Re-Wiring a Really Old Boat

[Rugger8]

I have been lurking on here and learning a ton about everything, but this is my first post. I am in the process of re-wiring my 1947 Chris-Craft, which still had the original wiring. I have nearly completed the AC side of things complete w/ 2 30A shore power inlets to a Blue Sea 8086 combined AC/DC distribution panel. 2 galvanic isolators installed as well. In process of bonding everything, as well. Now starting to think about the DC side of things and wanted to discuss the batteries.

I tyically use my boat for day trips but would like to be able to stay out on the hook for a weekend without issues. While my boat does not leak very much, all wood boats leak some and thus it is imperative for me to have my bilge pumps working at all times. I do not have solar or wind currently, but have a 2000 W portable generator, that I would only like to use for emergency purposes. I am installing 12V LED lights to reduce usage and have calculated an estimated Ah per day usage of aroun 80 Ah. That does not include an operating refrigerator. (I would load a cooler up with ice for the weekend).

I have space for 5 group 31 batteries and I have a 40A charger. I am thinking of using Odyssey batteries Odyssey 31M-PC2150T Group 31M Marine AGM Battery
, which have a 100Ah rating, but also 1150 CCA. So I could use them for both house and starting batteries. My question is, do you think it is reasonable to use 1 battery as a starting battery for both engines or should I have 1 separate starting battery for each engine and then the other 3 in parallel as the house battery. Obviously, if I only use 1 starting battery, then my house bank would be 400Ah instead of 300Ah, which provides a lot of extra power. I figure in an emergency, I could use the house battery to start the engines.

Let me know what you think.

Thanks,

Jeff

[Rugger8]

I forgot to mention, that I have the original Hercules engines with generators not alternators. Therefore, they do not put out enough power to really charge the batteries, only enough to maintain charge while running. I will probably look at putting in alternators, which if I go with the 2 bank idea (1 starting, 1 house bank), then I could have a alternator charge each bank.

Jeff

[SV Demeter]

Whoa you got a whole lot going on here but one thing jumped out at me. Bonding on a wood boat... Are you sure you really want to do that???

Donning flame retardant forum suit now.

[Rugger8]

well, I know there is a lot of views on this, but after reading calders and wings books, they acknowledge the debate but both indicated that it was generally accepted best practice to bond the boat. At least that's how I interpreted what I read. My understanding is that by bonding everything metal that goes through the boat together, coupled with galvanic isolators will provide protection from stray DC currents up to 1.2V. Above that I would be in trouble. The boat is mainly in fresh water, so from that point, you could argue that it is not necessary, but at the same time, if it provides more protection from galvanic corrosion, then I am willing to do it. But if there is a good reason not to do it on a wood boat, then of course I will pass. Originally it was not bonded and there were no galvanic isolators, but that was 1947, so will update to better where appropriate.

Jeff

[SV Demeter]

Bonding a wooden boat is an invitation to rot. I would rather live with some electrolosis and maybe have to replace a few metal underwater items every 5-10 years than deal with the rot that bonding will lead to. You say the boat was not bonded in 1947, how bad is the underwater metal on it? I would venture to guess it was not all that bad, and you probably dont have rot issues around your underwater metal fittings either. Yes lots of opinions on this stuff for sure. Calder speaks to this rot too in his books. I personally have just seen more problems with boats that were bonded than with the ones that were not and frankly the underwater metal fittings just are not that expensive to risk damaging all the other stuff on a boat that bonding can lead to. But hey its all just opinions here and my advice is worth what you paid for it.

[Chief Engineer]

I saw a wood boat that was "bonded". It was an unbelievable disaster.

The wood was "shot" at the rudders, shaft struts and thru hulls.

If I recall correctly it was an old Matthews

[delmarrey]

Re-Wiring a Really Old Boat

It's not a 6 volt system, is it?

Bonding has proven to be a not-so good idea. Fittings are usually different sizes and erode at different rates. So the process is as only good as the fitting itself.

To Marry or Just Live Together (Bonding)
Current wisdom is not to bond thru-hull fittings.

http://www.michel-christen.com/2T-H.pdf

[Ike]

Well it sounds like you have got your act pretty well together. However I would go with a separate starting battery for each engine. Starting requires lots of amps all at once which while it won't hurt a deep cycle battery if done in an emergency, such as a dead starting battery, but they are really better at slowly releasing amps over long periods of time. that is why the construction of the plates in starting batteries and deep cycle batteries is different.

I would also change out those generator s for alternators.

I also have huge misgivings about portable generators on boats. Frankly I think they shouldn't be on boats. See Portable Generators On Boats Pro and Con http://newboatbuilders.com/docs/portable.pdf

As for the bonding issue. Some very well respected people recommend bonding on wood boats. Some very well respected people think bonding on wood boats is a bad idea. Some more reading Corrosion on Boats http://newboatbuilders.com/docs/CorrosionOnBoats.pdf This is a very controversial subject. If your boat has been bonded for years and the fasteners are still holding the planking on, then I wouldn't worry about it.

[Rugger8]

Thanks Escape, Engineer and Delmarvay.

Just so you guys don't think I am a complete idiot. I have read both Calder's and Wing's books and both indicated there is a lot of argument on this, but the general consensus was that bonding was the way to go to protect metal components that are in the water. What is new to me, is the discussion that in wood boats, the wood itself deteriorates when bonded, causing potential catastrophic failure. I posted what I was doing on both the chris craft website and the wooden boat magazine forum, but did not get any warnings on this. I even had a marine engineer look at what I was doing and he indicated that since I installed galvanic isolators, I need to bond everything. Obviously, it appears that bonding for wood boats may be a different story. If I think on it now, the boat was unbonded for 65+ years and the fittings appear solid, so why would a new system be better. In any case, thank you for pointing this out. I am going to re-read calder and wing and see if I missed something. If there are others out there with experience with this please reply as obviously this is a very serious issue that I want to get right.

