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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... 😉
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Safe to seal a bow thruster tube with sealant?!
David Mack replied to Poppin's topic in Boat Building & Maintenance
Is that a flat plate bolted onto a curved BT tube with a varying thickness of sealant below? And what's on the other end of that bolt holding it down? Some sort of spreader bar which could quietly rust away with you none the wiser? As a temporary fix it may be OK, but I wouldn't like to live with it long term. A better solution would be to weld a plate on the outside over each end of the BT tunnel and keep the inside dry. The plates could always be cut off if you ever wanted to install a BT. -
And from images I was shown while preparing the "multi-skilling" BT diesel course a few in London (and possibly other large cities) that looked as if they would have powered that ferry Tommylad was talking about.
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Some seem to have a 13.4 cut out voltage, so with a bit of Far Eastern precision manufacturing that could easily be while the surface charge is disipatiing. In that scenario, I don't think I would want a bidirectional VSR because when charging stops, the bow thruster is unlikely to be operated to remove the surface charge. That means it might be possible to slightly discharge the BT batteries into the engine battery. It might help to study this: You might also find the notes on my website useful, you are free to print them out section by section. Web address in my signature, below.
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I know this is a very old topic but if anyone is still interested I saw Trelease, 77740 BT No 1, in 1986. Have photo.
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When I worked for BT (some 35 years) they monitored the failure of all types of equipment. Wound devices, such as transformers and relays had a much higher failure rate than power electronics,, such as diodes, transistors and thyristors. As long as quality, adequately rated components have been used, then I would expect a GI to last longer than an isolating transformer, and it will be quieter in operation and use less energy.
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Safe to seal a bow thruster tube with sealant?!
IanD replied to Poppin's topic in Boat Building & Maintenance
Yes because the BT tube is so short (BT was pushed forward as far as possible), you can easily reach the prop from both sides of the boat. Through the tunnel, it it's actually fitted like shown in the Vetus photo (which I can't confirm, that shows a GRP tunnel). There are grilles at each end of the tunnel to stop debris getting in. -
Nationwide : 999 Call not working use these alternative numbers
MtB replied to Alan de Enfield's topic in General Boating
A non-story nothing to do with boating if ever I saw one! "Almost two hours after the issue was first reported, at 9:55am, a BT spokesperson confirmed its back up system was up and running. It advised all callers to resume using the 999 line." -
Correct (Tim Tyler) 🙂 Not a gas locker here though (no gas!), bow locker has ballast and BT at bottom (boo, hiss...) and storage for anchor/chain/rope/hoses above...
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Which is basically what I have been saying, CRT will never approve random bods cutting trees officially because they can't, so best not ask them and just get on with it And that's my experience, tell a lie I do remember someone surveying for BT, lasted about 6 months and never went any further
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Charging start battery from MPPT
blackrose replied to blackrose's topic in Boat Building & Maintenance
So that would be between the domestic & start batteries? Would it interfere in any way with the VSR I already have between the start and BT batteries? Right now with the start and domestic banks paralleled all 3 banks are changing. -
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Safe to seal a bow thruster tube with sealant?!
magnetman replied to Poppin's topic in Boat Building & Maintenance
That is a good approach. I was thinking about the system employed in the OP's boat. I think the water tank is in front of the BT in this instance. -
Which is why domestic RCD's are set to 30mA (thirty thousandths of an amp for the benefit of those who don't understand the term "milli"). Even 30MA directly across the heart can kill in the right circumstances. I initially studied electronics at college, so was familiar with currents in the milliamp range. When I joined BT's predecessor Post Office Telephones, they put me on the power section, where I was put to work maintaining DC power systems rated in thousands of amps. Scared the living daylights out of me at first. Then they merged the AC & DC sides and I had to learn to work on 11,000 volt high voltage AC systems, which initially scared me even more!
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Yes, I did read all of it and saw the OP's correction. When I was working for BT I had access to low hour redundant diesel generators and could have purchased VRSLA batteries at the price BT paid, so considered (briefly) building a new boat using a diesel generator to drive an electric motor. Five minutes of "fag packet" calculations showed that a combination of LA charging losses and using a relatively large generator to feed the low mid and tail charge currents for the extended time taken to charge a lead acid battery would consume far more fuel than a conventional diesel engine and gearbox set up for a narrowboat, so I dropped the idea. Hence my comment. Since then lithium batteries, solar panels and readily available smaller generators have arrived and changed the viability of diesel electric boats, hence why I asked what batteries the OP had. You really must stop taking everything as a personal criticism. Incidentally how do you manage to read and respond to so many posts on so many threads whilst still at work? I'm retired and don't have that much time to read and respond to everything. Whilst I was working I only had time to read CWDF during the odd lunch break and after I had returned home from work.
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Engine losing power after running for an hour
Tony Brooks replied to moiuk's topic in Boat Building & Maintenance
Good luck with finding an engineer in London. I understand the London Boaters Facebook page is where you get recommendations. There is/was a yard at Laleham that seems to have a load of narrowboats around most of the time. You may pass them on your way downstream. Hhaev you found my website with the hopefully useful notes yet? Free for you to download and print. tb-tarining.co.uk. Look at the BT fuel system notes as well. -
Safe to seal a bow thruster tube with sealant?!
cuthound replied to Poppin's topic in Boat Building & Maintenance
Mine is accessed from a weedhatch in the BT compartment. I had been boating for over 40 years before I bought a boat that happened to have a BT fitted. I rarely use it (I had to have the motor reconditioned after I had owned the boat for a few years because it had seized up from lack of use) but it does come in very handy for long reverses. -
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