Reinforcing the uxter plate

[Trento]

Why dont you ask the builder for his/ their advice?. All this phaffing around seeking real or imaginary sounds and movement could be rectified by a telephone call to the builder.

 

Just a thought.

[MtB]

Why dont you ask the builder for his/ their advice?. All this phaffing around seeking real or imaginary sounds and movement could be rectified by a telephone call to the builder.

 

Just a thought.

 

Liverpool boats went bust long ago.

 

MtB

[bizzard]

It could have been (Old father Thames) groaning under the boat.

[Trento]

But the fabricators are still trading, under different names. Its only a phone call, cost about 4p. May save a shed load of agro later.

[Ron T]

 

I've no idea what you would know...

 

You're entitiled to your opinion of course, but as another engineer I don't think it would work. I've got loads of heavy stuff sitting on those uxter plates already including a 1/4 of a tonne of bricks on each side. If it deadens the vibration the effect is not perceptible.

 

In my opinion it would be much more direct and effective to simply lay on the uxter as someone else steers the boat through waves and feel for any vibration or flexing.

 

Mike

I'm getting a bit confused here.If I couldn't resolve the problem myself I would look for advice from the fabricator or an engineer.You do state that you are an engineer so either you shouldn't be or aren't .If you are then I wouldn't ask you to resolve any engineering problems.Appologies if I have missinterprated the profession,continents appart different qualifications e.t.c.Hope it's not just cavitating!Righto back to my christmas plonk.Hope you sort it out and are having a great Christmas.

[bizzard]

I'm getting a bit confused here.If I couldn't resolve the problem myself I would look for advice from the fabricator or an engineer.You do state that you are an engineer so either you shouldn't be or aren't .If you are then I wouldn't ask you to resolve any engineering problems.Appologies if I have missinterprated the profession,continents appart different qualifications e.t.c.Hope it's not just cavitating!Righto back to my christmas plonk.Hope you sort it out and are having a great Christmas.

There are hundreds of different kinds of engineers and not necessarily anything to do with metal.

[MtB]

There are hundreds of different kinds of engineers and not necessarily anything to do with metal.

 

Indeed. I'm sometimes accused of being a gas engineer!

 

Some peeps say an engineer is someone with a degree in engineering. Others say it is simply someone using their mind to devise solutions to technical problems. The word 'ingenuity' shares the same root apparently

 

From Wiki ... the word engineer is derived from the Latin roots ingeniare ("to contrive, devise") and ingenium ("cleverness").^[3][4]

 

 

MtB

 

 

 

(Edit to fixy my spellin' ...yet again!)

Edited December 25, 2013 by Mike the Boilerman

[onionbargee]

The answer is a couple of steel angle stiffeners nothing more, Barnes Wallis may not be needed on this one

[bizzard]

For maximum strength say four or six, two or three to each side gusset plates of elongated triangular shape, the short side say a foot high welded vertically on to the hull sides with the long sides of the gussets (however long they need to be) to stretch transversely across the uxter plate to the edge and welded down.

[DHutch]

Hard to really suggest out of the blue, with no photos of the inside, and I would at least so some hand calcs on loads before sizing steel work. A significant consideration is that by stiffening the structure you may actually increase the load on the welds etc rather than decrease it.

 

You also want to think a bit about how you going to go about keeping it painted.

 

Angle iron welded upside down is a good bet, if you can run them fully from one side to the other is much better.

 

Daniel

[blackrose]

Ahh, now that we are aware that you have loads of heavy stuff on the larger areas of the uxter plate then, going back to the original purpose of your question (would welding reinforcing bards to my uxter plate cure a suspected noise from that area?), I have some doubt as to whether the uxter plate is the true source of your problem. Even on a wide beam, if the plate is heavily laden with 'stuff' it should dampen any panting from the plate so, unless some of the stuff on the plate is chafing against each other creating the noise, then I'm not sure that it would be worth welding bars across. I'm pretty sure that accurate diagnosis of the problem source could prevent possible unnecessary trouble and expenditure. Have you thought that it might be air getting sucked under the uxter plate in choppy conditions? We certainly had air getting sucked under the uxter of our narrow boat on the Severn when we were passed by high speed cruisers going the other way and we were crossing their wash. This was so bad that the prop used to grip and slip as we crested/dug in on the chop from their wake and air was sucked under, and that was on a reasonably deep drafted nb with a good size prop.

 

It could well be air getting sucked under the uxter and nothing more. I'll know once I've got down there with the boat going through some waves or wash from passing boats. That will be an accurate enough method of diagnosis as far as I'm concerned.

 

As you say, you've had air sucked under your counter and I'm sure the same effect happens on plenty of narrowboats in waves. It's just the result of having a flat plate inches below the waterline and in my case the effect could be exacerbated because the uxter plate is bigger.

[blackrose]

I've got a mobile welder coming on Saturday to do this job - finally got motivated to do it as I'm epoxying the hull in a few weeks so I want to get this done first. I'm pretty sure the uxter does flex a bit. As you can see it's a big unsupported span in 6mm.

 

I've marked out where the 50mm x 50mm x 5mm thick angle will go and I'd be interested in what people think as I'm just guessing.

 

Does it matter if the angle doesn't cross at 90 degrees? I don't think it will matter in terms of strength, I'm just thinking about the cutting and welding. The angle will have a 1" weld every 6". On the starboard side I think it will need a long piece of angle running front to back because the batteries are in the way and I can't get the cross members in, but I might forget about the long front to back piece on the port side and just have the cross members.

