Fuel tank inspection hatch

[Sea Change]

My (stainless) diesel tank doesn't have an inspection hatch. Can I just buy a circular dinghy type hatch and use that? They're available with transparent covers which would be handy.
Are there any compatibility problems to look out for? Most tanks seem to use a stainless plate, which would be a slightly bigger job.

 

[rogerthebodger]

In my stainless-steel water tank, I simply cit a rectangular hole with an angle grinder with a cutting disk the bolted a clear Perspex sheet that just overlapped the cut hole and sealed with foam rubber strip wit bots at 40-50 mm pitch all-round the lip

Make the hole big enough to get your head inside so you can see in all the corners

 

[mrangry]

I installed inspection hatches in my fuel tank, I say hatches (plural) as due to internal tank baffles I needed 6 hatches. A fiend of mine made a video of installing hatches on his tank.

 

[Boathook]

I would get a hatch suitable for a fuel tank.

My experience of the dinghy type hatch is that they aren't 100% tight so you will always have a smell of diesel and possibly a trace.

 

[Stemar]

In my stainless-steel water tank, I simply cit a rectangular hole with an angle grinder with a cutting disk the bolted a clear Perspex sheet that just overlapped the cut hole and sealed with foam rubber strip wit bots at 40-50 mm pitch all-round the lip

Make the hole big enough to get your head inside so you can see in all the corners

How well would perspex stand up to diesel long-term?

 

[rogerthebodger]

How well would perspex stand up to diesel long-term?

I thinks but If the OP did not like Perspex other sheet plastic like HDPE or Polypropylene or even Polycarbonate.

HDPE is used to fabricte diesel tanks and I have a oil drip tray made from HDPE under my engine to catch any oil or diesel drips

 

[TomK]

I removed my tank and took it to a metal fabricator to weld in one of these - Inspection Hatch - Stainless Steel - Float Your Boat. It was a faff to get the tank out and back in again, but not that expensive all things considered. The peace of mind of being able to clean decades of gunk out and be able to keep it clean and know it's sealed tight feels worth it. Not sure I would be happy putting in a plastic hatch in.

 

[Tranona]

My (stainless) diesel tank doesn't have an inspection hatch. Can I just buy a circular dinghy type hatch and use that? They're available with transparent covers which would be handy.
Are there any compatibility problems to look out for? Most tanks seem to use a stainless plate, which would be a slightly bigger job.

Here are 2 types that are commonly used. wema.co.uk/products/flb-flange?srsltid=AfmBOoq9xXnLj3CSzerOY1OQ-Rs_Gq8tXXuTg7enCb8eGqavsuB7wJBN and tek-tanks.com/product/flb-1/ both designed for retrofitting.

Do you really need an inspection hatch? The boat has managed well over 30 years without one. Common practice to access the interior through either the filler spigot or the sender plate to suck out any debris or to use a polishing system to clean the fuel.

 

[Sea Change]

Here are 2 types that are commonly used. wema.co.uk/products/flb-flange?srsltid=AfmBOoq9xXnLj3CSzerOY1OQ-Rs_Gq8tXXuTg7enCb8eGqavsuB7wJBN and tek-tanks.com/product/flb-1/ both designed for retrofitting.

Do you really need an inspection hatch? The boat has managed well over 30 years without one. Common practice to access the interior through either the filler spigot or the sender plate to suck out any debris or to use a polishing system to clean the fuel.

The three hours I spent completely becalmed this morning, head down in a locker poking things up the outlet spigot have persuaded me that a hatch would be quite nice...
I did try to get the sender off, but failed. And the filler takes a fairly convoluted path to the tank.

 

[Tranona]

I have dome sympathy with that. Putting a proper hatch in is not a trivial job and the ones I posted are rather small. If you can get the tank out and clean it is much easier. I had to take the forward water tank out of my first Bav. The original plastic had been replaced with a stainless one which was foamed in (typical Greek bodge!). It started leaking on our trip back across the med. Inevitably the failed welds were at the bottom front. Took me over 3 days on and off to get it out. The repairs and mods were easy to do in the workshop including putting in a large stainless inspection hatch then pressure testing.

If you have reasonable access to the top of the tank cutting a 115mm hole for one of the nylon ones should be relatively easy.

 

[Farmer Piles]

I bought a Vetus kit like the one below - the hatch and the appropriate core drill supplied by them.

Vetus inspection cover 120 mm

The idea was great and it is suitable for diesel tanks - but we couldn't get the drill to cut through the stainless tank top. Despite the great pressure we put on the drill it just lost the edges on the cutting teeth and gave up. Despite the best efforts of the 30 year old, 15 stone marine engineer.

We had drained the tank - obviously - and ended up drilling a pilot hole then using a high speed airtool nibbler to cut a hatch. We then drilled holes around the hatch hole and tapped them, made a hatch and a gasket some Hylomar or similar, and screwed the whole lot down, Two seasons later and there has not been a slightest weep from it.

It was a slog though but worth the effort.

 

[Farmer Piles]

I forgot to say that the Vetus hatch part seemed really good and a smart setup. It was just the inability of the drill to cut through the s/s tank that was the issue - despite it being rated to do so.

 

[jwilson]

Don't use a dinghy buoyancy tank hatch - it would be 99.99% certain to leak diesel. I even had leakage problems with a Wema one supposedly suitable for diesel. A Vetus might work, IF you can cut a perfect hole in the tank. Post #11 could be your best bet.

 

[Sea Change]

I should add that I'm in Antigua so my options may be limited. And also the boat is very much in commission and I'm in need of a quick solution.
I take the point that the dinghy hatches may leak, although I must say that I've been very impressed with the ones I fitted to the plywood dinghy I built... if there has been a change of air pressure since they were last opened, there's an audible pop as you unscrew them, so they are clearly airtight.

Access to the tank isn't too much of an issue- it's under a berth in an aft cabin and I have full access to the top surface. Removal wouldn't be especially difficult either.

 

[HunterWanderer]

I fitted a dinghy hatch 20 years ago to the top of my diesel tank and its still fine, no leaks.

 

[Graham_Wright]

Henderson hatch. Aluminium, leak proof and easy to undo.
I think I have a couple (uncles I have already sold them).