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Old 04-05-2017, 12:57 AM   #21
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I bought a 42' boat and was recommended to fit a 75kg Vetus.
I was offered a 95 for the same price and fitted the larger one, the best decision I ever made as the 75 would have been fine on a calm day but would not have been man enough in higher winds.
A hydraulically driven one is far superior because it will run all day as opposed to the electrical with a thermal cut out, which may just cut out in bad conditions..
I highly recommend my mod for single lever control posted on Windmills and Wine thread which you can buy through Hopkins Carter.
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Old 04-05-2017, 01:16 AM   #22
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I have a 185TT Lewmar 8HP. Their largest 12V unit. I have had no issues with it, but it is too small for my boat, which is around #60,000lb. If there is much wind or current it has to run a lot, but I have yet to timeout. I ought to have gone for a larger diameter tunnel, two blades and 24V.

I installed it before I decided to add active fin stabis, other wise I might have gone hydraulic. And had I known at the time I would be entering a berth in the river going cross current in a narrow fairway, then a stern thruster would have been on the list as well ! I get envious when I see the guy in he Eastbay keeping his bow pointed up-current and moving along the fairway sideways until he is lined up with his berth.
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Old 04-05-2017, 01:34 AM   #23
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Insequent.
I had the same problem in a marina I was berthed in at the time. I'm not trying to be smart but if you're approaching your berth up river against the current try slowing your engines right down until you're stationary against the current. Now try a little helm so that your bow now is just slightly to the right/left and with a little practice you should be able to 'crab' your vessel sideways across the river.

When your adjacent to, and slightly upstream of your berth with some nifty throttle helm do a smart 90' turn right into your berth.
Practice in the open water until you perfect it, and keep practicing until your really capable.
Have plenty of fenders and try it in an open berth to begin with until you are perfect with the maneouver and only do it facing upstream. It will then become second nature just like riding a bike.
I would recommend half hour practice sessions so you don't lose concentration.
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Old 04-05-2017, 01:46 AM   #24
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Yes it can be done, and I have. But the existing boats on the finger (I'm 5 in from the river entrance, close to shore) change the current/wind behaviour, and I'm usually solo. I have a 1 yo liveaboard Jeanneau along side me that I really don't want to bump, even with a fender. So I prefer slack tide to get into the berth, put the engines in neutral, and have a little bit of time to secures a couple docklines.
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Old 04-05-2017, 01:51 AM   #25
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Hi Brian,
Good on you, a lot of people just give up or make a blue.
Glad to hear you have slack tide to help you. I certainly wouldn't want to touch anyone's boat either out of respect for the owner.
All that said once your safely in you can pop the top off a nice cool 'Gold'.
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Old 04-05-2017, 04:26 AM   #26
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Quote:
Originally Posted by Insequent View Post
I installed it before I decided to add active fin stabis, other wise I might have gone hydraulic..
When docking I'd assume you run your engines at low RPM or idle. Most hydraulic systems develop too low a pressure at idle to give the thruster the oomph it needs when docking. Many hydraulic thruster vessels are set up with a hydraulic pump on the genset or get home engine so high pump speeds can be developed when docking.

This is one reason why most Nordhavns up to 60 feet or so use 24V thrusters at each end. The newer electric designs can be variable speed and have few electric cut out issues. My Lewmar has never timed out, in a few cases with steady operation in excess of a minute.
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Old 04-05-2017, 05:31 AM   #27
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Yes, if just adding pieces I can see the 24V route. But a bunch of independent thrusters (bow, stern and props in forward or reverse) could be a handful. What I would have done is go for an integrated system, like the Twin Disc offering. A joystick system, and a wireless remote would be very nice!

http://www.twindisc.com/marine-produ...stems/ec300js/
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Old 04-05-2017, 08:22 AM   #28
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A hydraulically driven one is far superior because it will run all day as opposed to the electrical with a thermal cut out, which may just cut out in bad conditions.

Do 230/240 volt thrusters have that 2.5 minute duty problem or are they continuous rated like hydraulic?
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Old 04-05-2017, 09:21 AM   #29
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I am just in the middle of installing a bow thruster in my 40' Palmer. Based on opinions everywhere, hydraulic is a better way to go in the long run, and once I have the hydraulic system, I can add things like a hydraulic powered windlass and capstain system, prawn trap pullers, davits, 3" bilge pump, etc. As far as choosing a bow thruster, the MaxPower CT HYD 125 had some of the best specs for power at lower pressure and rpm in a 185 mm tube (7.28"). That was the model 317588 with a 11 cc or .671 cu in motor that produces 260 lbs of thrust with 9.25 gpm at 2320 psi. The math shows that to be 12.5 hp at motor 3184 rpm although the prop rpm is closer to 1/2 that I believe. Is it high prop rpm on some of these thrusters that makes them so noisy? I have sized my hydraulic pump to give me max thruster speed at 1100 engine rpm which allows me to throttle back the main to idle and allow the thruster to work at 2/3 speed when I need less than full power. I am running an open center valve with a remote cable to the helm which also allows me to feather the oil to the thruster. Cost wise I am just going to a hydraulics shop to buy a Permco P124 clutch pump - 8.8 gpm @ 1000 rpm. Max speed is 3000 rpm and 3500 psi so specs well over operating conditions. This pump is $500.

I did find a Kobelt thruster, KP 8 which is more of a commercial unit with brass prop and good specs but I could not get info out of the supplier on all the specs to design the pump myself. I still think it is a better unit and bigger 8" tunnel but also $1000 + more cost. Prop speed was 1500 rpm. I like the simplicity and reliability of hydraulic systems, as long as you don't get into fancy electronically controlled valves and controls. Nothing wrong with a good 24 V thruster, I just chose hydraulic.
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