Adirondack Challenger / Texas Water Safari

I've got two races in different parts of the USA and I want one boat doing both.
The adirondack boat has to be portaged, one section is 1.25 miles of rocky uphill trail,
and the 260 mile texas race has some narrow parts with logs and small rapids.
Now, what design to use?

http://www.macscanoe.com/90-Miler/90-miler_Index.htm

http://www.texaswatersafari.org/

Rick's V14 look really interesting, and his designs are race proven.
I'll think I'll follow the path of success!






rick, you mentioned flat panel construction. got any links or other info for me to get educated on?

every time I do a search here I get side tracked with some other thread .....
i discovered that BG_Geno lives down by me? I wonder if I know him? or he knows me?
I pm-ed him, anyway, like I said, distractions ......
I hadn't seen his boat that he was working on either btw ....

then there's the mitrpak gearbox. is there any gear reduction on this or is it 1:1?

the bicycle peddle bits I got no idea about .....
other than I know I can get quick drain bicycle shoes.
what bicycle bits should I be looking for?

there's an aluminum fab shop near me so I can use him to fab up the metal structure.

In the design I'll try and allow for my future enhancements once I know the method
I'll be using to build the hulls with. and of course what it is exactly I want done!
mounting points, stress areas, etc.

I saw that the hobie mirage drive uses stainless steel chain,
so I'll have to see if I can find and use that instead of something that will rust to pieces
after one outing in our hypersaline environment.
anything else I can on the drive system to make it last longer?

ok, this is enough for me to chew on for now .....

 

Just to be sure of the task. Do you have an option to portage through all the narrow shallow bits? And, if you did this, would it put you behind seriously?

This will have some bearing on the boat design because I would always go for light weight and ease of portage rather than heavy weight and indestructible as there is some portage involved.

The other thing is that you need to specify the engine capability. Unless you are a regular recumbent cycler with power data you need to get to a gym and do some calibration on a recumbent cycle machine. You need a machine that will display power and is accurate. Compare a few to see that they are consistent. The approach here is to set the resistance level to feel quite easy and spin at the preferred rpm. Keep trimming speed and resistance over 1 hour until you find what you can sustain. The power level over the last ten minutes is a good starting point for design. There are other ways like climbing stairs but you need a tall building to get a good idea. Using a GPS and jogging up steep hill is also another way to get useful power data.

I believe my last frame is the best. It is simply carbon fibre tube glassed taped at the joins. I was able to get some offcuts of high modulus tube that is 40mm OD and 2.1mm wall thickness. It is about ideal. Would maybe go a little thicker. Every time I lift the boat I appreciate the low weight of CF.

I show a little of how V14 was built in the pedal boat thread. Greg K is providing detail on the flat panel construction of his Ocean Within here:
http://www.adventuresofgreg.com/HPB/HPBmain.html
You can back track through the archives to pick up a lot of useful information.

The Mitrpak boxes have stainless shafts and are either 1:1 or 2:1. The best choice is 1:1 with 1/2" shaft. The shafts are stainless.

I doubt that an ordinary bike chain will cause great concern as it normally operates in air. Keep it well lubricated. If you do not like the idea of a bike chain then you could consider a toothed belt. I am starting to play with these and they look quite good. I am surprised by how little tension they need to avoid skipping but I have not put one on a boat yet.

Using "clipless" pedals is really essential for efficiency in the recumbent position. It reduces the effort noticeably. You have to make sure you can unclip during a roll. Practice rolling out at least once before you start racing.

It is good to have access to machining and fabrication but there is very little needed. A good mill-drill or decent drill press is useful.

One item that Greg found hard to come by in North America was spring steel for the prop shaft. The best is 5/16" (or 8mm) round bar. I paint mine to avoid corrosion. The spring steel is very strong making it hard to get a low corrosion alternative. In Australia I have to place a minimum order to get what I want so I tend to have some on hand and carry a spare shaft for the MM.

Rick W

 

thanks rick, you've given me some homework to do and I'll be getting on it. I gotta start looking for suppliers of material and give my design some thought. I won't actually be able to build anything until sept. but I can surely know what I'm gonna do when i do it. but now, it's off to those links and reading .......

 

It is surprising how quickly time goes by unless you can give it full-time attention.

Greg K first approached me about a boat in August 2006 and he is only now building it. He already had a huge amount of engine data. He still does not have much on-water experience but is getting there. He is retired so is able to devote considerable time to it.

One important consideration is if the rules will permit you to compete in the first instance and on what basis in the second. The first year I did the MM I did not have a class. Now I am at least competing in the unrestricted class, which is appropriate for the boat. I also get the same age allowance and this really favours the older guys like me in my view.

Rick W

 

I'll be gone for a couple of months during the summer so I have to wait until I get back before building anything. I am chomping at the bit to start building though, but I've got to learn all the boat building techniques first, your links have been keeping me busy! I like the idea of not using aluminum which will make me pretty much self sufficient after I learn how to use the epoxy stuff.

thats a good point about actually being allowed in a race, and if there's a class, or creating a class. I hope this isn't like the story between mono hullers and multihuller sailboat racing! I'd rather be in an unlimited class than being banned from an event.

engine data? I got none. and have no biking under my feet since I was a teenager. I'm more of a paddler than a peddler and actually I think I got a good build for paddling but being a soccer player for much of my younger life, still have the basic form from then. I have run a lot in my life, but just getting back into it again. I race offroad motorcycles in enduro events, so I know what it's like to be totally spent and will be working on ways to add supplements and nutrition to enhance my range on whatever type of event I'll be doing. though dirtbikes work my upper body, not my lower body as much, bummer ......

I live and work out of my house so when the time to build comes, I'll have the time to get after it. I got no wife, kids or other things that can get in the way.

