ballast

[pollip]

I bought a boat that needed some over plating done, over plating was carried out using 6mm steel adding approx 1.376 tons of steel if the boat was square to minus abit for the Uttoxeter plate the the shape of the bow.

after fitting the plumbing and filling the water tank to test the system I realised the well deck drain holes were under water -_-, back out everything came to remove some ballast. I'm really struggling with where to remove the ballast from, I'm in the midst of calculating how many slabs there is and how much they weigh, there's 48 2ftx2ft x 50mm concrete slabs and 24 2ftx1.5ft x 50mm slabs. I also need to calculate how big my water tank is to counteract the weight. I'm going to be putting approx 500kg of weight one side of the boat and 200kg the other so will be listing massively aswell as being to low. I don't actually know where a boat is supposed to sit in the water so cant just take some out and play around. I'm assuming I need to do all of this with a full water tank and full diesel tank, I'm planning to reduce the capacity of the tank by 100litres to save 100kg on the bow (integral big bloody tank). the boat is a 45ft cruiser stern 1976 built by bingley boats (bodge builders as I've figured out the hard way).  I've been told older boats were built to have their drainage holes relatively close to the water line for some bizarre reason. how close to the water line should my well deck drain holes be ?, the water tank is probably half filled approx the diesel tank has 80 litres diesel in it there's now no floor just the ballast with the walls I left up and the well deck holes are approx 4-5 inches out of the water. i should probably also mention I've completely moved everything round in the boat from what it was so there's also much more weight at the bow then there was, my beds now there along with a wardrobe... before there was an arm chair and that about it.

any help greatly appreciated

Phil 

Edited January 6, 2021 by pollip

[Dav and Pen]

2x2x2inch slabs weigh 22 to the ton so you have just over 2 tons.

[Alan de Enfield]

From the Boat safety scheme :

 

 

To reduce the risk of your boat sinking if it keels over or is excessively weighed down, it's a good idea for privately owned boats to only have openings which are at a height of at least 250mm (10ins) above the waterline. Where openings are necessary below this level this risk can be reduced by ensuring that these openings are permanently and securely connected to ducts or pipes, which are watertight up to that level.

Self-draining cockpits may not be able to meet the 250mm (10ins) recommendation but, for privately owned boats, it's a good idea to stop water getting into other parts of the hull by incorporating non-return valves in the drains and/or having bulkheads or cills up to a height of 150mm (6ins).

A weed hatch, if not properly secured, can allow water into the bilges of a boat, which could ultimately cause it to sink. It's advisable for privately owned boats to have a secure and watertight weed hatch which reaches to at least 150mm (6ins) above the waterline, when the boat is loaded up as normal. [10.3]

 

 

 

Edited January 6, 2021 by Alan de Enfield

[Alan de Enfield]

 

What other hull openings do you have ?

Engine air vents ?

Bilge pump ?

Exhaust ?

Cooling water inlet ?

 

 

If your boat only has 4 or 5 inches as a 'stripped out' + ballast hull, then I think you may have serious problems ahead,

You can only 'put 500kg' on one side (presumambly fitting out) if you put 500kgs on the other side to balance it (using ballast ?)

So you cannot take out the ballast on that side.

Taking out the ballast you may end up with a very top-heavy boat (even taking account the new base plate) and it will be very tender (wobbly)

 

Here is an article on a boat that was overplated and was too heavy.

I am not posting this for any other reason than to make you aware of the risks regarding the work you are doing and hopefully so that you can identify and work around the problems.

 

Port of London - River Thames (pla.co.uk) (Pictures and more detail)

 

Here it is probably apposite to quote the case of the narrow boat MINI MOO ex MARY MINT. The following is quoted verbatim from a Safety Bulletin issued by the Port of London Authority: –
On the 24th August 2012, a narrow boat was delivered by road to South Dock Marina in London for a new owner. The vessel was lifted into the dock and the new owner requested to lock out of the marina as they had an overnight berth in Lime House Marina; a short distance up the River Thames. The vessel departed the lock at 17:00 with 5 adults and 1 dog aboard. As they departed the lock the lock keeper commented to them that they should have lifejackets on board as they appeared to be missing. The crew decided to continue on and left the lock with 3 adults in the aft cockpit and 2 adults in the cabin. The vessel transited directly across the river to the starboard side of the channel and then turned upriver towards Lime House Marina. Shortly into their transit the crew noted a change in the engine note and opened the engine room hatch to find the engine half submerged. All persons quickly moved to the stern to try and bail out the engine room, but were unable to cope with the ingress of water into the vessel. The engine room continued to fill with water and flooded into the main cabin, submerging the aft coaming below the water, resulting in severe flooding of the vessel which sank within 10 seconds. All of the crew and the dog entered the water without lifejackets, but were rescued by a nearby RIB and Police Launch.

