Mooring at Thorpe Green

[Oddfellow]

We warn customers about the bridges which probably puts them off visiting. Our greatest concern is that people stay there on the last night and then get stuck and can't return the boat for 9am which would potentially cause huge problems. 

 

However, we do tell people to visit the area as it is a very pretty part of the river. 

 

To lose these moorings would be a travesty. 

[BroadScot]

I must have been very lucky, or the tides were lower in the 90's. Only once on returning back to Hearts did we have to moor up next to the Rowing Club and leave the boat there on the Saturday morning.

 

Iain. 

[MBA Marine]

We warn customers about the bridges which probably puts them off visiting. Our greatest concern is that people stay there on the last night and then get stuck and can't return the boat for 9am which would potentially cause huge problems. 

 

However, we do tell people to visit the area as it is a very pretty part of the river. 

 

To lose these moorings would be a travesty. 

Its digressing off topic i know but...... When a new boat is built for broads use i cannot see why the majority of the space under the floor is not bonded out to create a huge sealed void or floodable ballast tank, very simple to set this tank up with a high vent and a sea cock to open that fills the tank, once through the bridge I would have a engine driven bilge pump engage the clutch and rapidly discharge the ballast tank, you can easily add enough weight to drop a boat down by approx 4" maybe more and it will still be afloat.

 

All the boats systems should be routed down the sides to keep them clear of the bilges so no space needs to be lost.

 

Some say why not just flood the bilge?  If i was the owner of hire craft I would not want people potentially sinking my boats, but the ballast tank method takes out that risk.

 

The question of how it could be done is of no relevance, give me an empty hull and I could make it so, but my question is why don't they? set up this way all broads bridges could be passed with really high tide exception. 

[jillR]

Its digressing off topic i know but...... When a new boat is built for broads use i cannot see why the majority of the space under the floor is not bonded out to create a huge sealed void or floodable ballast tank, very simple to set this tank up with a high vent and a sea cock to open that fills the tank, once through the bridge I would have a engine driven bilge pump engage the clutch and rapidly discharge the ballast tank, you can easily add enough weight to drop a boat down by approx 4" maybe more and it will still be afloat.

hi mark

letting the tyres down is a good idea but the BA would need to keep

up with the dredging and some bridges like wroxham

are tubes ?

[MBA Marine]

hi mark

letting the tyres down is a good idea but the BA would need to keep

up with the dredging and some bridges like wroxham

are tubes ?

If enough boats travel though a bridge with props close to the bottom they will stay clear and not silt up. tubes get wider as you go lower, the advantage would still be there. or are you suggesting you might touch the bottom of the tube? 

[jillR]

thinking of wroxham and how it looks at high high water I guess

there would be more room from water level to the bottom and boats

have more air draft then water draft in most cases that are relevant.

[Guest]

Its digressing off topic i know but...... When a new boat is built for broads use i cannot see why the majority of the space under the floor is not bonded out to create a huge sealed void or floodable ballast tank, very simple to set this tank up with a high vent and a sea cock to open that fills the tank, once through the bridge I would have a engine driven bilge pump engage the clutch and rapidly discharge the ballast tank, you can easily add enough weight to drop a boat down by approx 4" maybe more and it will still be afloat.........

 

The concept of using water as additional ballast to lower a boat in the water below it's normal waterline is difficult to achieve without encroaching into the main hull area, rather than just the bilges.

 

The "huge sealed void" would need to be big enough to come up above the floor level to have any significant effect, because it would need to displace the buoyancy effect of the unflooded part of the boat.

 

Hire companies used to sometimes fill barrels with water within the volume of the accomodation space or on deck, effectively displacing the main buoyancy.

 

Putting it simply, if you attached a 200 gallon tank to the bottom of a boat, it would lift the hull with a force of 2000 lbs, but if you then flooded it completely, the boat would sink to the original water level.

 

Submarines work on the basis that their lead battery ballast and hull weight makes them sink anyway, and only float when their ballast tanks are filled with air.

 

Conventional boats however, have huge reserves of buoyancy because of their lightweight construction.

[BroadScot]

Or in the days past, pull all the punters out the Bridge Inn at Potter H and put them on a boat and get it through that hole! Good fun that was, going back afterwards, and hoping your pint was still there lol.

 

Iain.

[MBA Marine]

I was thinking more with practical knowledge than using the math, I have been on board a Hampton safari with water touching its floor bearers, it sat much lower in the water yet happily afloat! 

 

further to that it would also be simple in the construction stage to fit tanks higher in the boat that could have water pumped into them, my points come through hearing people talk about not being able to get under bridges, but people don't seen to try to find easy to use solutions to said problems, I hear many stories of piling bodies onto the boat to load it up, that's great but we can do better, its would seem just give up using the hard to get areas is the answer most choose.

