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Old 21-10-2014, 08:12   #31
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Re: Bow thrusters...

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Originally Posted by wingless View Post
My 7kW Westerbeke generator has a PTO mount.

It is not a tug, commercial workboat or fishing boat.

The plumbing would be "easy" on my boat.
Didn't say they didn't exist... Just not common... Whereas on workboats they definitely ARE!!!

And YES... it would be an awesome straightforward application for you to plumb your genset PTO

Personally... I would hate to have to "depend" on firing the genset whenever I wanted a bump.... OR NEEDED a bump in a hurry... Do you have your genset panel at the helm???

Just like all boats man... Everything is a compromise...
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Old 21-10-2014, 20:59   #32
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Re: Bow thrusters...

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Originally Posted by HappyMdRSailor View Post
Didn't say they didn't exist... Just not common... Whereas on workboats they definitely ARE!!!

And YES... it would be an awesome straightforward application for you to plumb your genset PTO

Personally... I would hate to have to "depend" on firing the genset whenever I wanted a bump.... OR NEEDED a bump in a hurry... Do you have your genset panel at the helm???

Just like all boats man... Everything is a compromise...
My gen is easy to fire up, as-required, if it not already running.

There is only one person who decides if the best is for others and if good enough is good enough for you.
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Old 22-10-2014, 09:49   #33
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Re: Bow thrusters...

I finished my last 10 work career years in NYC area with very tight get in/ out slips... sometimes with a beamy power boat docked side-to behind me reducing the alley way to less than 50' for my 46' ketch. I mostly singlehand and can't just push off the bow/ get a fender up there. So I was sitting out many great sailing days for fear of issues getting in/ out. So I was in the state of mind your appear to be and read a lot of boat show brochures, one-one sales discussions, internet researches, and even use a fish scale to pull my bow over during bad wind days to determine how much thrust I needed for reasonable high wind days. Before my 2nd year haulout I purchased a 'boat show display Vetus model 55 bow thruster with about 80lbs of thrust. I'm an engineer and installed it myself while on the hard (with many on lookers as I cut those two BIG oval holes on my bow. It was actually a pretty straight forward installation process if your know how to work with basic tools, West System, and big 12v circuits (but Vetus/ others don't provide self-install instruction) but found their staff very responsive to an occasional question.

That was 15 years ago and its still working great. While I'm very glad I did it and always felt better knowing it was there if I needed it... I rarely ever used it. Turns out I think we are all better at close quarter maneuvering than we think... but again it has been great to have as an 'insurance policy' at the ready. It's important to test it and dive/ clean the tube/ prop very regularly. Just one barnacle on one blade can cut its effectiveness/ thrust 30-40% and the only thing worse than not having a bow thruster is thinking you do... and then it not working when you really need it! Good luck!


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Old 22-10-2014, 10:39   #34
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Re: Bow thrusters...

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Originally Posted by W3GAC View Post
It's important to test it and dive/ clean the tube/ prop very regularly. Just one barnacle on one blade can cut its effectiveness/ thrust 30-40% and the only thing worse than not having a bow thruster is thinking you do... and then it not working when you really need it! Good luck!

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Great informative post!

And no doubt about the last sage advice...
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Old 23-10-2014, 05:55   #35
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Re: Bow thrusters...

I had a Sidepower SP150 mounted through Neeltje's protruding bow keel (outside the hull) before bringing her up from Ft. Lauderdale, and it proved to be invaluable in nosing her 40 tons around. I soon realized, however, that since her prop walk takes the stern to starboard in reverse, parking to port could sometimes be a little difficult, so I had a second one installed in the skeg. Each has it's dedicated 24V batteries and charger, and each is controlled separately (i.e., if one fails, it won't affect the other as it would have with a single joystick). Since her hull is made of 1/2" thick riveted iron, and I wanted the tubes to be properly cowled, there was quite a bit of metal work involved in both installations, and that jacked the cost up to over 20k a piece, but the boat would be useless without them.

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Old 23-10-2014, 06:02   #36
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Re: Bow thrusters...

They're great for tight SHELTERED work in a slip or next to a dock in a moderate wind. Don't count on it if it's really blowing hard
abeam.


