Boat question

[David L. Darnell]

Trolling motor power only:

Would doing a tunnel hull get the motor up any more than a regular hull?

an inch makes a world of difference when you are in a river

[MikeA]

I think it would David. Are you planning on building a wooden boat?

[David L. Darnell]

Mike,

I've been wanting to build a wooden boat for more years than I care to admit to. When I lived outside of Lynchburg, I had a basement under the house, my excuse back then was, it would be hard to get out of the house. Sold the house and lost my work space.

Now down here I have a parking garage, may park outside for a spell while I turn boat builder. It could turn out like my first gun I build back in the late 70's, it went in the woodstove, after I built a few more and got better at the craft. Looking back I wish I'd keep it but kept it hid.

It's an itch that I need to scratch and get that chapter over in my life, will always wonder, what if.

[Mike Hill]

Been Ruminating on the Hee Haw Hauler!

I'm thinking at least a longer tunnel would be needed.  I wouldn't think an electric trolling motor would be powerful or efficient enough to suck up water from below the bull and spit it out the back with enough force to push you along.  I've been toying with an idea for a longer wider tunnel combined with skegs on on either side.  Or mounting the tolling motor on some sort of spring loaded mount with a substantial and strong "bumper guard" on the front of the motor so that when a shallow rock, bottom, etc.. comes the bumper causes the motor to either swing back or lift until the obstruction is passed over, then the motor comes back down into position.  The other idea I've had is to have two motors, one mounted on each side in some sort of "tunnel"  Turning is accomplished with differential power.  Google "stream dancer" for a sophisticated version using of all things twin screws for propulsion.

Most tunnel hull type electric set ups I'v found are like this.  Of course with this design, which is going to be deeper your hull or your prop?

http://www.redeemedcc.com/id6.html

There was/is a duck boat that had sort or a step hull.  Don't know the performance, but here is a picture.

http://dallas.craigslist.org/boa/590279286.html

For less than $200 you could fish in comfort - or course you will have to watch out for those pesky hooks and fins!

http://www.gizmag.com/go/5223/


As a boy at heart, I want one of these so I can wake all those slow drift boats and human-powered kayaks!  Just waiting for the electric version!!!!   

http://www.gizmag.com/go/7720/

[RonS]

Woodsman,

I can't remember if it was bateau.com, or Glen-L Marine designs or where, probably both, but I have seen the same question asked.  The answer from the experts was yes, you can raise the prop but remember when you cut a tunnel, the entire hull will ride a little lower at that point. 

In high power applications, the design of the tunnel helps force water to the raised prop or impeller so it works pretty good.

In your case, using an electric trolling motor, the water isn't going to be forced through the "chute" of the tunnel to the prop. It still might get your motor up some, but I think you'd be splitting the difference with draft. 

What many flats boat designers do to make up for the draft lost in the tunnel, is to add sponsons behind the boat to keep the draft numbers low. The sponosons add the flotation lost to the tunnel.

I have drawn and dreamed about using bow thrusters, impeller fitted electric trolling  motors on each side and all sorts of whacy gizmo daydream small craft low draft powering ideas. So far, every time I research them out, somebody has already tried them or there are other issues  that pop up as to why no one uses  it. Weight, fuel, battery consumption, thrust efficiency etc. 

As far as cutting edge design on getting a boat to float shallow, you might peruse the East Cape Canoe site.  Here's a picture of their Caimen model, with the sponsons.



Their website is http://www.eastcapecanoes.com/index.php I haven't been there in quite a while so I'm not sure what's still going on but it looks good when I just stopped to get this picture for you.

Those guys build really pricey boats. They are nice. I think they know shallow pretty good.

[Mike Hill]

Forgot the other idea I had been thinking about.  Go to www.touryak.com or www.surfyak.com and see the flat bottomed yaks that this guy has devised.  He says low draft and I would imagine they would be stable.  Been wondering if one could make the yak a foot or so longer, put a "tunnel" as you have drawn in the rear.  Along about the end of April, I'm thinking about building one. 

[grumpy]

My take

It would raise the motor up, you might have to cut the shaft or standup, it would be taller.

It would ride lower in the water unless you used the sponsoons Ron is talking about.

You'll feel the boat hit before the prop in shallow water, normally the prop is a WARNING & generally cheaper of course, with a trolling motor, you won't be setting no speed records unless you're using the 3 HP Minnkota i have

Grumpy

[David L. Darnell]

I will most definitely cut the shaft if I go with a tiller handle, might do a Co-Pilot set-up, set up in the captains chair and direct traffic.

I realize this rig will not get up on plane and use the tunnel in the same effect as a fast prop rig would, just figuring with using the tunnel, the recessed motor well and the pontoon's sticking out the back it can't hurt. Plus, how many recessed trolling motor, tunnel rigs you seen on the Elk lately

Figure it will get me more forward in the boat, and the pontoon's sticking out on the back are just more surface area for displacement.

I know all about displacement, paddled (more like worked) a 15' canoe for over 20 years, now have a 18' Wenonah Champlain, that sucker is a Cadallic, 3 adults and 3" of water and I'm good to go, it has me spoilt.

[MikeA]

Your turning radius will be very restricted and turning the motor 180 to go in reverse will be impossible. The reverse can be fixed somewhat by having a switch that reverses the polarity on the trolling motor (turning the motor backwards) but the thrust you get from a reversed prop is not that much.