Can a bulkhead ever be an integral part of a boats support structure?

[Alethea Price]

Hi Canal community.

 

I've got an interesting one at the moment.

 

Over the past few months I've been stripping out the interior of my 1990 holiday boat built narrowboat, cleaning up and treating the hull and then replacing the floors and walls. There were a lot of pointless cubby holes and thus a huge number of unwanted cabin bulkheads so as I've been going I've also been removing a lot of them to create more spacious rooms and practical storage.

 

So the pondery...

 

In my strip out I came across an unusual bearer.

As would be expected there are bearers that traverse widthwise throughout the boat. However, about 1/3 of the length from the stern, separating the galley from the rest of the cabin, there is one bearer that is different from all the others. Rather than running the full width of the boat, it is sectioned into two separate pieces, one on either side and appearing more like a girder (I shaped) than any of the other bearers (which are more like an upside-down L in appearance).

 

This bearer is also unusual in that the Bulkhead directly above it is double the thickness of all the other cabin bulkheads. Still made of veneered marine grade MDF, but supported by wooden roof frame beams on both sides. The rest of the cabin bulkheads were half the thickness, and only supported by one wooden beam, with bolt fixings.

 

My inclination is to say that the thicker bulkhead could be a firewall. Although this wouldn't explain why the bearer is also different.

 

Ideally I want to move the bulkhead back 4ft to extend the size of the galley, but at the same time I don't want to remove anything that could be part of the structural support of the boat. I won't take any action until I have better knowledge but would love to hear the thoughts of others.

 

So my question is - have you ever come across a bearer like this? And why do you think this bulkhead is so much thicker and supported differently to the others?

 

[Flyboy]

31 minutes ago, Alethea Price said:

Hi Canal community.

 

I've got an interesting one at the moment.

 

Over the past few months I've been stripping out the interior of my 1990 holiday boat built narrowboat, cleaning up and treating the hull and then replacing the floors and walls. There were a lot of pointless cubby holes and thus a huge number of unwanted cabin bulkheads so as I've been going I've also been removing a lot of them to create more spacious rooms and practical storage.

 

So the pondery...

 

In my strip out I came across an unusual bearer.

As would be expected there are bearers that traverse widthwise throughout the boat. However, about 1/3 of the length from the stern, separating the galley from the rest of the cabin, there is one bearer that is different from all the others. Rather than running the full width of the boat, it is sectioned into two separate pieces, one on either side and appearing more like a girder (I shaped) than any of the other bearers (which are more like an upside-down L in appearance).

 

This bearer is also unusual in that the Bulkhead directly above it is double the thickness of all the other cabin bulkheads. Still made of veneered marine grade MDF, but supported by wooden roof frame beams on both sides. The rest of the cabin bulkheads were half the thickness, and only supported by one wooden beam, with bolt fixings.

 

My inclination is to say that the thicker bulkhead could be a firewall. Although this wouldn't explain why the bearer is also different.

 

Ideally I want to move the bulkhead back 4ft to extend the size of the galley, but at the same time I don't want to remove anything that could be part of the structural support of the boat. I won't take any action until I have better knowledge but would love to hear the thoughts of others.

 

So my question is - have you ever come across a bearer like this? And why do you think this bulkhead is so much thicker and supported differently to the others?

 

Can you post some pictures ?

[Alethea Price]

2 minutes ago, Flyboy said:

Can you post some pictures ?

Hi Flyboy. That's probably the best logical next step. Annoyingly I've already put the ballast and floor back in but I'll see if I can quickly get it up tonight and take some pictures. Can easily get on of the Bulkhead at a minimum.

 

Has also occurred to me that I might be able to track down the original maker and see if they can shed some light on things. Disappointingly all the paperwork I have refers to the Company it was manufactures for (Anglo-welsh) but I can't find anything to suggest who made her. I'll keep hunting thought. Could be my best bet.

 

Will update with photos asap.

[Ray T]

If the boat is ex Anglo-Welsh, there is a possibility it may be ex Black Prince. Does it have a large rubber vertical fender at the front?

Reeves and Pinder built hulls for B P.

 

I stand correction here but I think many were fitted out at B P's base at Bromsgrove.

 

• 

 

Edited May 29, 2018 by Ray T

[David Mack]

Is this a boat with a welded steel cabin? If so I doubt that bulkhead has any structural significance. The same cannot always be said for a wooden cabin.

[70liveaboard]

I think your inclination regards the bulkhead thickness is right. More time to burn through to allow for escape, probably a H/S thing. I've not been involved with hire boats and the bearer situation you explained may just be the way the builder did things.

Regards moving the bulkhead, if it is now in private ownership for your personal use, then you can more or less do what you want bulkhead wise and no, the bulkhead will not be concerning the structure of a steel boat, unless of course it was a steel bulkhead.

[Alethea Price]

41 minutes ago, Ray T said:

If the boat is ex Anglo-Welsh, there is a possibility it may be ex Black Prince. Does it have a large rubber vertical fender at the front?

Reeves and Pinder built hulls for B P.

 

I stand correction here but I think many were fitted out at B P's base at Bromsgrove.

