Marine System for 48' Sailing Catamaran

Boatsmith · March 2014

Hi. I am building a sailboat for a client and we have decided to install a solar charging system. I would welcome thoughts about our system.
system specs so far:
Honda 2000 gen set
6- 245 watt sharp solar panels wired in two banks of 3 wired in series through 2 Morningstar TS40 controllers. The banks would be to port and stbd on either side of the bimini. The boom and sail will shade one or the other sometimes. The house batteries are 4 245 a/h AGM deep cycle batteries from West Marine. Total load underway could be as high as 400 amps a day. AC is provided via a GP-SW2000 pure sine inverter, for the water heaters
(1-2.5 gal. 1-6 gal) and big LED tv and tools. Engine starting batteries are 75 a/h AGMs. Engines are 2- 70 hp Yamahas with 17 amp alternators. The house batteries can be used as one bank or as two banks. Boat can be seen at present completion on youtube if you look for Boatsmith. Thanks, please bring it!

BB. · March 2014

Re: Marine System for 48' Sailing Catamaran

Welcome to the forum Boatsmith!

Boatsmith wrote: »

Hi. I am building a sailboat for a client and we have decided to install a solar charging system. I would welcome thoughts about our system.
system specs so far:
Honda 2000 gen set
6- 245 watt sharp solar panels wired in two banks of 3 wired in series through 2 Morningstar TS40 controllers. The banks would be to port and stbd on either side of the bimini. The boom and sail will shade one or the other sometimes. The house batteries are 4 245 a/h AGM deep cycle batteries from West Marine. Total load underway could be as high as 400 amps a day.

Lets do this in pieces... Is this a 12 or 24 volt battery bank? And the batteries are 4x 12 volt @ 245 AH?

And are you looking at a 400 Amp*Hour (at what voltage) per day? Mostly at night, during day time too?

How much at time at port (shore power) vs sailing (engines off) and/or anchoring out?

AC is provided via a GP-SW2000 pure sine inverter, for the water heaters (1-2.5 gal. 1-6 gal)

Anyway you can use fuel (diesel, propane, etc.) for the water heating? Solar Electric is usually pretty expensive/difficult for portable installations.

and big LED tv and tools.

LED TV--look for the lowest power you can find (most efficient). Conservation is almost always a better investment vs trying to generate more electricity.

Tools--What kind of tools? Hand drill, welder, compressor, etc.?

Engine starting batteries are 75 a/h AGMs. Engines are 2- 70 hp Yamahas with 17 amp alternators. The house batteries can be used as one bank or as two banks. Boat can be seen at present completion on youtube if you look for Boatsmith. Thanks, please bring it!

Is the engine bank and house bank the same voltage (12/24 volt?). How many 75AH batteries (voltage/AH battery bank)?

Can you install larger Alternators? 17 amp is pretty small (just enough to charge the engine batteries?).

I like the Honda--But since you already have diesel on the boat--Could a small marine diesel genset or even a good sized true marine alternator (like a Balmar) on at least on of the engines. Saves having to fuel up/transfer gasoline except during extraordinary situations.

I worry that solar is not going to be a great solution if you need a lot of power... You might be looking at ~1,500 Watt*Hours (maybe 100-200 AH per day at 12 volts--really rough guess) from your array in "arbitrary" conditions (i.e., if 1/2 the array is covered under one tack or the other, or at anchor.

Where will the boat sail? Where there is lots of sun?

-Bill

Sandy · March 2014

Re: Marine System for 48' Sailing Catamaran

400 AH/day? at 12V? that's quite a bit of power - I assume a lot of it will be going into those water heaters. A typical cruising sailboat for 4 people will have a budget of about 100 - 160 AH/day, 50-75 of which are for the 'fridge. It sounds like you have outboards, so no big alternators there, right? Not that you have to follow the crowd, but must boats will run the engine for a few minutes to make hot water - it's more efficient than electric for that. One option wold be to install a water-cooled genset, which could run the water heater. With that size load and that house bank, you'll probably have to run the genset anyway to make hot water. You can also find instant water heaters that run on propane. (Make sure you vent those well!).

- Sandy

westbranch · March 2014

Re: Marine System for 48' Sailing Catamaran

a few quick thoughts from a long-since-sailor....

Do not run the panels in series as the variable sunlight will essentially kill the output from series connected panels.
This will limit you to 12 v though 24 v would be better for line loss etc but you would need a true (NOT GT panels) 24V PV panels so no series set up.
Get a good quality MPPT charger , look at Marine model MidNite Solar KID, good for ~ 1000W of panels, you will have to match the panels to it.
Do not expect max out put from all the panels so design for a long term average ~ 70% of 1/2 of array name plate value, yes some days you will get more but you will swing on the anchor so it averages out... If the PV s are flat on the deck, plan on less than that 70%.
Essentially you would have a 'virtual array', one one CC, probably the best of both worlds on a large sail boat.
match the Inverter/charger to the battery bank.