[Guest]

I was thinking more with practical knowledge than using the math, I have been on board a Hampton safari with water touching its floor bearers, it sat much lower in the water yet happily afloat! 

 

further to that it would also be simple in the construction stage to fit tanks higher in the boat that could have water pumped into them, my points come through hearing people talk about not being able to get under bridges, but people don't seen to try to find easy to use solutions to said problems, I hear many stories of piling bodies onto the boat to load it up, that's great but we can do better, its would seem just give up using the hard to get areas is the answer most choose.

 

I'm speaking from practical knowledge too Mark, having previously owned a Hampton Safari for many years.

 

I've gone under Potter with the gauges at 6ft 4ins, (with the Pilot) with ten extra volunteer adults "ballasting" the boat as Iain mentions. That pushed the hull down by about 2". (That hull has a tons per inch immersion factor of 0.4", i.e., it sinks by about 25mm for every additional half-ton added to it).

 

The design of un-ballasted inland motor cruisers maximises the use of the hull space, with the internal floors as low as possible to give standing headroom with minimum possible air draught.

 

This leaves very little flood-able volume in the bilge spaces, and much of that is used for batteries and tanks etc..  These cross section builder's drawings of the Hampton Safari show just how little underfloor space there is.

 

Your idea to fit water ballast tanks within the accommodation space above the floor would certainly work, but they would rob the boat of the equivalent volume of usable accommodation space.

 

Although that would reduce the problem of getting under Potter, the loss may be too great a compromise for most people.

[MBA Marine]

Strowger.

 

Did you just inform someone who has worked on boats his whole working life how much space is under the floor?,  from 18 yrs old I have worked on new boat fit out, design and plug making and for the last seven years working on every any of boat that comes my way.

 

You do love a debate, you also love to try and enforce your superior knowledge, although im sure you just see it as informing people, but every now and then you might want to take a moment and think about just how insulting your words truly are.

 

Oh and all that usable space you talk of.... well you had a safari so you will know just how much space is wasted, shaft driven models have copious amount of unused space at the stern, Caribbean style cruisers waste loads of space bow and stern outboard.

 

My points were aimed at development of new boats not focusing on old ones, make the keel 2" wider for the full length and that a lot more volume, what would this do to boat handling, well if you take a 45' boat thats shaped like a brick (just with curves) then restrict them to 5mph, handling is not going to change that you could notice, make tanks out of unused voids with tubes bonded through them and you can still pass morse cables and wires through, in fact this becomes easier as you create conduits in hard to access areas.  

[Guest]

Strowger.

 

Did you just inform someone who has worked on boats his whole working life how much space is under the floor?,  from 18 yrs old I have worked on new boat fit out, design and plug making and for the last seven years working on every any of boat that comes my way.

 

You do love a debate, you also love to try and enforce your superior knowledge, although im sure you just see it as informing people, but every now and then you might want to take a moment and think about just how insulting your words truly are........

 

Mark,

 

You seem to take offence at most of my replies to your forum posts, and often then lower the debate to personal insults.

 

If you feel I have insulted you, then I can assure you I had no intention of so doing, and was merely debating the idea you had posted, as is surely the purpose of forums?

 

You may be a boating professional, but you must also recognise that some life-long boating amateurs  may also have extensive experience in some areas, or you will have a false belief in always having  "superior knowledge".

[JennyMorgan]

There is an American boat, the Macgregor, that makes use of ballast tanks so it's not unheard of. In the Macgregor's case the use of water ballast relates more to reducing the weight for trailering more than it is going under Potter Bridge. 

 

If we take the Caribbean as a Broads boat with unused voids then experience in owning several does reveal problems. As it is it is surprising just how quickly their bilges flood to above floorboard level, especially aft. If we then glass over those voids in order to create floodable ballast tanks then bilge volume is reduced, or floors need to be higher which means reduced headroom or higher roofs. Everything comes at a cost.

 

Flooding and later vacating bilge tanks might carry unwelcome critters from one area of the Broads to another.

 

Increasing displacement to create floodable ballast tanks might increase wash.

 

A number of boats already have fuel and water-tanks under the floorboards. Replacing those tanks with ballast tanks mean putting fuel and water tanks elsewhere.

 

Costs would probably increase, for how often the facility to lower a boat two inches might be used, would that be worth the effort?

 

It's an idea worth discussing but I do wonder at the overall costs involved.

[MauriceMynah]

As this extra ballast would be needed only occasionally, and for short periods of time, couldn't flexible tanks be installed, taking little space when not in use and stowed in those "awkward" storage places most of the time?

