Stability of cafe boat

[Theo]

In converting a wide (12foot?) narrowboat into a cafe boat it is proposed to deck out the roof to make it level and have tables, chairs an customers sitting on the top.  Has this boat a chance of being stable? 

 

A heeling experiment coupled with the mass of the boat will give the length of the righting lever but you need to position of the CofG to move on from that to work out the effect of 40 people on the roof!  It all sounds very dodgy to me.

 

Am I being alarmist?

 

N

[Mad Harold]

3 minutes ago, Theo said:

In converting a wide (12foot?) narrowboat into a cafe boat it is proposed to deck out the roof to make it level and have tables, chairs an customers sitting on the top.  Has this boat a chance of being stable? 

 

A heeling experiment coupled with the mass of the boat will give the length of the righting lever but you need to position of the CofG to move on from that to work out the effect of 40 people on the roof!  It all sounds very dodgy to me.

 

Am I being alarmist?

 

N

Yes, you have only to have a boat passing with a gorgeous female sunbathing on the deck, and forty people wil migrate to one side to ogle, and over the cafe boat will go!  😂

[Peanut]

Stability calculations are every day work for naval architects, they charge for their service, but if you want to be sure, that is the way to go.  You could try Paul Fisher NA, at Selway Fisher, he has designed narrowboats.

[BEngo]

The boat might well be stable.  As it heels one way the roof customers, tables etc. will fall off. The hull might  then right itself.

 

I doubt that the MCA will be  keen on this as a stability mechanism, and I am not sure that depositing your "cargo" into the cut is acceptable under CRT by-laws.

 

 

 Serious bit.

 

 

Where is this planned?

 

If it is in UK and  there are to be more than 12  people on the boat the MCA will need to issue the appropriate certificates.  They will certainly want to see assured stability as one of their criteria, along with life rafts, flotation rings, fire precautions and a host of other things.

 @mrsmelly I think has experience and may have more detail.

 

N

 

[MtB]

18 minutes ago, Peanut said:

You could try Paul Fisher NA, at Selway Fisher, he has designed narrowboats.

 

 

I wonder what they looked like!

 

 

 

 

[Peanut]

3 minutes ago, MtB said:

 

 

I wonder what they looked like!

 

 

 

 

Have a look on his web site.

[MtB]

4 minutes ago, Peanut said:

Have a look on his web site.

 

I've a sneaky feeling I may not need to... 😅

[Theo]

This conversion is nothing to do with me.   I observed it in progess and asked, not quite in these terms "Do you know what your are doing sability wise?" and they, not quite in these terms said "No".  They had the grace to look somewhat alarmed and said they would look it up on the internet.

 

I might put a note through the door to get in touch with Paul Fisher.  The were pleasent, hardworking chaps and I would hate their dreams to be shattered at the stage of completion and getting the boat licensed to do whatever they intend to do.

 

Nick

22 minutes ago, MtB said:

 

I've a sneaky feeling I may not need to... 😅

They are very pretty boats in a variety of styles.  Worth a look just to admire.

 

N

[MtB]

5 minutes ago, Theo said:

They are very pretty boats in a variety of styles.  Worth a look just to admire.

 

N

 

Are they long and thin? Possibly?

 

But yes ok, I'll have a look! 

 

 

[ditchcrawler]

1 hour ago, Peanut said:

Have a look on his web site.

Its here  Motor Boats over 30' (selway-fisher.com)

[Ianws]

I'm not sure how other cafe boats do it but catering businesses usually require a separate sink just for handwashing, and a good supply of hot water throughout the service, to meet eho requirements.

[Ken X]

Many years ago I was involved in the stability testing of a new ferry for Christchurch Harbour.  We spent a long and very hot day shifting many many 75kg weights all around the vessel whilst the man from the ministry watched and directed.  At each configuration the freeboard was carefully measured all round the boat and calculations made.  I guess a similar test may be needed for this boat.

[1st ade]

11 hours ago, BEngo said:

The boat might well be stable.  As it heels one way the roof customers, tables etc. will fall off. The hull might  then right itself

Some years ago our office had a proliferation of wooden "wedges" to hold fire doors open - I (in jest) said to the Fire Officer "of course in the event of a fire the wedge will combust, and the door will close" - I think his response then will be similar to the one required here...