HTH, enjoy...

niel · March 2014

Re: Marine System for 48' Sailing Catamaran

if those are 6v agm batteries at 245ah for a 12v system then drawing 400ah will present a problem as you don't want to draw off more than 50% of your capacity to preserve battery life. same problem if they are 12v batteries in a 24v system.

now if they are 12v batteries each at 245ah in a 12v system then the total ah available is 4x245ah=980ah and 400ah would be less than 50% of that.

mike95490 · March 2014

Re: Marine System for 48' Sailing Catamaran

Boatsmith wrote: »

Total load underway could be as high as 400 amps a day.

AC amps or DC amps. peak amps or amp hours? Gotta get the numbers right now, not 2 weeks out, and dead radios.

AC is provided via a GP-SW2000 pure sine inverter, for the water heaters
(1-2.5 gal. 1-6 gal) and big LED tv and tools.

water heaters ?? You are kidding ? Electric water heaters ? There are diesel fuel domestic water heaters. use them, forget electric.
The "house" battery bank, 12, 24, 48V ??

Engine starting batteries are 75 a/h AGMs. Engines are 2- 70 hp Yamahas with 17 amp alternators. The house batteries can be used as one bank or as two banks. Boat can be seen at present completion on youtube if you look for Boatsmith. Thanks, please bring it!

Go to Balmar and upgrade those useless 17A alternators to something else. Diesel engine, or gasoline ?

Boatsmith · March 2014

Re: Marine System for 48' Sailing Catamaran

Thanks for the input.
There is no diesel on the boat. Yes the outboards have pitiful alternators. An on demand propane water heater has been discussed but shelved for now due to cost and installation requirements.That would be the first choice but we needed to decide that earlier on. It is an alternative that can be added later if needed.The batteries are 12v in 12v banks. Small tools such as drill, mini grinder. The water heater elements are 1000 watt elements and are energized as needed. they will run off the Honda and the we accept that heating water would be a good time to use the Honda. The reefer will use 60-100a/h a day? depending upon load and air and water temps. Well insulated 7cf box. Reefer usage is all day, at sea the autopilot will use about 170 amps in 24 hrs. Lights are all LED. TV draws 65 watts. If we run the autopilot 24 hrs and use both water heaters 1/2 hr and full electronics (radar at 20 %) we end up with about 400 amps a day,mostly 12v except the WH. 2 12v starting batteries. Initially the boat will be delivered to San Fransisco then probably points further south.

vtmaps · March 2014

Re: Marine System for 48' Sailing Catamaran

Boatsmith wrote: »

The house batteries are 4 245 a/h AGM deep cycle batteries

Boatsmith wrote: »

The batteries are 12v in 12v banks.

OK, so you have four AGM batteries in parallel. That is NOT best design practice. Short discussion here. The problems with parallel batteries are more pronounced with AGM batteries (because of lower internal resistance) than with flooded batteries.

Other than the inherent instability of parallel batteries, there is a statistical reason to avoid parallel batteries. You have 24 battery cells. They are NOT all above average, and the weakest of the below average cells will determine the lifespan and capacity of your entire bank. When one cell goes bad, it will take down the whole bank. At first, the bad cell will be masked by the other parallel batteries, and then after charging the batteries you may find that some batteries are discharging themselves into the other batteries. The whole bank will fail rather precipitously.

Statistically, the fewer cells you have in a bank (series or parallel), the less likely you are to have an outlier weak cell. A single 2 volt cell would be (from a statistical perspective) the ideal battery bank... half the 2 volt battery banks are above average. If you have 24 cells in your bank, there is virtually no chance that the cells could all be above average, and you have increased your chance of having an outlier weak cell. Your whole bank is no better than the weakest cell.

Of course, a 2 volt system is not practical. Best practice is to have a single string of cells at the lowest voltage that is practical for your current flows. If you can get by with 12 volts, that is better (statistically) than 24 or 48 volts as long as your battery cells are large enough to give you the capacity you need with a single series string. btw, you would have the same energy storage in your battery bank if you reconfigured it to be four batteries in series at 48 volts. That would be a more stable battery bank, but it doesn't help with the statistical issues. Your ideal battery bank would be six 2 volt, 1000 amphour batteries.

I'm not saying that four batteries in parallel can't or won't work... but you should be monitoring the bank (DC clamp ammeter) frequently for current imbalance. When you find (inevitably) one of your 12 volt batteries is weaker than the others, you should pull it from the bank and run on the other three batteries.

--vtMaps

mike95490 · March 2014

Re: Marine System for 48' Sailing Catamaran

Boatsmith wrote: »

Thanks for the input.
There is no diesel on the boat. Yes the outboards have pitiful alternators. An on demand propane water heater has been discussed but shelved for now due to cost and installation requirements.That would be the first choice but we needed to decide that earlier on. It is an alternative that can be added later if needed.The batteries are 12v in 12v banks. Small tools such as drill, mini grinder. The water heater elements are 1000 watt elements and are energized as needed. they will run off the Honda and the we accept that heating water would be a good time to use the Honda. The reefer will use 60-100a/h a day? depending upon load and air and water temps. Well insulated 7cf box. Reefer usage is all day, at sea the autopilot will use about 170 amps in 24 hrs. Lights are all LED. TV draws 65 watts. If we run the autopilot 24 hrs and use both water heaters 1/2 hr and full electronics (radar at 20 %) we end up with about 400 amps a day,mostly 12v except the WH. 2 12v starting batteries. Initially the boat will be delivered to San Fransisco then probably points further south.

are these 12v amp hours, or 120v ah ??? BIG difference.