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Old 23-10-2014, 07:14   #37
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Re: Bow thrusters...

Quote:
Originally Posted by wingless View Post
If I were ever to consider adding thruster(s), for me the only consideration would be one powered by hydraulic fluid, not electric.

A hydraulic thruster is rated for 100% duty cycle, not for short blips.

IMO a thruster is for bad situations, where the electric thruster will "give up the ghost", not for convenience where it really isn't needed.
Hydraulic thrusters are like hydraulic everything else -- they are great! But quite expensive and complicated to install and maintain.

The duty cycle would NOT be a factor for me in choosing electric or hydraulic. The Sleipner Sidepower units are rated for 2 1/2 minutes of continuous running, which is far more than you could ever need. I have been using mine for more than five years by now, in weather up to F9, and never needed it for more than maybe 10 seconds maximum at a time. Normal use is for a second or two at a time. "Short blips" is the normal use of a bow thruster.

That's because bow thrusters are for steering, not propulsion. And it either steers you, or if it's not powerful enough to get the bow around, holding the button down will never help anything. So continuous duty rating is not needed.
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Old 23-10-2014, 07:30   #38
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Re: Bow thrusters...

I should have added a small detail about bow thruster 'joysticks' on sailboats. They are usually expensive and too big to find a good mounting location at a sailboat binnacle (where you want it). But it's nothing but a BIG momentary on-off-on (SPDT) switch which can be substituted with a small standard over the counter $5 momentary on-off-on switch. My bow thruster 'joystick' is one of these small momentary switches mounted up on top of the left side of the binnacle instrument enclosure. I'm right handed but wanted to keep my right hand free for steering and throttle control. It's oriented such that pushing its little 3/4" toggle arm right (left) causes the bow to go right (left).

While on electrical topic. Bow thruster take 200-300+ amps @12v. While 24v bow thrusters are a good option/ necessary if I had gone for the next level if thrust... I have my big 12v AGM inverter battery bank about midship and wanted the weight/ charging efficiency of not having to install a separate 24v bank. ABYC requires a main shut off switch fir the bow thruster circuit which was easily located up on the inside rain locker just fwd of the saloon.

Location of the bow thruster. Getting it as far forward as possible get you more boat rotating torque. But the top of the tube must be located so that it's at least 1/2 diameter below water surface to prevent sucking air/ zero thrust. FYI- I taped a few magnets along the outside of the bow 6" above the water. Then with another magnet/ Boy Scout compass inside the bow area you can easily locate the position of each of the outside magnets and draw a pencil line where the actual waterline is located which will help greatly in the pre-planing location of a possible bow thruster process.

My brother has been considering one of the 'bolt-on' bow thrusters mentioned in another post. Saw them at the recent Annapolis Sailboat Show and they look well made and may be a good option with less installation complexity. They have an advantage that they can usually be mounted farther fwd which maximizes the turning force of their thrust. But like all bow thrusters... they are pricey too!


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Old 23-10-2014, 07:47   #39
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Re: Bow thrusters...

Responding to combined comments by RichandHelen and W3GAC, I have found that the thruster *IS* very useful when it is blowing hard (25-30kts) on the beam. However, when the seas are up, the thruster effectiveness is lower as it sucks in air.

On our boat, the joystick is mounted upside down under the pedestal instruments. With all the instruments there (wind/speed/depth, 2 autopilot controls, windlass/chain counter, vhf, etc.) there's nowhere else at the helm it could go!
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Old 23-10-2014, 10:03   #40
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Re: Bow thrusters...

Quote:
Originally Posted by W3GAC View Post
I should have added a small detail about bow thruster 'joysticks' on sailboats. They are usually expensive and too big to find a good mounting location at a sailboat binnacle (where you want it). But it's nothing but a BIG momentary on-off-on (SPDT) switch which can be substituted with a small standard over the counter $5 momentary on-off-on switch. My bow thruster 'joystick' is one of these small momentary switches mounted up on top of the left side of the binnacle instrument enclosure. I'm right handed but wanted to keep my right hand free for steering and throttle control. It's oriented such that pushing its little 3/4" toggle arm right (left) causes the bow to go right (left).