 

Starboard side (front to left of picture/back to right of picture). I'll tidy up those cable and protect the batteries with a welding blanket.

 

Starboard side (stern and diesel tank to right of picture). I pulled those isolators off so I can move the cables.

 

Port side (cabin bulkhead to right of picture)

 

Port side (cabin bulkhead to right - not in picture)

 

Port side (stern to left). I've pulled the diesel pipe for the heater away from the support on the uxter plate.

 

Edited April 26, 2015 by blackrose

[onionbargee]

I see.

 

Seeing the shape of

the swim in the foto I can imagine the whole thing wobbling up and down. I'm inclined to suggest some vertically diagonal bracing. A strut or struts from where the uxter plate meets the swim on one side, diagonally up and across to where the side deck meets the hull side opposite. The triangulation will add a LOT of stiffness and hopefully clear the engine too.

 

 

 

 

I'm inclined to suggest 3" x 3" angle though, or 2" box section or the struts themselves might flex.

 

 

MtB

 

 

(Spellin edit)

Pray tell us your qualifications in fabrication MTB ?

Edited April 26, 2015 by onionbargee

[Paul C]

Can't help thinking reinforcing the uxter plate will merely transfer the forces to somewhere else more critical/more likely to fail. The only issue is that the thing (is suspected - I don't remember reading that you proved it) bends under loads, and makes a groaning noise while in rough waters? Or are there other issues?

[blackrose]

Can't help thinking reinforcing the uxter plate will merely transfer the forces to somewhere else more critical/more likely to fail. The only issue is that the thing (is suspected - I don't remember reading that you proved it) bends under loads, and makes a groaning noise while in rough waters? Or are there other issues?

No I haven't proven it and there are no other issues, but it seems fairly obvious to me that the only large, horizontal, unreinforced area of the hull will flex. All I'm doing is stiffening the area.

 

Has reinforcing your boat's baseplate transferred the forces elsewhere on your boat?

Edited April 27, 2015 by blackrose

[Dave Clinton]

Pray tell us your qualifications in fabrication MTB ?

Certainly the concept of triangulation seems to have escaped him.

[X Alan W]

 

Yes, that's the sort of thing I was thinking of, plus one more right across the back. I think it's the wider areas that are more prone to flexing.

I would fit 2 more 1 each side running from the stern post area to the corners of the transom dividing the wide part into triangles

[Murflynn]

Mike, the structure is already stiff at the edges of the uxter plate in the long direction. I think the long pieces (1.83m) could usefully be omitted altogether. The cross pieces should extend to the very edges, with limber holes at the outside and rounded at the inside edges. Personally I would use flat bar to avoid hidden (more difficult) welding and making inspection and painting easier. You really don't need the 'belt and braces' of angle bar, just local stiffening. 50x6 flat bar should suffice, unless you plan to use the upper leg of the angle as a support for equipment. KISS principle should apply.

 

(chartered engineer)

[Neil Smith]

Would it not be better to ask the shell builder what he suggests or if no longer around then another reputable one.

 

Neil

[Paul C]

 

Has reinforcing your boat's baseplate transferred the forces elsewhere on your boat?

 

I don't own a Liverpool Boats widebeam which is styled upon a narrowboat but effectively, the design simply "stretched" widthways. BUT luckily, the rules meaning that forces will transfer, are fairly universal - Newton's Laws of Motion encapsulated this back in 1687.

 

Hopefully the fabricator will be able to look at the job and evaluate it a bit more scientifically than you have done. He might want seek the opinion of a shell builder, if not the shell builder which has now gone out of business. I'd certainly advise a more considered approach before randomly welding bits of metal to the boat.

[onionbargee]

Mike, the structure is already stiff at the edges of the uxter plate in the long direction. I think the long pieces (1.83m) could usefully be omitted altogether. The cross pieces should extend to the very edges, with limber holes at the outside and rounded at the inside edges. Personally I would use flat bar to avoid hidden (more difficult) welding and making inspection and painting easier. You really don't need the 'belt and braces' of angle bar, just local stiffening. 50x6 flat bar should suffice, unless you plan to use the upper leg of the angle as a support for equipment. KISS principle should apply.

 

(chartered engineer)

What he said.

Edited April 27, 2015 by onionbargee

[MtB]

Pray tell us your qualifications in fabrication MTB ?

 

 

Like you, I don't have any.

 

I'm an engineer not a fabricator.

[MtB]

[Murflynn]

[blackrose]

 

I don't own a Liverpool Boats widebeam which is styled upon a narrowboat but effectively, the design simply "stretched" widthways. BUT luckily, the rules meaning that forces will transfer, are fairly universal - Newton's Laws of Motion encapsulated this back in 1687.

 

Hopefully the fabricator will be able to look at the job and evaluate it a bit more scientifically than you have done. He might want seek the opinion of a shell builder, if not the shell builder which has now gone out of business. I'd certainly advise a more considered approach before randomly welding bits of metal to the boat.

The fabricator has already looked at it and agreed that the wider, unsupported areas need to be stiffened. Where those forces are transferred doesn't really matter long as they're transferred to a stronger part of the structure, the same as on your boat or any boat that's been strengthened.

 

While stretching the narrowboat design widthways will effectively weaken it, you're not quite right about this being done on my boat. As well as the bearers at 18" centre a going across the baseplate (the same as most narrowboats), my boat has two sets of bearers going along the full length of the baseplate.

 

The uxter plates are the only completely unsupported areas.

Edited April 28, 2015 by blackrose