Propulsion Pros & Cons

[rgranger]

Hey All:

I'm hoping you all can help me think through a decision I'm trying to make.

I'm now into the restoration of my 4th project boat in 10 years (a new 2-me Mac V222) and I'm trying to decide between to radically different propulsion options.

My first two boats (A Mac V21 and a Coronado 23) I powered with a 65lb thrust trolling motor. I kept two batteries on board that would get me through a weekend and I had a trickle solar cell to charge them back up. This worked fine for me since I was a weekend sailor on a reservoir and the trickle did the job if I gave it a week between sails. My third boat had an old 2-cycle 7HP mercury. Ran fine but smelled and was loud. I really missed having a quite engine and the 7HP 2-cycle did not push the boat any better than my 65# trolling motor did.

With my new project boat.... I plan on doing some extended cruises in the Albemarle & Pamlico sound. A new honda 4-stroke is expensive (and I already have the electric trolling motor). So I'm thinking instead of a 4-stroke OB engine I would like to go back to the electric motor and I'll get one of those portable Honeywell generators ($350 at Home Despot). They are very quite, I could keep my batteries topped off, and I could use the generator to run other fun stuff while at anchor (like a small microwave oven some fans and a DVD player).

http://www.homedepot.com/Outdoors-Gener ... ogId=10053


I'm not planning on taking my V222 offshore and the 65# electric motor pushes the boat at near hull speed anyway... but before I commit to this idea... I'd like to hear any pros & cons you all might think of that I have not considered. My fear is that since I have not seen anyone else use this option, there must be a really good reason why... and I'm just not thinking this through all the way.

Thanks in advance for any insights and/or thoughts you wish to share.

Fair winds,

Rob

[TAW02]

Hey Rob, congratulations on the V222. A real worthy project for sure. Great Sailing Vessel indeed.

Never saw a trolling motor as the sole source of docking power until I saw a 25ft Watkins putter in silently one day to a launch ramp in my neck of the woods. He had just bought the boat and was putting it through its course. I can't image what it would be like being caught 5 miles out from shore with a big summer storm sweeping in. Obviously a sailboat is a good or better than any nautical vessel to be aboard when it comes to storms and safety.

I had a MAC25 at the time and it had an Evinrude 9.9hp two stroke longshaft (22in). Fastest it would push that sailboat was about 4.5 miles per hour. But it was able to do so in storm conditions with 3-4 foot chop. Here in Florida when storms come unexpectedly and can roll one storm after another, you can bet you may be stuck anchored out there for many an hour. Even overnight (calling into work sick!)

I believe having only a trolling motor for emergency landing can get you into a tight spot during testy conditions. Be that as it may, there is nothing like good ol fashioned internal combustion engines. Gotta love them

Big T

[rgranger]

Thanks T

All good points to consider.

r

[Sumner]

Most of those generators have limited 12 volt amperage output. Do you know what that one has and if so how high is it. If it does have a 12 volt output is it high enough to charge a battery. For that you need 14 volts or so. Now you could hook a 12 volt charger to the 110 volt side, but most of those only put out 10 amps or so unless you spend some money to get a nice one that will step the charge or you aren't going to gain much in my opinion.

We needed a reliable 12 volt source for the CPAP machine I use at night, so I made a dedicated...



Generator Build

....gas driven 12 volt generator/charger for what you would be spending on that one and it would probably power the electric motor indefinitely if the amp draw was under 50 amps or so.

c ya and congrats on the boat,

Sum

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[noahvale]

I didn't see him mention using the 12v output for charging. Using a regular 120v battery charger would be the way to go. Only problem I see is that deep cycle batteries should be charged at 2 amps, which will take a long time. But I guess it wouldn't really matter if you charged them faster other than the chance of reducing their lifespan. If I didn't have a good outboard, I would consider the trolling motor option too.

[Duane Dunn, Allegro]

You might find my current project interesting.

www.rudderprop.com

The goal is to offer kits to convert small sailboats to hybrid electric power.

