Hmmmm - Bowthrusters ??

[DSDman]

that long distance drag and fuel consumption/half knot speed penalty has me thinking about some sort of plug to install, if you know you won't be using it much. streamline the hull shape for the long distance cruises then when you get to the islands and your going to goof off in all those rum soaked crowded anchorages you dive in and pull it out.

[minaret]

Originally Posted by DSDman

that long distance drag and fuel consumption/half knot speed penalty has me thinking about some sort of plug to install, if you know you won't be using it much. streamline the hull shape for the long distance cruises then when you get to the islands and your going to goof off in all those rum soaked crowded anchorages you dive in and pull it out.

That's an idea I've considered when doing an install before. Carefully make a perfect cutout and save it for the plug, bond in a shaped G-10 flange for it to land on, a couple of screws and a rubber gasket, and voila!!

[minaret]

Originally Posted by Auspicious

We haven't even talked about how close they are to the waterline and the resulting cavitation and aeration.

I've installed thrusters from most major manufacturers and they all have some basic tube installation requirements. One of the universal ones is how many tube diameters they have to be below the waterline. Another is placement distance aft from the cutwater. I agree that some manufacterers minimum depth requirements could be higher. I think they do this to sell more units, as it can be difficult to shoehorn a tube in the right place and still have enough tube width for the motor body and prop with a little bury.

[DSDman]

Since mine doesn't function right now and I'm about out of rebuild funds for a while I may try making one out of something. While I'm fabricating davit wedges I might give thruster plugs a go as well.

[jgbrown]

Why are thrusters using messy brush motors? My only experience of them so far is one we installed for a customer, but it was a totally sealed unit inside the boat so no mess...

If the tube is the issue, why not an outboard on a side bracket that can go up and down, similar to what was on Jean-de-Sud. Double purpose the engine that way. I have considered this mostly while trying to figure out how to get my A30 to back up in anything approaching a straight line. I think practice will solve it just as well, but not to say I don't wish I had it now.
Seems to me external and manual up and down would solve a lot of the issues though not as elegant on the top perhaps?

[minaret]

Originally Posted by jgbrown

Why are thrusters using messy brush motors? My only experience of them so far is one we installed for a customer, but it was a totally sealed unit inside the boat so no mess...

If the tube is the issue, why not an outboard on a side bracket that can go up and down, similar to what was on Jean-de-Sud. Double purpose the engine that way. I have considered this mostly while trying to figure out how to get my A30 to back up in anything approaching a straight line. I think practice will solve it just as well, but not to say I don't wish I had it now.
Seems to me external and manual up and down would solve a lot of the issues though not as elegant on the top perhaps?

How do you handle it single handed? Run an outboard helm back to the cockpit? If it requires you to have crew on the foredeck you shout at while they are leaning over the side trying to handle an outboard, I think that might be more dangerous than anything.

[Black Diamond]

I've had 45' boats without thrusters and a 50' boat with a thruster. I have to back my boat into the slip with a 16' beam Swan in the slip next to me. Its like threading a needle with a bus and much easier with a thruster. On my 45 I had to use half the marina to get the thing to track well enough in reverse (it was a full keel) to get near the dock. Mine is faired in nicely and does not affect (it seems) the boat sailing.


My bow thruster is a SIDEPOWER 125 and its got plenty of thrust in the wind to push a 45,000lb boat. You need to have a good battery bank and charging system. I have 4 8Ds in the bank it uses. There is a 400amp fuse as these things draw *HUGE* amounts of power for short duration.

Thrusters are meant for a pop here and there, not 20 second long, battery draining, thrusts to compensate for a missed approach. Its for small adjustments, not for steering the boat.

Rick
Hylas 49-057 "Black Diamond"
Portsmouth, RI.

[carstenb]

Some cruisers on this thread argue that you don't need a BW when long range cruising. AGreed with a couple of exceptions. I will be circumnavigating starting in 2 years. Lots of ocean, but our trip will also include the ICW in the US and lots f marinas in Australia and NewZealand so a portion of this will resemble coastal cruising. BWs are great for that.

We will also use our boat for coastal when we get back - so we'll keep the BW

[barnakiel]

Originally Posted by carstenb

Some cruisers on this thread argue that you don't need a BW when long range cruising. AGreed with a couple of exceptions. I will be circumnavigating starting in 2 years. Lots of ocean, but our trip will also include the ICW in the US and lots f marinas in Australia and NewZealand so a portion of this will resemble coastal cruising. BWs are great for that.

We will also use our boat for coastal when we get back - so we'll keep the BW

Plenty depends on what boat you are in. Boats with bodies like Jeann/Bene/Bava back up and maneuver very well in tight spaces. This is typical for flat bottom and saildrive combination. Up to about 50' a bw in such boats is truly a luxury item.

b.

[barnakiel]

Originally Posted by jgbrown

Why are thrusters using messy brush motors?(...)

Look up new Vetus's - no brushes ma! (And no mechanical link between the props and the drive either!)

b.

[Auspicious]

Originally Posted by DSDman

that long distance drag and fuel consumption/half knot speed penalty has me thinking about some sort of plug to install, if you know you won't be using it much. streamline the hull shape for the long distance cruises then when you get to the islands and your going to goof off in all those rum soaked crowded anchorages you dive in and pull it out.

I think that is an excellent idea, although you still have the issues of space consumption and such.

I'd rather keep a couple of extra round fenders with dinghy anchors and practice to'ing and fro'ing around and between them.

Wait - I do have a couple of round fenders with dinghy anchors and I do go out to practice periodically. *grin*

Originally Posted by minaret

I've installed thrusters from most major manufacturers and they all have some basic tube installation requirements.

Agreed. I still regularly see some combination of cavitation and aeration which will greatly reduce thrust.

Originally Posted by jgbrown

Why are thrusters using messy brush motors?

Beats me. I haven't taken them apart. My experience is on the boats I deliver and work on. The bow thruster compartment in the majority of cases coated in black gritty film that I assumed was carbon from brushes. Perhaps I am wrong as to the source, but the effect is clear. I haven't kept a log of it (*grin*) but I sure see it often.

[barnakiel]

Originally Posted by DSDman

that long distance drag and fuel consumption/half knot speed penalty has me thinking about some sort of plug to install(...)

No penalty and no plugs when you have the drop-out type. Also, there are thrusters that have a (sliding?) door and there is no penalty there either. Except the ones with the door I have only ever seen big ones.

b.

[Auspicious]

Can you point to thrusters with doors for recreational boats? I haven't seen them on anything but ships.

[minaret]

Originally Posted by Auspicious

Can you point to thrusters with doors for recreational boats? I haven't seen them on anything but ships.

Me either. As far as I know that's big ship stuff. If there was a thruster with doors for recreational boats I probably would have been asked to install one by now. Unless there's something brand new I haven't heard about....

[micah719]

Any bowthrusters mounted in a circular shroud? Like a ball valve....to seal the tunnel, turn it fore & aft. Not as neat as a flush door, though.