Marine surveyors and others concerned with narrowboats should obtain a copy of the Bulletin from the PLA and take note of its recommendations.

It was noted by the PLA that the vessel had been the subject of extensive overplating. Whoever had recommended the overplating had also recommended partly blocking off the engine room air jalousie on the port side as its bottom edge was considered even then to be too near the waterline. The following Figure 1 below shows the effect of the overplating and the number of persons seated aft.

 

The buyer of the MINI MOO bought the boat on the strength of a survey report provided by the seller. The marine surveyor concerned had estimated the height of the engine air intake jalousie from water level marks on the hull although the vessel had been out of the water for a considerable time prior to his survey. He had estimated the intake to be 200 mm above the waterline but when it measured after the salvage it was only 65 mm. The marine surveyor had covered himself with the caveat that it was an estimate only. In that particular case, when the vessel sank, no life jackets were on board and at least one person on board could not swim. The survivors were very lucky that nearby boats managed to pluck them from the water immediately. The fact that a marine surveyor’s report perhaps covers him with words such as estimated does not provide much comfort if bodies have to be pulled from the water.

The yellow line indicates the original free board in still water this was meassured to be 65 mm. The red line indicates the waterline incurred from three people standing on the aft deck which pushed the engines jalouise below the water.

The vessel was fitted with an air cooled Lister engine and, in accordance with common practice, had a ventilation jalousies cut into the topside aft to give the necessary combustion air supply for the engine. The overplating was such that the jalousie at the engine room was within 65 millimetres of the waterline. That highly dangerous situation was not helped by the presence of a small lop on the water surface. Some five people plus a dog called Gus were on board (three of them sitting aft and two in the cabin) to make the journey and, hearing unusual noises from the engine, the engine room cover was lifted and the boat was found to be rapidly taking water. The situation was made worse by all of the people on board moving aft to have a look and to try to bale the water out, thereby increasing the trim and pushing the lower edge of the jalousie 50 mm under the water. The boat rapidly filled and sank within 10 seconds but, fortunately, a nearby RIB and a police boat arrived within two minutes and all personnel, plus Gus the dog, were picked up by the police and the nearby RIB. Despite the fact that none of them were wearing life jackets and at least one of them could not swim, there were, thankfully, no fatalities although all were suffering from shock. What Gus said was not recorded. It was later said that the owner had relied on a marine survey report prepared for the previous owner and that the vessel was uninsured.

 

 

[Onewheeler]

A photo of the well deck and cabin door arrangements would help. If too low, you're in danger of water entering the cabin. Don't forget that you could easily get an extra few hundred kg on the front deck if a few "large" visitors got on board (self-loading ballast).

 

In my opinion, whoever did the overplating has some responsibility for ensuring that the ballasting is OK (morally if not contractually). Where in Oxford are you? I'd come and have a look, but we're not supposed to visit our boat in Oxford under current restrictions.

Edited January 6, 2021 by Onewheeler

[pollip]

2 minutes ago, Onewheeler said:

A photo of the well deck and cabin door arrangements would help. If too low, you're in danger of water entering the cabin. Don't forget that you could easily get an extra few hundred kg on the front deck if a few "large" visitors got on board (self-loading ballast).

 

In my opinion, whoever did the overplating has some responsibility for ensuring that the ballasting is OK (morally if not contractually). Where in Oxford are you? I'd come and have a look, but we're not supposed to visit our boat in Oxford under current restrictions.

I’ll see if I have some, I’ve spoken to someone who said the same thing. Any good boat yard would tell you to counteract the ballast weight to how much over plating has gone in, tbh the guy starline boats shafted me from day dot. We aren’t actually in Oxford I don’t like advertising where we are, we are near coventry basin on the coventry canal. I never thought of the whole people on the deck adding weight, it’s also where I store the genny and firewood so that will add weight. It’s more a storage area than anything else 

[Tracy D'arth]

Ballasting a short overplated boat is always difficult. Small amounts of ballast make big changes.

