Diesel Fuel Tank Inspection Hatch - Important or Not

[mark1882]

Hi
I Am having a new Stainless Steel tank made for my Westerly Oceanlord and I have been pondering the usefulness of having an inspection hatch. Good practice seems to suggest that I should have one but I am not sure how useful it will be and I could be introducing another leak potential.

To explain the Oceanlord is centre cockpit and as a result the only access to the fuel tank apart from the fuel filler at the top is from the engine room. So an inspection hatch would have to be high up on the front of the tank the only side you can access the tank from. It's a tall tank 965 high x 540 ( the front) x 380 deep, so if I had an inspection hatch high on the front you would not able to see much in the tank due to the angle you would be looking in and with two baffles in the tank not likely to see much.

I can see the benefit of having an inspection hatch in the top of a tank as you would be able to see the whole of the inside of the tank, but on the side I am not sure.

I guess my other question is having never had an inspection hatch in fuel tanks in other boats I have had and never needed one why should I have one now??

Any thoughts and other members experience of having/ not having an inspection hatch would be appreciated

Thanks

Mark

 

[RichardS]

Hi
I Am having a new Stainless Steel tank made for my Westerly Oceanlord and I have been pondering the usefulness of having an inspection hatch. Good practice seems to suggest that I should have one but I am not sure how useful it will be and I could be introducing another leak potential.

To explain the Oceanlord is centre cockpit and as a result the only access to the fuel tank apart from the fuel filler at the top is from the engine room. So an inspection hatch would have to be high up on the front of the tank the only side you can access the tank from. It's a tall tank 965 high x 540 ( the front) x 380 deep, so if I had an inspection hatch high on the front you would not able to see much in the tank due to the angle you would be looking in and with two baffles in the tank not likely to see much.

I can see the benefit of having an inspection hatch in the top of a tank as you would be able to see the whole of the inside of the tank, but on the side I am not sure.

I guess my other question is having never had an inspection hatch in fuel tanks in other boats I have had and never needed one why should I have one now??

Any thoughts and other members experience of having/ not having an inspection hatch would be appreciated

Thanks

Mark

I would suggest that it would more important to have a take-off valve from the bottom of the tank than an inspection cover in the side. Keep your fuel dosed with biocide and draw off fuel from the drain occasionally to check that it is clear.

Richard

 

[lw395]

These days, things like USB borescope cameras make inspection a lot easier.
So, if you can access the filler hose inlet, maybe it's not needed?

Having a plan of how you will get the tank clean to your satisfaction, if it ever got a lot of crud in it, seems to me to be the main thing.
IMHO, that means being able to access at least with a tube to pump out with and some sort of view to see the contents.
The tank I had most crud in, not having a hatch was no issue as the tank was small enough to remove.

 

[NormanS]

If it's at all possible, if you're having a new tank made, get them to build a small dirt sump on the bottom of the tank. Ideally fit a drain valve to the sump, but if there is no space for that, arrange a system of being able periodically to pump out from the sump. Any dirt or water in the tank will find its own way into the sump.

 

[William_H]

If it's at all possible, if you're having a new tank made, get them to build a small dirt sump on the bottom of the tank. Ideally fit a drain valve to the sump, but if there is no space for that, arrange a system of being able periodically to pump out from the sump. Any dirt or water in the tank will find its own way into the sump.

Plus 1 A vee bottomed tank or better a conical shaped bottom with an outlet right at the bottom to enable you to drain off water etc from the bttom is important. The engine take off should be somewhat higher. A sump of about .5% total capacity which can hold water which will not get to the engine is about right size. good luck olewill

 

[jwilson]

I would suggest that it would more important to have a take-off valve from the bottom of the tank than an inspection cover in the side. Keep your fuel dosed with biocide and draw off fuel from the drain occasionally to check that it is clear.

Agreed with that: inevitably some water/muck gets in eventually, and a take-off valve at the bottom is much easier to seal reliably than a large inspection hatch.