 

• 

 

That's very helpful thanks. This dilemma aside it would be great to track down the original makers for my own knowledge. Will try both of those thank you.

6 minutes ago, David Mack said:

Is this a boat with a welded steel cabin? If so I doubt that bulkhead has any structural significance. The same cannot always be said for a wooden cabin.

It is a full steel welded cabin. As you say I am assuming it offers no structural support was just unusual to find one varying from all the others. Thanks for the feedback sounds like we all generally agree.

[Alethea Price]

4 minutes ago, 70liveaboard said:

I think your inclination regards the bulkhead thickness is right. More time to burn through to allow for escape, probably a H/S thing. I've not been involved with hire boats and the bearer situation you explained may just be the way the builder did things.

Regards moving the bulkhead, if it is now in private ownership for your personal use, then you can more or less do what you want bulkhead wise and no, the bulkhead will not be concerning the structure of a steel boat, unless of course it was a steel bulkhead.

Its a Veneered Ply bulkhead - no steel so it sounds like I could be on the right tracks. It also occurs to me the the old shower unit was supported by this wall, so the thickness could have also be support for that.

 

Sounds like I'm safe to move the bulkhead then, sad news for the horrible old shower - great news for my new galley.

Thanks for the input.

[WotEver]

28 minutes ago, Alethea Price said:

It also occurs to me the the old shower unit was supported by this wall, so the thickness could have also be support for that.

And also to hide the plumbing perhaps?

[Alethea Price]

2 minutes ago, WotEver said:

And also to hide the plumbing perhaps?

Very possible.

 

TY

[PeterF]

My boat has a double thickness bulkhead between galley and kitchen with wall cupboards hung on this bulkhead in the galley and a cabinet in the bathroom, so it could be to take extra weight.

[Tony Brooks]

As some boats have 3mm or thinner steel roofs then if that bulkhead touched the roof it may be intended to give a thin roof some support for when people jump onto it from the lock side. If the roof id 4mm or thicker I doubt this could be the explanation.

[David Mack]

2 minutes ago, Tony Brooks said:

As some boats have 3mm or thinner steel roofs then if that bulkhead touched the roof it may be intended to give a thin roof some support for when people jump onto it from the lock side. If the roof id 4mm or thicker I doubt this could be the explanation.

And if you jump onto the roof anywhere other than at this bulkhead??

[70liveaboard]

Many narrowboats have/had 3mm cabins, there is no problem with them at all, provided they have 1" box section rolled/curved @ 2' centres (ish), that is the real strength, not the actual steel plate. That configuration gives/allows the builder to bow the steel over, adding even more strength. Could park a car on a well made 3mm steel cabin roof. Certainly any of the boats I've seen built.

Edited May 29, 2018 by 70liveaboard

[Alethea Price]

40 minutes ago, 70liveaboard said:

Many narrowboats have/had 3mm cabins, there is no problem with them at all, provided they have 1" box section rolled/curved @ 2' centres (ish), that is the real strength, not the actual steel plate. That configuration gives/allows the builder to bow the steel over, adding even more strength. Could park a car on a well made 3mm steel cabin roof. Certainly any of the boats I've seen built.

Thanks for that. Being total transparent I don't recall the thickness of the cabin steel off the top of my head but it had a recent survey I can refer to that this evening.

 

Saying that I'm not totally understanding what you mean re: "1" box section rolled/curved @ 2' centres (ish)"

 

Could you clarify in layman's terms for me? Many thanks!

[Neil2]

The only reason why the H section bearer under the bulkhead would have a gap in it must have been to route something under the cabin floor rather than through the bulkhead.  If the bulkhead separates the galley from the shower it may have been to allow the plumbing to go under the bulkhead.  It seems an odd way to do it but I have had one boat where the plumbing went through the bilge.   

[70liveaboard]

Its the formation used for the steel shell on the interior steelwork of standard cruiser style narrowboats. Builders have various ways they might reinforce the roof of the cabin, many go for rolled steel box section, box section is 'just that', a steel box tube, probably 4mm thick walls. These tubes are cut to the desired length (width of the roof), then rolled to form a curve in the bar. The amount of curve will vary from builder to builder (personal pref), plus builders may use other methods, but this is the most common. The curve will help the steel shape/strength of the roof. After this process the steel plate (for the roof) is pulled over the curve, which adds more strength, and the end item is a nice sturdy, very strong cabin, with a curve to the roof.

These bars once cut and rolled tend to be placed 18" to 24" apart (ish) and stitch (3-4" stitch) welded to the underneath of the cabin roof both sides of the bar. (cabin roof may be done upside down on the workroom floor then lifted, just depends again, on builder)

 

 

Not all builders build the same way, it varies greatly from builder to builder, but on the whole this method is the most common used for cruiser style narrowboat roofs..

 

Edited May 29, 2018 by 70liveaboard

[Alethea Price]

9 minutes ago, Neil2 said:

The only reason why the H section bearer under the bulkhead would have a gap in it must have been to route something under the cabin floor rather than through the bulkhead.  If the bulkhead separates the galley from the shower it may have been to allow the plumbing to go under the bulkhead.  It seems an odd way to do it but I have had one boat where the plumbing went through the bilge.   

