Re: What again? Another thread on Watermakers?

> *nothing* should ever share the hull plating for any kind of bunkering

In theoretical terms I'd agree. However, the theory is a Catch 22. The
minute you fit tanks in a steel boat you create more inaccessible areas
behind the tanks, with the potential for unseen/unreachable corrosion. We
have stainless water tanks above the keel, for example, and we took them
out last year to check the plating - it was a serious pig of a job.

Hence a diesel tank using the hull plating is a reasonable compromise,
provided you are careful about keeping water out of the tank. Water tanks
though are not a good idea, for obvious reasons.

Mike

Mike Cobbe wrote:

>
>> *nothing* should ever share the hull plating for any kind of bunkering
>
> In theoretical terms I'd agree. However, the theory is a Catch 22.

I disagree.

> The
> minute you fit tanks in a steel boat you create more inaccessible areas
> behind the tanks,

only if they were designed and installed by an idiot, there is absolutely no
reason to make the gap between bunkers and hull inaccessible.

>
> Hence a diesel tank using the hull plating is a reasonable compromise,

I disagree, there should not be 1 sq inch of hull plating that you cannot
access from inside the boat either in 15 minutes with tools or in 15
seconds with a prybar in an emergency.

> provided you are careful about keeping water out of the tank. Water tanks
> though are not a good idea, for obvious reasons.
>
> Mike

stainless steel tanks are never a good idea, unless you are using them to
hold something *very* biodegradeable such as fresh milk for human
consumption, which is unlikely on a boat.

naturally galvanised tanks are verboten for diesel, but there is no reason
not to coat the insides of the tank liberally with 2 pot, unless of course
you have managed to be idiot enough to build a tank without a decent sized
manhole in it.

--
Merry Yule
http://www.surfbaud.co.uk/images/christmascard.jpg
http://www.surfbaud.co.uk/images/bagsanta.jpg

Liquid Cooled PC? --> http://www.surfbaud.co.uk/

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Cable server http://80.235.132.38:800/
EoF

On Fri, 05 Dec 2003 22:29:02 +0000, Guy Fawkes <look@my.sig> wrote:

>Mike Cobbe wrote:
>
>>
>>> *nothing* should ever share the hull plating for any kind of bunkering
>>
>> In theoretical terms I'd agree. However, the theory is a Catch 22.
>
>I disagree.
>
>> The
>> minute you fit tanks in a steel boat you create more inaccessible areas
>> behind the tanks,
>
>only if they were designed and installed by an idiot, there is absolutely no
>reason to make the gap between bunkers and hull inaccessible.
>
>>
>> Hence a diesel tank using the hull plating is a reasonable compromise,
>
>I disagree, there should not be 1 sq inch of hull plating that you cannot
>access from inside the boat either in 15 minutes with tools or in 15
>seconds with a prybar in an emergency.
>
>
>> provided you are careful about keeping water out of the tank. Water tanks
>> though are not a good idea, for obvious reasons.
>>
>> Mike
>
>stainless steel tanks are never a good idea, unless you are using them to
>hold something *very* biodegradeable such as fresh milk for human
>consumption, which is unlikely on a boat.
>
>naturally galvanised tanks are verboten for diesel, but there is no reason
>not to coat the insides of the tank liberally with 2 pot, unless of course
>you have managed to be idiot enough to build a tank without a decent sized
>manhole in it.

I tend to agree with both Mike and Guy. In an ideal world, you could
get to all parts of the hull easily, but boats are always a
compromise. As with any part of a steel boat in contact with water
(or fuel), the key is keeping the paint system up to spec - and
checking regularly.

Hindsight is 20/20 vision. We checked the inside of the tanks when we
bought Hinewai and after over 15 years, the paint system still looked
good. To be honest, there were that many things we were looking for
or didn't even think about when checking her out, it did not score
highly on our radar. Maybe it should have done - we'll know next
time.

I have no great conceptual problem with the fuel tanks being intergral
to the hull, but will now be fitting a lowest point drain to ensure we
can decant out any water that settles out of the fuel (especially the
stuff that comes over in square cans when overseas).

I did seriously consider cutting the tanks out completely and
replacing them with plastic tanks as Steve suggests in another post,
but frankly the work that would be involved in all the new supports
for a big weight of water and the momentum it gets up as you meet a
big sea would have been a huge job. The tanks are not under the sole
- there's no room - but just aft of midships - the tops make up the
workbench on one side and the galley bench on the other. Retaining
the steel of the tanks to support the bladders seemed to be the best
way to go.

