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Showing results for 'BT'.
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No, my colleague in headquarters liaised with Yuasa from 2000 to get their pure lead thin plate VRLSA's specifically to reduce the number of early life VRSLA failures. I left BT at the end of 2007, so they may have changed the specification since then. The Gates pure lead acid VRSLSA's used in the 80's certainly had much thicker plates than their competitors. -
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The devastating reason London's BT Tower's iconic revolving restaurant stopping spinning - MyLondon
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Safe to seal a bow thruster tube with sealant?!
IanD replied to Poppin's topic in Boat Building & Maintenance
If the OP wants to keep open the possibility of fitting a BT in future -- which will bolt down to a flat flange above the BT tube, with a seal between them -- then there's nothing wrong with having a flat plate where the BT would go, bolted to the flange and sealed in the same way -- this is no worse than having a BT installed as far as leaks are concerned. But a bulkhead is a very good idea just in case a leak *does* happen, whether the BT is installed or not. Either way the solution posted by the OP is a bodge -- no proper plate/seal *and* no bulkhead... 😞 -
So do they run on BT or Three?
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Safe to seal a bow thruster tube with sealant?!
IanD replied to Poppin's topic in Boat Building & Maintenance
I assume that's on top of the BT tube where the thruster itself would be mounted? If so there's normally a circular hole cut into the BT tube with a short length of pipe welded into this and then a flat flange on top which the BT is bolted/sealed down to. It looks like all they've done is bolt a cover plate down onto this with some sealant -- not as good in the long term as a welded plate but easier to do and reversible, and no riskier for leaks than having a BT bolted to it -- and if a plate was welded on (and later cut off, not easy) you wouldn't have a flat surface to mount a BT on in future if you wanted to. -
I don’t see anything much wrong with the figures and description you’ve given. The 69A is going to the thruster motor, not to the battery. The 17A is going to recharge the battery. The only thing that is non-ideal is the 13.9 charge voltage, probably a consequence of the long cables and or the diode splitter. If it is a conventional diode splitter it would be better to replace it with a zero volt drop electronic equivalent. Or as suggested, if there is normally ac mains on the boat (usually-on inverter) then a battery charger located near the BT battery is a better idea.
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Correct. Mine is variable speed too. I chose a 24v bowthruster because of the (percieved) benefit of redundancy and 2 x 12v batteries in the bowlocker adds 60kg useful weight in the bow. The battery cables are short as the BT and batteries are next to each other so 75mm2 cable more than does the job. For me the cost was secondary to the benefit of redundancy (and useful weight in the bow). I don't worry about keeping the batteries charged - who does with an appropriate charger/system installed?
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My 16 year old boat boat was fitted with a Victron Combi and a Victron charger for the BT battery. Both have performed faultlessly over that time. Enough said. Furthermore unlike any of the other "marine" brands, Victron make power equipment for professional telecomms companies, so have a pedigree where reliability is paramount.
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The longer comms cables on my boat are screened, for example from the Vetus Pro BT controller at the stern to the BT. Victron also recommend this for long cable runs in noisy environments, which is exactly what I said. The shorter ones are unscreened. If you want to charge a battery from a system with a different DC voltage on the GND terminal then you need an isolated B2B -- the case you quoted which has 2 B2B with parallel inputs (0-24V) and series outputs (0-24V and 24V-48V) needs one for the upper B2B, just like I said. Though this does raise potential balancing issues with the centre tap of the 48V battery, which I assume is connected to the series centre tap of the B2B outputs. The fact remains that this is an unusual case for a boat, and in the normal case under discussion -- 12V in to 12V out -- there's no need for isolation, or indeed any point in it. The same applies for conversion between different voltages where the low rail is a common 0V GND in all cases, which again is the most common case -- for example my boat has 12V for the generator start battery, 24V for the boat lighting etc, 48V for propulsion, all referred to 0V, and with non-isolated DC-DC converters for 24V (48V input, no 24V battery) and to trickle-charge the genny battery.
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Safe to seal a bow thruster tube with sealant?!
IanD replied to Poppin's topic in Boat Building & Maintenance
Indeed, but if you have a BT that means putting it in a long tunnel behind it (in the cabin area?), or losing the front 4' or so of the tank to fit the BT in front of it. Not having a well deck, I chose to push the BT into the bow and have a deep stainless steel water tank behind it, with storage space above extending into the forecabin. Can't do this unless you're building from new, obviously...
