v8kid
|
| posted on 14/5/11 at 01:27 PM |
|
|
240v wiring in a 52' concrete boat
Bro in law has just bought a part finished concrete ketch and it has a 12kw 240v genny installed. Rather than change it to 110v is it OK to have 240v
on a boat?
All the exterior stuff (winches, thrusters lights etc) will be 24/12v dc but we were thinking of having the cabins and bridge 240v ac so we could use
cheaper microwaves, computers, etc. Wiring will be done in multistrand in plastic conduit with separate earth bonded to engine/anode and rcd's
on each cct.
Anything to watch out for?
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
|
|
PSpirine
|
| posted on 14/5/11 at 01:30 PM |
|
|
A boat made of concrete, with 240v running through it? Is it just me or is that blasphemous boatbuilding? 
I don't know whether it's safe/acceptable etc. But keep in mind if you do want to switch to 110v, you can just get all your appliances
etc. from USA
|
|
|
MakeEverything
|
| posted on 14/5/11 at 02:37 PM |
|
|
240 is fine on a boat, in fact most are fitted with inverters.
As long as the protection (fuses and RCD/RCBO devices) are satisfactory and the installation is sensible. There is a specific section of the wiring
regs that covers marinas but doesnt extend to vehicles so i dont know what these do come under.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
|
|
|
britishtrident
|
| posted on 14/5/11 at 03:51 PM |
|
|
Lloyds will set the rules but where to get the info is another question you might find info in the "Category - Marine Electrical
Systems" on this page http://www.marinesurveyor.com/library.html
|
|
|
britishtrident
|
| posted on 14/5/11 at 03:54 PM |
|
|
quote:
Originally posted by PSpirine
A boat made of concrete, with 240v running through it? Is it just me or is that blasphemous boatbuilding?
I don't know whether it's safe/acceptable etc. But keep in mind if you do want to switch to 110v, you can just get all your appliances
etc. from USA
In WW2 they built a test ship out of ice mixed with sawdust & straw.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
Simon
|
| posted on 14/5/11 at 04:44 PM |
|
|
quote:
Originally posted by britishtrident
In WW2 they built a test ship out of ice mixed with sawdust & straw.
Called Pyecrete iirc
ATB
Simon
[Edited on 14/5/11 by Simon]
|
|
|
alistairolsen
|
| posted on 14/5/11 at 06:05 PM |
|
|
Yeah its fine, most boats in the UK are 240v internal, fed from a 16A shore connection plug with a normal mains consumer unit and RCD inside. Just be
aware of vibration and moisture in your installation, no cables without grommets etc etc
My Build Thread
|
|
|
plentywahalla
|
| posted on 14/5/11 at 06:45 PM |
|
|
There's nothing wrong with concrete (ferrocement) construction if it was done properly. Unforunately there are a number of poorly build DIY
hulls which have generally given the construction an undeserved bad reputation.
Also there is no problerm with 240 volt sytems. I have installed these on many boats. Key points are always use multistrand or flex cable, never use
single strand 'twin and earth' as vibration with work harden and fracture the wire. its also preferable to use marine tinned wire to
prevent poor contact through oxidation.
Also be very careful with electrolytic erosion effecting the steel re-inforcing in the ferrocement. Check out the advice on the MG Duff website. Its
also recommended to fit a galvanic isolator.
|
|
|
dhutch
|
| posted on 6/6/11 at 02:02 PM |
|
|
quote:
Originally posted by MakeEverything
240 is fine on a boat, in fact most are fitted with inverters.
Certainly very common in narrowboats.
- As said, low voltage for core systems (bilge pump, domestic water pump, lights, etc) but mains for microwaves and laptops, and increasingly,
fridges (cheaper then low voltage fridges) and lighting.
As said, there are diffrent rules, such as using flexable cables, and keeping the 240v and lowvoltage in separate conduate and suitable marked.
Favor for 110vac is falling as i understand, with HSE now recomending 240v and the correct rcd protection for building sites rather than using
transformers. Never heard of it on a boat, but again, thats from narrowboats no bumpy water boats.
Daniel
|
|
|
v8kid
|
| posted on 7/6/11 at 07:27 AM |
|
|
Thanks for the tips guys. Starting next week so contributions welcome especially the seperate conduit for seperate voltages I never thought of that.
