Why aren't diesel tanks supplied with large inspection hatches for thorough cleaning?

Greenheart

Greenheart

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Just a little question. I don't have a diesel engine or tank, so I don't have any diesel problems, but the sometimes-doubtful purity of marine diesel seems to cause plenty of headaches for yacht-owners...let alone diesel bug and the thick filter-clogging sludge that is said to occupy the bottom inch or so of many old tanks...

...so, given that the tank itself is usually quite a large structure...why are filler-tubes so small? Wouldn't it be beneficial if tanks also had large access hatches, to facilitate scooping out sludge and cleaning the tank's insides?
 
dancrane said:
Just a little question. I don't have a diesel engine or tank, so I don't have any diesel problems, but the sometimes-doubtful purity of marine diesel seems to cause plenty of headaches for yacht-owners...let alone diesel bug and the thick filter-clogging sludge that is said to occupy the bottom inch or so of many old tanks...

...so, given that the tank itself is usually quite a large structure...why are filler-tubes so small? Wouldn't it be beneficial if tanks also had large access hatches, to facilitate scooping out sludge and cleaning the tank's i

Some do and some don't. All my tanks (Water and diesel) have inspection hatches that can be removed. I have sailed other boats that do not. Depends on the tank (probably cost related)....
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Thanks gents, I see. I'd only heard the frustration of people who must presumably pay packets for professional cleaning, because their unreachable tank inside-walls defy cleaning.
 
Would add £20 (or whatever) to the overall price. YES, of course you would happily pay that. But then there are all the other 'just £20' s all over the boat. Too soon the average new boat buyer is saying 'I can afford boat A, but cannot afford boat B'.
 
I don't doubt that's true, Vic. It's probably also the basis for all the scorn suffered by budget boats, conspicuously built down to a price, rather than up to a decent standard.

Considering how crippling contaminated fuel can be, I'd reckon easily-accessed fuel tanks would be fairly high on the "necessary" list, rather than "preferred but superfluous".
 
dancrane said:
I don't doubt that's true, Vic. It's probably also the basis for all the scorn suffered by budget boats, conspicuously built down to a price, rather than up to a decent standard.

Considering how crippling contaminated fuel can be, I'd reckon easily-accessed fuel tanks would be fairly high on the "necessary" list, rather than "preferred but superfluous".
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Like many so called problems dodgy diesel is not common. Of course not good if you do get it, but probability is likely to be very low. Difficult to get any real data, but you only tend to hear of the small number of boats it does affect - ignoring the vast majority which never have a problem.

Ready for the deluge of horror stories to disprove!
 
Tranona said:
Ready for the deluge of horror stories to disprove!
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The plural of "anecdote" is not "data", but nevertheless...

With two boats in five years, we've had two serious doses of diesel bug. One "homegrown" in an unused part-filled tank, one donated all at once from a dodgy fuel barge. One tank with an inspection hatch, pumped out into jerrycans and the tank cleaned by hand in an afternoon. The other tank without an inspection hatch, still an ongoing problem.

Pete
 
Jamesuk said:
Only Plonkers don't have good inspection hatches for their diesel tanks :-)
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I know a couple of non-plonkers who have had leaks from their inspection hatches-one causing pollution that caught the attention of the Marina staff when the bilge was pumped.

The previous owner had stripped the threads on many of the screws and had gobbed it up with snot.

The tank was filled and the seal leaked real bad.

He was lucky not to have had a serious enviromental cleanup bill.

It was only the fact he was a long time bertholder that cut him some slack.

I got the job of going up to M5 from M4 on the dozen or so screws that held the inspection hatch on, and making a decent gasket.

Fix one thing and find another problem!

My chosen boat has no dedicated inspection hatch, but good access can be got through the sender unit hole.

I have made a fuel polisher with a submersible pump that fits down the hole easily, and can be manipulated into all of the corners of the tank.

Funny thing is, my fellow clubmembers and friends tend to need it more than me.......................................
 
I don't think that there is any doubt that an access into a diesel fuel tank is vital in the long run. Certainly over the life (usually quite long ) of a boat there will be need to get in and clean it out. So why don't builders put in the provision for access. primarily because new owners don't think to insist on it and the bulders can only see to the warrantee period not beyond. Like so many things made these days. Not actually built in redundancy but certainly no consideration for the long term future. Certtainly in all aircraft there is provision to reach allo corners on small tank or actually climb into a big tank. regardless of difficulties of sealing the inspection hole. olewill
 
dancrane said:
Just a little question. I don't have a diesel engine or tank, so I don't have any diesel problems, but the sometimes-doubtful purity of marine diesel seems to cause plenty of headaches for yacht-owners...let alone diesel bug and the thick filter-clogging sludge that is said to occupy the bottom inch or so of many old tanks...