While on electrical topic. Bow thruster take 200-300+ amps @12v. While 24v bow thrusters are a good option/ necessary if I had gone for the next level if thrust... I have my big 12v AGM inverter battery bank about midship and wanted the weight/ charging efficiency of not having to install a separate 24v bank. ABYC requires a main shut off switch fir the bow thruster circuit which was easily located up on the inside rain locker just fwd of the saloon.

Location of the bow thruster. Getting it as far forward as possible get you more boat rotating torque. But the top of the tube must be located so that it's at least 1/2 diameter below water surface to prevent sucking air/ zero thrust. FYI- I taped a few magnets along the outside of the bow 6" above the water. Then with another magnet/ Boy Scout compass inside the bow area you can easily locate the position of each of the outside magnets and draw a pencil line where the actual waterline is located which will help greatly in the pre-planing location of a possible bow thruster process.

My brother has been considering one of the 'bolt-on' bow thrusters mentioned in another post. Saw them at the recent Annapolis Sailboat Show and they look well made and may be a good option with less installation complexity. They have an advantage that they can usually be mounted farther fwd which maximizes the turning force of their thrust. But like all bow thrusters... they are pricey too!


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24 volts has a ton of benefits for bow thrusters.

Among other things, it makes it much easier (requiring half the weight of cables) to get the power from your main battery bank, which is much preferable to a separate bank, if the main bank is close enough.
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Old 23-10-2014, 10:20   #41
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Re: Bow thrusters...

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Originally Posted by Dockhead View Post
24 volts has a ton of benefits for bow thrusters.

Among other things, it makes it much easier (requiring half the weight of cables) to get the power from your main battery bank, which is much preferable to a separate bank, if the main bank is close enough.
That's how mine is set up, and it works fine. The 24-volt house batteries are located within 12 feet of the thruster.
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Old 23-10-2014, 14:59   #42
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Re: Bow thrusters...

Quote:
Originally Posted by RichandHelen View Post
They're great for tight SHELTERED work in a slip or next to a dock in a moderate wind. Don't count on it if it's really blowing hard
abeam.


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Unless, of course, you've got a flat bottom, low profile, and 300 lbs. of thrust...

Jacques
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Old 23-10-2014, 15:32   #43
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Re: Bow thrusters...

Quote:
Originally Posted by W3GAC View Post
Location of the bow thruster. Getting it as far forward as possible get you more boat rotating torque. But the top of the tube must be located so that it's at least 1/2 diameter below water surface to prevent sucking air/ zero thrust. FYI- I taped a few magnets along the outside of the bow 6" above the water. Then with another magnet/ Boy Scout compass inside the bow area you can easily locate the position of each of the outside magnets and draw a pencil line where the actual waterline is located which will help greatly in the pre-planing location of a possible bow thruster process.

My brother has been considering one of the 'bolt-on' bow thrusters mentioned in another post. Saw them at the recent Annapolis Sailboat Show and they look well made and may be a good option with less installation complexity. They have an advantage that they can usually be mounted farther fwd which maximizes the turning force of their thrust. But like all bow thrusters... they are pricey too!


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I think most thruster specs require them to be a little deeper than "1/2 tube dia." to work efficiently. These little beasties cavitate like nobody's business.

It's true that "bolt-on" thrusters should give more bang per power rating because of their offset, and they're great space-savers to boot. But all the ones I've seen somehow swivel up when not in use, and that's got to involve some type of added lift mechanism, so I don't see that as being particularly advantageous as far as installation or maintenance is concerned. Besides, knowing me, I'd probably lob it off when dropping anchor...

I think through-hull thrusters are the way to go, even for smaller boats. You'd be surprised at how small of a space the thruster motor itself takes up, and pros like Florida Bow Thruster have hull drilling jigs that make a proper tube installation a breeze.

Jacques
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Old 23-10-2014, 16:46   #44
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Re: Bow thrusters...

Installed a Vetus in my Irwin 38". Wasn't that hard if you are handy and ballsy. Drilling a hole in a perfectly good hull takes stones. Have pics if you want to see them.
Jim
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Old 23-10-2014, 17:15   #45
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Re: Bow thrusters...

Pics would be awesome, I'm sure everyone on this thread would love to see 'em!

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