Bow thruster tubes

[matty40s]

This week's Bow thruster story is a fairly recent Reeves hull, grill welded on and tube hasn't been blacked since boat launch. The fairly bad galvanic corrosion across the hull is duplicated inside the tube.

 

 

 

 

Solution was to angle grind an access hatch in each grille, black inside and then secure with removable stainless clips.

Funnily, even though Clauderose pooh - pooed the problems and told everyone to go out and cruise, he had the same problem in 2006 with the build of his widebeam and sought advice on the best way of rectifying it!!

Edited July 8, 2016 by matty40s

[ditchcrawler]

What's missing? I tried opening link but got hammered by spam popups.

Yes I got a window up wanting me to download something as well

[David Mack]

This week's Bow thruster story is a fairly recent Reeves hull, grill welded on and tube hasn't been blacked since boat launch. The fairly bad galvanic corrosion across the hull is duplicated inside the tube.

 

 

 

 

Solution was to angle grind an access hatch in each grille, black inside and then secure with removable stainless clips.

Funnily, even though Clauderose pooh - pooed the problems and told everyone to go out and cruise, he had the same problem in 2006 with the build of his widebeam and sought advice on the best way of rectifying it!!

 

Why is nearly half the tube blanked off?

[matty40s]

From seeing the boat in the marina entering the dock, I think it is because the waterline is so close to the top of the tube.

When the Bow thruster was operated, I would guess it was getting more air than water through the prop and it was ineffective.

[David Mack]

From seeing the boat in the marina entering the dock, I think it is because the waterline is so close to the top of the tube.

When the Bow thruster was operated, I would guess it was getting more air than water through the prop and it was ineffective.

I guessed that might be the reason. But a bit of a bodge and must reduce the effectiveness of the bow thruster compared with what it should be capable of.

[WotEver]

Sounds like the boat is under-ballasted?

[Jess--]

Sounds like the boat is under-ballasted?

it seems that some of these widebeams that are built to budget are under-everything.

 

although to be fair you could say the same about anything built to be as cheap as possible..... you get what you pay for.

[DHutch]

A decent welder by the look of it

The cable tied on mesh sums up the gulf between some of the builders out there.

 

I was more looking at the failure to black the tube at all.....

Why is nearly half the tube blanked off?

Just ouch all round.

 

Why are people willing to put out this level quality. Truly awful.

 

 

Daniel

[BruceinSanity]

Just ouch all round.

Why are people willing to put out this level quality. Truly awful.

Daniel

Because there are ignorant and ill-advised mugs out there who will pay for it. I think two things are missing from this market that might help:

 

1) A Which? type source of objective reviews of boats. The ones in CB and WW have to pull their punches to a degree, the builders are also their advertisers.

 

2) A professional body with teeth, prepared to name and shame poor quality builders. CBA doesn't seem to fulfill that role, don't know why.

[ditchcrawler]

There are photos on facebook at https://www.facebook.com/photo.php?fbid=580163242161943&set=pcb.1069515983132663&type=3&theatershowing the erosion in the tube

[crossley]

If the tunnel is properly engineered I can't see it posing any undue risk.

Poor quality thin wall tube with little corrosion protection is another matter entirely, and like others have said,the wall thickness needs to be a thick as the hull.

I work on tunnel thrusters as part of my job,and have had a fair few in and out, aquamaster,KaMeWa,stone Vickers,and lianenen types come to mind. They are all heavily reinforced around the propeller area,some have a sacrificial wear ring of stainless too.

You do get some erosion in the tunnel where the propeller is, running, a shallow groove by the blade tips,but it's never deep,just a few mm. On supply boats and ferries they are mostly cpp propellers,and clock up lot of hours maneuvering in port or holding station on dp. Two pack epoxy is generally used and seems to last the

5 year docking periods quite happily.

So given that example, a good thick wall seamless tube,epoxy painted internally, and inspected at every docking, say 2 years poses no great risk.

[FadeToScarlet]

So given that example, a good thick wall seamless tube,epoxy painted internally, and inspected at every docking, say 2 years poses no great risk.

That's the thing, Matty40s is pointing out the poor engineering of several examples; I can fully understand that properly specced, installed, and maintained they are fine, but a bit of tube, welded in, no wear ring, and not properly painted inside.... Seems a recipe for trouble to me.

[DHutch]

There are photos on facebook at https://www.facebook.com/photo.php?fbid=580163242161943&set=pcb.1069515983132663&type=3&theatershowing the erosion in the tube

Really interesting to see that, thanks for sharing.

[ditchcrawler]

Here are the photos from facebook, the plan is to line the tube with a second tube welded at each end.

[WotEver]

... the plan is to line the tube with a second tube welded at each end.

Painted, I hope.