Motorized Piccolo sailing canoe

[John A. Campbell]

I am now in the final stages of constructing a glued lap version of the "Piccolo" sailing canoe and want to install a Minn Kota trolling motor as an auxillary power source but I definitely want it installed in inboard fashion. The motor normally drives a 9-inch 2-blade plastic prop and develops 36 pounds of thrust. I will use two 23 Amp-hour batteries at 23 pounds each, one on each end of the boat connected in parallel. I would like to use a somewhat smaller diameter prop than the 9-incher......something around 5 inches perhaps and with a 3/8" bore if available. The motor develops .58 hp at 1100 RPM. I plan to have a strut made up that will incorporate a double universal joint to get the prop stub shaft essentially parallel with the bottom of the boat. I need some suggestions as to prop diameter, number of blades, and recommended pitch. Thanks in advance for the usual fine responses.

[ssor]

John, One of the cleanest arrangements that I have seen mounted the motor on the bottom of the rudder. The motor is designed as a submersible, so I can think of no reason not to put it in the water.

[Hwyl]

I've seen them with the fake motor head cut off and slid in and out (vertically) through a tube.

I don't know about prop' diameter. I know that there is a book by Dave Gerr just about prop's.

Have you talked to the manufacturer of the engine or aprop shop?

I like the "in the rudder" idea too. I'd hate to have that thing in the rudder all the time though.

Changing rudders when you wanted Watt power would be a pain.

Have you seen the arrangements that bass boats have for dropping them over the bow.

[RonW]

-- Suggestions for prop diameter,number of blades,recommended pitch for a 36 lbs thrust minkota trolling motor.-----

Why wouldn't you just use the props manufactured for it? I would be surprised if you could actually improve on them. After all minkota is under the impression that they work. I have a 48 lb.minkota I use on a canoe, and it pushes it quite fast.

--I will add, it would seem to me that with a 5in prop you will loose a lot of your power and you really don't have any loss of power to spare. Also you don't have much in amperage on your batteries, most trolling motors will use just under a amp for each pound of thrust, so you can only run on high for about a hour. You can only deplete about 75% of your batteries before your start loosing top end power.
Is this a little model boat with remote control? if so then maybe my statements don't really apply.

[ 02-05-2005, 06:38 AM: Message edited by: RonW ]

[JimConlin]

I think i've heard of Piccolos being sailed or paddled.

[Bradley Stemen]

John, you may want to check with MinnKota on running their motors out of water, since there are no cooling fins or air ports in the housing the motor may overheat. Remember these motors were designed for in submirsed use, hence water-cooled.

Brad

[Bruce Hooke]

Is it your plan to pretty much only move the boat with electric power? If so then the in-rudder installation may be the cleanest and easiest approach. If you also want to sail or paddle the boat then whether you use the in-rudder approach or the through-hull approach that prop is going to create an awful lot of very undesirable drag when it is not in use unless you have some way of getting it out of the water. This boat does not have much sail area -- it can't because it couldn't stand up to lots of sail area, and it doesn't need it because it is thin and sleek, or would be without a prop dragging it down.

It may well be possible to come up with dimensions for a smaller diameter prop, but it's going to take some work. You may need to go to a three-bladed prop. Dave Gerr's prop book might be a good place to start.

Personally, putting a motor in a Piccolo feels like a bit if a sacralige to me, but it's your boat and I can see the pleasure in silently cruising along uner electric power.

[ssor]

If you are planning to install the batteries at the ends of the canoe be sure to allow for the voltage drop on the long cable run.
Also as far as propeller drag is concerned the easiest why to find the effect is to tow a tin can of the same cross sectional area as the motor and prop. A three point bridle will make it tow open end first.

[almeyer]

I don't mean to hijack the thread, but I've been thinking of doing something similar to my Penobscot 14. There was a thread some time back that dealt with building a separate rudder stock to which the shaft and power unit of the trolling motor was mounted. Much more aestectically pleasing than simply hanging the trolling motor off the transom. This would be an either/or situation - run the boat with the trolling motor, or swap rudders and run the boat under sail. the transom is raked, so that will make mounting the shaft a little more difficult, but do-able. I'm wondering if I should include any incidence on the thrust angle, the idea being that a small amount, say 5 or 10 degrees, would help keep the bow down?
Al

[ssor]

I don't think that the angle of thrust at this power level is very significant. My sloop has a shaft angle of 15 degrees and at WOT the boat settles into her own wave. So down thrust doesn't seem to lift the stern.

