120/240 boat electrical question...

[Navatech]

I posted this on the other thread but seeing as I didn't get any replies I thought maybe a thread specific to the issue will get some response...

I'm hoping the brothers that do electrics professionally (I seem to recall that we have a few of those) can advise me here...

At the time I purchased the new generator I didn't have the boat's electrical schematics, I also knew a lot less about the boat then I know now... When it came time to ship the generator the MASE rep asked me whether I wanted the generator set up as a straight 120 or as a 120/240... The (original) cable running from the electrical panel had 4 wires in it:

1. Black 4 gauge wire (presumed to be line 1)
2. Black with red stripe 4 gauge wire (presumed to be line 2)
3. White 4 gauge wire (presumed to be a common neutral)
4. Green 6 gauge wire (presumed to be a common ground)

So the generator was set up as 120/240...

Yesterday, while waiting for something else I studied the relevant electrical schematic and the actual panel... It took me a while and I had to track the wires electrically because the schematic and what's actually on the boat do not add up... Here's the schematic:



According to the yellow highlighted area the wiring is for a straight 120 volt setup... Terminal block 10DTB/120 (highlighted in red) receives power from from the generator... In the schematic the terminal block is shown horizontally with the top side receiving the power... In practice the terminal block is vertical with the left side receiving the power... And what's there is as follows (from top to bottom):

1. Black with red stripe wire: presumed to be Line 1
2. Black wire: presumed to beLine 2
3. White: presumed to be Neutral (common)
4. Green: presumed to be Ground (common)

The right side of the terminal block actually does add up to the schematic... What's there is as follows (from top to bottom):

1. Black with red stripe wire: not used
2. Black wire: 2 red wires, one connected to the "A/C" selector (off, shore, generator) switch and the other one connected to the “house” selector (off, shore, generator) switch in the panel
3. White wire: 2 white wires, one connected to the "A/C" selector (off, shore, generator) switch and the other one connected to the “house” selector (off, shore, generator) switch in the panel
4. Green wire: connected to ground strip in the panel

Looking further at the schematic (see red highlighted section) it seems to me that after the 10DTB/120 terminal block the “house” and “A/C” sections are basically separate... This leads me to “THINK” (a dangerous - pun intended - thing, especially with high voltage electricity) that this boat has a provision allow either a straight 120 volt or 120/240 volt setup... If true, then all I have to do is split the common line (see green highlighted section) in order to run a 120/240 setup... I really want to run a 120/240 setup because I want to ditch the heavy and bulky 120 volt water heater and run an on demand water heater...

Basically what I’m thinking is the following change (blue text) to the right side of the 10DTB/120 terminal block:

1. Black with red stripe wire: (a.k.a. line 1) connected to the "A/C" selector (off, shore, generator) switch in the panel
2. Black wire: (a.k.a. line 2) connected to the “house” selector (off, shore, generator) switch in the in the panel
3. White wire: 2 white wires, one leading to the "A/C" selector (off, shore, generator) switch and the other one leading to the “house” selector (off, shore, generator) switch in the panel
4. Green wire: connected to ground strip in the panel

Will this work?!... Is it safe?!...

[Bruce]

It was common for old Bertrams to have two seperate power feeds, one to air conditioners one to everything else. Most boats run every thing thru one power system shore or generator. On 120vac 50 amp service its common for current to reach peak quickly as ac power usage on 120v has higher current draw than 220v. 16k btu ac's are the biggest you can get in 120vac.

What you want to do will work. Just make sure to keep the two black leads from being hooked to to anything non 220vac.

What I would do is eliminate this system and bring 220 into the panel in one transfer switch then in the panel split it off into two 120vac legs.

Is your shore 50a 120vac? 50a 120vac is tough to find in marinas any more without getting an expensive splitter.

[Navatech]

My shore connection is two 50 amp 125 volt on each side which are indeed connected to a single 50 amp 125/250 volt cable through an expensive (I believe they go for about $800) Y connector... I think this is why my electrical panel is kinda "split" (house and A/C) in its design...

I'm also pretty sure your suggestion of basing the generator input on a 240 volt setup will require also revamping the shore connection... IOW, a pretty thorough rebuild of almost everything there... I think I'll leave that for when I revamp the whole electrical system...

[Navatech]

OK, so I found a local qualified marine electrician and, according to him, I COULD do it my suggested way HOWEVER the generator's load would never be balanced... In fact, it would be severely imbalanced most of the time... NOT a good thing so I'm going to hook up as a straight 120 connection...

