Bouyancy

[jddevel]

Well my sailaway was finally put into a marina mooring last weekend. However although I`ve not been aboard a craft since hiring a couple of times last year it seems to "rock" side to side quite easily when moving about. Am I just not use to this movement again yet or is it possibly a ballast issue. I would add it currently has no water or fuel on board. When no movement it sits slightly bow up and level but as stated has no water on board and the tank is in the bow.

[howardang]

How long is the boat (presumably a narrow boat), any ballast on board  and does it appear to be very high in the water?

Howard 

[jddevel]

57 feet semi trad narrowboat ballasted by builder (Bourne Boats) and not especially although as stated higher at the bow than stern so not level fore and aft.

[WotEver]

It could be lacking ballast but most sailaways are pretty tender until they're fitted out. 

Slightly bow high is both good and normal. 

Edited September 3, 2017 by WotEver

[jddevel]

8 minutes ago, WotEver said:

Slightly bow high is both good and normal. 

Any suggestions how I modify allowing for two of my lads totaling nearly 40 stone

 

10 minutes ago, WotEver said:

are pretty tender until they're fitted out. 

Actually apart from water and fuel tanks being empty now fitted out.

[WotEver]

1 minute ago, jddevel said:

Any suggestions how I modify allowing for two of my lads totaling nearly 40 stone

 

Actually apart from water and fuel tanks being empty now fitted out.

Then I guess you need to keep both the lads permanently on board in the well deck and then see if you need to add any ballast

[jddevel]

Just now, WotEver said:

if you need to add any ballast

A keg for me and a couple of dozen Chardonnay for my dear wife. Troubles although a holding tank on board I suppose this is a variable factor

[Jen-in-Wellies]

Once the fitout is complete and your stuff is on board the boat will settle a lot lower in the water and be less sensitive to someone wandering around on board. A solid fuel stove is around 80Kg for example. Similar weight to an average person. Wouldn't worry about it. My boat was about 2" higher in the water when in sailaway condition and the underside of the counter barely touched the water. Once fitted out it was fine.

Jen

Edited September 3, 2017 by Jen-in-Wellies

[rusty69]

18 minutes ago, jddevel said:

Any suggestions how I modify allowing for two of my lads totaling nearly 40 stone

One on the front. One on the back. Opposite sides

[Alan de Enfield]

Assuming your builder has undertaken the RCD stability test and the 'results' are a 'pass' then you should have nothing to worry about.

Some hull designs are just more wobbly than others - did you 'sea-trial' a Bourne Boat before placing your order ?

[Bee]

Unless it is a radically different shape it will be absolutely fine, its because narrow boats are odd things. I wonder if any builder has actually carried out an RCD stability test?

[MtB]

More ballast under the floor will always improve stability.

Is the uxter plate nicely under water?

The builders will have ballasted light as they don't know how much stuff you'll use fitting it out.

[Alan de Enfield]

21 minutes ago, Bee said:

Unless it is a radically different shape it will be absolutely fine, its because narrow boats are odd things. I wonder if any builder has actually carried out an RCD stability test?

As it is a requirement of the RCD I would have thought that it was a 'must', and, if they didn't they would be in serious trouble by declaring RCD compliance and issuing an RCD Declaration of Conformity.

With a 'sailaway' the owner who completes the build is responsible for the testing / compliance (inc Stability testing)

Anyone who buys a bare or partly completed hull with a view to completing it, even for their own use, will be the responsible person (not the hull builder) and become responsible for RCD Compliance including the requirements relevant to the hull. It is therefore very important to obtain the necessary Declaration from the hull builder that the hull has been built in accordance with the Directive’s scantling requirements.  
 

Edited September 3, 2017 by Alan de Enfield

[jddevel]

36 minutes ago, Mike the Boilerman said:

Is the uxter plate nicely under water

In my opinion yes

[Neil2]

3 hours ago, jddevel said:

Well my sailaway was finally put into a marina mooring last weekend. However although I`ve not been aboard a craft since hiring a couple of times last year it seems to "rock" side to side quite easily when moving about. Am I just not use to this movement again yet or is it possibly a ballast issue. I would add it currently has no water or fuel on board. When no movement it sits slightly bow up and level but as stated has no water on board and the tank is in the bow.

