Bow thruster tube replacement

[ebenezer]

Hi eveyone.

 

any one cleaned  there bow thruster tube . how did they clean it?

or did you take it to a boat yard ? and photos before and after

[Boater Sam]

Please all keep your thrusters, how else are we going to get all those poly bags taken out of the water?

[Mike Tee]

I’m not impressed by whoever said ‘if it’s down to 2.5 that’s nothing to worry about’.

It started at 5.0mm in 2009 and is now at 2.5mm? If you are planning on keeping the boat for 10 years, best keep a life jacket handy.

[Sea Dog]

1 hour ago, Mike Tee said:

I’m not impressed by whoever said ‘if it’s down to 2.5 that’s nothing to worry about’.

It started at 5.0mm in 2009 and is now at 2.5mm? If you are planning on keeping the boat for 10 years, best keep a life jacket handy.

Please miss, it was @jonesthenuke wot said it - and then he ran off!

 

14 hours ago, ebenezer said:

Hi eveyone.

 

any one cleaned  there bow thruster tube . how did they clean it?

or did you take it to a boat yard ? and photos before and after

Usual practice is to do prepare and repaint the tube when you black the hull - the boat is, of course, out of the water for that.

[jonesthenuke]

12 minutes ago, Sea Dog said:

Please miss, it was @jonesthenuke wot said it - and then he ran off!

 

Usual practice is to do prepare and repaint the tube when you black the hull - the boat is, of course, out of the water for that.

Whilst perhaps entertaining to say I ran off, I am still here. My post said don't panic.  The situation will need dealing with but 2.5 mm will not perforate in the short term.

[Sea Dog]

Just now, jonesthenuke said:

Whilst perhaps entertaining to say I ran off, I am still here.

I was only joking - it just sat well with the schoolgirl humour... which by my tagging you flagged the post for your attention.   (There's method in the madness) 

 

[jonesthenuke]

Well these guys know how to fix bowthrusters

 

 

[matty40s]

46 minutes ago, jonesthenuke said:

Well these guys know how to fix bowthrusters

 

 

We have a 5 1/4 " tall chap from Lilliput comes in to do ours.

14 year old boat.

 

[blackrose]

12 hours ago, Boater Sam said:

Please all keep your thrusters, how else are we going to get all those poly bags taken out of the water?

In 14 years I've never had a bag or anything else stuck in my BT.

[David Mack]

1 hour ago, jonesthenuke said:

Well these guys know how to fix bowthrusters

 

 

But didn't do much to patch the tube.

[yabasayo]

The bow thruster tube is effectively part of the hull and should be the same thickness as the hull. Would you be happy with hull thickness of 2.5mm ?

Loss of thruster tube material is much more likely to be from corrosion than erosion. As unseen area typically not adequately protected by paint or anode. It is also possible that thruster tube is of a different grade steel than the hull. There may be some galvanic corrosion going on.

Thrusters can be very useful, especially if you are in a tight marina berth, and should not be dismissed simply on macho grounds. No doubt similar 'sissy' comments were to be heard when the flushing toilet replaced the bucket.

Edited March 10, 2019 by yabasayo

[Sea Dog]

2 minutes ago, yabasayo said:

No doubt similar 'sissy' comments were to be heard when the flushing toilet replaced the bucket.

You forget that that hasn't happened for everyone here. 

 

[jonesthenuke]

7 minutes ago, yabasayo said:

The bow thruster tube is effectively part of the hull and should be the same thickness as the hull. Would you be happy with hull thickness of 2.5mm ?

Loss of thruster tube material is much more likely to be from corrosion than erosion. As unseen area typically not adequately protected by paint or anode. It is also possible that thruster tube is of a different grade steel than the hull. There may be some galvanic corrosion going on.

Thrusters can be very useful, especially if you are in a tight marina berth, and should not be dismissed simply on macho grounds. No doubt similar 'sissy' comments were to be heard when the flushing toilet replaced the bucket.

