddle!
I will say this for the Kite...it's a great all around solo. Very comfortable, maneuverable, seaworthy, and fast enough. It does everything pretty well, and that creased knuckle has looks to die for.
You're welcome to swing by my house on one of your trips north, you can try out one of my Kites and see if it might suit you as designed...you never know!

 

[memaquay]

Contact Martin at greenval.com and ask him for the plans for the Raven. The Raven is J. Winter's large volume river tripping canoe, but also fine on the flats. I usually travelled with total loads around 350 and it was great.

 

[Cookannapurna]

Stripperguy, thanks for the offer! I have paddled one a friend here build a couple of years ago. I loved it, but when I put me and the frost river pack in it felt "sluggish". I should have thought of upping the scale. That's a good suggestion, and may be just what the dr ordered.

Mem, I didn't know that he designed a larger solo, I'll look into that.

 

[Jim Dodd]

I think either way, it will be a fun build to follow along. I like both ideas !

Jim

 

[dogbrain]

I regularly use my Kite with a bit of ballast for day trips on lakes or in calmer sections of the river. I'll put in something like 2 6-gallon containers of water plus another 15 pounds of gear and me at 190 pounds or so. That comes out somewhere in the neighborhood of a little over 300 pounds. Although I think the boat would be fine with more weight, I agree that its performance is on the decline at this weight. The design load that stripperguy cited above seems quite accurate from my experience.

 

[memaquay]

When I gained weight, I had to upgrade from the Osprey. I paddled the heck out of my first build, putting many 1000's of kilometers on it. I was 170 at the time, and carried between 50 to a hundred pounds. Once total weight got around 260, it became pretty sluggish for things like eddy turns, stuff like that. For big guys, the Raven is a great hull when built as a stripper.

 

[frozentripper]

Swift gives the upper optimum load capacity for a Shearwater (which is the scaled-up version of the Osprey more or less IIRC) as 320 pounds, while the Osprey is 260...? The simplest option might be to order the Shearwater plans in electronic form from greenval.com and stretch the stations a little for more capacity if needed. Or not, if you can test-paddle a Shearwater somewhere and find capacity and performance adequate.

A print shop should be able to scale up the plans for added load capacity by magnification if you want to stay with the Osprey/Kite or scale up the Shearwater a little. Scaling up should increase capacity as the cube of the size increase... eg. a 10% scale-up on the Osprey should result in a capacity increase of 1.1 x 1.1 x 1.1 = 133% which increases capacity to 345 pounds... 260 x 1.33 = 345.

Stretching should increase capacity linearly... a 20% stretch should increase Osprey load capacity by 20%... 260 x 1.2% = 312 pounds.

This is all fine in theory but if this won't work out for some reason in real world use, maybe some of you more experienced builders could comment.

 

[frozentripper]

PS... for some real-world validation FWIW ( does load capacity increase as the cube or square of the scale-up, methinks it's the cube - length x width x depth for the volume increase), I scaled up the load capacity on an Osprey to match the size increase to the Shearwater. Osprey vs Shearwater, about 7.7% scale-up in order to make an Osprey the same size as a Shearwater.

So 7.7% cubed... 1.077 x 1.077 x 1.077 = 1.25, a 25% volume and load capacity increase. The Osprey's 260 pound capacity scaled up by 7.7% = 260 x 1.25 = 324 pounds which is close to the Shearwater's 320 pounds given by Swift. So maybe there is actually some on-the-ground reality to this (on the water actually)... yes, Will Robinson, this is not a warning, it does compute... buzzzzz click.

 

[Jim Dodd]

I have had two plans scaled up at a print shop. It doesn't just increase volume, but also changes handling characteristics. Widening makes it more difficult to reach the water. Stretching makes it harder to turn. Just saying the that computer enlarging is not always the answer.

On the other hand. When Bruz Kunz enlarged his Merlin by 3.8% and called it the 38 Spl. it was a big improvement in my book !

Jim

 

[memaquay]

I have never asked Martin if the shearwater plans were for sale, but that is another viable option for bigger guys. Don't think I'd scale it up though, as it is already over 16 feet long.

Cook - have you considered smaller tandems, like the chestnut Pal? I used the Pal for a while as a dedicated solo, it's a good canoe for a larger person.

 

[frozentripper]

Jim, my two pesos on scaling-up and effects thereof... scaling up a canoe should match scaled-up humans and their larger needs... canoes that will be too small for large humans should be scaled up to be larger and more suitable. That's if everything is equal... an Arnold Schwarzenegger will not be the scaled-up version of a Peewee Herman, there's a lot of subjectivity in canoe choice as well. Oh well, ja, no mattah, we gonna pump you up baby.

 

[Trevor Paetkau]

Amongst other things.
Scaling vertically will change windage and rocker and load capacity.
Scaling laterally will change stability and frictional resistance.
Scaling length will change wavemaking, jullspeed, and and stability.
All will change displacement.

Assuming a displacement of 350 pounds plus 50 pound build spec why not a narrow tandem outfitted as a tandem?

 

[Jim Dodd]

Jim, my two pesos on scaling-up and effects thereof... scaling up a canoe should match scaled-up humans and their larger needs... canoes that will be too small for large humans should be scaled up to be larger and more suitable. That's if everything is equal... an Arnold Schwarzenegger will not be the scaled-up version of a Peewee Herman, there's a lot of subjectivity in canoe choice as well. Oh well, ja, no mattah, we gonna pump you up baby.

Totally agree. Bruce Kunz, was in the 125# range when he designed and built his first Merlin, The 38 SPL, handles us bigger guys, or bigger loads !
Bruce also lengthened the 38 to 16' 1", as opposed to the 15' 6" Merlin.

Jim