cleaning fuel tanks

[windrose]

What is the best way to clean the fuel tank while it remains in the boat....

What proactive steps should I take for an old A-Bomb that has been laid up for over two years? I put some MMO in the spark plug holes and slowly turned the old motor over with the hand crank to move it thru the system-- cranked easily and readily built compression (a good sign).

I have opted to get to know the Atomic Four before making any decisions about it's removal... it is the older model engine with points etc. However, I would like to mount a motor mount on the transom for this year as a back up. I would simply keep an outboard on the stern rail that could push the dinghy or put it on the motor mount if needed. What would be a good choice OB for this.... ideally light weight enough to use in the dink, but enough h.p. to push the boat if necessary. (The dinghy is the original Pearson dinghy that was sold as an option with the boat--- similiar to a Fatty Knees).

Thanks! Ang

[Figment]

Throw a bit of MMO into the crankcase as well.

Take a close look at the ignition system components. After sitting for two years, I'd replace the points and condensor at minimum.
If things look suspect, and if you feel like throwing a bit more checkbook at it, it may be worth your peace of mind to just replace the plugs, wires, cap, rotor, and coil while you're at it. Start fresh.

After sitting for two years, she's likely to run a bit rich at first. The first set of plugs may foul up on you rather quickly. I'd have an extra set on hand.

backup outboard size.... well, what kind of performance are you looking to get out of it? get you home against adverse wind, waves, and tide? or just get you from the dock to the mouth of the harbor?
I think a triton could get away with as little as 2.5 hp (or just get a pair of 9' oars), or it could use as much as 10, depending on the conditions of use.

[Tim]

I think a 3.5hp outboard might be a good choice--still small and light, like the 2.5s, but with that little extra kick. You'll need a long shaft if you think you'll really use it on the Triton. Personally, I think it is worth the small price upgrade to go for an outboard that has a forward/neutral selector, at least. The smallest ones do not; this feature usually starts with the 3.5. I found www.onlineoutboards.com to have the best prices on Nissan/Tohatsu. Note that Nissan and Tohatsu motors are the same exact thing, differing only in price (Nissan being higher). Also, the smallest Mercury motors are identical to Nissan and Tohatsu as well.

Any outboard will push the Triton in a pinch, in calm weather. Don't look for any of these small outboards to provide stellar maneuverability at the dock, though--particularly for backing or "braking", since these small motors don't have a dedicated reverse gear, meaning you have to swivel the whole motor around. Tight situations is when you will notice the small size of the outboards, but with care, you can overcome this as needed.

Forget about using one of these tiny things to push your boat against waves and wind. I see it as a home-with-no-wind useage only, or for mooring/docking activities. Even a larger outboard will run into problems in a seaway, which is one of the main disadvantages of an outboard slung off the transom. Access to the engine controls, with the engine mounted way aft and down low when in use, would be difficult and would always require care and forethought.

Have you seen--or considered--the sort of mount that the Frenchman Yves Gelinas built for the Alberg 30 Jean de Sud? It's an interesting idea--and apparently proven through his own success. It addresses some of the shortcomings indicated above.

(For more detail, go to www.capehorn.com and choose "The Alberg 30 Jean de Sud" from the menu.)

The only way to really clean a fuel tank is to get your hand in there and clean. This involves the need to cut a large-enough access hole in the top, and a means to then close off and safely seal this hole. (Aside: I think all permanent fuel tanks should have this built in from the manufacturer. Alas, they do not.) Obviously, cutting a large hole in a gasoline tank--and then safely resealing it--is not something to be taken lightly. I recall seeing some writeups on this somewhere in Triton land--maybe on the MIR pages (www.tritonclass.org), or possibly even here on the forum somewhere.

There's bound to be sludge, varnish, and gunk in the tank. If you can't remove the tank for detergent agitation and that sort of treatment, opening the top is the only way. It's best not to shortcut the cleaning step, since many engine failures at critical moments are caused by dirty fuel, whether gas or diesel. If you don't have one, I'd install a really good primary fuel filter too, whether or not you clean the tank.

[windrose]

Thanks Guys!

My boat does have the top access lockers.... last night I was reading on the MIR pages where one fellow simply unhooked, cut the tabs and lifted it out.... he said it only took about 30 minutes.... hmmmm.

Thanks for the advice on the motor... I have a little Honda 2 hp long shaft that might do in an emergency (and a radio/cell phone if I absolutely had to call the vultures for a tow).

[Tim]

The tank does not fit through the cockpit locker opening--another brilliantly-poor conception by Pearson.

You have to remove the galley and pull it out that way, as described on MIR.