And their collapability when empty means we'll be able to taken them
out to check the steel.

At the end of the day, it may not be ideal, but it feels a pretty good
compromise to us.

Now, how to stop the bladders chaffing and stop the condensation.

Thx

Peter

www.oceanodyssey.net
"Do not measure your life by the number of breaths you take,
Rather by the number of times life just takes your breath away"

> fuel tanks being intergral to the hull, but will now be fitting a lowest
> point drain to ensure we can decant out any water

I'm intrigued. Our diesel tank is top plate, hull each side, bottom plate
above the lead in the keel - all directly under the engine. The only way
to fit a drain would be outside the hull. How is yours set up?

You probably know this but if you do have inaccessible diesel tank
problems and need to get inside it, just chop a hole in the hull. It's no
big deal. Then after welding shut, to check the integrity of the weld,
make up a paste of chalk and acetone and apply to the outside of the weld.
The acetone will evaporate leaving chalk on the weld. Fill the tank to
weld level. The chalk will draw the diesel through even the tiniest hole.

Obviously that method can be used to check weld integrity in most places.

Mike

Guy Fawkes <look@my.sig> wrote in message news:<YC7Ab.3995$xa.1856@fe07.private.usenetserver .com>...
> Mike Cobbe wrote:
>

> > The
> > minute you fit tanks in a steel boat you create more inaccessible areas
> > behind the tanks,
>
> only if they were designed and installed by an idiot, there is absolutely no
> reason to make the gap between bunkers and hull inaccessible.

I disagree, Large tanks with a low center of gravity usually are made
to the shape of the hull. Mine are and sit on racks that hold the
approx 4 inches from the hull. 2- 150 gallon tanks that measure approx
6'X4' each. It is a problem to get under them. Removing them with a
pry par is a joke. It might not be an issue on a boat that carries 50
gallons or less, but on a large vessel its a diffrent story.
>
> >
> > Hence a diesel tank using the hull plating is a reasonable compromise,
>
> I disagree, there should not be 1 sq inch of hull plating that you cannot
> access from inside the boat either in 15 minutes with tools or in 15
> seconds with a prybar in an emergency.

In a perfect world this would be true, But if you need a large amount
of fuel on a large vessel it aint going to happen. my tanks weigh
approx 400 pounds each empty and i have 4. They cover the whole
midship below the cabin sole, except the keel board box. The thing to
do is make sure the hull is clean, painted before installation of the
tanks, and kept dry. I have almost 30 years on my tanks, they are not
painted inside. Ive lowered a camera on a timer down and have taken
pictures of the hull under the tanks and they are free of rust.

Joe
MSV RedCloud

>
>
> > provided you are careful about keeping water out of the tank. Water tanks
> > though are not a good idea, for obvious reasons.
> >
> > Mike
>
> stainless steel tanks are never a good idea, unless you are using them to
> hold something *very* biodegradeable such as fresh milk for human
> consumption, which is unlikely on a boat.

Never ever use SS for fuel tanks!!!!

>
> naturally galvanised tanks are verboten for diesel, but there is no reason
> not to coat the insides of the tank liberally with 2 pot, unless of course
> you have managed to be idiot enough to build a tank without a decent sized
> manhole in it.
>
>
>
> --
> Merry Yule
> http://www.surfbaud.co.uk/images/christmascard.jpg
> http://www.surfbaud.co.uk/images/bagsanta.jpg
>
> Liquid Cooled PC? --> http://www.surfbaud.co.uk/
>
> E-mail (rot-13) qnirahyy NG oyhrlbaqre QBG pb QBG hx
> Cable server http://80.235.132.38:800/
> EoF

	#1
Mike Cobbe	Re: What again? Another thread on Watermakers? > nothing should ever share the hull plating for any kind of bunkering In theoretical terms I'd agree. However, the theory is a Catch 22. The minute you fit tanks in a steel boat you create more inaccessible areas behind the tanks, with the potential for unseen/unreachable corrosion. We have stainless water tanks above the keel, for example, and we took them out last year to check the plating - it was a serious pig of a job. Hence a diesel tank using the hull plating is a reasonable compromise, provided you are careful about keeping water out of the tank. Water tanks though are not a good idea, for obvious reasons. Mike

