weed hatch/mud box?

[number four]

having a shell built, and at prescent would like to put raw water cooled engin and genorator in.

 

so i understand that it would be wise to use a mud box for the water intake.

 

i am wondering if i could redesign the weed hatch to do both as i dont know what the inside of a weed hatch looks like i am not shure weather i can do this.

what are your thoughts (apart from why raw water)

and does any one have a cross section drawing or picture of the inside of a weed hatch they could post.

 

thanks in advance.

[Machpoint005]

The weed hatch is flush with the uxter plate underneath. I think your idea is a non-starter for all sorts of reasons, not least because you will still need access to the weed hatch for its intended purpose (for weeds read carrier bags).

[number four]

The weed hatch is flush with the uxter plate underneath. I think your idea is a non-starter for all sorts of reasons, not least because you will still need access to the weed hatch for its intended purpose (for weeds read carrier bags).

 

what is an uxter plate

and would you have the time to give you reasons

[NB Alnwick]

what is an uxter plate

and would you have the time to give you reasons

 

The Uxter Plate is the horizontal flat plate above the propeller and the forward part of the rudder - it usually sits at or just above water level when the boat is static and drops below water level when underway. Looking at it another way, it is the 'bottom' to the traditional stern deck of a narrow boat and one of its purposes is to prevent 'cavitation' - a loss of drive that occurs when the prop sucks air from the surface.

 

With regard to your requirement for raw water cooling, I would suggest that the best person to consult would be your boat builder.

Edited September 11, 2009 by NB Alnwick

[nb Innisfree]

The Uxter Plate is the horizontal flat plate above the propeller and the forward part of the rudder - it usually sits at or just above water level when the boat is static and drops below water level when underway. Looking at it another way, it is the 'bottom' to the traditional stern deck of a narrow boat and one of its purposes is to prevent 'cavitation' - a loss of drive that occurs when the prop sucks air from the surface.

 

With regard to your requirement for raw water cooling, I would suggest that the best person to consult would be your boat builder.

 

Sorry if I am being pedantic but air drawn in is aeriation

 

Cavitation is low pressure at the propellor blades and doesn't result in loss of drive

Edited September 11, 2009 by nb Innisfree

[alan_fincher]

Unless there is something special about the engine you plan to fit, I would seriously suggest not going the raw water cooling route.

 

People haven't largely switched over to skin tank ("keel") cooled systems as a fad - they have done it because raw water cooling can often be a real pain in the arse in a way that the newer approaches are not. (I'm talking steel boats here - pleas of "we have raw water cooling" from owners of other boat types are not that relevant, in my view).

 

If you are cost cutting, I still think I'd try and avoid trying to filter river and canal water, and resort to cost cutting in areas that less affect reliability.

 

If you have a genuine need, then go ahead, but you will need to have the proper arrangements built by someone who understands them, (which many modern shell builders may not). I can't see how a weed hatch can be utilised in any way !

[NB Alnwick]

Sorry if I am being pedantic but air drawn in is aeriation

 

Cavitation is low pressure at the propellor blades and doesn't result in loss of drive

 

That's useful - I have always wondered what the difference is

 

>snipped<

I can't see how a weed hatch can be utilised in any way !

 

The reason people say this is because a properly constructed weed hatch will be almost sealed at both deck and uxter plate level so as to prevent the ingress of water when the boat is in motion. Therefore it would not be a suitable place from which to draw large quantities of cooling water. The engine in our boat was designed for raw water cooling but we now have a closed system which is not perfect but it is better than having all the detritus from the canal drawn in to the cooling system.

[Tony Brooks]

Unless there is something special about the engine you plan to fit, I would seriously suggest not going the raw water cooling route.

 

People haven't largely switched over to skin tank ("keel") cooled systems as a fad - they have done it because raw water cooling can often be a real pain in the arse in a way that the newer approaches are not. (I'm talking steel boats here - pleas of "we have raw water cooling" from owners of other boat types are not that relevant, in my view).

 

If you are cost cutting, I still think I'd try and avoid trying to filter river and canal water, and resort to cost cutting in areas that less affect reliability.

 

If you have a genuine need, then go ahead, but you will need to have the proper arrangements built by someone who understands them, (which many modern shell builders may not). I can't see how a weed hatch can be utilised in any way !

 

 

If you do have a genuine need for a raw water cooled engine then unless you also need a wet exhaust I think you will find drawing fresh water from a large area skin thank and then returning it, hot, at the top will be fine. You will need a header tank of some sort and possibly a small bore thermostat bypass.