Are the "well deck" drains level with the deck inside? If so 4.5" freeboard is not enough. I would suggest that you ballast the bow higher with the counter at the stern just in the water with full tanks. I could be that the boat was low in the water to start with.

Take as much ballast out as you can, fill tanks, position furnishings then add ballast to achieve the correct freeboard.

 I doubt that you will be able to calculate how much and where to add ballast without physically doing it.

Edited January 6, 2021 by Tracy D'arth

[TheBiscuits]

1 hour ago, pollip said:

the boat is a 45ft cruiser stern 1976 built by bingley boats

 

how close to the water line should my well deck drain holes be ?, the water tank is probably half filled approx the diesel tank has 80 litres diesel in it there's now no floor just the ballast with the walls I left up and the well deck holes are approx 4-5 inches out of the water.

 

i should probably also mention I've completely moved everything round in the boat from what it was so there's also much more weight at the bow then there was

 

Mine is a Bingley 45' Trad of a similar age.  

 

The scuppers on the well deck are usually between 3 and 6 inches above the waterline depending on how full the water tank is (and how much crap is in the well deck!) so 4 or 5 inches wouldn't be a concern to me.

 

If you have trimmed the boat too far nose down by having too much weight in the bow (with the new bedroom and storage) then that is the cause of your problem.  Remove a tonne or so of ballast, mostly from the forward half of the cabin and you should be OK, but be careful when trimming for the list, especially if you are planning on such an extreme difference in the fitout.

 

 

Edited January 6, 2021 by TheBiscuits

[David Mack]

If you've added 1.4 tons of steel then you need to remove 1.4 tons of ballast to put the boat back at the same average depth in the water as before. Since the added plating is all presumably below the water line, then removing the same weight of ballast from the bilges is going to mean little or no change in the overall stability of the boat.

Whether you can trim the boat (fore and aft, and side to side) the same as before depends on how the ballast was distributed before. If it was evenly spread across the whole boat, then no problem. But if it was all lumped to one side or one end to counteract the out-of-balance loads of fuel/water/pumpout tanks, a heavy engine or one sided internal fitout, then you may have more difficulty.

Calculation will only get you so far. So better to put enough liftable floor panels in the boat that you can rearrange the ballast as you add other loads.

[TheBiscuits]

1 hour ago, pollip said:

I'm going to be putting approx 500kg of weight one side of the boat and 200kg the other so will be listing massively aswell as being to low.

 

If you are thinking of adding 700kg of extra stuff in the boat (why?!) you probably need to remove nearly all the paving slab ballast to counteract this extra weight as well as the new overplating.  A 300kg difference in lateral trim is like having 15 sacks of coal all along one side - it's a lot of difference.

 

That's a bad idea on a Bingley - they are notoriously "tender" (rock a lot) anyway.  They were usually built with 1/4" steel hull and baseplate and have quite a lot of hull "flare" - mine's 8" narrower at the baseplate than the gunwales.

 

I'd strongly recommend rethinking your fitout so as much weight as possible is below the waterline, and try and shave as much weight as possible off that 700kg. 

 

What does that weight include, and how much of it could be reduced or left out entirely? 

 

 

[Alan de Enfield]

2 minutes ago, TheBiscuits said:

 

If you are thinking of adding 700kg of extra stuff in the boat (why?!) you probably need to remove nearly all the paving slab ballast to counteract this extra weight as well as the new overplating.  A 300kg difference in lateral trim is like having 15 sacks of coal all along one side - it's a lot of difference.

 

That's a bad idea on a Bingley - they are notoriously "tender" (rock a lot) anyway.  They were usually built with 1/4" steel hull and baseplate and have quite a lot of hull "flare" - mine's 8" narrower at the baseplate than the gunwales.

 

I'd strongly recommend rethinking your fitout so as much weight as possible is below the waterline, and try and shave as much weight as possible off that 700kg. 

 

What does that weight include, and how much of it could be reduced or left out entirely? 

 

 

 

Particularly as 500kg is on one side and only 200 on the other side - he will need 300kg (on one side) of ballast to 'balance' that out.