[Todd Bradshaw]

I wonder about building in some sort of small motor well to reduce drag when the motor isn't being used. Might be too much building hassle, I don't know. The other thing that comes to mind is that Minn Kota has done a pretty good job of designing their props to be weedless - or pretty close to it. We used to moor our trimaran in a spot where we had to cross a big weedy area in our Avon Rover area to get to it. With the Nissan outboard on I'd have to stop every fifty feet to clear the prop. I took the Nissan off, put my Minn Kota 65 on the transom instead and could cut right through the weeds. The places that might be most interesting to gunkhole in a Piccolo might be weedy at times and I doubt you want to be hanging over the side trying to clear the prop of a fixed motor installation.

[John A. Campbell]

The Minn Kota motor will only be used as an auxillary power unit (the boat is to be sailed, paddled, and occasionally powered) and if the manufacturer says that it must be run submerged for cooling purposes, then I'll use another type of 12 VDC motor of equal power..........the point is well taken about submerging the Minn Kota for cooling purposes......will check with the manufacturer on this. As for mounting the motor on the bottom of the rudder, it sounds okay but I am concerned about the weight of the motor hanging on a relatively slender rudder not to mention the appearance. And I most definitely do not want any type of outboard motor hanging on this boat. Also, will tie the two batteries together with No. 6 AWG THW stranded copper cable run through a 1/4" slot cut in the bottom of each inwale so as to be hidden from view. And I will do some more research on prop sizes.......I can obtain 3 or 4 blade polished brass or bronze props of anywhere from 1.5" to 7" diameter and bored to whatever dimension is needed.....thanks to all for their input!

[skuthorp]

I'm in the final stages of adapting a brushcutter to power my Outred Macgreggor. Doing some research on props tomorrow. Using the machine largely as-is, suspending it in a rowlock arrangement aft of the cockpit. This is 'I wonder if' stuff so I'll keep you posted. Biggest problem I can see is the speed of the motor and getting a small enough prop. I dont really need a motor but I just wondered if..........., well, you know, I couldnt resist trying.
Best part was I picked up the brushcutter free on a council throw out, and it worked first time.
If it works, then I may consider a new machine and a more professional conversion.
smile.gif

[Chris Stewart]

Originally posted by John A. Campbell:
if the manufacturer says that it must be run submerged for cooling purposes, then I'll use another type of 12 VDC motor of equal powerPerhaps I am missing something, but I can't imagine why that is a problem. I've had a few MinnKota motors, and the only part that has to be submerged is the lower housing where the prop is. If the prop isn't in the water, there is no reason whatsoever to run the motor, right?

[Banjo]

Hahah I love it.


I'm in the final stages of adapting a brushcutter to power my Outred Macgreggor Would also be handy if ya get stuck in the reeds on the riverbank too! :D

[skuthorp]

Garn Banjo! It's just for fun, just to see if a wacky idea works! Fitted a nylon prop today, the prop cage looks like being the hardest part. Course I dont know if it will work but who cares!
I'll set up a static test first in my pond of course (look out tadpoles!) just for safety's sake.
Even if it does I dont anticipate a lot of use, on the other hand if performance is stunning, well.............
:D
PS It's better than my steam canoe idea anyway! :rolleyes:

[PeterSibley]

How about an electric one(240V) and a long lead :D at least it would be quiet !!!

[skuthorp]

Peter, solar power?? I looked at an electric trolling motor but Western Port at my end can be very shallow, cm's not tens of cm's, A long-shaft motor can cope with this if fitted with a prop cage and skid I think. If I had more engineering skills I guess I could make an electric one, but this is cobbled from scrounged materials. I dont imagine I'd rely on it for primary power though, she's such a good sailer. Just a bit of fun!

[John A. Campbell]

Brad, you were right on about the cooling of the Minn Kota.....I called the manufacturer and they said the motor dissipates heat through the outer shell and NOT to run it out of water. So I'm back looking for an economical 12 VDC motor in an inboard arrangement......maybe an automotive starter motor......or something else.....anyone got any more ideas? Several months ago I entered a thread about using a Honda Mini-4 Stroke 31 cc commercial air-cooled horizontal shaft engine.....they are fairly quiet, rated at 1.5 hp, weigh 7 1/2 pounds, very easy to start, etc......I may use this approach.........I KNOW! I KNOW!...THERE WILL BE HOWLS OF PROTEST BUT "PICCOLO" WILL, SOONER OR LATER, COME TO LIFE WITH SOME SORT OF SMALL INBOARD POWERPLANT!!