 

MY ex Viking Afloat DV36 is like this and I love the simplicity. I suspect most Bukhs on the system are direct cooled via a skin tank. The only downside I can think of is that you do need to change the "Jabsco" impeller every couple of years.

[PaddingtonBear]

The other point is that in the past, when raw water cooling was almost universal, the canals were a lot deeper. Now where dredging is rare and boats are on the whole a lot shallower drafted mud and silt are a particular 'joy'.

Edited September 11, 2009 by PaddingtonBear

[DHutch]

We have raw water cooling of our inboard condenser (steam boat) due to the simply massive amount of heat that needs to be removed a sink tank wasnt really feasible an of cause the canal water only goes through the condenser (basically a very large bore heat exchanger made up from 3/8" tubing that can be rodded through) rather than the engine.

 

Im surprised at how little attention the system needs, with the mud box rarely needing cleaning and the circulating pump being the original and only needing attention to the non return valves every few months when one gets stuck on somthing.

 

That said, i would certainly agree that for almost all applications, cooling using a skin tank would be my first choice for sure. Cant really see it costing much more either really?

 

 

 

Daniel

[Naughty Cal]

they have done it because raw water cooling can often be a real pain in the arse in a way that the newer approaches are not. (I'm talking steel boats here - pleas of "we have raw water cooling" from owners of other boat types are not that relevant, in my view).

 

Whys that then?

[FadeToScarlet]

Don't go for a raw-water (direct or indirect) cooled main engine.

 

I ahve one on my 48' narrowboat, and it is (one of) the banes of my life. Yes, it does have advantages; working on the rivers, the engine will run literally all day at a sensible temperature, enable us to open her up to over 2,200 revs on boring (piled!) river stretches and not overheat. It is simple, doesn't need bleeding, and I have solved problems with it myself.

 

But my other half and myself are taking the boat to a boatyard soon to spend a great deal of money on having a skin-tank fitted.

 

Why? Because the water inlet keeps getting clogged up, and so you have to stop the engine and attach a hose-pipe to the shower head and run it back through the boat in order to flush out any obstruction. If that doesn't work, then you have to go swimming.

 

It's just particularly frustrating to have to keep stopping to clear it. At one point, I had to stop 11 times in one 400m stretch. It was night, raining, and I was on my own, and in the end I just gave up and moored up at the pub instead of forging on to my destination.

 

The biggest problem is the size of the inlet. "Proper" cooling systems, for Dutch barges, trip boats and the like that have massive engines, need to have big 2 inch or bigger diameter ports. Mine is 20mm, and a single leaf will block it. It's "protected" by a baffle plate, but that's not fool-prof, especially when going astern.

 

In short, you COULD go for raw-water cooling if you put a lot of time and effort into designing it, and were prepared to occasionally get wet to clear blockages. If you have a massive inlet on the hull-side, and a HUGE mudbox with a series of mesh in decreasing sizes, then the system might work.

 

If every single floating plastic carrier bag (or urban jellyfish!) requires you to steer an avoiding course, because sucking it up will guarantee a dip in the cut to prise it out, then go for raw water cooling!

Edited September 14, 2009 by FadeToScarlet

[number four]

Don't go for a raw-water (direct or indirect) cooled main engine.

 

I ahve one on my 48' narrowboat, and it is (one of) the banes of my life. Yes, it does have advantages; working on the rivers, the engine will run literally all day at a sensible temperature, enable us to open her up to over 2,200 revs on boring (piled!) river stretches and not overheat. It is simple, doesn't need bleeding, and I have solved problems with it myself.

 

But my other half and myself are taking the boat to a boatyard soon to spend a great deal of money on having a skin-tank fitted.

 

Why? Because the water inlet keeps getting clogged up, and so you have to stop the engine and attach a hose-pipe to the shower head and run it back through the boat in order to flush out any obstruction. If that doesn't work, then you have to go swimming.

 

It's just particularly frustrating to have to keep stopping to clear it. At one point, I had to stop 11 times in one 400m stretch. It was night, raining, and I was on my own, and in the end I just gave up and moored up at the pub instead of forging on to my destination.

 

The biggest problem is the size of the inlet. "Proper" cooling systems, for Dutch barges, trip boats and the like that have massive engines, need to have big 2 inch or bigger diameter ports. Mine is 20mm, and a single leaf will block it. It's "protected" by a baffle plate, but that's not fool-prof, especially when going astern.