[pollip]

On 06/01/2021 at 18:09, TheBiscuits said:

 

If you are thinking of adding 700kg of extra stuff in the boat (why?!) you probably need to remove nearly all the paving slab ballast to counteract this extra weight as well as the new overplating.  A 300kg difference in lateral trim is like having 15 sacks of coal all along one side - it's a lot of difference.

 

That's a bad idea on a Bingley - they are notoriously "tender" (rock a lot) anyway.  They were usually built with 1/4" steel hull and baseplate and have quite a lot of hull "flare" - mine's 8" narrower at the baseplate than the gunwales.

 

I'd strongly recommend rethinking your fitout so as much weight as possible is below the waterline, and try and shave as much weight as possible off that 700kg. 

 

What does that weight include, and how much of it could be reduced or left out entirely? 

 

 

It’s taken me awhile to figure out how I actually reply on here, last time was pot luck ??‍♂️?. It’s not necessarily extra stuff and none of it can be lost, that include the fire gas bottle cratch board bed mattress sofa work top fridge cooker leisure batts shower tray toilet sink wardrobe log burner calcium silicate board hearth, and the likes. The sides probably do taper down like yours as the walls under the gunnels are on the piss because the hull is on the piss. The highest thing on that is the wardrobe which is going to be just pigeon holes all floor to ceiling and the worktop that sits about 80mm off the underside of the gunnel, the rest is relatively low. 

[pollip]

On 06/01/2021 at 17:59, David Mack said:

If you've added 1.4 tons of steel then you need to remove 1.4 tons of ballast to put the boat back at the same average depth in the water as before. Since the added plating is all presumably below the water line, then removing the same weight of ballast from the bilges is going to mean little or no change in the overall stability of the boat.

Whether you can trim the boat (fore and aft, and side to side) the same as before depends on how the ballast was distributed before. If it was evenly spread across the whole boat, then no problem. But if it was all lumped to one side or one end to counteract the out-of-balance loads of fuel/water/pumpout tanks, a heavy engine or one sided internal fitout, then you may have more difficulty.

Calculation will only get you so far. So better to put enough liftable floor panels in the boat that you can rearrange the ballast as you add other loads.

This is what I was thinking, although I wasn’t sure if taking any weight out the middle row of ballast would cause stability issues. I’ve actually weighed the ballast now and measuring the diesel and water tank tomorrow to get guesstimations on the litre capacity, all the new plate is on the bottom so couldn’t get any lower if it tried. The ballast was evenly spread bar 2 slabs in the middle where the inspection hatch it right near the bulkhead for the engine bay and 4 slabs on the left hand side where the bathroom was (swopped sides now so I may do the same). After reading that I’m going to try make the whole floor removable so like you say any issues next time and I haven’t got to go back to square one

[Alan de Enfield]

9 minutes ago, pollip said:

The highest thing on that is the wardrobe which is going to be just pigeon holes all floor to ceiling and the worktop that sits about 80mm off the underside of the gunnel, the rest is relatively low. 

Whilst keeping the CoG as low as possible the fact that you have more (300kg, 500kg, 700kg) more on one side than the other means that it will have a list of (probably) several inches. This means that the stability will be affected and even 2 or 3 people on that side could actually tip the boat over.

 

Walking, sleeping and cooking will be very uncomfortable in a boat with a list - my 14 foot beam boat has a list of about 1" from side to side, in the lengthways beds you get a feel of 'rolling out of bed'. It would be twice as bad on a 7' beam boat

 

Stability testing is part of the boat builders reponsibility and test methods are detailed in the RCD.

 

There was a useful notice issued to Surveyors of which an extract is below :

 

 

The marine surveyor should remember that overplating, though a common practice, is often carried out without thought as to the unintended consequences.
We should realise that it adds weight to the vessel’s structure without adding much compensating volume and, as a direct result, the vessel necessarily sinks lower in the water. It also has a number of other unintended and often unrealised side effects.

