Canoe Hull Design

Southern,
Don't forget to keep your paddlers comfortable. Kneeling position is better than sitting for power output, but you don't want knees on unpadded concrete. If the position causes pain, it will reduce the paddler's effectiveness; they'll be shifting position to get more comfortable instead of using all their energy to power the boat.

Get some foam cushions for the paddlers if they'll be kneeling. Not just any foam, either, you want the right kind. If your university has a medical school, check with the Physical Therapy department; if not, look for a durable medical equipment dealership that does custom seating work (that was my job for twelve years). They should have a therapist on staff, and may offer services in exchange for advert space on your boat. The ideal situation would be to have them custom-mold (called "foam-in-place") a support pad for each of the paddlers. These would not only provide comfort, but also keep the paddler in a secure, stable position, sort of locking their lower body in place in the boat. The cushion can be made to support the feet and ankles as well as the knees.

If you can't get a therapist to make it for you, at least get good foam. Some of the best is here:

http://www.sunmatecushions.com/sunmate.php

If you do foam-in-place, it would be best to do the mold in the actual boat. Molding is pretty quick, and excess can be trimmed with an electric knife.

Good luck!

Curtis

 

Rick,

This is a revised version of the Excel spreadsheet from earlier. All of this data is based on 4 paddlers weighing 610 lbs. or 277 kg plus the weight of the hull. For the hull weight I used the surface areas of the various designs to give me a more accurate hull weight. It was tedious to say the least, but this should give us more accurate data.

As you will see, I'm basically splitting hairs with allot of these hulls. I have however noticed two trends:

1) I used Godzilla to optimize for rocker and found it to decrease the power requirement below 300 W, but the difference becomes insignificant at higher power requirements.

2) I used Godzilla to optimize the cross section of one of my better hulls to make it squarer. This decreased the power requirement at lower levels (below 400 W), but increased the power requirement at higher levels.

Unfortunately, I'm still having problems with the Delftship-Michlet exchange on the Tri-Canoe. I made the draft change based on the associated displacement in Delftship before exporting as I did with the other hulls. I have attached the Delftship export file for it. Could you please take a look at it and compare it with your own, I'm stumped.

In the spread sheet I have the Opt_850 hull that you made for Corey. A couple of my hulls have better performance above the 400 W level, but they are nearly identical below that. I also included the Panel hull. As you will see most of the hulls out performed it above 100W.

The 200 W power output you suggested sounds like a good average. I would think the guys may be a little above that while the girls may be below. Most of the guys that are interested in paddling the canoe are in good shape, myself included. The girls are a little harder to judge for me. Almost all of them will be green to paddling a canoe, so practice will be very important for us.

I will work on making another spread sheet based on a 2 paddler displacement tomorrow.

 

Reid
You need to delete the side hulls on the f-tri. It is not exporting properly. It is going into Michlet with wings rather than separate tiny hulls. To do it properly you need to load the little hull separately but you can build it so they do not contribute to drag. I neglect the power on the stabilisers. They are only there for emergency stability. When you do this you will get comparative performance.

For the 4-man displacement you are interested in the hull power around 500W. I think all your Opt hulls are similar. The f-tri is a bit slower. Are you constraining the beam to a minimum value?

You now need to take the same hulls or your preferred ones and see how they compare for the 2-man displacement and a power level of say 250W on the hull.

To do a proper comparison you need to know the events and scoring system.

Rick W

 

Rick,

I'm sorry I didn't get back to you yesterday. A couple of the guys and myself worked on a "canoe mover" yesterday. This is a stand I designed with input from our group that will have large pneumatic casters attached. This should prevent us from needing a team of people to carry it from place to place once we arrive at our location. Although the canoe is light enough for two guys to carry it, you really need a team of hands to help distribute the force throughout the hull. This should also prevent any problem that could occur if someone were to fall and the canoe potentially being dropped.

We have about 18 hours into the build and its 85% completed at this point. If you would like to take a look at it, give me your e-mail address and I will send you a rendering of it.

Concerning the power outputs of the paddlers, I was figuring on the following:

2 Guys: 625 W at 4 W/kg and 400 W at 65%.
2 Girls: 425 W at 3.5 W/kg and 275 W at 65%.
Coed: 525 W at 50%

I derived these power outputs from the graph you posted in the other thread. I'm guessing that with 4 in the canoe they will be less efficient individually then if there were only 2 in the canoe. Would you agree with this? Also, considering our graphs are already taking into account the power loss in the requirement, wouldn't you use the 100% paddler outputs for the graph?

Additionally, yes I was using a minimum constraint of 28" for my Godzilla optmizations. I will work on that 2 paddler displacement tonight and tomorrow.

 

Emai is:
rickwill@bigpond.net.au

You should test what power you can put out in a rowing or paddling ergometer. Most gyms have such things. Do it for a typical race time and see what the power averages. 4W/kg is quite athletic and trained if it is an aerobic output.

I am much older and with some conditioning I can sustain a little under 2W/kg. For anaerobic output for 5 minutes or so I might hold 3W/kg.

You only need to allow for the 65% once.

A GPS is a valuable training tool.

Rick W