Is that a motorcycle rear sprocket used as the front sprocket on the peddling system/drive? and what, if any, sprocket is used before it hits the mitrpak? figuring out the gear ratios would seem to be quite challenge? should I just be prepared to try out a few different combinations?

I'm having trouble seeing how your drive shaft works btw .......
and where the prop sits in relation to the boat.

 

A gear ratio around 4 or 5:1 gets the prop about the right size. The prop pitch is set to match the required cadence.

The attached photo might give you a better idea of the curved shaft set up. It is spring steel and I design the curve so the shaft has infinite fatigue life. It works well within its yield limit. A pushing prop is self stabilising so it does not actually need a strut but I have one to avoid the prop hitting the hull in a turn or in waves. The strut also allows me to swing the prop outwards and upwards so I can inspect it.

Rick W

 

prop design and manufacture:
edit: see this thread
http://www.boatdesign.net/forums/propulsion/prop-manufacture-17931.html

Is this cast, forged, cnc-ed, or hand shaped?

I'd bet it would be wise for me to carry a spare huh?

the design looks simple enough,
but shapes like this must be a bear to get just right!?
I got a caf airwing near by, I wonder what wisdom they can share on
prop design and manufacture. They are some knowledgeable and crafty guys!

I noticed that greg in his record breaking run was using wool socks but his feet were not even in his shoes that were attached to the peddles? gotta change thing up some to stay comfortable I'd gather ......

 

Here is another picture of the curved shaft with the boat flat on the ground. Shows how the spring steel works:
http://www.boatdesign.net/forums/at...3-most-efficient-propulsion-v11j_cf_frame.jpg

I have attached an image of a prop I hand fabricated and an aluminium one milled from aluminium using my CAD file. The prop is an important bit and I have done a lot of design to get the best from them. These shown here achieve efficiencies of 85 to 86% at design condition. It is much better than normal boat props because the blade loading is so low and the high aspect blades. The efficiency is similar to what is achieved with aircraft props.

I design props specifically for the application. My current challenge is to make a folding prop.

Rick W

 

for my purposes in the waters I'll be in with rapids and waves the craft need to be a bit stronger. the single outrigger needs to be strengthened with a second arm. also it'll have to fold up or swing in, both for portages and for thinner and narrower routes. I did a bit of photoshop to this pic adding the forward arm to help show the concept.

 

The two braces are probably a good idea. I would try to save weight by adding a clevis to the ends of both fore and aft cross tube of the frame. It means you have to climb over one of the braces or the outrigger to board but this is not a big issue.

Try to keep the component count as low as possible.

Aluminium main frame is almost as good as CF and you can bond it with glass tape. Epoxy and glass tape work well with aluminium tube.



Rick W

 

I can see I might have a bit of a problem with the prop shaft if the outriggers swing forward, hummm .....

I already have some old windsurfing booms around and aluminum tubing is easier to get so I'll use that to help prototype the seat/drive/brace mount/structure and simulate it sitting on a boat and I can see the geometries at work. I can have this all done before I even start building the boat. I can do this during the summer. I'll also know exactly where the mounting points on the hull will be so I can add in bulkheads. this will also show me the weight distribution of this system for me to know exactly where it should mount on the hull.

(I'll have to give this seat/drive/brace mount/structure a shorter name!)

do the almas ride mostly out of the water?
this could affect my mounting/swing system if the outrigger arms need to be angled up slightly.
I guess I could always just bend the tubes huh?

I can also worry about what type of seat to use ....
and really look into the peddle and drive system.

ok, time for my morning run, and I can mull this over thru my head as the paces tick by .....

 

The DRIVE FRAME can be made from aluminium tube as noted earlier. To join it you cut/rasp the ends of the tube that form leg of the 'T' to fit snugly to the top of the 'T'.

I wrap a layer of fibreglass tape on the end of the leg and in the middle of top. I then use balsa blocks or foam corner blocks to acts as side gussets either side of the leg. This is then allowed to set to form the 'T'.

Once the epoxy is set I wrap lengths of wetted fibreglass tape perpendicular, diagonally and around the join. Usually 2 or 3 layers in each direction. Once this is set you will have a bond better than welding.

You need to mechanically clean the aluminium before you do the initial wrap.

Three of these joints produces a frame. The mounting for the gearbox can use the same method of attachment. I use light angle section for the actual gearbox bracket. There are some subtleties here that I will explain when you get to that stage.

Fibreglass and aluminium have similar mechanical properties so they work well together.

The tube I use is around 40mm diameter and 1.6mm thick.

The main dimensional control on the frame is getting the crankshaft at the right height to avoid heel clipping. For me this is around 300mm. Experenced recumbent cyclists can operate with less. It is also nice to be able to move the bottom bracket along the tube to optimise the leg stretch.

Rick W

 

Not sure if I have said this before but having so-called "clipless" pedals is really a must for efficient recumbent operation. Using them is much less tiring than without. It also allows you to "spin" with more even torque than just the push-push of unclipped pedaling.

I can drop my heart rate by about 5bpm by spinning rather than push-push because it is more efficient to keep the prop at constant speed. However my leg muscles are not sufficiently trained to do it continuously.

Rick W

 

In looking over some previously saved pics I came across this. interesting ....

http://www.humanpoweredboats.com/Photos/Individuals/PedalWaa/PedalWaa.htm

 

I went digging thru my aluminum windsurfing parts and pieces and might adapt some of that technology in setting up my initial prototype/mockup. I even stumbled into some bamboo. that could be an interesting material to use, though it's not very uniform in size, but strong and light! I might have to play with that stuff some more, but later. windsurfing gear is what I got to play with to start off with.





I came up with this interesting connection method for some other project.



this is some cool stuff .....