MASE will have to talk me through the conversion... Their tech support guy said it was pretty easy...

BTW, MASE have been very good with their support!...

[Bruce]

It all depends on how much in the way of 220vac items you are going to use on whether the load gets semi balanced because no gen load split 220/120 is ever perfectly balanced.

If all your running is 120vac stuff then your original question on conversion was not an option to begin with.

[Yannis]

Nav, you can run at least the fridge AND freezer with solars.
For the rest pick 110 or 220 and go for it.
Now, if your hairdryer is 110 while your food processor is 220, buy another dryer or processor.
I cannot but admire, though, your schemes and structured presentation!

[Navatech]

Right now I'm only running 120 volt stuff... However, when I convert from galley down to galley up I'll have to, at least, relocate the electrical panels (32 volt and 120 volt)... Considering the age of the wiring (30 years) and its condition (abisimal is a word that comes to mind) I might as well go for new panels and redo the whole wiring...

My A/C units, though currently working, are also on their last legs... My current range & stove are also 110 and barely work... I'll get a new 240 volt unit when I do the galley conversion...

So, going forward, new panels, new wiring, redesign for 24 volt, run all heavy draw stuff (mainly A/C's, range, stove and water heater) as 240 and the rest (fridge, lights, TV etc) as 120... I'll also change to a single 50 amp 240 shoreline connection (in the cockpit)...

I'll be busy with this boat for a few more years... But she'll be good for another 30-40 years and she'll be exactly the way I like it :-)

Yannis, solar is nice but in SEF (South East Florida) with about 30 Celcious and what feels like 100% humidity whenever she'll be used the A/C's will be on so the generator will run... Plus, when you're consuming 15 gallon of diesel an hour (at least) anothe 1 or 1.5 gallon for the generator is negligible... I doubt you have 720 liter fuel in your tanks... My 46' takes 720 gallon from empty to full..

Yes, they are both Bertrams but the 42' and above models are completely different animals... Feel free to come and visit, we'll take her out into the Gulf Stream, do some deep sea fishing, maybe hit Bimini... You'll see for yourself that these boats have a very different usage then the 28's or 31's...

[Yannis]

Nav, thank you.
My best friend's ex wife had a 42. When we were younger we would spend numerous weekends on it, so I'm familiar with the 42. Also my cousin had a CHrisCraft 42 too.

The usage you're referring to, if its not fishing, is the only one I'm aware of. Swimming, clubbing at the islands, etc. Boats in the Med are mainly liveaboards with all amenities. My 28 has most of them too. Fishing is done by fishermen in their caiques, or pensioners in their little 4-5 meter grp boats. Non pro fishing is either by speargun or line, there could be a few,like you , who would do ocean fishing , but I hardly know anyone.

A typical 6-7 meter inflatable has a genny, a fridge, two convertible beds , a deck shower, a mini galley....and carries 2-4 people (family or just friends) for the whole duration of the summer vacation, usually more than a week. All boats of American origin that one might see around use their cane holders for the broom and to hang swimsuits...A different world. Much more interesting to me too, as I hate fish and its smell, but even if I didn't, there wouldn't be anyone to go with me to fish !

[Navatech]

Boats in the Med are mainly liveaboards with all amenities.

Basically floating caravans (or what they call RV's in the US)... That can be fun too... Island hopping in the Caribbean or SEF... Miami to the Bahamas to Key West back to Miami through the Keys is quite a trip... And that's one of the reasons I went for something like the 46' as opposed to a center console... Admiral and half of the mates aren't fishing fans...

I hate fish and its smell

In order to suffer the fishy smell you first have to catch some fish... And fresh fish doesn't really smell that fishy... Once you hook up a fighting fish say like a sailfish or any of the other billfish or a big tuna you'll enjoy the fight... It's not like most of the fishing in the Med where people bottom fish for grouper etc... Where once hooked all you have to do is pull in the line... This is different... Especially if you don't use heavy equipment and line... You set the drag on the reel to be below the test strength of the line... When the fish is taking line it's fighting the drag... But then again, you might find yourself spinning the real against the drag too...

It's fun... And you don't have to like fish... Catch and release also works... I'm not a fan of mounting (taxidermy) so if I can't or won't eat it I throw it back...

[Yannis]

Nav, I'll be sitting dringing ouzo and eating sea urchins while you fish.
When you come back from fishing, I might be taking a nap, so don't be noisy; We're invited at that party tonight, remember?

By the way , there are quite a few seaworthy boats around here too. I got one for starters.
I thank you for the offer too, who knows, it sounds tempting !