Trolling Motor- Rudder Question

[PAR]

Hi all, I've begun to build two Weekenders and having made several major changes to the boats, one look at the rudder box, it's attachments and blade design and I decided to make a simpler and stronger affair. I've always disliked "boxes" as they're called, preferring an internal rudderhead and a thicker blade sandwiching the head. At the displacement speeds of these boats, a thicker foil is welcome and is much stronger. The rudderhead is a plate of aluminum with hardwood cheeks for the tiller. This design permits surface piercing properties, necessary on transom hung rudders in the upper portion of the blade/head area. The increased thickness also permits a nice 0012 section in the major bulk of the blade and a wash out area towards the tip, which I typically make elliptical, to decrease eddies on the blade end. The other advantage to this "internal" head setup is the lack of turbulence cause by the box.

As designed I think the box on Weekender/Vacationer could hold up to a small (to 50 pounds of thrust) trolling motor, but I would not use a fixed mount. The motor I intend to use is the 47 pound Minn Kota and the motor isn't light, but not that heavy either.

The original idea for the mount was to get this fat bellied, heavy, early, Catalina off it's dock and into an area with the sea room to hoist without embarrassing the crew on a lee shore. It was then stowed below or hoisted clear of the water, while under sail. It worked so well I adapted one to my, similar sized sloop. In a Weekender it would provide good power, a Vacationer may want a 24 volt model if bucking any reasonable current or chop.

A rudder that had a kickup feature would not serve well housing a built in motor. In reverse it would want to kickup. I suppose it could be locked in the down position to solve this, but I'd be the type to forget to release it when in the shoals and I break the blade when I ran up on something. A fixed rudder could have this feature, but as has been pointed out by all, the drag.

I like a boat to sail as well as it can and keep lines from dangling in the drink, motor/kickers clear of the wet, good sail set, etc. The idea of a prop stealing a knot or more from a boat that will want as much of it's hull speed as possible isn't palatable to me. That's 20 to 25% of a Weekenders hull speed to the convenience of an always wet prop.

The weight issue is a concern, but under power it isn't that much so, under sail it is. This rig can be stowed (forward if desired) while under sail so I think the weight issue can be handled. The cheek pieces remaining attached to the rudder box or head would weigh little without the motor attached. It's as simple as pulling two quick release rigging pins, unplugging the bulkhead connector and tossing it in the cabin.

Leaving the prop in the water can generate a lot of drag. I've never seen a feathering or folding prop in this size range, besides they cost as much as the boat.

I've debated removing the aluminum case surrounding the motor and replacing it with a 'glass one, but that seems more trouble then it's worth. I suspect the weight is in the armature anyway. The only other option I can think of is to mount it in the deadwood with an aperture (more resistance) and align the prop behind the deadwood to improve the drag a bit. There again would be more engineering then I'm willing to put into the issue, finding a way to insure the motor stops with the blades aligned vertically.

A friend of mine suggested I try and make a flexible shaft from a table saw work, leaving the motor inside the boat. This idea has some merit, as I have a flexible tool attached to a 1/2 horse motor I use for detail and cut off work. I could replace the chuck with a prop shaft and mount the other end on the Minn Kota. This puts the weight in a more favorable location and the shaft could be aligned easily enough to hide behind the deadwood.

For now, I'll stick with the idea I know works. It's simple, fool proof, has few parts, is easy to operate, stow and repair.

[JTam]

Sorry about the dragonfly link...there's an extra "dot" in the url.

The correct url is http://dragonfly-trimarans.org/d920_motor_link.htm

Hi all' date='

I linked my trolling motor to my tiller/rudderbox. I did this for two reasons: 1. The power unit on the trolling motor is very long and did hit the rudder, and 2. moving the motor and the rudder as a unit increased my control and decreased my turning radius when motoring.

I combined two designs found on the following websites:

www.geocities.com/thomas_m_stockwell/TillerToMotor.html and http://dragonfly-trimarans.org/d920_motor_link.htm.

I also converted my weekender from a wheel to a tiller. So my rudderbox is taller than the plans show. This made constructing the linkage simpler

I'll try to post some pic's of what I did later.[/img']

[kydocfrog]

Those are both really neat and simple. Gotta do some drawing here...

Thanks.

DocA