godevil on canoe

[John O`Neal]

[quote=fishon91;178734]i might go through some thin mud sometimes, but mainly through thick lily pads, if not open water, i think the scooter idea could be much better. i probably don't know waht i'm getting into considering how little experience i've had with engines. and with the money situation i'm in it will be a while before i can even get involved with this. thank you very much for the info though. i would love to give it a try eventually and be able to go a little farther without so much struggle in my canoe. i also love to make my own stuff, another reason i want to try it. thank you fishon!![quote]A
As a duck hunter myself I speak from experience on propelling a long narrow boat. My layout boat is 13ft 6" . I use several different motors during the season depending on where I hunt and what restrictions are in place. ie (no gas motors allowed). I use a Minn Kota trolling motor 75lbs with battery, or a Cruise n Carry Model 6600 air-cooled outboard 12lbs, or my favorite and the most versatile, a Weed-eater mini-longtail conversion ( pictured) about 16lbs. The least desirable being the trolling motor due to weight and limited battery range. Last season I followed a hunter out of the marsh who was in a Tote Boat (a version of a canoe) he was using a curved shaft weedeater with a non-ducted Young`s propeller on the end. He used it like a powered oar. He certainly wasn`t slow and appeared to have a high degree of control. In the weedy areas he would just lift the prop briefly out of the water and it would throw them off. I think the YouTube video Whippella and Finn Kayaks will assist you in making a decision on which direction to pursue.

[Guest625101138]

Originally Posted by grob

Rick,

What does shrouding the prop do for efficiency?

Gareth

Gareth
Not as much as I thought initially after doing the numbers. Depending on loading condition the efficiency for the prop shown could go from 58% to say 62%.

The shrouding in this case provides a measure of safety as well as the thing would be quite a weapon.

Rick W.

[grob]

Originally Posted by Rick Willoughby

Gareth
Not as much as I thought initially after doing the numbers.
Rick W.

Rick,

Thanks for that, do you have any references for this calculation, or do you use a piece of software?

Thanks

Gareth

[Guest625101138]

Originally Posted by grob

Rick,

Thanks for that, do you have any references for this calculation, or do you use a piece of software?

Thanks

Gareth

Gareth
I have my own prop analysis software only because I can do all sorts of manipulation with different foils. It does not give results much different to JavaProp:
http://colaco.freeshell.org/mhepperl.../jp_applet.htm

As downloaded, the options are set for air but you can change them to suit water.
Density for saltwater is 1025
Viscosity for water is OK at 0.0000013

You have to select the type of foil. Most boat prop blades are thin so I usually use the MH 9.8% 500,000 for bigger/faster boats and the E193 100,000 foil for smaller boats. You can adjust the AoA to get a suitable chord.

I have attached the screen dump from one of the calculations I did for the Whipella. Note that there is a checkbox that can be ticked to have with and without shrouding.

Effective shrouding will eliminate induced drag so it is particularly effective in heavily loaded applications.

As far as the boat goes conserning speed and power, I just guesstimated the speed and drag by looking at the video. I was only interested in the relative performance of the shrouding.

I have seen loading conditions where shrouding has had a dramatic increase in efficiency. Better than 10% gain in efficiency. This gain is offset a little by the extra drag of the shroud.

JavaProp provides a primarily anylitical result based on the underlying physics rather than relying on empirical data so it gives good understanding of what is going on if you care to work through the various analysis tabs.

Rick W.

[masalai]

And he hasn't even cleaned the weed growth off