rocking boat

[miller]

ive have just finished a two week cruise on my new boat the boat seems to rock from side to side a lot any ideas

[Richard Bustens]

How deep is the draft?

[John Orentas]

ive have just finished a two week cruise on my new boat the boat seems to rock from side to side a lot any ideas

32272[/snapback]

 

 

Geoff.

 

Have you any idea of the metal thickness of cabin sides and roof, could be a bit top heavy. Apart from adding ballast there is not much that can be done. You will get used to it.

 

You did say you would let us know how you got on with your little problems.

[alan_fincher]

Geoff.

 

Have you any idea of the metal thickness of cabin sides and roof, could be a bit top heavy.  Apart from adding ballast there is not much that can be done.  You will get used to it.

 

You did say you would let us know how you got on with your little problems.

32279[/snapback]

Yes,

 

Use of an un-necessarily thick steel for the cabin can cause a degree of instabilty and roll.

 

Our boat has relatively "standard" 10mm bottom plate, and 6 mm hull sides, but the topsides are all in 5mm plate. 4mm is more common.

 

We were warned by the surveyor that, although this was in no way making the boat overly unstable, that it would be more likely to roll for a bit, as people change sides, and get on and off. Also that once rolling from side to side, it would take longer than a boat with a less substantial top to settle down again.

 

In practice you quickly get used to it, and it only ever seems to be a real issue when the livelier of my two sons, (who simply has too much energy!) is onboard.

 

Additionally we were told it would not be sensible to pile the roof with earth filled planters, or bags of coal, but do not have any intention of so doing anyway.

 

On the plus side, although there seems to be little additional bracing, the cabin flexes remarkably little, even if descended onto really quite firmly from a high lockside.

[DHutch]

All boats rock.

 

Ours is relatively stable most of the time, as were 22ton with 2'8" draught, and our steel is 12/6/3, so the cabin/roof is thiner than some.

- But even so shes quite 'tender' when full of coal, as the bunker is full hight, so a lot of the coal is quite high up at times.

 

 

 

Daniel

[AJLintern]

Daniel - Do you know what sort of ballast was used to get a draft of 2'8"?

[Liam]

The extra 2 mil on the base plate would help.

[DHutch]

Daniel - Do you know what sort of ballast was used to get a draft of 2'8"?

Two layers of 2" concrete flags over almost all of the floor.

- And then about 150kg of lead ingots to get it trimed.

- Some of which are moved about as we use our coal, which is stored off-center.

 

The one of the main reasons for the draught is to sink our 29" prop. and also the headroom is nice as we're all 6'+ i my familly

 

 

Daniel

[miller]

How deep is the draft?

32275[/snapback]

not sure about the draft would it help to and some more ballest maybe sand ?

it list to the side as the toilet tank fills

re the problems lnb sorted most of it out but still requires a repaint they fitted it with an inverter control panel c/heating and a pump out toilet

[John Orentas]

Hi Geoff.

 

You will need a lot of extra ballast to make a significant difference to the draft, I am sure there will be concrete flags under your floor it would be one hell of a job to get access and add to them (sand is not good to use, holds moisture and not very heavy), I would just get used to it, it is a boat after all and boats rock a bit.

 

You can alter the trim re the pump out tank, all you can really do is trim it level when the tank is half full. Can you get access to the ballast to adjust it on the appropriate side to add or subtract, it not try to sneak some steel bar into the bottom of cupboard or under beds.

 

P.S. Half empty fuel and water tanks will add the rocking effect, has that can be a factor.

Edited September 25, 2005 by John Orentas

[bottle]

Half empty fuel and water tanks will add the rocking effect, has that been a factor.

 

a pessimist

 

[Paul Evans]

It list to the side as the toilet tank fills.

32375[/snapback]

Without refitting the toilet tank, so that it lies along the centre line of the boat, there is not a lot you do to trim the boat totally. As John O says, you could try adding some ballast to counteract the effect of the tank filling but otherwise you will get used to it. And a gently rocking boat can be very peaceful and stress relieving.

[ChrisPy]

Half empty fuel and water tanks will add the rocking effect, has that been a factor.

 

a pessimist  

 

32413[/snapback]

yeah, you'll probably find the problem goes away if you keep them half full.

[rayman]

I assumed all tanks were baffeled?(spelling) this i thought would completlely stop all rocking, within reason of course.