	#2
Guy Fawkes	Re: What again? Another thread on Watermakers? Mike Cobbe wrote: > >> nothing should ever share the hull plating for any kind of bunkering > > In theoretical terms I'd agree. However, the theory is a Catch 22. I disagree. > The > minute you fit tanks in a steel boat you create more inaccessible areas > behind the tanks, only if they were designed and installed by an idiot, there is absolutely no reason to make the gap between bunkers and hull inaccessible. > > Hence a diesel tank using the hull plating is a reasonable compromise, I disagree, there should not be 1 sq inch of hull plating that you cannot access from inside the boat either in 15 minutes with tools or in 15 seconds with a prybar in an emergency. > provided you are careful about keeping water out of the tank. Water tanks > though are not a good idea, for obvious reasons. > > Mike stainless steel tanks are never a good idea, unless you are using them to hold something very biodegradeable such as fresh milk for human consumption, which is unlikely on a boat. naturally galvanised tanks are verboten for diesel, but there is no reason not to coat the insides of the tank liberally with 2 pot, unless of course you have managed to be idiot enough to build a tank without a decent sized manhole in it. -- Merry Yule http://www.surfbaud.co.uk/images/christmascard.jpg http://www.surfbaud.co.uk/images/bagsanta.jpg Liquid Cooled PC? --> http://www.surfbaud.co.uk/ E-mail (rot-13) qnirahyy NG oyhrlbaqre QBG pb QBG hx Cable server http://80.235.132.38:800/ EoF

	#3
Peter	Re: What again? Another thread on Watermakers? On Fri, 05 Dec 2003 22:29:02 +0000, Guy Fawkes <look@my.sig> wrote: >Mike Cobbe wrote: > >> >>> nothing should ever share the hull plating for any kind of bunkering >> >> In theoretical terms I'd agree. However, the theory is a Catch 22. > >I disagree. > >> The >> minute you fit tanks in a steel boat you create more inaccessible areas >> behind the tanks, > >only if they were designed and installed by an idiot, there is absolutely no >reason to make the gap between bunkers and hull inaccessible. > >> >> Hence a diesel tank using the hull plating is a reasonable compromise, > >I disagree, there should not be 1 sq inch of hull plating that you cannot >access from inside the boat either in 15 minutes with tools or in 15 >seconds with a prybar in an emergency. > > >> provided you are careful about keeping water out of the tank. Water tanks >> though are not a good idea, for obvious reasons. >> >> Mike > >stainless steel tanks are never a good idea, unless you are using them to >hold something very biodegradeable such as fresh milk for human >consumption, which is unlikely on a boat. > >naturally galvanised tanks are verboten for diesel, but there is no reason >not to coat the insides of the tank liberally with 2 pot, unless of course >you have managed to be idiot enough to build a tank without a decent sized >manhole in it. I tend to agree with both Mike and Guy. In an ideal world, you could get to all parts of the hull easily, but boats are always a compromise. As with any part of a steel boat in contact with water (or fuel), the key is keeping the paint system up to spec - and checking regularly. Hindsight is 20/20 vision. We checked the inside of the tanks when we bought Hinewai and after over 15 years, the paint system still looked good. To be honest, there were that many things we were looking for or didn't even think about when checking her out, it did not score highly on our radar. Maybe it should have done - we'll know next time. I have no great conceptual problem with the fuel tanks being intergral to the hull, but will now be fitting a lowest point drain to ensure we can decant out any water that settles out of the fuel (especially the stuff that comes over in square cans when overseas). I did seriously consider cutting the tanks out completely and replacing them with plastic tanks as Steve suggests in another post, but frankly the work that would be involved in all the new supports for a big weight of water and the momentum it gets up as you meet a big sea would have been a huge job. The tanks are not under the sole - there's no room - but just aft of midships - the tops make up the workbench on one side and the galley bench on the other. Retaining the steel of the tanks to support the bladders seemed to be the best way to go. And their collapability when empty means we'll be able to taken them out to check the steel. At the end of the day, it may not be ideal, but it feels a pretty good compromise to us. Now, how to stop the bladders chaffing and stop the condensation. Thx Peter www.oceanodyssey.net "Do not measure your life by the number of breaths you take, Rather by the number of times life just takes your breath away"