[windrose]

Hmmm.... the fellow who owns Akasha #140 tells in the MIR about simply lifting his out the top of the locker. Are there different types of fuel tanks between EC and WC boats.

I just put pretty white formica/beaded birch throughout the boat so the idea of tearing out the galley does not appeal to me.... I would probably be more likely to cut out the old tank and install a somewhat smaller version that would fit through the locker.

[Tim]

My tank didn't come close to fitting through the locker opening. I tried every which way. I don't know of anyone who's had success, so I was interested in #140's experience.

Give it a go--you never know, but don't expect success! Again, each boat is different, so there's a chance.

[Dan]

Years ago my Father cleaned out an old fuel tank by putting a large handfull of nuts, bolts and screws in the tnak with a quart of diesel and shook it up a lot. Cleaned the inside of the tank real nice. Obviously, don't use gasoline with this method.

[windrose]

Tim, after careful consideration and head scratching I have concluded you are right, again. No way is that tank going to come out that locker. :(

I am going to explore replacing it with a smaller tank... got any suggestions? pros/cons of polyethylene vs. aluminum

Seems the poly would eliminate some problems of rust, corrosion, etc. What are the down sides? Does it get brittle with age?

[dasein668]

To me, the biggest drawback of the poly tanks is that they are not baffled. They are reasonably priced, though. The best solution, in my opinion is a custom tank with baffles. Pricey though!

[Tim]

The lack of internal baffling is of particular concern if you choose a tank that is shallow and side--in other words, with a large free surface area. I chose a wide, shallow tank for Glissando because I could get it to fit inside the tight space beneath the cockpit. I hadn't g iven the lack of baffling a thought at the time, but I would not make the same decision again.

I never let my wide, shallow tank drain to less than 1/2 tank in order to prevent excessive sloshing that might cause an air problem in the diesel line at an inopportune time; the pickup is on one side of the tank, and if the tank were under 1/2 full, it's conceivable that the fuel could slosh sufficiently in the opposite direction to expose the pickup tube and draw in air. I have not yet had a problem with this, partly because I am well aware of the possibility and am vigilant in its avoidance--but it is always on my mind when using the engine in these sorts of conditions.

(Yes, sometimes one uses an engine when there happen to be seas. There are not always winds accompanying sloppy seas.)

A deeper, more square tank would avoid much of this issue. There is a description of one (Alaya or something) on the MIR. Access for installing the tank is an issue, though--you'll find that locker opening to be ridiculously tight even for this sort of thing, and its size will limit your choice of tanks.

The premium choice is definitely an aluminum, internally-baffled tank, one preferably custom-built for the space. Knowing what I know now, I would not consider otherwise for my cruising boat--never mind the cost. Keep your own needs in mind when choosing--a poly tank will work fine in many instances. I'm using another poly tank in the Daysailor build. Just try to avoid wide shallow ones. Tall and skinny is a better choice if you can make it work.

Ideal tank specs (off the top of my head and not in any order or even necessarily complete):

5052 aluminum alloy, min. .125" wall thickness

Constructed with internal baffles

Installed in such a way that the tank bottom does not sit on a solid platform or tightly to the hull or compartment--lack of air and water circulation beneath the tank can promote corrosion

Strapped in place with metal straps, isolated from the tank surface with neoprene gasket material

Cleanout access hatch in the top, accessible for maintenance

Natural deep point on tank with an additional little sump area, to which is attached a drain point for removing inevitable sludge buildup

Fuel pickup line held an inch or so above the bottom of the tank, to avoid sludge pickup

[Figment]

A common-enough solution to the unbaffled tank in the powerboat world is the addition of a "day tank".

I'll spare you the diatribe on the origins. In this application, it's essentially a small (2 gallon or less) vessel in the fuel line immediately after (preferably below) the main tank. The fuel can slosh about all it wants in the main tank because the flow of the fuel through the day tank is slow enough that any bubbles or other impurites (the actual purpose of the day tank) have time to settle out and only clean stable fuel makes its way on down the line.

For the ultralow consumption engines such as those used in boats of our size, a double-set of those monster Racor filters can act as a half-decent day tank.

[Dan]

If using a Poly tank for gasoline, the Coast Guard requires natural ventilation based on the permeability rate of the tank as well as some other calculations. If a metal tank is used, and there are no spark producing devices in the same space, no ventilation is required.

At least that's the way I read it. I can point you to the regulations if you want.