Richard

 

[Baggy]

I wanted to put an inspection hatch in my Fuel tank, the only access was on the side,
Decided against this. Not practical, expensive and worried about leaks

My tank also has a flat bottom.

I ended up having an outlet fitted at the bottom
of tank and connected it to a fuel polishing system

 

[Seajet]

I was once asked to take a 1960's twin screw motor sailer across the Bay of Biscay.

As events before I got there left a big ? over the engines and general maintainence over years before, I of course had a very good look at the fuel filter bowls.

These had large amounts - say the bottom inch of 6" high inspection tubes - full of a heavy residue - there was alot of water as well but that was relatively easy to deal with.

I insisted we remove the big inspection hatches on the ( thankfully accessible ) tanks and we found a thick layer of gunge just waiting to be stirred up as the boat rolled...

In fact because of other snags found as well I ran out of holiday but the boat made it OK later.

I rate inspection hatches - big enough to easily get a hand through - essential.

 

[prv]

due to the angle you would be looking in and with two baffles in the tank not likely to see much.

I can see the benefit of having an inspection hatch in the top of a tank as you would be able to see the whole of the inside of the tank

You're obviously focusing on the "inspection" part, but really it's a misnomer. They're actually "cleaning" hatches, and invaluable if you get a bad case of fuel contamination.

I spent most of last season trying to clear a small 80l tank without a hatch, to no avail - having to drift and change fuel filters was a regular occurrence and not always convenient, including just off Portland and in the approach to Chichester Harbour. In the end I gave up and got the angle grinder out, and am very glad I did. A big nitrile gasket and closely-spaced bolts means there's no sign of any leakage.

Pete

 

[lw395]

A hatch is clearly great for cleaning when the tank is disastrously dirty, but alternatively you can sort systems to stop it getting in that state.
A means of drawing off crud from the bottom regularly (whether that's a tap at the bottom or a dip tube, polishing system, whatever) might be better than a hatch that can only be used after things have gone bad. Normally the time you want to remove a few litres of water is when you've just filled the tank. If you can do that at the first sign of water, then your tank is unlikely to need getting in and scrubbing.

 

[Seajet]

lw395,

that would be spiffing if one has owned a boat from new and knows one is careful, as must be any crew let alone any friends who have borrowed the boat etc...

In real life I suppose a newish modern yacht will probably get away with just an eye on water contamination and the filter/s for quite a while but in the end a big ' cleaning ' hatch as PRV rightly calls it, is worth its weight in gold !

 

[prv]

A hatch is clearly great for cleaning when the tank is disastrously dirty, but alternatively you can sort systems to stop it getting in that state.
A means of drawing off crud from the bottom regularly (whether that's a tap at the bottom or a dip tube, polishing system, whatever) might be better than a hatch that can only be used after things have gone bad. Normally the time you want to remove a few litres of water is when you've just filled the tank. If you can do that at the first sign of water, then your tank is unlikely to need getting in and scrubbing.

True up to a point, but our second-ever fill after putting a new tank in Kindred Spirit came with a free dose of black sludge from the bottom of the fuel barge.

Pete

 

[prv]

that would be spiffing if one has owned a boat from new and knows one is careful

Not quite - it's ownership of the tank from new that matters. Which the OP obviously will have, since he's getting it made.

Pete

 

[Jock89]

Any thoughts and other members experience of having/ not having an inspection hatch would be appreciated

Thanks

Mark[/QUOTE]

Mark, A week ago I installed a new deck-filler & then pipework into my St'bd wing tank & a new bronze 90 degree fitting screwed into the inspection hatch on the tank-top underneath my cockpit locker.
I had to scrape out the semi-solid crude oil gunge from the 'V' shaped bottom with a broad flat screwdriver. This would definitely have clogged up a succession of filters had it become more liquified, as in the next big fill-up.
I now have the satisfaction of knowing that my tanks are 100% clean, so that's a big YES from me for having an inspection hatch cut out on top.
The dimensions of the hatches on my 2 wingtanks (30gal + 25gal) would be about (W)300mm x (D)200mm x 5mm aluminium & it's a good size to work through, especially if you have baffles in yours.
I have no draw-off fittings on my wing tanks except the almost inaccessible wheel shut-off valves that link each tank to the main keel tank, so the pre-existing inspection covers were a godsend. (34 4mm bolts on each cover!)

