paul salliss
Well-Known Member
What the pros and cons of these when compared to standard electric versions that are normally supplied by main stream builders of boats please?
Hydraulic thrusters / bow and stern
- Thread starter paul salliss
- Start date
Gentlemanracer
Well-Known Member
My understanding is the current draw on electric versions will eventually cause an overheat at which point the thruster cuts out. So fire risk and use of these is normally intermittent to mitigate heat build up. Hydraulic operation imposes no such operating restrictions. Guess which has greater cost!
paul salliss
Well-Known Member
Gentlemen racer/ as I suspected, and obviously standard electric will no doubt be cheaper. Thank you for replying
jfm
Well-Known Member
Hydraulic or 230v x 3 phases becomes necess at about 80 feet and 30hp thruster because that's 1000 amps at 24v which would be crazy. Below 60 foot electric 24v is more sensible. Sure you are limited to 3 mins continuous or whatever, but the absence of a hydraulic pack (oil tank oil filters valves pto pumps coolers etc) and then hoses to both ends of boat is probably worth having
At the crossover 70-80 feet you can have either. If you have hydraulic stabs then you have the hydraulic pack anyway so adding Hydr thrusters isn't much more work
At the crossover 70-80 feet you can have either. If you have hydraulic stabs then you have the hydraulic pack anyway so adding Hydr thrusters isn't much more work
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stelican
Well-Known Member
Thrusters
Your knowledge isadmiralable! but this chap has a 38ft boat!
Your knowledge isadmiralable! but this chap has a 38ft boat!
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paul salliss
Well-Known Member
Stelican. Put simply you are wrong
Piers
Well-Known Member
A consideration is whether your engines, at idle, produce enough hp to drive the thrusters at the required oompf (a technical term used on Play d'eau....)
Robg71
Well-Known Member
if your going hydraulic power from gearbox pto, bear in mind flow through rates at max revs dictates a large hydraulic tank. if using a clutch operated system used at low rpm, you can use a much smaller tank.
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Deleted User YDKXO
Guest
The Horizon broker in my marina does a very effective demo of hydraulic thrusters every time he fills up one of his customers' boats, some of which must be 70-80ft long. He just pins the boat against the fuel dock with the hydraulic bow and stern thrusters and keeps them running continuously whist he fills up the boat. He does this all singlehanded and doesn't even bother tying the boat to the dock. Most impressive except for the noise of the thrusters themselves and the engines which have to be running to power them. I think if I was speccing an ideal hyd thruster system, I'd want a back up pump powered by a gennie too just in case of an engine failure which would be the one situation in which you'd really need the thrusters
MapisM
Well-Known Member
Well, for that purpose alone, you might as well have an hydraulic pump on both engines.
Though if you would have also hyd STAR stabs, the genset driven (either via genset PTO or electric motor) hyd pump is a must anyway.
Regardless, I strongly disagree with the refueling method of that folk, fwiw.
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Deleted User YDKXO
Guest
In fact the Horizons do seem to have a hyd pump on both engines (both gearboxes in fact) but I was told that one was dedicated to the stern thruster and one to the bow thruster so, in the event of an engine failure, one thruster would be AWOL. Thats why I suggested that an additional pump on a gennie plus a valve to feed oil to either circuit would be a plus
True
The broker is trying to sell boats and he's very proud of the fact that all Horizons are fitted with hyd thrusters and he likes to show off
MapisM
Well-Known Member
Mmm... never heard of such setup.
Technically feasible I suppose, but imho pointless vs. a single circuit arrangement.
I accept that with the engine(s) idling, one pump could be not man enough to run both thrusters together at their max power, BUT it's still better to have the choice of which thruster to use alone at its max power (or both together at lower power), regardless of which PTO pump is working, rather than be restricted to either bow or stern depending on which PTO pump/engine is spinning. Or am I missing something?
LOL, can't argue with that!
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Deleted User YDKXO
Guest
Well there were definitely 2 pumps on the 64ft Horizon I looked at recently, flanged to each gearbox and when I asked the broker, he said each was dedicated to bow and stern thruster independently. To divert the flow of both pumps to one thruster or cross over the flow to the other thruster would require additional pipework, valves and some kind of proportional control system, all doable of course but at a cost. IMHO, it is unusual for a builder to fit hyd thrusters to a boat of this size as standard anyway but to then expect the builder to fit a crossover system as standard as well is probably an expense too far unless a buyer is willing to spec it as a cost option. Don't forget most production 64 footers are only fitted with an electric bow thruster as standard with an electric stern thruster as an option so for a builder to fit both bow and stern hydraulically powered thrusters as standard is already a step further, even if they are independent
MapisM
Well-Known Member
Well, I might be missing some obvious bits here, and I'll gladly stand corrected if anyone knows better.