Is a galvanic isolator requires where there is no shore connection? I thought it was to stop circulating earth currents?
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
mangogrooveworkshop
|
| posted on 7/6/11 at 08:23 AM |
|
|
Oh ferro mmmmmmm take it he got it real cheap
Insurance nightmare but hey ho
What yard is he in? We use Arbroath and Tayport
Heres a good artical that kinda sums up ferro
My take on ferro-cement is that it is, in fact, pound for pound the weakest of all of the commonly used boat building materials. Ferro-cement operates
by the same principle as fiberglass, in other words, a high tensile strength reinforcing held by a high compressive strength, low tensile strength
cement. The cement in ferro-cement ideally is a high strength Portland cement. The cement in fiberglass is polyester, vinylester or epoxy resin. The
tensile reinforcing material in ferro-cement is steel (sometimes with glass fiber), and in fiberglass its glass in a variety of forms, kevlar, carbon
and all kinds of new variations on these materials.
Ferro-cement's weight comes from a number of sources. First of all, no matter how small the boat, there is a practical limit to how thin
ferro-cement can be. ferro-cement needs to have a minimum thickness in order to have sufficient depth of material to protect the reinforcement from
moisture. Because of this boats below 40 to 45 feet are generally considered too small to use ferro-cement efficiently. (i.e. they weigh way more than
they would or should in some other material.)
The implication of the weight issue is not readily obvious. At the risk of sounding like a broken record, Weight in and of itself does nothing good
for a boat. It does not make it stronger, or more comfortable or more stabile. Weight does increase the stress on the various parts of a boat. It
increases the size of a sail plan required to achieve a particular speed. It increases drag and typically means that for a given draft a boat will
have a less efficient keel (i.e trading off greater drag for the same amount of leeway.)
In order to carry more sail area the boat needs greater form stability, which comes at the price of a choppier motion and greater drag, or greater
ballast or deeper ballast which adds more weight and drag and perhaps depth.
To keep the weight down, many ferro-cement cement boats have reduced ballast ratios when compared to other construction techniques. This means that
they need more sail area because of their weight but they can't carry more sail area because of reduced ballast ratios without using lower
aspect rigs which are by their very nature less efficient and further compromises performance.
This is further complicated by the fact a higher proportion of the weight in a ferro-cement boat is carried in the in the topsides (and sometimes
decks). This means a high center of gravity which has a variety of implications; reduced stability, wider roll angles, smaller angles of ultimate
stability, and more prone to excitation rolling (which may be slightly offset by the greater inertial moments due to weight).
Then there is maintenance costs. In a study performed some years back looking at the life costs of various materials, ferro-cement-cement came out as
the highest maintenance cost material (if I remember worst to best was ferro-cement, steel, conventional wood, aluminum, fiberglass, cold molded wood)
Of course, as with any generalized study there will be case by case exceptions and given the comparatively small sampling of non-FRP boats it can be
easily skewed by a few bad apples.
Other problems with ferro-cement are the difficulty of connecting things to it, and prevention of rot in wood in contact with ferro-cement. The
difficulty in bolting to ferro-cement is that ferro-cement hates localized loadings. It's hard to glue things to ferro-cement since secondary
bonds are greatly weaker than primary bonds.
Ferro cement requires a high level of skill and a large labor force to build properly. The best materials, either galvanized or epoxy coated steel
reinforcing rod, are very expensive making a well built ferrocement hull more expensive to build than a glass boat.
Then there is the market value thing. Ferro-cement has a poor reputation in the States that does not match the comparatively high regard that it is
held in other countries. Some of this is just plain unfair prejudice, but most of this distrust comes from real shortcomings in the materials as noted
above. A well-built ferro-cement boat can be a good cruising boat. But the image of the crudely finished 'hippie' built cement and rust
buckets still clouds the perception of ferro-cement for many North Americans.
The other problem is telling whether the boat that you are looking at is a good boat. It is very hard to do non- destructive survey techniques to tell
whether the original work was done well and is in good condition. While sounding will reveal any major separations in the cement to reinforcing bond,
it does little to determine the affects of fatigue, poor curing practices or cold joints. With Ferro-cement it is particularly important to maintain
the ferro-cement and non-ferro-cement parts in good condtion. That can be very significant. People who buy boats because they are priced well below
the market, often are overly frugal or just plain do not have the money that it takes to properly maintain a boat. An otherwise good Ferro-cement boat
left to poor maintenance and miss-handling can quickly become a poster child for why North American's don't trust Ferro-cement.
