A while ago I read a post, by Paul I believe, concerning having the electric motor drive unit in the blade of the rudder. I think it was more like adding a wood blade to an outboard type electric motor. I tried searching for it but couldn't find it. Anyone remember or have their own method of doing something like this? I think the diagram attached showed a remote controlled power head embbeded in the wood blade either that or the wooden rudder blade attached to the electric power shaft and the power unit was attached to the bottom of the blade. Old age and one to may rum drinks have soddened my memory I guess.
I remember a thread like that a few years ago, but they were looking to attempt the Bolger arrangement, which in practice actually sucked pretty bad. Bolger had a trolling motor enclosed in a low aspect, barn door style rudder. The reality is, you have a lot of drag from this thing when not using it (under sail). The design it was used on was pretty much a pig anyway, so the drag was partially justified.
If you want to sail, the motor and blades have to come out of the water or you can kiss off a knot or two. When your boat is only able to make 4 or 5 knots on a good day, kissing off a a couple really sucks.
I have a remote mount motor that I've used on a few designs. It separates the powerhead from the motor, which typically is mounted on the tiller and the motor is arranged in a bracket that permits it to attach to the rudderhead. This way you can lower it, raise it or remove it all together, depending on need. This is the logical setup for trolling motors on sailboats, unless you just want to leave it hanging on the transom.
The nice thing about this setup is the motor is turned with the rudder, so it acts like an outboard and best of all, it can't chew up the rudder either, as it's mounted on the trailing edge when in the lowered position. Another feature is the remote powerhead, which is hose clamped to the tiller. This places all the controls right at hand, but doesn't restrict the use of the tiller. The only additional equipment needed for this are a couple of cheek pieces to sandwich the motor shaft to the rudderhead and a bulkhead connector for the power to the motor. A heavy duty, 2 pin connector is all I use, which works fine. This connector allows you to remove and store the motor and shaft, while leaving the powerhead attached to the tiller.
Lastly, electric trolling motors don't have much umpf, nor much range. It's just simple physics and if you carry enough "fuel" for the trolling motor, to have reasonable range, it weighs a lot more then a small gas engine. Simply put it's all about wattage. A typical 55 pounds of thrust trolling motor is producing about .8 of a HP (assumes 50 amp draw on 12 VDC), but only for a few minutes, with a typical size battery (500 AH, group 24, etc.). Within a half hour you're actually working with about a .7 HP motor, within an hour less then 1/2 a HP and so on. A 1/2 HP isn't a lot of push when the wind dies, you've opened you last beer and the launch ramp is a few miles away.
I like this idea PAR, do you have any pictures?
The Super Skipjack drawings come with an addition on how to remove the rudder blade, and install an engine instead. Personally I think a boat ought to have a working rudder, no matter what, so I am not very fond of that idea.
Personaly, I'm not much of a fan of the electric motor, having sailed on a boat with strictly battery power, I found it drained alot faster than Paul describes, not alot of umph as well I must agree. Friggin power dies easily, and leaves you to be towed more often than you like, Or short sails.
I prefer having the gas motor, and putting a protective ring around it so's not to dammage the rudder, like Craig did, and having the power I need when I need it, and the prop out of the water when I don't.
A lot depends on the battery you select. Most opt for the "usual suspects" from West Marine or Wal-Mart, which aren't really very good, unless you're willing to spend the money on an AGM or other well "fitted" battery. The group 24/27 lots just don't have enough meat in them to offer much. If you can hardly lift the battery, it might be well suited to your boat, but it's better to just do the simple math, find your expected load and size the battery to it. For short runs, like mine, it's a fine substitute for the gas outboard, but my motor time is usually less then a 15 minutes for a full day's outing. One of these days I'll size up some lithium, string them together and see how well I do. For double the cost, I'll probably get about 20% more run time and a slower drop off, though these numbers are hard to quantify after the cost.
Thanks Paul that is the info I needed. I only use the electric to get away from the dock and back to it when the wife is onboard. If she is not at the outing I use oars. Since my second heart "incident" my wife has insisted I not do any more rowing. It's not like I am doing laps or timed runs with the oars just a few pulls for out and a few back are usually enough.
I have an issue with clutter in the cockpit and having the electric stashed on one side of the dagger board box takes up a good bit of room. I also dislike the look of a motor hanging off the transom, especially if it is off center.
The Amanda Marie is a wee small boat, only 12 feet and like her owner a bit wide in the center so 4 knots is about normal. Losing 1-2 knots from drag would be a drag so I'll just muddle by with what I have. Another dream or scheme in the discard pile. If only there was a way to recycle discarded dreams I would be a very wealthy man.