Yes but consider the original post. The advice requested was essentially whether it's an immediate problem.

 

Oh and I agree that BT's are not works of the devil!

[yabasayo]

The bow thruster tube is effectively part of the hull and should be the same thickness as the hull. Would you be happy with hull thickness of 2.5mm ?

Loss of thruster tube material is much more likely to be from corrosion than erosion. As unseen area typically not adequately protected by paint or anode. It is also possible that thruster tube is of a different grade steel than the hull. There may be some galvanic corrosion going on.

Thrusters can be very useful, especially if you are in a tight marina berth, and should not be dismissed simply on macho grounds. No doubt there similar 'sissy' comments were to be heard when the flushing toilet replaced the bucket.

 

Edited March 10, 2019 by yabasayo

[ditchcrawler]

1 hour ago, yabasayo said:

The bow thruster tube is effectively part of the hull and should be the same thickness as the hull. Would you be happy with hull thickness of 2.5mm ?

Loss of thruster tube material is much more likely to be from corrosion than erosion. As unseen area typically not adequately protected by paint or anode. It is also possible that thruster tube is of a different grade steel than the hull. There may be some galvanic corrosion going on.

Thrusters can be very useful, especially if you are in a tight marina berth, and should not be dismissed simply on macho grounds. No doubt similar 'sissy' comments were to be heard when the flushing toilet replaced the bucket.

That is not the view of everyone, erosion around the blade tip area has been documented

[calon]

In my case it certainly apeared to be  erosion around the Blade tip,  the tube came as part of the kit suplied to the builder by Nobel's apparently only 5.5mm thick when new and in this kit with a bronze prop and there were no anodes in the tube.  In the end we had the tube was cut out and replaced with a 9.5mm seamless tube,  and we fitted two anodes inside the tube as well so hopefully good for a good while now.

[ditchcrawler]

19 minutes ago, calon said:

In my case it certainly apeared to be  erosion around the Blade tip,  the tube came as part of the kit suplied to the builder by Nobel's apparently only 5.5mm thick when new and in this kit with a bronze prop and there were no anodes in the tube.  In the end we had the tube was cut out and replaced with a 9.5mm seamless tube,  and we fitted two anodes inside the tube as well so hopefully good for a good while now.

Here is a photo I posted some time back 

 

[ditchcrawler]

16 minutes ago, ditchcrawler said:

Here is a photo I posted some time back 

 

PJ Barber also put some photos on his Facebook page 

 

[Dr Bob]

When we were lumpy water sailing, we travelled across the Med meeting another boat in every other port we stopped in. It was a 40 ft GRP sailing yacht and we became good friends. They had a bow thruster. We didnt. Every time coming into moor in a marina it was whirr, whirr, whirr. By the time we met up with in Greece, disaster struck. Their bow thruster stopped working. They couldnt moor the boat any more. They didnt have a clue. They had become so reliant on the BT that they couldnt even do the simplest things in any sort of breeze.

I guess that is the problem with a large proportion of narrow boats today.

The only time I wish I had a bow thruster is when I need to reverse long distances but with a bit of forward thinking, those instances are rare and certainly dont warrant the cost of maintaning the electrics and batteries etc of a BT.

We shared a set of wide locks last year where the boat we shared with swore blind that the BT was the best thing to use when sharing a lock with a smaller boat and only using one gate (ie a 60ft boat sharing with a 40 ft boat). Not convinced. It is not difficult at all to get our 63 ft boat through the 'wrong' gate if sharing a lock and only using one gate.

I wouldnt have one. Too much faffing around.

[cuthound]

1 hour ago, Dr Bob said:

When we were lumpy water sailing, we travelled across the Med meeting another boat in every other port we stopped in. It was a 40 ft GRP sailing yacht and we became good friends. They had a bow thruster. We didnt. Every time coming into moor in a marina it was whirr, whirr, whirr. By the time we met up with in Greece, disaster struck. Their bow thruster stopped working. They couldnt moor the boat any more. They didnt have a clue. They had become so reliant on the BT that they couldnt even do the simplest things in any sort of breeze.