 

[fisherman]

I'm in two minds. I have a skip-shaped tank athwartships, 1000 litres, with baffles in the middle and at the angle where the ends rise. Two hatches, either side of centre. I took them off once to clean out, not much to show, and when I put the (800l) fuel back in it turned black, either from some sort of residue in the drums it was stored in, or from muck I hadn't accessed in the tank ends. I have a square sump under the central baffle, so muck should hit it and drop in from either side. Never got anything but clean fuel from it. So, either the muck is being drawn to the filter because I process a lot of fuel, and use Fuel Set, or it is stuck in the tank somewhere, not stirring up enough to get moving. Unlikely given the way I roll about. I had a boat with a huge home made sediment trap in the pipeline. Never drained anything but clean fuel, but after twelve years or so it was removed and cleaned by a subsequent owner, it was jammed full of muck, about ten litres, to the top. Seems you have to agitate things to get it moving, and my current sediment filter is on flexi pipework so I can slosh it about, otherwise the crud doesn't move, even though the outlet is at the bottom of a transparent cone shape. That and the two Crosland 522 type engine filters is enough that I never have stop issues. I am by no means sure that even a drain at the bottom of a tank will get the muck out, it may only make a small hole in the muck for clean fuel to flow through, if the muck is solid enough. If so, you may need a side or top access to chase the muck with a suction tube.

Edit: the post above says the same, had to scrape the muck out, a drain-off would not help.

 

[Deleted member 36384]

If you subscribe to the adage that the 'safest job is the one you don't do' then if there is no inspection/access/cleaning hatch you have no leak risk. Lets face it, both leaks and contamination are low risks, from a properly designed hatch and using a decent filtering funnel (although funnels will slow filling up time). I have two tanks, centre cockpit and both have a pair of hatches in each tank. The hatches were cut and fitted retrospectively by a previous owner to clean out the tanks after many years of use (+ 30 years before hatches were added). I know of at least on other older yacht (+20 years) which also had access hatches retrospectively cut to clean the tank out.

The way I see it you should leave the hatch out of the design and fit the new tank hatchless, then do what w395 suggest and control the filling up process to keep out dirt and drain off water from the bottom from time to time. Years later you can cut a hatch if there is a build up of sludge that is causing problems.

 

[RichardS]

Just to point out to all the replies which are opting for the hatch is that the OPs hatch will be in the side of the tank, so a constant leakage risk unless the level is well down, and that the hatch when removed will be facing a baffle rather than the bottom of the tank where any gunge will be.

Hence my recommendation in post #2 with a brand new tank of regular dosing and a bottom drain point, with a small sump if that option is available.

Richard

 

[Saltram31]

Cut an ispection hatch into the top of my mild steel diesel tank. Have not had a leak in 10 years as I made a proper fitting lid held down by s/s nuts and bolts and good sealant.It allows me to check and clean my tanks whenever i want to.

 

[RichardS]

Cut an ispection hatch into the top of my mild steel diesel tank.

The OP doesn't have that option.

Richard

 

[geem]

In your case a would design the tank to have the largest dirt pocket you can sensible install. Slope the bottom of the tank towards the dirt pocket. Pull fuel from a position above the dirt pocket. Put an over sized drain cock on the dirt pocket so you can drain dirt pocket with some decent flow. If tank it drained you can clean dirt pocket through the over sized drain cock