...so, given that the tank itself is usually quite a large structure...why are filler-tubes so small? Wouldn't it be beneficial if tanks also had large access hatches, to facilitate scooping out sludge and cleaning the tank's insides?
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With the usual thin-walled and quite flexible polyethylene tanks fitted to most AWBs it is actually quite difficult to put in an inspection hatch that won't leak - I fought leaks for 2 years after fitting one before I finally managed to get it sealed.

It would I suspect cost significantly more than £20 extra to make the tank more rigid and fit a decent inspection hatch - though even if it was £200 extra I'd have been happy to have paid it. Then a bit more for putting in DZR or bronze seacocks instead of brass, putting on Aquasignal lights instead of .... etc. etc...

.... and then you put on Profurl rather than Facnor furling, North or Hood Sails instead of Elvstrom etc. etc....

There is much good about many AWBs, some of the design engineering is well thought through, but there is no doubt that there is a cumulative cost-cutting that gets irritating at about the ten year life point.
 
Even my little 10 gallon stainless diesel tank has its filler fitting, vent pipe and fuel guage sender all fitted to a large (ish) round fitting so the lot can be removed in one go leaving a decent sized hole for tank cleaning.
 
dancrane said:
Just a little question. I don't have a diesel engine or tank, so I don't have any diesel problems, but the sometimes-doubtful purity of marine diesel seems to cause plenty of headaches for yacht-owners...let alone diesel bug and the thick filter-clogging sludge that is said to occupy the bottom inch or so of many old tanks...

...so, given that the tank itself is usually quite a large structure...why are filler-tubes so small? Wouldn't it be beneficial if tanks also had large access hatches, to facilitate scooping out sludge and cleaning the tank's insides?
Click to expand...

When we had long-range s/s tanks made for Equinoxe we made sure that we had 9" filler/inspection plates built in.
 
Jamesuk said:
Only Plonkers don't have good inspection hatches for their diesel tanks :-)
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Thanks! I now realise I am an "anxious plonker",,,,,,,,,,,,,,,,,,,,,,,

In defense m'Lud the tank on Khamsin is tucked away under the port deck, built in to various supporting glassed-in woodwork and appears as old as the boat itself (1980?) - and it was there when I bought her and I've been scratching my head since then, wondering how to fit a sender and inspection plate/hatch/thingy.
It seems the only way I could do it is to dismantle the whole lazarette.

I live in fear of "the bug", gunge and unwanted contamination.
 
"The bug" is a relatively new thing... pre dating the design and build of many currently existing boats..... 20 years ago people generally had far fewer problems with diesel than they do now.
 
When I designed the tanks (water diesel and waste) I made the inspection hatches as big a possible, big enough to get my head inside. Also I made the inspection hatches rectangular and not round for IMHO ease of fitting. The hatches can be cut with an angle grinder of jig saw depending on material and a backing frame bolt down that goes inside to support thin tank material.

WEB0813_zpsb0befb04.jpg


This is my waste tank made from flat sheet GRP then lined/sealed with epoxy. The lid was made from polycarb but could be any any flat material. My diesel tanks are mild steel with mild steel lid done in the same way. If any of the threads do strip they can be replaced by unscrewing from the inner frame.

WEB0815_zps04fc69f0.jpg
 
Looks like a nice bit of work, Rogershaw.

I expect it's normal for motor yachts to have easily internally-accessible fuel tanks, just because a crisis with their fuel would be so immobilising...although I daresay twin engines always use independent tanks, and perhaps it's extremely uncommon to suffer contamination with both at once?

But much as I would like to believe that sailing men aren't daunted by the occasional necessity to make a passage without using their engine, I reckon most would admit to routine reliance upon it - and on the purity of its fuel, and ultimately on being able to clear the tank of any issue arising therein, without massive, costly inconvenience.

So if I was looking at a yacht without a good-sized, well-constructed access hatch in the fuel tank, I'd wonder what other cost-corners had likewise been cut in her specification.
 
Every aspect of design involves some choice in the compromises employed. The tank on my boat, has several drawbacks by today's standards. It is too large (100l for a 14hp engine), it is GRP and is glassed-in and has a large inspection hatch on one side. Plus points - 1) no sender, just a sight glass. 2) level above the filter if more than half full.

OK, so many of these disadvantages were considered advantages when she was built - excellent range, no risk of tank movement - but now I must accept that the size is likely to encourage bug and it can't be removed for cleaning. "Ah!" you say, "you've got an inspection hatch". Yes, but here's the problem - I don't know how it's fastened until I break the seal and nobody so far has been certain of what will make a seal on a vertical joint to hold diesel. Any further suggestions? I just want a diesel proof mastic.

Rob.
 
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