Ventilation for the engine and fuel tank, to meet the regulations is another wrestling match I'm having with myself.
I think a dealer, and not the factory, installed the saildrive engine on my boat. The current installation does not meet the regulations as it is. I am modifying the engine compartment to meet those regulations.
If the tank is in the same compartment as the engine on you boat, the powered ventilation may suffice.

[Tim]

Many boats do not meet every aspect of the currently-required regulations, for a variety of reasons: perhaps when the boat was built, the requirements differed; perhaps a previous owner modified something without regard to what the requirements might be (whether by himself or by hiring the job out).

Gasoline engines and related fuel systems are one of the cases where the oft-quoted "regulations" are actually law, and required; they exist in the CFR. Many of the standards often referred to in boat construction are voluntary standards, lacking any statutory means of enforcement. Surveyors who love to quote boring regulations chapter and verse often forget the voluntary nature of said regulations in most instances. The fact that voluntary compliance with most standards is a prudent practice is not germaine to this particular point.

CFR 183.620(a)(5) (also ABYC H-2.5.3.3) reads as follows:

Except for compartments open to the atmosphere, a natural ventilation system that meets the requirements of Section 183.630 must be provided for each compartment in a boat that:

(1-4; not relevant here)

(5)Contains a non-metallic fuel tank:

(i)With an aggregate permeability rate exceeding 1.2 grams of fuel loss in 24 hours per cuibc foot of net com partment volume, or

(ii)If the net compartment volume is less than one cubic foot, having a permeability rate exceeding 1.2 grams of fuel loss in 24 hours.

This natural ventilation requrement is generally met by the typically-installed ductwork/dryer hose-type material found in most boats, usually for engine room ventilation and powered blower installation. In most small sailboats, the engine and fuel tank share a space, at least by the definitions of what entails a shared, or open, space. (Few bulkheads or dividers in boats like ours are truly separations between the space. Typically, the various openings in those dividers constitute a "shared" space by these standards.) Therefore, the engine room, cockpit lockers, lazarette, and other adjacent spaces actually end up being defined as "shared", or open, by the nature of the various natural openings between then.

The details of permeability ratings and ventilation requirements are too detailed to discuss here, and are too dependent on the boat's individual construction and systems installations to generalize. This is where prudence (once referred to as "common sense", but there's sadly nothing common about it) comes into play in any gasoline-powered boat.

Nothing beats proper maintenance, visual inspections, and the sniff test. The engine and fuel tank compartments should be sniffed before startup each time. If you smell gas, you shouldn't, and you should be therefore concerned. All the ventilation calculations in the world will not beat this simple process, which is the only way to ensure that your fuel system is safe. I have no data, but I suspect that nearly all gasoline-related explosions and fires in pleasure boats could have been completely prevented had some basic prudence come into play. It takes a pair of seconds to sniff the spaces, and hardly more time in the overall scheme of things to keep the system maintained to a high standard (which it must).

The larger and best-known manufactures of polyethylene gasoline tanks for the marine industry (companies like Todd, Krakor, and Tempo) usually state that their tanks meet applicable CFR/ABYC requirements in their construction. I have not seen permeability ratings for these tanks, and don't know if "meeting applicable requirements" also indicates that the permeability ratings are at or below the threshold indicated in the regulation quoted above for a given space. (I wouldn't lose any sleep over it either way...)

Diesel...the simpleton's choice!

[windrose]

Figment, I had decided to proceed with your idea of using the "day" tank in combination with a big canister Racor filter and someone at the yard mentioned he thought the day tank was illegal..... any idea? Seemed like such a sensible solution!

[windrose]

Figment, I had decided to proceed with your idea of using the "day" tank in combination with a big canister Racor filter and someone at the yard mentioned he thought the day tank was illegal..... any idea? Seemed like such a sensible solution!

[Tim]

...someone at the yard mentioned he thought the day tank was illegal

There is so much misinformation floating around there with these supposed requirements, "legal" or "illegal" installations, and recommended standards. Most people don't have a clue what's actually in the regs or standards, and which ones are required and which are not.

I see nothing in the applicable regulations prohibiting day tanks--or even mentioning them, for that matter.

Any fuel tank that is installed, regardless of its purpose, should be installed according to the applicable standards of ABYC H-24, as well as the required regulations found in 33 CFR 183.501-590. If you install a true day tank, it should be safely installed just like your main tank should be.

If you're really using Figment's idea to use the large capacity of an oversized Racor filter to act as a sort of day tank, there's absolutely no "legality" issue. Fuel filters, when installed, should meet the applicable standards found in the ABYC recommended practices and, if applicable, the CFR.

The whole idea here is safe gasoline installation. Period. The regs, such as they are, are designed with safety in mind and are generally worth following.