[bottle]

I assumed all tanks were baffeled?(spelling) this i thought would completlely stop all rocking, within reason of course.

32468[/snapback]

 

In the ideal world they would be but I cannot find this world, does any one know where it is. With the s**t tank of course there would be the problem with cleaning

[John Orentas]

Baffling of the tank would not help much, it is a question of weight transfer.

 

Imagine holding a half full pop bottle, with the bottle horizontal an equal amount of pop will be at each end and it will be roughly balanced. Lean it over a few degrees, it becomes unstable and a disproportionate amount of weight is transfered to the 'down side', the more pop changes sides the more it leans and so on.

 

With a full or empty tank there is no significant weight transfer.

[rayman]

john, i would prefer slow tranfer than fast for obvious reasons.

[DHutch]

Baffling of the tank would not help much, it is a question of weight transfer.

Baffles would help it stop rocking, but they dont help general list.

- Moving water is a very unbalecing (sp) thing.

- Just think about the ferry that rolled over.

 

 

 

Daniel

[rayman]

Baffles would help it to stop/slow rocking, thank you, first post

[David Schweizer]

I doubt whether baffling the water tank or the effluent tank would have any significant inpact on the stability of a boat. Firstly because water will move very rapidly within a restricted space and create that Frying pan effect, and secondly the amount of floorspace occupied by the tanks is insignificant when compared with the overall floor space, and would have a proportional impact upon stability.

 

We do not really have any indication of the extent to which your boat rolls, but one factor on the rocking effect, which I have learnt from experience is the internal layout of the boat. My boat used to have a central walkway right through from the front entrance to the rear cabin and was reasonably stable. However, after a re fit, side walkways with a cross over in the middle of the boat were installed, now when someone walks through the boat their weight is transferred from one side to the other as they walk through the galley, this produced a not inconsiderable rolling effect on the boat. But you soon learn to live with it.

Edited September 25, 2005 by David Schweizer

[Keeping Up]

We do not really have any indication of the extent to which your boat rolls, but one factor on the rocking effect, which I have learnt from experience is the internal layout of the boat. My boat used to have a central walkway right through from the front entrance to the rear cabin and was reasonably stable. However, after a re fit, side walkways with a cross over in the middle of the boat were installed, now when someone walks through the boat their weight is transferred from one side to the other as they walk through the galley, this produced a not inconsiderable rolling effect on the boat. But you soon learn to live with it.

32533[/snapback]

I find exactly that with mine as the passageway moves from side to centre and back again; and twice as much if someone crosses from the passageway at the side across and into the bathroom. Also some people such as my wife naturally seem to time their steps so as to maximise the roll, especially if they are themselves somewhat broad in the beam (hoping my wife doesn't read this posting) whereas others such as my son naturally time their steps to minimise any rolling effect.

 

As David says, you soon learn to live with it.

[bottle]

Millenium Bridge syndrome naturally seem to time their steps so as to maximise the roll

 

I find it is the land that rolls, when I have been on the boat for any length of time.

[John Orentas]

The whole point of the 'frying pan effect' as David called it and which most of you missed is that it exaggerates the rolling of the boat, I find it quite noticeable at times.

[colinjw]

ive have just finished a two week cruise on my new boat the boat seems to rock from side to side a lot any ideas

32272[/snapback]

 

Hi miller,

 

When I first got my boat it was very tender...i.e. it rocked very easily.

 

I have since found out with the toilet tanks (2) empty, the boat rocked very easily. With the toilet tanks full or nearly so, the boat is much more stable.

 

Two years ago, I put an extra 1 tonne of steel ballast into the boat. Approx 600 kg. was placed almost exactly in the middle of the boat and the rest was split between underneath the seats in the lounge up at the pointed end.

 

Because one toilet usually gets used more, the ballast in the lounge can be transferred from one side to the other to counteract any list every few day.

 

This tonne of extra ballast increased the draft by about 3" at the most and with a cruising draft of 22" max it is no great problem with scraping the bottom.

 

When I added the ballast I was able to bring the boat onto a more even keel instead of dragging its bum by about 6" (stern trim) and now the max trim is 3" by the stern.

 

The moral of the story is that if you add weight low down, the boat is less tender....it works on the various ships I have been on for the past 35 years.

[Amicus]

It also helps if you can concentrate the ballast away from the centre line, out to the sides