 

In short, you COULD go for raw-water cooling if you put a lot of time and effort into designing it, and were prepared to occasionally get wet to clear blockages. If you have a massive inlet on the hull-side, and a HUGE mudbox with a series of mesh in decreasing sizes, then the system might work.

 

If every single floating plastic carrier bag (or urban jellyfish!) requires you to steer an avoiding course, because sucking it up will guarantee a dip in the cut to prise it out, then go for raw water cooling!

 

 

 

 

thank you that is verry helpfull.

my idear was to have a large intake that was set close or in the weed hatch so it can be cleard from inside.

also to use large marine straners.

it is a wide beem and i do intend to use it uk and europe.

[GUMPY]

Don't go for a raw-water (direct or indirect) cooled main engine.

 

my other half and myself are taking the boat to a boatyard soon to spend a great deal of money on having a skin-tank fitted.

 

Why? Because the water inlet keeps getting clogged up, and so you have to stop the engine and attach a hose-pipe to the shower head and run it back through the boat in order to flush out any obstruction. If that doesn't work, then you have to go swimming.

 

It's just particularly frustrating to have to keep stopping to clear it. At one point, I had to stop 11 times in one 400m stretch. It was night, raining, and I was on my own, and in the end I just gave up and moored up at the pub instead of forging on to my destination.

 

The biggest problem is the size of the inlet. "Proper" cooling systems, for Dutch barges, trip boats and the like that have massive engines, need to have big 2 inch or bigger diameter ports. Mine is 20mm, and a single leaf will block it. It's "protected" by a baffle plate, but that's not fool-prof, especially when going astern.

 

I would say that its not the raw water cooling that is wrong but the design of the system,

Anyone who sets up a system with a 20mm inlet or even a 50mm inlet is asking for trouble.

To do it properly you need a proper mud box, mine is adjacent to the swim and has a 4 inch x 6inch inlet that has a 3/8 inch grid over it.

The box is 2ft6 tall and is divided in two by a diagonal plate this is solid at the bottom and a mesh at the top so any water has to pass over the plate to where the inlet is. the inlet is 32mm and goes directly to a fine mesh filter, which is the only part that ever gets blocked, Takes about a minute to clear, normally done whilst waiting for a lock to fill or empty as the engine is off then.

The mudbox gets cleaned out when we black and that's it

[Albion]

thank you that is verry helpfull.

my idear was to have a large intake that was set close or in the weed hatch so it can be cleard from inside.

also to use large marine straners.

it is a wide beem and i do intend to use it uk and europe.

 

If the skin tank is porperly designed and fabricated then you shouldn't have any problem running flat out for hours. So many systems though are not designed/made correctly and it is those that sometimes cause the grief for owners. One aspect that hasn't been mentioned is the ease of winterising and lack of maintenance. A skin tank sytem only has to be kept topped up with a suitable mix of antifreeze and water; job done, no different to a car radiator, can be left any time, any where, and is ready to go instantly. A raw water cooled system needs more care with anticipating any freeze up, vigilance about the raw water pump impellor, and can require a bit of recommissioning before use. For the UK canals I wouldn't, personally, use a raw water system.

Roger

[Naughty Cal]

If the skin tank is porperly designed and fabricated then you shouldn't have any problem running flat out for hours. So many systems though are not designed/made correctly and it is those that sometimes cause the grief for owners. One aspect that hasn't been mentioned is the ease of winterising and lack of maintenance. A skin tank sytem only has to be kept topped up with a suitable mix of antifreeze and water; job done, no different to a car radiator, can be left any time, any where, and is ready to go instantly. A raw water cooled system needs more care with anticipating any freeze up, vigilance about the raw water pump impellor, and can require a bit of recommissioning before use. For the UK canals I wouldn't, personally, use a raw water system.

Roger

 

Winterising is easy. Stick a heater in the engine bay (assuming you can keep it fairly moisture free) adjacent to the heat exchanger. Plug it into a thermostatic plug and it then switches on when the temperature dips below a set minimum thus keeping the engine bay and any raw water pipes, heat exchangers, water pipes etc. from freezing. This worked for us last winter and had the added benefit that it kept the engine warmer so it started easier. This of course only works if plugged in or using an invertor when out and about but we found that if we had been out somewhere and moored up for the evening the engines heat kept the engine bay warm enough to not have freezing issues.