To me the real cost of owning a boat is the difference between what you paid for the boat, the cost of upgrades and maintenance and the price that you
can get when you sell the boat. The problem with a lot of low value boats is that the sales price is always limited no matter how much you put into
the boat. This too works against ferro-cement boats as thier prices will generally be limited by perceptions of Ferro boats and their poorer sailing
performance.
[Edited on 7-6-11 by mangogrooveworkshop]
|
|
|
blakep82
|
| posted on 7/6/11 at 08:36 AM |
|
|
any photos of this beast? i'm intruiged.
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
v8kid
|
| posted on 7/6/11 at 12:47 PM |
|
|
Will take photo's when it arrives. Crane hired for next week to offload.
Moorings are at Loch Etive Bro in law has had his trawler moored there for the past 5 years or so as it is a good diving base.
Hull is professionally built, new and is Lloyd's certificated - I'm surprised that there is an insurance problem with these boats
I'll alert Bro in law to it The construction is cellular with ribs and stringers cast in and the skin is quite thin in between. Sure it is
heavy but not as heavy as the trawler. The keel is massive and it is a cruiser not a racer. A lot of the weight "up top" is sails, masts
and booms I should imagine and as he is under masting it for cruising and installing loads of equipment below decks - generators, compressors, lifting
winches long range tanks etc I did not think there would be a problem - will research it though ta for the nod.
Yup he got it at a good price as the previous owner was "temporarily financially embarrassed".
It is being stored ashore at Queensferry until we complete the fitting out and then it will go north.
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
Neville Jones
|
| posted on 7/6/11 at 02:46 PM |
|
|
240 volt on a yacht is no problem in itself, just make sure that the boat has plenty of zincs linked to the reinforcing mesh. Also a good idea to have
some magnesium anodes as well, as these will go before the zincs, and give a quick indication of the electrical integrity of the boat.
Also, fit an earth fault or earth test meter to the DC system.( I've got a schematic of one somewhere. We fit them to metal and carbon yachts in
particular.) Don't allow the hull to become live, one way or the other. All dc electrics should be 2 wire. This applies to the starter motors
and alternators, if not, these can then give leccy paths to the hull.
For a famous 'concrete' raceboat, look up Helsal from the 70's. Was a big 70+' thing that was nicknamed 'the floating
footpath'. Was quite fast as well.
I did some pro racing up around the lochs many,many moons ago(based at Kip Marina in Inverkip for a while), and always wanted to go and cruise that
area. Have to find the one fine day that is summer, and then there's the midges......
Cheers,
Nev.
|
|
|
v8kid
|
| posted on 7/6/11 at 03:46 PM |
|
|
Thanks Nev I never thought about using magnesium anodes as indicators. Are the dc earth fault indicators you were thinking of type B RCD's? If
not I'd appreciate a copy of that schematic or a link if its handy.
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
Neville Jones
|
| posted on 9/6/11 at 11:15 AM |
|
|
quote:
Originally posted by v8kid
Bro in law has just bought a part finished concrete ketch and it has a 12kw 240v genny installed. Rather than change it to 110v is it OK to have 240v
on a boat?
All the exterior stuff (winches, thrusters lights etc) will be 24/12v dc but we were thinking of having the cabins and bridge 240v ac so we could use
cheaper microwaves, computers, etc. Wiring will be done in multistrand in plastic conduit with separate earth bonded to engine/anode and
rcd's on each cct.
Anything to watch out for?
Cheers!
NO, NO NO!!!!!!
I missed this first time around.
The 240 system has got to be fully isolated. The incoming shore power should run through an isolation transformer. ( This is different for GRP boats,
but not cfrp boats. Carbon can be very nasty electrically in a boat. Very noble and eats anything metallic, all the way up to titanium.)
The gen system same as inboard side of the 240 system. Lots of RCD's, and a separate neutral/earth bus linked to a main rcd.
Depending on what main systems are running on 240 and rely on 240 to operate the boat, an earth leak and rcd system breaker is essential.
NEVER LET THE HULL BECOME LIVE, OR EVEN AN EARTH! ( With the exception of the radio groundplane connection.)
Cheers,
Nev.
[Edited on 9/6/11 by Neville Jones]
|
|
|