1. By increasing the draft, it reduces the available freeboard and, therefore, the amount of reserve buoyancy.
2. It also, therefore, reduces the transverse metacentric radius (BMT), and slightly, increases the height of the centre of buoyancy (KB) usually with very little compensating reduction in the height of the centre of gravity (KG) so that the end result is a reduction in the metacentric height (GM) and a negative alteration to the characteristics of the statical stability curve i.e. a reduction in the maximum GZ value and the range of positive statical stability. [The average metacentric height of a narrowboat is about 150 mm (6 inches)].
3. It may also, depending upon where the overplating is sited, alter both the longitudinal trim and the transverse heel of the vessel with further indeterminate alterations in her statical stability curve.
4. It lowers the deck edge immersion angle and, therefore, any downflooding angle(s).
5. The double plating is usually not secured to the primary supporting structure – the shell side framing. It is also rarely fitted with centre plate plug welds and is dependent only on the edge weld for security.
6. The double plating is secured only at its edges and the greater the area of plate, the smaller the length of the attachment weld per unit area and, therefore, the greater the stresses in those welds.
7. The corrosion or pitting, being the reason for fitting the doubling plates, means the corrosion or pitting will still remain there and, if it is on the inside of the original shell plate, will still be increasing. Doubling, therefore, is merely hiding the problem, not repairing it.

The marine surveyor should remember that time spent considering the consequences of his actions is never wasted. A lot (too many) of boats, particularly inland narrow boats and private pleasure boats, are doubled or over plated to various degrees in both terms of area and quality of welding and finish. When presented with a vessel that has a length of 6 mm plate some 250 mm or so wide welded astride the normally laden waterline, it is not unreasonable to conclude that the plating in way has severe corrosion or pitting (for whatever reason) and that somebody in the past has recommended overplating as a cure.

Edited January 8, 2021 by Alan de Enfield

[pollip]

On 06/01/2021 at 17:54, TheBiscuits said:

 

Mine is a Bingley 45' Trad of a similar age.  

 

The scuppers on the well deck are usually between 3 and 6 inches above the waterline depending on how full the water tank is (and how much crap is in the well deck!) so 4 or 5 inches wouldn't be a concern to me.

 

If you have trimmed the boat too far nose down by having too much weight in the bow (with the new bedroom and storage) then that is the cause of your problem.  Remove a tonne or so of ballast, mostly from the forward half of the cabin and you should be OK, but be careful when trimming for the list, especially if you are planning on such an extreme difference in the fitout.

 

 

That’s 4-5 inches with nothing but ballast inside and a relatively empty water tank so I imagine by the time I’ve boarded the floor viynl on top put the bed mattress in and the wardrobe filled any day bits and bobs under the bed we will drop a considerable amount, I’m sure I had about an inch no more than 2 before I ripped everything out without the wardrobe and a relatively empty water tank.

[TheBiscuits]

1 minute ago, pollip said:

all the new plate is on the bottom so couldn’t get any lower if it tried.

 

Ah, you didn't say that!  If it's only had a new baseplate then just remove all the slabs and don't worry about it.  We were assuming it had been overplated base and hull sides.

[pollip]

2 minutes ago, Alan de Enfield said:

Whilst keeping the CoG as low as possible the fact that you have more (300kg, 500kg, 700kg) more on one side than the other means that it will have a list of (probably) several inches. This means that the stability will be affected and even 2 or 3 people on that side could actually tip the boat over.

 

Walking, sleeping and cooking will be very uncomfortable in a boat with a list - my 14 foot beam boat has a list of about 1" from side to side, in the lengthways beds you get a feel of 'rolling out of bed'. It would be twice as bad on a 7' beam boat

 

Stability testing is part of the boat builders reponsibility and test methods are detailed in the RCD.

How do you stability test ??, I’m not very good with the web so surfing it doesn’t always give me the answers I need

[pollip]

On 06/01/2021 at 17:32, Tracy D'arth said:

Ballasting a short overplated boat is always difficult. Small amounts of ballast make big changes.

Are the "well deck" drains level with the deck inside? If so 4.5" freeboard is not enough. I would suggest that you ballast the bow higher with the counter at the stern just in the water with full tanks. I could be that the boat was low in the water to start with.

Take as much ballast out as you can, fill tanks, position furnishings then add ballast to achieve the correct freeboard.

 I doubt that you will be able to calculate how much and where to add ballast without physically doing it.

