Trolling motor for aux power

[LP]

Just curious if anyone out there would consider using a trolling motor as their auxilary power in a 16' daysailer.

My thoughts would be to mount it to the rudder or at least have a mechanical interconnect between the sailboat tiller and the motor tiller to have the advantage or vectored thrust and rudder steerage.

I see the advantage of reduced weight on the stern of the boat, as compared to a gas powered motor. Increased weight where it should be. i.e. the battery located down low and towards the center of the boat. Quiet operation. The addition of lights to the craft. A cleaner and less bulky installation than gas. Possible conversion to a solar charging system in the future.

The main disadvantage that I see is the need to periodically recharge the battery. The boat is not a cruiser so I don't see it as a major problem.

I'm open for input.

[Ike]

You would have to strap the battery in very securely in case you capsize. You don't want it falling out or sliding around.

[FAST FRED]

Should work just fine , an AGM batteruy would work with out the chance of an acid spill.

One HP from an engine will produce about 20 lb of thrust from a reasonable propeller.

The electric motors are RATED in thrust , making the selection EZ.

FAST FRED

[DanishBagger]

I'll stick with a paddle, but it seems like a good idea that one, especially if you consider pollution and noise (or lack thereof) in comparison to petrol auxillary.

One thing, though, how about charging it, have you considered how you will do that until you get the solar charging thing up and running? I mean, it's a small boat and all, and batteries are heavy. Or do you take your boat home with you (i.e. no problems then)?

[LP]

Fred,

I was hoping to get some positive response. Thanks for the numbers. I hadn't sat down yet to convert HP to thrust or vise versa. Yeah, I was thinking of going with a gel cell battery. In a standard lead-acid battery, I'd be concerned with battery fumes. Is this also a concern in an AGM type battery?

DB,

The boat is trailerable, so it goes home with me. I'll just get an inexpensive battery charger. I drove 12-14 hours one time to get down to the gulf of mexico and could only manage to wander around in the channel because the winds were squirrly and the current stiffled any progress we made. Long story short, a little bit of a kick would have gotten us out of the channel and on our way.

[Figgy]

I used a trolling motor (with lead-acid batt.) on my Coronado 23 for awhile with absolutely no problem. Pushed her right along!
edit: It was20lb. thrust.

[kjell]

I was using this trolling motor as an active rudder on my catamaran with very good result.

[yokebutt]

Kjell,

With the standard propellers you are typically stuck at 2-1/4 knots.

Yoke.

[LP]

Yoke,

Are there different pitched propellers for trolling motors. I suppose trolling motors are pretty limited and specific in any change pitch to their propellers. A displacement hull would be easier push than a planing hull could, I would think, be able to accept a higher pitched prop. Is there an effect on power consumption? From your statement, it sounds like these motors are designed to operate at a max top speed of 2 1/4 kts.

[Figgy]

For what it' worth now, it is a 32# thrust, not 20. Don't know what I was thinking.

[Figgy]

Are there different pitched propellers for trolling motors.
If you don't mind me answering that, I only found one, the Vanishing Prop from Minn Kota. I would'nt worry so much about pitch as I would thrust.

[LP]

The problem is that the thrust rating is only accurate at one speed. It could be at static power or it could be at a certain speed. There is a speed limit on any prop based on pitch and RPM. The drag of the boat obviously comes into play too. The point I'm trying to make is, a displacement hull offers lower resistance than does a comparable planing hull, would I be operating at a lower efficiency with a standard prop due to the fact that my mission is different from the trolling motors intended mission? And, if so, can I increase the efficiency by increasing the pitch of the propeller? (if such a beast even exists.)

[LP]

For what it' worth now, it is a 32# thrust, not 20. Don't know what I was thinking.

Do you have any idea of what speed you attain.

From most literature that I've seen, the emphasis is on low speed power and dealing with weeds. (I think)Top end efficiency isn't part of the performance profile in a trolling motor.

[Figgy]

Do you have any idea of what speed you attain.
Well I didn't leave much of a wake, but it got the job done. 3 to 4 knots was about it, and it took a few seconds to get there, no kiddin'.
Top end efficiency isn't part of the performance profile in a trolling motor.
No, its not. But the manufacture does expect fishermen to fight currents. While you might not have any numbers on top speed or efficiency, i would'nt by too worried. Do you have a friend you could borrow one from, maby try it before you buy one?