[ExMemberBobdog]

I'm not sure this is quite relevant to the 'getting under bridges' theme, but water ballasting is certainly feasible.  I sailed last year with a friend who brought his 'trailer sailer' to the Broads for a week - a Bay Raider that is water ballasted.  As JennyMorgan says above about the Macgregor, it's more about trailerable weight and/or adapting to the wind/sea conditions than anything else, but the point is that the principle works.

http://www.swallowboats.com/our-boats/open-boats/bayraider-20

[Hockham Admiral]

Mark, Hi.

 

We used to have a Colvic 30ft centre cockpit boat which on our first cruise we took from Brundall to York and then to Lincoln. We were moored in the Brayford and needed to get under the 'Glory Hole' in order to get back home in time for my next flight.

 

 

"It won't go, Dad!" said Giles........... he was correct, by about 4 inches.... 

 

We just didn't have the time to go all the way back down the Trent and Humber, plus the journey from Spurn Head to Gt Yarmouth... so I disconnected the cooling water input pipe and opened the sea-cock. I remember I had to flood the bilge to nearly half way up the engine to get us that extra headroom! We then poled under the Glory Hole and I then started the engine with the pipe still disconnected and pretty soon sucked the bilge almost dry.

 

Yes, it is possible but the pitfalls associated with doing it are various and obvious to most, particularly the sequence of opening and shutting the seacock.... As Mark said, whether I'd want someone else to do it with my boat is a completely different matter!   :naughty:

[Guest]

As this extra ballast would be needed only occasionally, and for short periods of time, couldn't flexible tanks be installed, taking little space when not in use and stowed in those "awkward" storage places most of the time?

 

I think that would probably be the best compromise solution, because as long as the flexible tanks were sturdy enough to not rupture and spill river water over the interior, a significant additional weight could be added throughout the boat without sacrificing any interior space in the normal layout.

 

As a yardstick, a 100 gallon bladder would have a volume of about 16 cubic feet, and would weigh just under half a ton, which would lower a 25ft Hampton Safari by an inch.

[Guest]

There is an American boat, the Macgregor, that makes use of ballast tanks so it's not unheard of. In the Macgregor's case the use of water ballast relates more to reducing the weight for trailering more than it is going under Potter Bridge........

 

If you mean the MacGregor 26X Peter,  then it has the water ballast for a much more important reason than just trailering.

 

It is one of the very few good sailing boats that can also plane at high speed under power.

 

The 26X can flood it's false bottom to add essential stability when sailing, and yet it can empty it to be able to shed the weight and lift itself up onto the plane with it's 50 horsepower outboard motor.

 

It must be quite a sight blasting past you with it's sails furled..

[Hockham Admiral]

It must be quite a sight blasting past you with it's sails furled..

 

Oh, Yes!   ............  

[MauriceMynah]

Strow, whilst I take your point should you need to lower the WHOLE boat, but normally it's just one end that needs lowering, so it's the trim that needs adjusting. that would take far less weight.

[Guest]

Quite true Maurice, for many boats.

 

I was thinking about single-level bathtubs and also rear cockpit boats with folded canopies and screens though, where I guess both ends are fairly level.

[marshman]

Is it really worth the effort when there are areas some boats cannot reach - why not just hire a boat to go to the upper reaches like a day boat??

 

 Must be cheaper than building such a facility into new boats? And as that would only apply to a very very limited number of boats annually, the overall water level continuing to rise would render them obsolete in another 50 years!!

[MBA Marine]

Mark,

 

You seem to take offence at most of my replies to your forum posts, and often then lower the debate to personal insults.

 

If you feel I have insulted you, then I can assure you I had no intention of so doing, and was merely debating the idea you had posted, as is surely the purpose of forums?

 

You may be a boating professional, but you must also recognise that some life-long boating amateurs  may also have extensive experience in some areas, or you will have a false belief in always having  "superior knowledge".

If I have personally insulted you, then I should be hugely insulted by many of your words or sometimes the way one "​Punctuates"  to change the tone of voice.

[ExUserGone]

 

the overall water level continuing to rise would render them obsolete in another 50 years!!

So just wait 50 years and go around PH bridge, simples.....

Or go out through yarmouth and back in through horsey harbour.....

[Guest]

If I have personally insulted you, then I should be hugely insulted by many of your words or sometimes the way one "​Punctuates"  to change the tone of voice.

 

Sorry Mark, if you find my italics insulting then you're imagining insults that just aren't there.

 

I have no disrespect for you personally, I just don't agree with some of the things you post on the forum.

 

 

I italicised "some" to emphasize that I do agree with plenty of other things that you've said.

 

Is that insulting ?