I guess that is the problem with a large proportion of narrow boats today.

The only time I wish I had a bow thruster is when I need to reverse long distances but with a bit of forward thinking, those instances are rare and certainly dont warrant the cost of maintaning the electrics and batteries etc of a BT.

We shared a set of wide locks last year where the boat we shared with swore blind that the BT was the best thing to use when sharing a lock with a smaller boat and only using one gate (ie a 60ft boat sharing with a 40 ft boat). Not convinced. It is not difficult at all to get our 63 ft boat through the 'wrong' gate if sharing a lock and only using one gate.

I wouldnt have one. Too much faffing around.

 

This problem arises from having a BT too early in your boating skills development, so that you use the BT rather than learning the necessary skills.

 

I had been boating for about  40 years before I bought a boat I liked which just happened to have a bow thruster.

 

Since having it I have found it very useful for long reverses. However it packed up 18 months ago and I haven't felt the need to get it repaired but might do so when the boat comes out off the water this year for blacking.

[blackrose]

1 hour ago, Dr Bob said:

When we were lumpy water sailing, we travelled across the Med meeting another boat in every other port we stopped in. It was a 40 ft GRP sailing yacht and we became good friends. They had a bow thruster. We didnt. Every time coming into moor in a marina it was whirr, whirr, whirr. By the time we met up with in Greece, disaster struck. Their bow thruster stopped working. They couldnt moor the boat any more. They didnt have a clue. They had become so reliant on the BT that they couldnt even do the simplest things in any sort of breeze.

I guess that is the problem with a large proportion of narrow boats today.

 

 

Surely that's the problem with some owners who become over-reliant, not the equipment itself? This isn't a phenomenon restricted to bow thrusters, it's possible to become over-reliant on one's engine for example and I see lots of boaters who do just that - instead of using the boat's momentum, currents or wind, they use far too many engine revs when the conditions and the manoeuvre don't require it. I knew a narrow boater who regularly used to come into his mooring much too fast and slam the engine into reverse using high revs to stop. He pretty much mastered the manoeuvre until one day when he slammed it into reverse his morse cable snapped and he went crashing into two other boats quite hard.  

Edited March 10, 2019 by blackrose

[yabasayo]

4 hours ago, ditchcrawler said:

That is not the view of everyone, erosion around the blade tip area has been documented

Possibly not. However it is more likely that soft protective coating in the blade tip area has been eroded leaving bare metal to quietly corrode away unseen.

It takes a lot of high velocity water over a substantial period to erode steel.

[Boater Sam]

Not got one, don't want one, no need of one.

But I have seen the advantage for some folk in having one.

They do a grand job of removing poly bags but rubbish, mussels and stones going through must inevitably mark the blades and the inside of the tube leading to rapid corrosion.

 

I am surprised that the tube was only 5mm wall thickness, presumably rolled and welded not seamless drawn like steam pipe which I would have thought to be more suitable.

A wall thickness in excess of the hull thickness would seem to be prudent considering the likelihood of accelerated corrosion and difficulty of access for inspection and protective coating renewal.

 

 

[matty40s]

8 hours ago, yabasayo said:

Possibly not. However it is more likely that soft protective coating in the blade tip area has been eroded leaving bare metal to quietly corrode away unseen.

It takes a lot of high velocity water over a substantial period to erode steel.

It isn't the water thst erodes it, it is the silt, small stones and other debris which is prevalent in the shallow ditches...especially at the bankside.

All the failed or very thin ones I have seen have had the worst wear at the propeller area.

[calon]

I was told that the manufacturers kit came with a 5.5mm walled tube because its largest market was lumpy water were there's less silt and stuff  so the thinner wall isn't as much of a problem