But in principle, I see no reason why the two pumps couldn't just feed (in parallel) a single hydraulic circuit driving both thrusters (and/or anything else, like winches or stabs).
IIRC, jfm has hyd thrusters and double PTO pumps on M2. Maybe he can tell us how they are configured?
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Deleted User YDKXO
Guest
I wait for jfm to explain but AFAIK, hydraulic motors cannot operate in series or parallel from the same circuit, if that is what you are suggesting, because the oil exiting the motor (the return oil) is at a much lower pressure than the feed oil, so each hydraulic motor has to have it's own feed and return pipes. Yes it is perfectly possible to have 2 hyd pumps feeding 2 or more hyd motors such that you could feed 100% of the oil to one motor or a proportion of the oil to more than one motor but as I said that would require an electrically operated valve system to distribute the oil flow to each hyd motor feed pipe and an electronic system to control the operation of those valves in response to inputs from the operator. It becomes more complex if the hyd motors have different pressure/flow requirements and then if the functions driven by the motors require proportional operation and prioritising one over the other, the system may need some kind of programmable control system. All this is bog standard hydraulic stuff but there is a cost to it as I said
jfm
Well-Known Member
Mike I think it's much easier than you say. On match I have two pto's and each/both runs both bow and stern thruster. I'm amazed horizon doesn't do same. Each pto just supplies pressurised oil to a single manifold that all the users are piped off. In parallel obviously, not series. Excess pressurised oil is just bled off back to the tank. When that happens less work is done so the engines use less diesel. The energy isn't really wasted. As more users demand more oil eg the stern as well as the bow thruster then more work is done and less pressurised oil returns to the tank via the waste gate. The two pto's and the electric pump are all plumbed in parallel to the one manifold off which the users take their oil via solenoid valves, proportional on a sexy system
Nothing more elaborate than this is needed. Same for a jcb that has perhaps 10 rams all drawing off the same manifold
So I'm perplexed by horizons installation and don't like the sound of it
Having said all that you can then tweak it. On my boat this is done via the control electronics. When I demand thrusters the electronics don't allow the stabs valves to operate. The logic is that thrusters are more important, which makes perfect sense. If you were docking boat on one engine and needed max thruster power you wouldn't want to waste. Power on stabs. But that's all achieved via control softwAre not plumbing
Nothing more elaborate than this is needed. Same for a jcb that has perhaps 10 rams all drawing off the same manifold
So I'm perplexed by horizons installation and don't like the sound of it
Having said all that you can then tweak it. On my boat this is done via the control electronics. When I demand thrusters the electronics don't allow the stabs valves to operate. The logic is that thrusters are more important, which makes perfect sense. If you were docking boat on one engine and needed max thruster power you wouldn't want to waste. Power on stabs. But that's all achieved via control softwAre not plumbing
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MapisM
Well-Known Member
Yep, exactly what I thought to be the logic on every boat I've seen with hyd PTO(s) plus separate pump for STAR usage.
I was unsure about the need for separate returns though, and I thought Deleted User might have had reasons to mention them...
Btw, your JCB example doesn't prove a lot actually, because (afaik) those things only have one PTO pump feeding all rams.
So, it's a single pump feeding mutiple users, while here the doubt was related to multiple pumps/multiple users.
Anyway, M2 installation is more than good enough as a pudding proof.
Oh, and couldn't agree more on your comment re. Horizon installation.
jfm
Well-Known Member
Ah ok. I thought mike was questioning multiple users off one pto but maybe I misread his post. That was the reason for mentioning jcb. I'm only on little iPhone screen and reading while doing airport security sorry!
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Deleted User YDKXO
Guest
Well yes thats what I was trying to describe but there is a cost to that and I presume that Fairline didn't include hyd bow and stern thrusters as standard on the Sq78 (correct me if I'm wrong there) and almost certainly not on the Sq65 which would be equivalent to the 64ft Horizon I saw. All I was trying to say was that 2 hyd thrusters fitted as standard on a 64 footer, even if they are independent circuits, is better than1 or 2 electric thrusters as fitted to most other boats as standard. I'm sure you could have an integrated system on the Horizon, just as you specified on Match, but I guess you'll pay extra for it
Absolutely which is why I said its all bog standard hydraulics stuff
Yup thats simple hydraulic prioritisation which is common on many hydraulically driven machines and has been around for years but as I said, it's the kind of sophistication which costs a bit more money and you probably wouldn't expect as standard on a boat
MapisM
Well-Known Member
Mmm... I struggle to see how a manifold could add any meaningful costs to a setup with two PTO hyd pumps and two hyd thrusters.
It would have been a different story if, as you said, the two pumps couldn't work in parallel for some reason, but if they do in M2 there's no reason why they couldn't on any other boat.
All considered, it just sounds like a nonsense plumbing choice from Horizon, imho...
