Putting diesel access hatches in installed tank ?

[Sven]

Our 30-year old aluminum diesel tank has no access or clean-out hatches. It is an 80 gallon built-in ... literally, it extends under cabinetry and (partial) bulkheads.

I can see how to cut access hatches in the teak (plywood) sole and make that work well.

What I am much less sure about is how to cut access holes in the tank itself while it is installed. Some of the cuttings would certainly end up in the tank and even if they never got through the filters into the engine it just doesn't seem right to have them in the tank. Would the access port covers just be round plates with bolts around the perimeter into threaded holes ? What kind of gasket should be used ... a big o-ring or some special rubbery material ?

Maybe I just shouldn't worry about access unless there is a real need ?


-Sven

 

[sailor11767]

Sven,

I don't have an answer, but I do have a question. I am looking at a 77 E-35/II, and noticed that the tank is aluminum. I thought these boats had steel tanks, so I figured it was a replacement -- but after your question, I have to wonder if they changed materials in later year boats. Do you have any knowledge on this?

Harry

 

[Sid]

access

Sven
I have a 36c and had to get into my tank also. Lucky for me it was an easy project as the tank is mostly exposed under the aft cabin bunk. I cut 3 square holes (one for each chamber) approx 6", cleaned the mess out and made 3 square plates large enough to cover the holes by 1 1/4 inch, then drilled and tapped holes about every inch. This was done in Mexico so I had limited resources. In my travels I have now seen a kit for just that project but right now I am not sure where I saw it. I think it was in the Bahamas. If you have control of the internet I think you can find them. Good luck.

 

[treilley]

- Drain out as much fuel as you can thru the tank pickup port.
- Try to get a rag down in there where you plan to drill. You need a small hole to get the nibbler started.
- Next use some sheet metal nibblers.
http://www.amazon.com/Bessey-D23-Pu...ref=sr_1_2?ie=UTF8&s=hi&qid=1235135672&sr=1-2
I have a pair of these and they work great. It cuts out a 1/8" strip of metal continuously leaving no bits behind.

- Tap your holes and fabricate a top. Be sure to also have a rag under where you do your drilling and tapping here.
- Clean the tank affix the top.

 

[Glyn Judson]

Fuel tank access.

Sven, I enlarged the existing hole in our 39 gallon aluminum tank using a saber saw and drilled mounting holes around the larger opening. I let the chips fall into the almost-full tank and used a 12v Reverso oil changing pump that I afterwards fitted to the fuel line to facilitate priming the engine when/if necessary. I bought two lengths of hose, some clamps & barbs, an in-line ITT fuel filter and two pair of Nylon peds (women's ankle Nylons). The peds got clamped to the return end of the hose and the in-line filter to the intake hose close to the pump. It was then a simple matter of "vacuuming" the bottom of the tank and returning the fuel at the same time while I periodically cleaned the filter and the peds until I couldn't pick up any more aluminum chips. Amazingly, I could actually see the very clean bottom of the tank through the diesel which helped locate errant chips as I recall. The factory installed plastic access hatch reacted to the diesel, had cracked badly and been poorly patched over the years necessitating its replacement. I bought a cast almag, 6" round Bomar access plate like this http://www.pompanette.com/pompweb.n...d1cd98a083a69c63852567d70053686c?OpenDocument except 6" round. Sorry, I can't find the round one I bought, maybe you can contact Pompanette to get a quote for one. It's my recollection that a butyl(?) gasket came with it. Email me back channel at glynjudson@roadrunner.com and I'll send you an image of it installed in the tank top. Hope this helps, Glyn

 

[Sven]

I don't have an answer, but I do have a question. I am looking at a 77 E-35/II, and noticed that the tank is aluminum. I thought these boats had steel tanks, so I figured it was a replacement -- but after your question, I have to wonder if they changed materials in later year boats. Do you have any knowledge on this?

I think the specs for the 39-B specifies SS water and Al diesel tanks.


-Sven

 

[Glyn Judson]

Getting a round Bomar access plate.

Sven, I'm as sure as I can be that you could still get a round access plate like mine from Bomar if you wanted to. You see, when I ordered mine, the woman on the phone muttered something like, "OK, I'll have one cast and mail it out to you right away". Apparently they don't keep stock of every hatch, they cast them as the orders come in, way cool. Glyn

 

[Sven]

... I cut 3 square holes (one for each chamber) approx 6", cleaned the mess out and made 3 square plates large enough to cover the holes by 1 1/4 inch, then drilled and tapped holes about every inch.
...
In my travels I have now seen a kit for just that project but right now I am not sure where I saw it. I think it was in the Bahamas. If you have control of the internet I think you can find them. Good luck.

How did you cut them and how did you get the cuttings (if any) out ?