Sandy · March 2014

Re: Marine System for 48' Sailing Catamaran

Where are you getting these numbers from? A "well insulated 7cf box" won't use 100 AH unless you leave the lid off or consider 1" of foam to be "well insulated" (3"-4" is the norm). Check the forums on what other people are using. Ditto for the autopilot. It won't run all the time. Check the forums, or talk to other people about what they get. Start with 15A times one second every 30 seconds, or 1/30 x 24 hrs = .8 hour = 12AH. Or double it and get 24 AH, maybe more in a storm. 170 is not realistic. (Better yet, use a vane).

Vtmaps is spot on, though on a practical basis figure on L16 or T-125 type 6 volt batts to get the most amps into as few volts as possible. A lot of people find that there's just no way to avoid some parallelling, so use 4 L16s in two banks of two. If you do that, put a switch on them so you can isolate each 12V set for testing or problem resolution.

CDN_VT · March 2014

Re: Marine System for 48' Sailing Catamaran

Boatsmith wrote: »

The water heater elements are 1000 watt elements and are energized as needed. .

Over propane SOD ?
Your not going forward .
Recalculate as my GPS say's .
Sailor of our Vessel , and there are killer wind turbines that are so scary on a good breeze.

Rethink it.
VT

Boatsmith · March 2014

Re: Marine System for 48' Sailing Catamaran

Amp /hours are figured in 12 v.The batteries are bought and the battery boxes fit 2 banks of 2 8ds. Next boat can be designed using other batteries. Owner does not want a windmill. They make a lot of noise and vibration. The ice box has 5-6" of insulation. But if we load it up to make ice for the cockpit cooler or excursion cooler and the water temp is md 80's and the air temp is mid 90's it will run pretty hard. The boat is a light fast boat and windvanes don't perform as well as electric pilots. The boat accelerates quickly on puss and the apparent wind angle goes forwards and the vane drives off and the boat then slows and the wind comes aft and the boat again heads up. Too much serpentine action. Vanes work much better on monos and condomarans.

mike95490 · March 2014

Re: Marine System for 48' Sailing Catamaran

towable generator ?

Boatsmith · September 2014

Re: Marine System for 48' Sailing Catamaran

The 400 a/h figure is very likely close to twice what normal consumption will be. Yes , the Honda will be likely for hot water. The on demand gas was not considered until late in the project. It could be added later at at significant cost if the water heaters load proves to be inconvenient. The panels have been changed to Aurinco Suncatchers. Six 150's and two 132's, 1164 total. Thinking 8 individual controllers , would like to use the Genasuns, which are rated at 10.5 amps, but only 140 watts, panel specs are Isc 8.48 amps but 150 watts. The Genasuns fit waaay much better for my mounting/ wiring options. I also don't want to overwork a controller. I am thinking the BlueSky Pentametric for a monitoring system. Also house batteries are in two separate banks. There are three ACR connecting the two house banks and the two starting batteries. Would I want to be able to send all solar input into one house bank while drawing from the other?This would enable me to achieve full charge more often in each bank. Thanks for the input so far.

Boatsmith · November 2015

System is installed. Went with 4 Blue Sky mppt controllers; 3 2512's and a 3000i as a master. We ran 2 panels , each with 6 awg to a controller and then with 2 more 6 awg wires to a bus bar with 2/0 from there to the battery switch which decides which pair of 8d AMG batteries gets charged. There is a trickle charge from one of the controllers to the starting batteries. There is a Pentametric battery monitoring system with a shunt for each battery bank and one for the solar input. The system is performing very well . The boat has not left the dock except for short test sails so the loads have not been significant. The two house bank system allows one bank to be completely charged while we are drawing one bank down. We are thinking of adding a smaller inverter to handle just the TV and computer charging loads. Right now the end of November in Palm Beach FL pointed south with 1/2 the array shade by the main sail at 11 am with 13.3 amps going in. Maximum we have seen so far is 45 amps

Dave Angelini · November 2015

Try and always keep in mind how critical it is too keep the voltage from exceeding the spec. I say try because there are always things on a cruising boat that keep you busy. You probably have check lists and a significant other (co-captain) who adds to the lists. I use to cross things off even if i did not do them. Good to feel good about things getting done in bad weather. Do not cross off the battery voltage getting too high. It will take you back to the docks for batteries and that is the last place a cruising boat wants to go.
Fair winds and following seas!

Marine System for 48' Sailing Catamaran

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