I’m just trying to gauge a rough idea on where to start. I may try taking 1.3ton throughout the length and then see where I’m at, yes the well deck drains holes are level with the bow well deck. And that 4-5 inches is with a mostly empty tank and nothing but ballast inside so like you say a rather big issue really, I worked out that the overplating of the boat was square end to end including the utoxeter plate would drop me 48mm so just shy of 2 inches. So take off a few hundred kg for discrepancy even say a ton

On 06/01/2021 at 16:53, Alan de Enfield said:

 

What other hull openings do you have ?

Engine air vents ?

Bilge pump ?

Exhaust ?

Cooling water inlet ?

 

 

If your boat only has 4 or 5 inches as a 'stripped out' + ballast hull, then I think you may have serious problems ahead,

You can only 'put 500kg' on one side (presumambly fitting out) if you put 500kgs on the other side to balance it (using ballast ?)

So you cannot take out the ballast on that side.

Taking out the ballast you may end up with a very top-heavy boat (even taking account the new base plate) and it will be very tender (wobbly)

 

Here is an article on a boat that was overplated and was too heavy.

I am not posting this for any other reason than to make you aware of the risks regarding the work you are doing and hopefully so that you can identify and work around the problems.

 

Port of London - River Thames (pla.co.uk) (Pictures and more detail)

 

Here it is probably apposite to quote the case of the narrow boat MINI MOO ex MARY MINT. The following is quoted verbatim from a Safety Bulletin issued by the Port of London Authority: –
On the 24th August 2012, a narrow boat was delivered by road to South Dock Marina in London for a new owner. The vessel was lifted into the dock and the new owner requested to lock out of the marina as they had an overnight berth in Lime House Marina; a short distance up the River Thames. The vessel departed the lock at 17:00 with 5 adults and 1 dog aboard. As they departed the lock the lock keeper commented to them that they should have lifejackets on board as they appeared to be missing. The crew decided to continue on and left the lock with 3 adults in the aft cockpit and 2 adults in the cabin. The vessel transited directly across the river to the starboard side of the channel and then turned upriver towards Lime House Marina. Shortly into their transit the crew noted a change in the engine note and opened the engine room hatch to find the engine half submerged. All persons quickly moved to the stern to try and bail out the engine room, but were unable to cope with the ingress of water into the vessel. The engine room continued to fill with water and flooded into the main cabin, submerging the aft coaming below the water, resulting in severe flooding of the vessel which sank within 10 seconds. All of the crew and the dog entered the water without lifejackets, but were rescued by a nearby RIB and Police Launch.

Marine surveyors and others concerned with narrowboats should obtain a copy of the Bulletin from the PLA and take note of its recommendations.

It was noted by the PLA that the vessel had been the subject of extensive overplating. Whoever had recommended the overplating had also recommended partly blocking off the engine room air jalousie on the port side as its bottom edge was considered even then to be too near the waterline. The following Figure 1 below shows the effect of the overplating and the number of persons seated aft.

 

The buyer of the MINI MOO bought the boat on the strength of a survey report provided by the seller. The marine surveyor concerned had estimated the height of the engine air intake jalousie from water level marks on the hull although the vessel had been out of the water for a considerable time prior to his survey. He had estimated the intake to be 200 mm above the waterline but when it measured after the salvage it was only 65 mm. The marine surveyor had covered himself with the caveat that it was an estimate only. In that particular case, when the vessel sank, no life jackets were on board and at least one person on board could not swim. The survivors were very lucky that nearby boats managed to pluck them from the water immediately. The fact that a marine surveyor’s report perhaps covers him with words such as estimated does not provide much comfort if bodies have to be pulled from the water.

The yellow line indicates the original free board in still water this was meassured to be 65 mm. The red line indicates the waterline incurred from three people standing on the aft deck which pushed the engines jalouise below the water.

The vessel was fitted with an air cooled Lister engine and, in accordance with common practice, had a ventilation jalousies cut into the topside aft to give the necessary combustion air supply for the engine. The overplating was such that the jalousie at the engine room was within 65 millimetres of the waterline. That highly dangerous situation was not helped by the presence of a small lop on the water surface. Some five people plus a dog called Gus were on board (three of them sitting aft and two in the cabin) to make the journey and, hearing unusual noises from the engine, the engine room cover was lifted and the boat was found to be rapidly taking water. The situation was made worse by all of the people on board moving aft to have a look and to try to bale the water out, thereby increasing the trim and pushing the lower edge of the jalousie 50 mm under the water. The boat rapidly filled and sank within 10 seconds but, fortunately, a nearby RIB and a police boat arrived within two minutes and all personnel, plus Gus the dog, were picked up by the police and the nearby RIB. Despite the fact that none of them were wearing life jackets and at least one of them could not swim, there were, thankfully, no fatalities although all were suffering from shock. What Gus said was not recorded. It was later said that the owner had relied on a marine survey report prepared for the previous owner and that the vessel was uninsured.