By the way, the above statement that Deep Cycle batteries should be charged at only 2 amps is not correct.

[rgranger]

Thanks Guys....

The CPAP generator has a serious "high-tech red-neck" look to it. Very cool. I bet you turn some heads when you pull into a new port. He he.... I hope you have a glib answer ready made ....

When I have charged my batteries at home, I was always able to complete a charge by morning. So I have been doing some calculations to see if I can expect the same on my boat.

Assuming my battery charger is running at 14V then the amp output of the battery charger would be 900W/14V = 64amps. The deep cycle battery is rated at 1800 amp-hours. So if it were half discharged it would take me 900 amp-hours/64 amps = 14 hours to completely recharge the battery.

That is longer than I want...

So maybe I should spend an extra hundred dollars and get the 2000W Honewell

http://www.amazon.com/gp/product/B001DS ... KJCAGMS8EC

That would drop my charge time for a half depleted battery to ....

900 amp-hours/143 amps = 6.3 hours to recharge the battery from half dead or 13 hours to recharge a full dead battery.

If I started the trip with two fully charged batteries and I added a solar panel to the mix I think I could keep up and have enough juice in reserve for the unexpected crisis.

So.... anyone see anything I'm overlooking?

I really do appreciate y'all's insights and I'm not necessarily looking for someone to agree with me so ... tear at it if you see something wrong with my thinking here.

Thanks in advance,
Rob

[Retcoastie]

What type battery bank do you expect to cram 143 amps into for 6 hours? It is going to take a lot of lead-acid batteries to accept that current without cooking the water out. AGMs will take a much higher charge rate and should be considered if you go the electric path. They are more expensive.

[Hamin' X]

An 1800 Amp/hr battery is one serious dude. Must weigh close to 1,000 lbs. What the heck do you have?

~Rich

[rgranger]

Ah right! I screwed that one.... it is 180 ahr battery. I should never rely on my memory of things when it has been 6 months since I last looked at it.


r

[Hardcrab]

On an unpractical note, your proposed method will be inefficent at best with so many conversions taking place.
Each conversion is wasteful of the energy supplied.
Gasoline to make 110vac, 110vac to 12vdc battery charger to make high current 12vdc to keep the thrust batteries charged.
Not a real issue, but perhaps a point to ponder.

At least turning gasoline to thrust directly puts the exhaust noise underwater vice on the deck somewhere, and it will be quiet once you get to your destination.

[Sumner]

If you want to run a 110 generator and want to charge the batteries I would take a hard look at this....



http://www.iotaengineering.com/dls30.htm

....John posted it a while back and it or another one from that company is what I would get. We don't run anything on the boat off of 110, so we saw no need for a 110 generator and went straight to something that was designed to charge 12 volt batteries and it has worked great. We could also add another charge controller that would even make it work better, but haven't seen the need.

I agree with Hardcrab that with all of the conversion and waste of energy you will probably end up running the generator longer than you would running an outboard and use more gas in the process. Solar is great and we are adding to it, but it would be hard to provide enough juice there unless you are running the trolling motor for very short periods of time.

Good luck,

Sum

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[Catigale]

Something is wrong with those calcs...a 60# thrust motor usually pulls 24 Amps at 24 Volts according to Minnkota site...thats 576 Watts or about 0.6 HP - a 7HP motor should blow that away performance-wise.....even with the overall efficiency being 1/2 as good...

[mikelinmon]

Testing now the electric "Torqeedo" 401 equal to 2hp gas.(since replaced by the new "503" with similar weight and 30% more power. Worked OK on my V-23, 4.7mph for 20-30 min only. Can't see it pushing against storm but wonderfull for harbor use in and out of slip. I want one! Next will try the larger equal to 6hp. Stay tuned, maube
Mike Inmon

[rgranger]

Well maybe I should just bite the bullet and get an OB

Tohatsu seems to be the best price that I've been able to find.

Anyone with experience with this model?

http://www.onlineoutboards.com/Tohatsu- ... A3EFL.html

r