[David Mack]

12 hours ago, ditchcrawler said:

Its here  Motor Boats over 30' (selway-fisher.com)

Including a plywood narrowboat. I wonder how many of those have been built!

[mrsmelly]

13 hours ago, BEngo said:

The boat might well be stable.  As it heels one way the roof customers, tables etc. will fall off. The hull might  then right itself.

 

I doubt that the MCA will be  keen on this as a stability mechanism, and I am not sure that depositing your "cargo" into the cut is acceptable under CRT by-laws.

 

 

 Serious bit.

 

 

Where is this planned?

 

If it is in UK and  there are to be more than 12  people on the boat the MCA will need to issue the appropriate certificates.  They will certainly want to see assured stability as one of their criteria, along with life rafts, flotation rings, fire precautions and a host of other things.

 @mrsmelly I think has experience and may have more detail.

 

N

 

Each craft that falls under the MCA is dealt with on a case by case basis. On the Princess we used 50 gallon drums filled with water ( lots of them ) places at various locations, sides, decks etc etc and measurements were taken each time they were re positioned. Talking about just that one boat for instance, the max capacity is 172 people including crew which is a regular occurence. Apart from max capacity of 172 the specifics are no more than sixty on the upper deck alone with or without persons on the lower deck. 

The host of other things is very true, inspections took most of a day and were very thorough, the checks on each of the ( 8 ) seperate water tight compartments even included screw holes, grommets for cable passing through etc etc etc. The last time I did it there was two of them and one of me lol.

[ditchcrawler]

9 hours ago, Ken X said:

Many years ago I was involved in the stability testing of a new ferry for Christchurch Harbour.  We spent a long and very hot day shifting many many 75kg weights all around the vessel whilst the man from the ministry watched and directed.  At each configuration the freeboard was carefully measured all round the boat and calculations made.  I guess a similar test may be needed for this boat.

Similar at Fox narrowboats where they weighed us all and then we all sat down one side and then other places while they measured the angle with an Ipad

[Sea Dog]

When dining on the roof of said boat, stop and think twice should you be asked "Soup of the day, Sir? Certainly. Would you like a roll with that?" 

[Theo]

Thanks for all the comments.  I had the impression that thse two young men had an idea and didn't do their homework.  What will happen now is up to them.  They had thought about stability and someone was going to do some tests for them but the someone hadn't turned up so they were carrying on anyway.  I think that it may all end in tears.

 

 

N

[TheBiscuits]

3 hours ago, Theo said:

Thanks for all the comments.  I had the impression that thse two young men had an idea and didn't do their homework.  What will happen now is up to them.  They had thought about stability and someone was going to do some tests for them but the someone hadn't turned up so they were carrying on anyway.  I think that it may all end in tears.

 

 

N

 

If they haven't thought about stability issues, they've probably not realised they need a commercial BSS or worse  MCA certification.

 

That could be a very expensive oversight!

[ditchcrawler]

29 minutes ago, TheBiscuits said:

 

If they haven't thought about stability issues, they've probably not realised they need a commercial BSS or worse  MCA certification.

 

That could be a very expensive oversight!

It looked good on the back of the fag packet 🎢

[Momac]

Is the  proposal like this ?

[David Mack]

1 hour ago, TheBiscuits said:

 

If they haven't thought about stability issues, they've probably not realised they need a commercial BSS or worse  MCA certification.

And a CRT commercial licence (assuming they are on CRT waters) as well as a commercial insurance policy.

Edited July 22, 2023 by David Mack

[Francis Herne]

On 21/07/2023 at 21:07, Theo said:

They are very pretty boats in a variety of styles.  Worth a look just to admire.

My wooden canoe (red thing on the roof in my profile pic) is built to one of his plans. Very clear and easy to work from, and the result is ridiculously stable for a canoe while still easy to paddle. Strongly recommended.

 

EDIT: so far as the topic goes, my feeling is that it can probably work. Say the limit is 40 people to avoid going up an MCA category, that's pessimistically 4 tons, maybe 10% of the boat's weight? Even on one side of the roof they're still about a foot in from the edge of the hull, and the railings could be placed further in if necessary.

 

The paperwork will kill it though, if they've got this far without even considering what's required.

Edited July 23, 2023 by Francis Herne

[ditchcrawler]

Talking of Stability, maybe @blackrose would like to give his thoughts on this setup.

 

[Tam & Di]

I assume there are no low bridges between there and a dry dock