 

 

I remember reading that a few years ago, we have engine bay vents but they sit on top of the back deck so no major issues. All skin fitting have been raised, the exhaust could certainly be higher and I have seen water going up the exhaust when turning the tiller that particular way with a relative amount of revs. Stern deck drain holes were raised as it’s a pants pipe system that goes out a skin fitting. The main concern is the well deck drain holes and the gas locker holes aft of the well deck, the gas locker holes sit slightly higher than the well deck holes but not by alot

[Alan de Enfield]

5 minutes ago, pollip said:

the exhaust could certainly be higher and I have seen water going up the exhaust when turning the tiller that particular way with a relative amount of revs.

 

That is not good - is there anti sort of anti-syphon / swan neck in the exhaust system ?

You DO NOT want water running back into  the exhaust system.

 

I am looking thru my RCD stuff to see what I can find for you on Stability testing.

[pollip]

2 minutes ago, Alan de Enfield said:

 

That is not good - is there anti sort of anti-syphon / swan neck in the exhaust system ?

You DO NOT want water running back into  the exhaust system.

 

I am looking thru my RCD stuff to see what I can find for you on Stability testing.

I’ve thought this myself, I believe the swan neck runs down towards the engine ??‍♂️ Through the silencer. Marvellous Thankyou, I do intend to get it raised at some point when out for blacking one year but being now again at the start of a refit and sofa surfing with my 2 dogs during this pandemic life is rather stressful and money is short all round

[pollip]

On 06/01/2021 at 18:09, TheBiscuits said:

 

If you are thinking of adding 700kg of extra stuff in the boat (why?!) you probably need to remove nearly all the paving slab ballast to counteract this extra weight as well as the new overplating.  A 300kg difference in lateral trim is like having 15 sacks of coal all along one side - it's a lot of difference.

 

That's a bad idea on a Bingley - they are notoriously "tender" (rock a lot) anyway.  They were usually built with 1/4" steel hull and baseplate and have quite a lot of hull "flare" - mine's 8" narrower at the baseplate than the gunwales.

 

I'd strongly recommend rethinking your fitout so as much weight as possible is below the waterline, and try and shave as much weight as possible off that 700kg. 

 

What does that weight include, and how much of it could be reduced or left out entirely? 

 

 

 

25 minutes ago, TheBiscuits said:

 

Ah, you didn't say that!  If it's only had a new baseplate then just remove all the slabs and don't worry about it.  We were assuming it had been overplated base and hull sides.

Sorry I should of been clearer first time round. So just remove the approx weight of the steel through the whole boat ?

[Alan de Enfield]

All I can quickly find is the ISO specifications for testing, but I do know that some boat builders (who have probably built dozens of boats and have read the specifications) have translated it to  a 'bloke number' and will have (say) 5 'big blokes', or '10 big blokes' (depending on boat size) standing all on one side, on the gunnels. If they don't get wet, it passes.

 

Anyway - mechanically propelled boats over 6 metres in length :

 

Downflooding Angle

This requirement is to show that there is sufficient margin of heel angle before significant quantities of water can enter the boat. A simple method of calculating this is provided in BS EN ISO 12217-1, Annex C (Methods for calculating downflooding angle) and similarly to the downflooding height, if this method does not show compliance with the requirements, practical testing or computer simulation may provide an alternative method.

 

Offset Load Test

This test demonstrates sufficient stability for the boat at loaded displacement mass against offset loading by the crew. BS EN ISO 12217-1, Annex B (Method for offset-load test) gives the procedure for conducting the test with the maximum allowable heel angle that may be obtained which is a function of length given in Clause 6.2 of the standard

 

I'd suggest, fit it out (loosely) get some mates on board, if it doesn't fall over, screw all your 'fittings' down, go out and enjoy yourself, but take take it to sea.