I will try to get control of the internet The kit you mention sounds very interesting so I'll search for it.

- Drain out as much fuel as you can thru the tank pickup port.
- Try to get a rag down in there where you plan to drill. You need a small hole to get the nibbler started.

The nibbler sounds like a good idea, I'll have to check that out. I think the pickup is welded to the tank (have to double check) so there is probably no port to use to get a rag in before starting any drilling.

I enlarged the existing hole in our 39 gallon aluminum tank using a saber saw and drilled mounting holes around the larger opening. I let the chips fall into the almost-full tank and used a 12v Reverso oil changing pump that I afterwards fitted to the fuel line to facilitate priming the engine when/if necessary. I bought two lengths of hose, some clamps & barbs, an in-line ITT fuel filter and two pair of Nylon peds (women's ankle Nylons). The peds got clamped to the return end of the hose and the in-line filter to the intake hose close to the pump. It was then a simple matter of "vacuuming" the bottom of the tank and returning the fuel at the same time while I periodically cleaned the filter and the peds until I couldn't pick up any more aluminum chips. Amazingly, I could actually see the very clean bottom of the tank through the diesel which helped locate errant chips as I recall. The factory installed plastic access hatch reacted to the diesel, had cracked badly and been poorly patched over the years necessitating its replacement. I bought a cast almag, 6" round Bomar access plate like this http://www.pompanette.com/pompweb.n...d1cd98a083a69c63852567d70053686c?OpenDocument except 6" round.

Good info ! I think I now remember reading an earlier post where you described the work. I'll see if I can find that too.


Thanks to all for the suggestions. It is encouraging that it has been done before even if it will still be terrifying to start the job


-Sven

 

[Sid]

access plate

check out a company called Seabuilt they make access plates kewl ones

 

[Loren Beach]

diesel trivia

Sven,

I don't have an answer, but I do have a question. I am looking at a 77 E-35/II, and noticed that the tank is aluminum. I thought these boats had steel tanks, so I figured it was a replacement -- but after your question, I have to wonder if they changed materials in later year boats. Do you have any knowledge on this?

Harry

The fuel determines the optimal tank material. For diesel fuel it is 5000 series aluminum. Gasoline engines usually seem to have had steel (aka "black iron") tanks installed.

LB

 

[treilley]

Sorry Sven, I meant the fuel sending unit.

 

[Sid]

cutting the holes

to I used a saber saw to cut the hloes after the tank was emptied. What went into the tank came out when it was cleaned. I used a scrubby and gunk to start with, that was pumped out and I used soppy water, lots of it, a shop vac sucked it dry then used a towel to dry the tank, let it dry and vac again. If you leave fibers they will clog the check valve if you have one. Internet is tuff here, we are in Trinidad W.I

 

[WhiteNoise]

Be careful

On a new tank I would say no problem but on an old tank you have to be careful with the welds. You do run the chance of compromising the welds from the vibration of the saw. I know the motor, boat, etc. may vibrate a bit but nothing like a sabre/jig saw cutting through.

Not a definite issue but unless you have an issue that requires you cut a hole I would avoid it. There are other methods such as fuel scrubbing.
If you do it I would wait until the beginning of your off season, just in case there is a problem, you could order new tank with an access port.

Not trying to be negative, just realistic and a little cautious.

Sid
I like those access plates. Thanks for mentioning Seabuilt. I will look into that for an access plate on my water tank.

 

[Sid]

fuel scrubbing

I didn't go cruising until I had owned my boat for twenty years. I had the fuel polished a few times, but until I opened up the tank and saw all the crap that was growing in it I thought that my fuel filter problems were due to bad fuel. I even put in a duel filter system that can be changed at the flip of two valves. Now that I can get into the tank I haven't had to use it but once. I always keep the tank full and treat with a biocide, but stuff still grows in the tank and when it starts to rock around the sloshing knocks stuff loose. The #1 problem with boats that head south is that they do not manage their fuel system well prior to leaving, I thought I had but after 20 of short motoring I was wrong.
Experience is something you do not have until just after you need it.

 

[newgringo]

Another port design

The access port in our E32-3 is about 6 in dia with a bolt ring (8 bolts as I remember). Inside the tank is a bolt ring flange of 6 in ID and 8 in OD with the 8 bolt holes and bolts fastened somehow into the ring. Then there is two flat sheet rubber gaskets, one between the tank inside and the bolt ring and the other between the tank outside and the cover plate. I would think this kind of arrangement could be added after a tank is fabricated if the inside bolt ring flange has a slot for installation. Someone has probably done it with a tank in the boat. I would try. Yes, saw vibration is a concern and a fine tooth small saw wound be better than a sawzall. Lots of good ideas here for dealing with the metal chips. Good luck.