380: Fuel Tank NOOBIE question

[Zoid]

One year of cruising on my 380 under my belt and it's time for some of the annual maintenance tasks. One of which is to drain any water and sediment from the fuel tank. I have an owners (3 cabin) 380 with aluminum tanks that came from Lagoon, no inspection hatches. I can see the drain bolt on both tanks but they don't leave much room for access. My tanks are full right now but I wanted to try and drain off any water, etc. on the bottom. Before I slowly open the drain bolt I thought I'd ask other Lagoon owners with these or similar tanks for any advice or thoughts before I do something stupid and fill my bilges with diesel.

Any thoughts or advice? Any ideas on how to catch what comes out in such a tight space without getting diesel everywhere?

Thanks,
Zoid

[Zoid]

Forgot to add pictures. The one with more access room is the port tank, the other starboard.

[Zoid]

After further consideration I think the weight of a full tank will make this a disaster. Need to drain the tanks before I crack that seal.

Sorry to drag you all through my thought processes on this, I guess I could have waited to post once I had thought through it some more...

[monte]

HeHe Kenny. I as waiting to see answers but agree that it's best done close to empty if at all. I wouldn't bother personally. Have you drained the water separator on the fuel line? Funny our 380 had plastic tanks, I wonder why the change. Also has a top inspection hole so you could always siphon the bottom off I guess. Other option is a professional fuel polisher who would come and run all the fuel through filters. After a years use I would t expect there to be any sludge though

[a64pilot]

I'd either wait until they are as empty as possible, or try to suction from the top somehow, maybe using an oil change vacuum pump and tube.

[bsurvey]

have the fuel polished it will eliminate the water until you figure out what and where the inspection ports should go

[Rough Magic]

I don't think you probably have any water in the tanks, if you use the engine frequently. I would just add a can of Seafoam to the tank at the next fill up, and watch your filter... it will dissolve gums and varnish.

If you really want to open the tank, you're right to empty it first. Then you might be able to remove the fuel gauge sender to clean the bottom, and drain the last bit of fuel through the bottom drain. I would then install a shut off valve with a hose attached, and you can drain a little fuel now and then.

I have a boat with an aluminum tank, 11 year old, never had a problem.

Dave

[David M]

A dual Racor filter will eliminate the need to have drain the fuel tank. Unless you put the garden hose down it or shovel dirt into it, you really don't need to drain your fuel tank after only a year.

[Hud3]

Yes, the Racor is very good at trapping water. But I wanted to keep tabs on what, if anything, was lurking at the bottom of my tank, so I made a contraption to selectively sample the low points in the tank.

Buy a replacement outboard motor gasoline tank hose with in-line squeeze bulb for priming. Cut the fittings off the two hose ends. Insert a length of 3/8" copper tubing into the tube which will fill the bulb when it's squeezed. Secure it with a hose clamp.

Now you have a probe which you can poke around in the bottom of the tank. Squeezing the bulb delivers a convenient amount of fuel to a plastic jar without any mess or spillage. Works great. Drain the hoses and coil them up so it can be stored right on top of the fuel tank.

[ontherocks83]

Originally Posted by Hud3

Yes, the Racor is very good at trapping water. But I wanted to keep tabs on what, if anything, was lurking at the bottom of my tank, so I made a contraption to selectively sample the low points in the tank.

Buy a replacement outboard motor gasoline tank hose with in-line squeeze bulb for priming. Cut the fittings off the two hose ends. Insert a length of 3/8" copper tubing into the tube which will fill the bulb when it's squeezed. Secure it with a hose clamp.

Now you have a probe which you can poke around in the bottom of the tank. Squeezing the bulb delivers a convenient amount of fuel to a plastic jar without any mess or spillage. Works great. Drain the hoses and coil them up so it can be stored right on top of the fuel tank.

I like that alot. Very resourceful. Thanks for the info

[ontherocks83]

To answer the OP's question. I would definitely burn off the fuel to as low as possible. Leave just enough fuel so that when you do open the drain the fuel will "flush" the water out with it (if there is water or dirt). Kind of like rinsing the tank with the small amount of fuel that is left inside. (not sure if that makes sense) . Realistically an inspection port would be much better to have installed.

[a64pilot]

There is a paste that can be bought at about any NAPA store, this paste's purpose is to smear it on the end of the stick that gas stations use to measure their tanks with, the paste goes through a drastic color change when dipped in water, but none with fuel, so the exact depth of water can be determined.
So if you think you have water in the tank and don't have an access port, remove the sending unit, put some of this paste on a wooden dowel and you can find out if you have water, and how much.

[Zoid]

Thanks for all the responses. I've been very diligent about checking my water/fuel separator and changing filters as needed. I have no reason to suspect there is water in there, just going through the annual checklist of items. I think the standard Lagoon comes with a plastic tank that I didn't know has an inspection hatch. The aluminum tanks where an upgrade (I didn't choose the upgrades, long story...). Anyway, at some point I might put them in.

Thanks everyone. Monte, hope you are enjoying the warmth of the Caribbean. Sicily has been cold, wet, and rainy...

[Nobody]

you can purchase dip strips that will tell you if water is present in fuel
take a sample of fuel at the bottom of tank and then dip the test strip in sample it will change colour if water is present
Same as paste but easier to use

[thinwater]

Originally Posted by a64pilot

I'd either wait until they are as empty as possible, or try to suction from the top somehow, maybe using an oil change vacuum pump and tube.

That. Since most already have an oil suction pump, simplisity itself. If you find a lot of anything, then you can decide on a next step.

Checking the pH of the water can be smart. If it is very low you probably have an infection and corrosion is likely.