Thanks,

Jeff

[Strygaldwir]

I have been using a single starter battery for my two engines for several years now. I have never had any issues. I do have battery switches that allow me to use the house bank ( 750 amp hours) to start the engines in when I choose. Combined with a portable generator, this has served me well over the years.

I will say I was VERY hesitant to try this configuration originally, but time is proving it to be a very workable solution.

[Ike]

The issue of whether to bond or not to bond on wood boats is really all about corrosion of metal fasteners, the screws that hold the planks in place. Generally speaking the screws are counter sunk into the wood and a bung is put in the hole to seal it. These days it may all be coated with epoxy, but on your old boat that's not the case. Then water seeps in one way or the other, but oxygen is excluded so sodium hydroxide forms around the fastener, that eats the wood and the screw. You can't tell unless the wood around the screw darkens which doesn't always happen. Usually you don't know until you remove the bung and try to remove the screw and all you get is the head. But you can tell by spraying white vinegar on it. The White Vinegar reacts with the sodium hydroxide and foams.

This is strictly a chemical process. But some people think that stray currents can make it worse, or even initiate the process. Thats what the galvanic isolators are for. They block stray currents. But since the green wire (AC grounding wire) is also connected to the boat's ground, and so is the DC and the bonding wire, some people believe that even if you have a galvanic isolator it won't stop stray current from the bonding system. The stray current supposedly enters the water through the metal fittings that are all connected. They then think this accelerates the wood burning around the fasteners.

Personally, I don't think so. I believe it has everything to do with how well the fasteners are sealed into the wood. But others disagree.

However, as I said, If what you have has worked for all these years don't screw (bad pun) with it.

[delmarrey]

Originally Posted by Ike

The issue of whether to bond or not to bond on wood boats is really all about corrosion of metal fasteners, the screws that hold the planks in place. Generally speaking the screws are counter sunk into the wood and a bung is put in the hole to seal it. These days it may all be coated with epoxy, but on your old boat that's not the case. Then water seeps in one way or the other, but oxygen is excluded so sodium hydroxide forms around the fastener, that eats the wood and the screw. You can't tell unless the wood around the screw darkens which doesn't always happen. Usually you don't know until you remove the bung and try to remove the screw and all you get is the head. But you can tell by spraying white vinegar on it. The White Vinegar reacts with the sodium hydroxide and foams.

This is strictly a chemical process. But some people think that stray currents can make it worse, or even initiate the process. Thats what the galvanic isolators are for. They block stray currents. But since the green wire (AC grounding wire) is also connected to the boat's ground, and so is the DC and the bonding wire, some people believe that even if you have a galvanic isolator it won't stop stray current from the bonding system. The stray current supposedly enters the water through the metal fittings that are all connected. They then think this accelerates the wood burning around the fasteners.

Personally, I don't think so. I believe it has everything to do with how well the fasteners are sealed into the wood. But others disagree.

However, as I said, If what you have has worked for all these years don't screw (bad pun) with it.

Sealing is the key to keeping fasteners. As a previous wood boat owner (boat was 20 YO) I've had to replace fasteners. The ones I could get out were still sealed. And the ones I couldn't the bungs had fallen out. The unsealed ones I could get out, the heads were almost eroded away but the threads were fairly good.

It comes down to the quality of the work. Sealed with bungs and a good bottom paint job. I'm not sure a barrier coat on a planked hull would work. I would think it would crack at the seams as the boat flexes.

Now a days the thru-hulls can be sealed off from the wood with epoxy so the the bronze is not even in contact with the wood. Which would eliminate the rot to bronze problem. Or one could use Marelon fittings.

[GordMay]

Michael Kasten writes, in "Corrosion, Zincs & Bonding"

“... On a wooden boat it is extremely difficult to recommended bonding of any sort, due to the extreme problems created for any wooden structures in proximity to the noble fittings. Consider the following: In the galvanic couple created by bonding, the protected fittings are the cathodes and the remotely placed sacrificial zincs are the anodes. The water-soaked wood below the waterline is electrically conductive. In the area around each of the noble metal fittings (the cathodes) highly alkaline sodium hydroxide is formed, and the wood is destroyed. A white fluff is formed that looks like small ice crystals or snow, and is very caustic. The lignin is stripped out of the cellular matrix of the wood leaving only soft spongy cellulose behind. Sodium hydroxide, where found, can on the surface be neutralized with vinegar, but the problem is not cured.

On a wooden boat, the system put aboard to protect the underwater metals eats the boat instead! ...”

"Corrosion, Zincs & Bonding"
Here ➥ http://www.kastenmarine.com/_pdf/mbqCref.pdf

See also his “Marine Metals Reference”
Here ➥ http://www.kastenmarine.com/_pdf/mbqMetRef.pdf

[Ike]

Yep, I know what Michael says. Even the USCG has a NVIC on this. But they only caution about it. As I said, I don't agree, but I do agree that everybody disagrees. who do you beleive? I don't know.

The first time I saw something on this was back in the eighties. It was an article by Giffy Full probably the #1 wood boat surveyor ever. He was against it. But since then I would say the opinions run 50 50.

[Rugger8]

Well, thanks everybody. At this point, I think I will stick with history. IE, the boat was unbonded for 65+ years in saltwater and did not have any issues with wood rot around fittings. Also, the fittings seem to be very solid as well. I am now mainly in freshwater as well, so galvanic corrosion should be less of an issue. So, I will keep it unbonded.

Any other thoughts on the battery arrangement and the Odyssey batteries in particular. Seems like these are deep cycle, but with a significant amount of CCA's that should also be suitable for starting.

Thanks,

Jeff