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I do know BT has statutory powers to do this but it's certainly not something I never saw, shame it would have been something else I could have done, a lot less scary than powerlines
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Even better ws the interpretation of the old BT logo . . .
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I still don't understand why the OP isn't testing the battery voltage off charge? He's asking for advice and then dismissing it. I'm assuming the controller he refers to is a solar controller and he's expecting the batteries on float voltage to be powering the BT? That isn't going to happen if the batteries are knackered and the voltage drop he's measuring is irrelevant if the batteries are being charged. What you're measuring is the voltage drop with volts coming out of the controller. PLEASE DO WHAT OTHERS HAVE SUGGESTED: TAKE THE BATTERIES OFF CHARGE, LEAVE THEM FOR A FEW HOURS AND THEN TEST THE RESTING BATTERY VOLTAGE. I would actually press the BT button to take any surface charge off the plates. If when you test the voltage it's 12.7v or 12.8v then fine at least you know the basic condition of the batteries and can look for other causes, but without that information you're wasting everyone's time.
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I had a couple of pints in there in 1999 when I was running a project to test all of BT's standby generators to see if they would be affected by the millennium bug. They weren't but it must have cost BT a small fortune to prove it, despite them being told by myself and others that most generators were not in any way computer controlled.
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Safe to seal a bow thruster tube with sealant?!
blackrose replied to Poppin's topic in Boat Building & Maintenance
Yes I agree with that. Mine doesn't have a bulkhead so I effectively created a low bulkhead by sealing up the steel cross member on the baseplate aft of the BT and installing a bilge pump. If a BT does leak it's not going to be a catastrophic leak. -
From Canal Plan: Goldberry Built by Shrops Union Bt Bldr - Length : 13.41 metres ( 44 feet ) - Beam : 2.07 metres ( 6 feet 9 inches ) - Draft : 0.01 metres ( 0 feet ). Metal hull N/A power of 19 HP. Registered with Canal & River Trust number 62453 as a Powered Motor Boat. ( Last updated on Sunday 29th May 2011 )
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This post cannot be displayed because it is in a forum which requires at least 10 posts to view.
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Safe to seal a bow thruster tube with sealant?!
Guest replied to Poppin's topic in Boat Building & Maintenance
Dont think its been mentioned but a BT can be very useful when reversing. It saves having to pause and go forward to correct the stern swinging caused by prop walk. A quick blip of the BT can bring the boat back in line whilst maintaining rearward progress. -
Safe to seal a bow thruster tube with sealant?!
IanD replied to Poppin's topic in Boat Building & Maintenance
Do you mean a weedhatch down into the BT tunnel? That would have to be pretty tall (on top of the tunnel) and difficult to get down, given how far the BT is underwater, certainly not just on top of the tunnel like the plate in the OPs photo which is just asking for trouble with leaks being underwater. At least the BT itself -- at least, one like the Vetus one I pictured -- is designed to need only a small hole though the tunnel wall, which the prop/gear assembly fits into and seals from the inside, properly designed to be as leakproof as possible (and with no weak spots or things that can come loose). As you say, on a widebeam (or even a narrowboat...) a BT is normally installed close to one end of the tunnel, to allow prop access and removal of the BT gear if needed. It's only in the middle on mine because the tunnel is so short anyway that it can be easily accessed from either end. -
Safe to seal a bow thruster tube with sealant?!
magnetman replied to Poppin's topic in Boat Building & Maintenance
Vessel interaction I think one potential issue with a bowthruster is that it could confuse the person on the other boat. If you are approaching another craft in a limited channel it is very important that both steerers know exactly what the other one is going to do. The person without the BT will think the other is going to manoover in the same manner as him whereas the person with the BT will assume the opposite. There is no flag (apart from water movement and noise) which indicates if someone has a BT so this differential in assumption increases the likelihood of accidents.
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A bowthruster uses a negligible amount of energy because it's only on for a short time. IIRC mine's about 5kW flat out (it's variable speed and I rarely use full power), even running it for a minute uses less than 0.1kWh. When I looked at the costs it was cheaper to run 48V cables along the boat (only 25mm2 IIRC) than to add separate batteries for the 48V BT, and have to worry about keeping them charged and lifetime. Not really feasible with 24V though, you'd need 100mm2 cables, and definitely a no-no for 12V which would need 400mm2... 😉