 

Raw water cooling can have its moments, plastic bags are the worst culprit however on the whole they are a good cooling system. Given the large amounts of water we need to cool our lump it is the only viable option for our cruiser. Just make sure your boat builder knows how big the inlet needs to be.

[Albion]

Winterising is easy. Stick a heater in the engine bay (assuming you can keep it fairly moisture free) adjacent to the heat exchanger. Plug it into a thermostatic plug and it then switches on when the temperature dips below a set minimum thus keeping the engine bay and any raw water pipes, heat exchangers, water pipes etc. from freezing. This worked for us last winter and had the added benefit that it kept the engine warmer so it started easier. This of course only works if plugged in or using an invertor when out and about but we found that if we had been out somewhere and moored up for the evening the engines heat kept the engine bay warm enough to not have freezing issues.

 

Raw water cooling can have its moments, plastic bags are the worst culprit however on the whole they are a good cooling system. Given the large amounts of water we need to cool our lump it is the only viable option for our cruiser. Just make sure your boat builder knows how big the inlet needs to be.

 

Quite correct if you happen to be in a marina where copious and uninterrupted electrical supply is available. I would suggest that, for the majority of narrowboaters, this is the exception rather than the rule.

On the other hand, if you have need of an ability to fire up and go in a hurry (cough) it might be the ideal solution.

Roger

[casper ghost]

having a shell built, and at prescent would like to put raw water cooled engin and genorator in.

 

Why are you wanting to raw water cool? Did you get the idea from someone else. It's not the thing most people think about when having a shell built, everyone has a new shell with a keel tank.

[Naughty Cal]

Quite correct if you happen to be in a marina where copious and uninterrupted electrical supply is available. I would suggest that, for the majority of narrowboaters, this is the exception rather than the rule.

On the other hand, if you have need of an ability to fire up and go in a hurry (cough) it might be the ideal solution.

Roger

 

Why ever would i want to do that

 

A tube heater (greenhouse heater) doesnt use much power. Much less than say a fridge which all (or almost all) NB come equipped with. Powering a small heater uses very little power and is worth it for the piece of mind of not freezing up. Works for the fresh water (drinking water) side as well.

[casper ghost]

A tube heater (greenhouse heater) doesnt use much power. Much less than say a fridge which all (or almost all) NB come equipped with. Powering a small heater uses very little power and is worth it for the piece of mind of not freezing up. Works for the fresh water (drinking water) side as well.

 

Heaters are not much use unless you have a shoreline. Went down below -13 here last winter. The problem is if you leave the boat, thinking you'll be back soon so no need to drain it, then somethink crops up and you don't get back, then it freezes .

 

I can't see any reason why a narrowboat with a diesel engine should have anything other than a keel tank cooling.

[ChrisPy]

you cannot guarantee that there will be an adequate head of water in the weed hatch box. The Uxter plate is close to the water surface level.

The uxter plate does not seal, and allows a higher level of water in the weedhatch, forced in by the rotating prop. If you ran in neutral or tickover there would be insufficient head of water.

 

I know that the water lubricated vetus shaft gland and bearings take water from the weedhatch, but if the water level drops it is not catastrophic.

[Naughty Cal]

I can't see any reason why a narrowboat with a diesel engine should have anything other than a keel tank cooling.

 

Heavy river useage? An inadequately sized keel tank would cause it to overheat. Raw water cooling allows a lot of heat transfer. Just because keel cooling has become the norm it doesnt mean it is the best or only solution.

Edited September 15, 2009 by Phylis

[casper ghost]

Heavy river useage? An inadequately sized keel tank would cause it to overheat. Raw water cooling allows a lot of heat transfer. Just because keel cooling has become the norm it doesnt mean it is the best or only solution.

 

Clearly a boat needs the correct size keel tank. Most diesels like to work hard, overheating is not much of an issue, more getting to a good working temperature, on canals at least.

On mine I have a lever to allow cooling water to either go to keel tank and callorifier, or just the one.

[Naughty Cal]

Clearly a boat needs the correct size keel tank. Most diesels like to work hard, overheating is not much of an issue, more getting to a good working temperature, on canals at least.

On mine I have a lever to allow cooling water to either go to keel tank and callorifier, or just the one.

 

Most people dont realise their keel tank is undersized until they get off the canals and the engine is asked to work harder. The problem only arises under hard work. By the time you find out it is often too late to do anything about the problem.

 

What happens if you forget to change your lever?

[casper ghost]

What happens if you forget to change your lever?

 

I get sent to the naughty step