[LP]

Thanks for the input. If your getting 3-4 kts with 32#'s on a 23'er, I shouldn't have any problem with 40#s on 16'.

[Figgy]

Thanks for the input. If your getting 3-4 kts with 32#'s on a 23'er, I shouldn't have any problem with 40#s on 16'.
No.. I don't think you will have a problem:) Good luck!

[LP]

No.. I don't think you will have a problem:) Good luck!

I notice your location is San Diego. Are you using a saltwater motor? The smallest one I've found is a 40#er by Minnkota. In fact, they are the only saltwater trolling motor I've found. Are you aware of any others?

[Figgy]

I really didnt want to spend the money on one. I just take it off, bring it home with me, and wash it really good. I havent had one problem yet.

[Figgy]

Wow, I sound so cheap! At the price I paid, and the fact I wasnt going to leave it on the boat, I'm not too worried. It's not stuffed in a damp environment, and I take care of it. Personally I wouldnt spend the money on a saltwater motor. Some here are going to disagree.

[messabout]

I have a Thistle (17 ft.) that is converted to a beach cruiser. A 28# Minn Kota pushes the boat along at , I'm guessing, 3 knots. It takes several seconds for the boat to come up to speed. The all up weight of the boat is about 600 pounds. Strong head winds or tide diminishes performance of course. It still works. The battery has given no trouble, but I have not motored for long periods of time...15, 20 minutes maybe. Birdwatching and other voyeuristic pursuits make the electric a joy to use. No noise, no fuss. The boat has a 9.9 Johnson with an alternator. The gas engine has kept the battery topped up quite nicely. The gas engine is for use in rivers and other places that are difficult to sail. The 9.9 is way too much power for this application so it runs at idle most of the time.

A larger electric, like the 40 pounder, would be plenty of power in most circumstances, however battery drain will need to be monitored more closely.

[LP]

I've had the boat now for a couple of year's now without using any motor and have managed. There have times though when a kicker would have been nice. I figure it's primarily going to be used to maneuver in and out of marinas, occasionally save me when the wind dies and, at the extreme, help me go to windward when time constraints keep me from beating to windward.

The last scenario is also worst case in regard to battery consumption. I purchased an Optima gel cell marine battery, but it is only rated at 55 AH. I will probably return it for a higher AH rated battery. The specs. that I received for a 40# thrust motor are 42 amps at full power, 8 amps at 1/5 power with 8 amp increments up to full power, give or take. Thats 1.3 hours at full power and 6.8 hours at 1/5 power on a full charge. I'm sure actual usage will fall somewhere in between. A 100 AH would double those values, but I'm hessitant to sacrifice the safety of a gel cell.

Due to the expense of gel cells, I'm thinking of going with an AGM, but I believe these batteries are also expensive for the AH rating. My main concern is to not have an acid spill if the boat is upset. I'm wondering a sealed marine deep cycle would offer adequate spill resistance for my use. I'm also concerned about battery fumes. I believe that the gel cells, AGM's and the sealed batteries are all safe in this regard. (?)

[mattotoole]

Just curious if anyone out there would consider using a trolling motor as their auxilary power in a 16' daysailer.

My thoughts would be to mount it to the rudder or at least have a mechanical interconnect between the sailboat tiller and the motor tiller to have the advantage or vectored thrust and rudder steerage.

I see the advantage of reduced weight on the stern of the boat, as compared to a gas powered motor. Increased weight where it should be. i.e. the battery located down low and towards the center of the boat. Quiet operation. The addition of lights to the craft. A cleaner and less bulky installation than gas. Possible conversion to a solar charging system in the future.

The main disadvantage that I see is the need to periodically recharge the battery. The boat is not a cruiser so I don't see it as a major problem.

I'm open for input.

Schock's Harbor 20 (http://www.wdschock.com/boats/harbor20/harbor20.htm) uses a trolling motor for auxiliary power. So check out the specs, and possibly contact a Harbor 20 owner for an explanation and/or demo.

[LP]

Here's what we ended up with.

[DanishBagger]

That looks nice (I mean, if you have to have an engine). Much better solution that most I have seen.