You know someone else suggested it could have been for plumbing.

From what I can see there's nothing going through the gap anymore, but I know a lot of the plumbing got switched around sometime before I bought it, so it's certainly possible.

 

It looks to be in good condition either way so as long as I'm not interfering with anything by removing the bulkhead above this bearer then I think I'll just make note that it's there and carry on as normal.

[Tony Brooks]

1 hour ago, David Mack said:

And if you jump onto the roof anywhere other than at this bulkhead??

 

The longer the unsupported distance the easier it will be for the dome of the roof to deform and move down. By putting a bulkhead in to support such a roof you in effect halve the distance where deformation can take place.

 

 

1 hour ago, 70liveaboard said:

Many narrowboats have/had 3mm cabins, there is no problem with them at all, provided they have 1" box section rolled/curved @ 2' centres (ish), that is the real strength, not the actual steel plate. That configuration gives/allows the builder to bow the steel over, adding even more strength. Could park a car on a well made 3mm steel cabin roof. Certainly any of the boats I've seen built.

There is the nub - I did not notice the OP stating he had such cross members under the roof or anything similar. I agree with what you say and its how I would do it but would a "down to a price" budget builder?

[Alethea Price]

1 minute ago, 70liveaboard said:

Its the formation used for the steel shell on the interior steelwork of standard cruiser style narrowboats. Builders have various ways they might reinforce the roof of the cabin, many go for rolled steel box section, box section is 'just that', a steel box tube, probably 4mm thick walls. These tubes are cut to the desired length (width of the roof), then rolled to form a curve in the bar. The amount of curve will vary from builder to builder (personal pref), plus builders may use other methods, but this is the most common. The curve will help the steel shape/strength of the roof.

These bars once cut and rolled tend to be placed 18" to 24" apart (ish) and stitch (3-4" stitch) welded to the underneath of the cabin roof both sides of the bar. (cabin roof may be done upside down on the workroom floor then lifted, just depends again, on builder)

After this process the steel plate (for the roof) is pulled over the curve, which adds more strength, and the end item is a nice strudy, very strong cabin, with a curve to the roof.

 

Not all builders build the same way, it varies greatly from builder to builder, but on the whole this method is the most common used for cruiser style narrowboat roofs..

 

Very interesting thanks. I think I can follow you. I must say from my minds eye I don't recall much in the way of steel supports for the roof, and having just looked at some photos I have of the roof with ceiling taken away, it's all just timber supports. Would that be common, or something to worry about?

[70liveaboard]

3 minutes ago, Tony Brooks said:

 

The longer the unsupported distance the easier it will be for the dome of the roof to deform and move down. By putting a bulkhead in to support such a roof you in effect halve the distance where deformation can take place.

 

 

There is the nub - I did not notice the OP stating he had such cross members under the roof or anything similar. I agree with what you say and its how I would do it but would a "down to a price" budget builder?

Budget builders, as you call them, do it exactly the same. Any steel roof should be no more than 24" centres unless thicker steel i.e. 4mm even then 24" would be better.

1 minute ago, Alethea Price said:

Very interesting thanks. I think I can follow you. I must say from my minds eye I don't recall much in the way of steel supports for the roof, and having just looked at some photos I have of the roof with ceiling taken away, it's all just timber supports. Would that be common, or something to worry about?

That would be bad....   I think your looking at timber possibly fastened to steel support i.e. you may not see the steel bars/support.

 

[Alethea Price]

3 minutes ago, 70liveaboard said:

Budget builders, as you call them, do it exactly the same. Any steel roof should be no more than 24" centres unless thicker steel i.e. 4mm even then 24" would be better.

That would be bad....   I think your looking at timber possibly fastened to steel support i.e. you may not see the steel bars/support.

 

Let's assume that's the case (although I'm not convinced from the attached image from my phone). Appears to be just wood to me. Checking will now be top of my list for this evening.

 

 

Roof beams

[70liveaboard]

Just now, Alethea Price said:

Let's assume that's the case (although I'm not convinced from the attached image from my phone). Appears to be just wood to me. Checking will now be top of my list for this evening.

 

 

Roof beams

I can't open that image, but I would be very interested in seeing it. Could you attach it here on the forum. ?

[Alethea Price]

Just now, 70liveaboard said:

I can't open that image, but I would be very interested in seeing it. Could you attach it here on the forum. ?

Oh sorry about that maybe the forum doesn't like the format. But saying that I've just remembered there absolute are steel beams. I know because I messed up all my insulation measurements measuring from wooden beam to wooden beam and had to cut them all down to size again to accommodate the steel beams sitting next to the wood.

 

Panic over! ?

[70liveaboard]

1 minute ago, Alethea Price said:

Oh sorry about that maybe the forum doesn't like the format. But saying that I've just remembered there absolute are steel beams. I know because I messed up all my insulation measurements measuring from wooden beam to wooden beam and had to cut them all down to size again to accommodate the steel beams sitting next to the wood.

 

Panic over! ?

Good.