Provisioning water and power. Solar Recharging is it the right answer? - SailNet Community
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post #1 of 21 Old 03-31-2006 Thread Starter
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Provisioning water and power. Solar Recharging is it the right answer?

I intend to live aboard my MacGregor 26M. I have been warned that the three things you must be constantly aware of on a sailboat are:
1) Weight Capacity and the distribution of that weight onboard to maintain an even keel. I am going to be very, very careful about this.
2) Water Supply, especially for longer trips. I have provisioned my boat with a 35 gallon water resevoir in addition to the five gallon supply under the sink.
3) Power; I am going to have a dual battery system, especially important for my 50 hp Honda outboard. I have been told that redundancy is an absolute necessity, because most people who get in trouble on a sailboat do so for two reasons, bad weather and dead batteries.
Vigilence and a good weather radio should do as much as possible against bad weather, but...

backing up my power system so I am never dead in the water is the one that worries me.

My proposed solution:

A) A Honda EU2000i generator, which is capable of generating 2000 Watts but only weighs 47lbs.

B) Either a Coleman Solar Charging system @ 45 Watts


Can anyone help me in picking out the right recharging system?
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post #2 of 21 Old 03-31-2006
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First of allI'm wondering about the need of a 50Hp engine? If you need that much change it to an Evinrude E-tech that may even be stared manually and have a much more powerfull chargingsystem even with a splitter for dual batteries.
I carried on my trip a Honda 1000W (ie1000) which is plenty of power, but the 12 volt output is not good for charging, you need a separate battery charger.
Solar panels does (normally) not charge an empty battery, but you may probably need some 3 - Amp efective charging. I advice to have one or two smaller panels that may be directed than fixed big ones. Note that just the shadow of a stay or shroud severly reduces the efficiency.
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post #3 of 21 Old 03-31-2006
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The little Honda generators are pretty nice but you really can't do much except turn them on and use the AC power they make. As noted you can't charge batteries with them.

Your solar panel solutions are too small to do you much good. With a really efficient fridge you might be OK with 150 watts. That is about what it takes in hot climates. It's just hard getting the real estate on a smaller boat for adequate solar panels - but they do work great and are pretty much trouble free. A voltage regulator is a requirement for them too. You have a serious power problem you can't solve easily unless you don't use refrigeration and add some solar panels.

I would not consider 35 gallons of water "generous" but perhaps adequate. I would try to add another 20 if you could. You'll be hauling water several times per week.

Gasoline may be your biggest problem. A 50 HP outboard and the generator will take a fair amount of it. I too wonder about a 50 HP outboard. There is a reason?

You are facing perhaps the biggest problem - a boat large enough to hold all your stuff and tankage. It's the part you will be forced to deal with the most. It may be so full you can't go sailing. It would not be the first time that happened.

Last edited by PaulBl; 03-31-2006 at 03:26 PM.
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post #4 of 21 Old 05-04-2006
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I have a friend who recently bought a Honda EU2000i for ham radio power use, he's quite happy with the 12VDC output for charging deep cycle batteries. And, the AC output is incredibly clean for a genset, see for some photos of scope tracings.
But a gasoline genset on a small boat is a danger. Once from the gasoline, a second time from the monoxide in the exhaust and I'd be more concerned about that.

I'd opt for the genset if AC and "power now" was the need...but if possible I'd prefer solar panels and just waiting it out until the starting battery was OK. (I've used a 12V 17Ah gel/AGM cell to start an 18hp diesel, I'd guess it will start a 50hp outboard just as well if there's no pull start hidden in there. Didn't think it would work, but that's what is inside a lot of those "jump" boxes.)

The problem with solar panels is derating the output medium latitudes and mixed wx, 25-30% of the rated output for six hours is about all I'd expect on any given day. (Better in June, worse in February, etc.)

A wind or water generator might be a better idea, certainly higher power output per hour for the initial cost.
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post #5 of 21 Old 05-04-2006
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I don't know what the longevity of the Honda generator will be in a marine environment. Most cruisers and liveaboards use wind and solar generation for electricity. The problem with using a generator is that you will constantly need to get fuel for it and the outboard. Fuel is heavy... wind generators and solar panels do not require fuel, but do add some weight.

For my boat, I'm using two 130 Watt solar panels, and plan on adding a wind generator in the future. When I am at the marina, I do have a shore power system, and an A/C powered battery charger, but when I'm out on the hook, I rely on the solar panels.

The main problem with solar panels is that cloudy weather really cuts their output. Wind generators can help make up the deficit.

One thing you haven't mentioned is what your typical electrical load will be. I have converted a lot of the lighting on my boat to LED-based lights, to cut down on the electrical load.
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post #6 of 21 Old 05-05-2006
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Power management is key

The bottom line to all the charging discussion is that you MUST know 1) your daily usage in amp/hours, 2) your usable battery capacity in amp/hour--most people use 50% of rated capacity, and 3) your charging capacity in amps per hour. So, you must figure out your usage first, and only then can you decide if you have enough battery capacity to live that way. If so, then you need to match your charging ability to that battery bank, i.e. you want to be able to replace used amp/hrs regularly without straining your charging setup. If you're talking about a boat at a mooring with a small bank that has nothing normally on, then a small solar panel will probably do to keep the battery charged. However, if you have a 1000ah battery bank and use 400ah a day, obviously even a wind generator won't get the job done and an auxilary generator (diesel) would be necessary or a high output alternator that you would run once a day. It's really hard to speak to your situation without having specifics.

One thing you might consider is a low-voltage cutoff switch for a high use device like a 12v fridge. It's basically a relay switch that keeps the power on as long as your battery voltage is above a certain level, then cuts off when it drops below that (only uses about 10 mA when in use). I have one on my boat wired only for the 12v fridge so that if I go away from the boat for longer than expected I won't come back to a dead battery bank. I even use this at the marina because sometimes even shorepower fails for a while.

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post #7 of 21 Old 05-05-2006
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When you have an engine that you cannot start by hand, it is vital that you separate your battery (banks). We have, for years now, had a house bank with good deep-cycle batteries, and a starting battery or bank with good cranking power. We NEVER draw from the engine batteries for house loads. Be sure you can fully isolate the engine battery from other uses. This way if your house batteries fade away, you can be sure of being able to start your engine and recharge.
The new battery monitoring systems that track your usage and indicate remaining time can be very helpful in analyzing your usage and to let you know when it's time to recharge before it's too late. Just be sure to set them up to accurately reflect your amphour capacity.
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post #8 of 21 Old 05-07-2006
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You are trying to get a quart out of a pint pot. The mac 26 is great for what it is, but a long term passage making boat with storage capacity is not one of those.

It achieves its dual role by being as light as possible, thus it is not within its design parameters to be loaded up for cruising in the way that you envisage. IMHO either use it in the way it is designed or get a more suitable boat for proper cruising.
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post #9 of 21 Old 08-26-2006
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The reason for a 50HP motor on a 26' Mac is speed. The hull is semi-displacement and the motor can push the boat upwards of 20mph, according to MacGregor owners.
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post #10 of 21 Old 08-26-2006
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Bkohatl... You speak of longer trips. What kind of trips and where do you plan to head. Will you have refrigeration or an ice chest?
If you really plan to live aboard on "the hook" for extended periods then your boat does not have the ability to carry the needed solar and wind power to keep your batteries topped up without impairing your ability to sail! MANY cruisers today are happily charging their batteries with the little Honda...With a small battery bank and a decent small charger driven by the will have everything you need and since you are already carrying gas for the outboard, there is no additional safety risk. Just try to turn the damn thing off before dark!
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