When you say "moving about" do you mean on deck or in the cabin?  And do you mean it rocks when moored or when under way?

[Bee]

1 hour ago, Alan de Enfield said:

As it is a requirement of the RCD I would have thought that it was a 'must', and, if they didn't they would be in serious trouble by declaring RCD compliance and issuing an RCD Declaration of Conformity.

With a 'sailaway' the owner who completes the build is responsible for the testing / compliance (inc Stability testing)

Anyone who buys a bare or partly completed hull with a view to completing it, even for their own use, will be the responsible person (not the hull builder) and become responsible for RCD Compliance including the requirements relevant to the hull. It is therefore very important to obtain the necessary Declaration from the hull builder that the hull has been built in accordance with the Directive’s scantling requirements.  
 

Thing is though that unless the boat is one of a class of identical boats almost every boat is a 'one off' as regards length. swim length, depth of counter, weight and everything else you can think of. I would bet my life savings (£7. 50) that no narrowboat has ever been tested. I certainly didn't try and turn my boat over after building it just to see when it would roll over and sink. However if I bought a cruiser that was supposed to be ok for coast hopping I would expect it to be safe with no nasty habits.

[Alan de Enfield]

5 minutes ago, Bee said:

Thing is though that unless the boat is one of a class of identical boats almost every boat is a 'one off' as regards length. swim length, depth of counter, weight and everything else you can think of. I would bet my life savings (£7. 50) that no narrowboat has ever been tested. I certainly didn't try and turn my boat over after building it just to see when it would roll over and sink. However if I bought a cruiser that was supposed to be ok for coast hopping I would expect it to be safe with no nasty habits.

There have been several forumites who have purchased sasilaways and have commented on the stability tests that they have had to subject the boat to – If I remember the tests have to be witnessed by a surveyor who then calculates the weight limits, number of people etc in accordance with the RCD Maybe when one of them reads this and ‘comes forward’ you will be kind enough to donate your life savings to the RNLI

Edited September 3, 2017 by Alan de Enfield

[Bee]

1 minute ago, Alan de Enfield said:

There have been several forumites who have purchased sasilaways and have commented on the stability tests that they have had to subject the boat to – If I remember the tests have to be witnessed by a surveyor who then calculates the weight limits, number of people etc in accordance with the RCD,

Damn, that's £7.50 to some sort of charity.

[howardang]

2 minutes ago, Bee said:

Thing is though that unless the boat is one of a class of identical boats almost every boat is a 'one off' as regards length. swim length, depth of counter, weight and everything else you can think of. I would bet my life savings (£7. 50) that no narrowboat has ever been tested. I certainly didn't try and turn my boat over after building it just to see when it would roll over and sink. However if I bought a cruiser that was supposed to be ok for coast hopping I would expect it to be safe with no nasty habits.

It is certainly not necessary to turn your boat over to test its stability! This is a well known (and  mandatory) procedure on every ship and many other smaller craft.

The title of this thread is also incorrect. It is possibly a stability issue, not buoyancy, although I think that the problem here may go away once all the fit out is complete.

Howard

 

 

[sharpness]

2 hours ago, howardang said:

 although I think that the problem here may go away once all the fit out is complete.

Howard

 

 

According to post No 5, apart from fuel & water it is complete.

[howardang]

55 minutes ago, sharpness said:

According to post No 5, apart from fuel & water it is complete.

Sorry, missed that. Perception of the  rolling is  subjective  and it might be worth asking an experienced boater to go on board with him to get an independent view. Alternatively, it may just be a case of not enough ballast has been fitted.

Howard

[WotEver]

Or it may just be a somewhat tender boat. 

[howardang]

18 minutes ago, WotEver said:

Or it may just be a somewhat tender boat. 

And within reason, that can be mitigated by loading ballast low down, bearing in mind that he needs to maintain s sensible draught..

Howard

[Alan de Enfield]

9 hours ago, howardang said:

And within reason, that can be mitigated by loading ballast low down, bearing in mind that he needs to maintain s sensible draught..

Howard

And - sufficient 'freeboard' for any hull fittings (10" recommended minimum)

[WotEver]

But if the uxter plate is under water does it really want to sit any lower? Genuine question.