Fuel purifiers and additives

Hi to all, A few BCC owners and the Sam L. Morse Company?are investigating two products that clean and purify diesel fuel.?We are considering using?these products?on our boats and perhaps as standard on new boats.

The fuel purifier does not use a replaceable element but will separate water and solids from the diesel by passing the diesel through this canister that forces the diesel into a vortex which forces the water and solids to separate and settle in the bottom of the canister to be drained off later.

This purifier is called?RCI Fuel Purifier. Apparently, the Coast Guard and Navy are using this unit…so I am told by the rep.

The other product is a fuel additive called Hammer Down that conditions the fuel. I don’t want to go into anymore details because my purpose is to find out if anyone out there has had any experience with these two products.

I pay more attention to our owners than I do to any sales representative.?Hope to see everyone for the rendezvous in June.?

Roger Olson

First hand experience - none. Does not prevent me from having

My understanding is that vortex type separators work due to a rate
of flow that is not achieved with our little engines. Works fine for
the fuel hogs run by the govt. My big Racor has this feature, but
again, low flow prevents the swirling of the fuel necessary to
generate the centrifugal force that causes separation of impurities.
The Racor rep told me to buy a smaller filter (!). I wanted the
sight bowl and replaceable element of the 500 size, he warned me
the “turbo” feature would not work right at less than a gallon an
hour (it is rated at 500 gph).

The prior owner was an obsessive about clean fuel, changing filters
every 50 hours, etc. The boat did not have a deck fill (leaky O-ring
is a common unrecognized source of H2O in fuel) and he got fuel at a
truck stop to ensure its freshness, filtering it into the jerry jug
and again into the tank. I still had crud in the bottom of the
tank. It has kind of made me fatalistic about fuel contaminants,
that they are unavoidable and that actual fuel tank cleaning
(manually, not one of these “fuel polishing” schemes) should be a
maintenance item every few years.

Fuel flow is too low to work in the RCI filter. I use them in my fleet of trucks and they work just fine but the don’t work in the small fuel flow situations. The cannot swirl the fuel which is essential for the operation as designed.They will cause a drop in fuel pressure and introduce a greater likelihood of air in the fuel lines.

Thanks to those who responded on the RCI fuel purifier. It seems there is agreement as to its?efficiency based on the flow rate. This was my concern as well but the president of the company said it made no difference but I cannot see how it would not make a difference. Thanks for the input Jcskua and Jim.

Roger Olson

This is probably not practical, but worth a thought for future designs. All aircraft have a sump drain located at the lowest point of the fuel tank that can be drained regularly. Water and other stuff that is heavier than fuel settles to the bottom and can be easily removed from the tank as part of the “pre-sail” check. A valve and cup is all that is needed. As I said this may not be practical
for boats since there is not much room below most fuel tanks for the valve, but it may be worth looking at.

Coast Guard regs prohibit a drain at the lowest point. Interesting though, Lloyds insists on it for boats built on the other side of the pond (Atlantic pond that is)

My Sabb came with a 10 gallon monel(?)fuel tank that incorporates a sediment bowl and drain on the bottom. I drain a bit into a glass jar every so often and it will show any water droplets and heavy debris.The fuel outlet hose also comes off the bottom and I think it is this feature in particular that the U.S. regs are against since a fire that burns through the fuel line at any point would drain the tank. When the fuel line comes off the top of the tank, it will only syphon into a fire if the break occurs at a point lower then tank itself.
However I don’t see why a bowl and drain petcock on the bottom of a U.S. tank would harm anything since it is all metal.
At the same time, as has already been pointed out, many fuel tanks are located where a bottom drain isn’t possible anyway, such as in the bilge, keel envelope or wedged under a settee or bunk.I have my tank, (horizontal cylinder) mounted against the hull in the port quarter, under the cockit.
For my money, the regs be damned. I like my set up and because of it I’ve never clogged a filter or run water through my injector…a very expensive occurance.

Stan ,
hull #22,

The USCG regs about tanks, etc only apply to inspected (eg passenger for hire) vessels. They also forbid a number of other things common on our strictly pleasure boats such as plastic bowls on the fuel filters. We can do almost anything we want as those rules do not apply to us. I think a drain bowl is a fine idea but not always readily implementable.


A drain sump just makes good sense. In aviation, a similar life critical
discipline where high emphasis is placed on continued rotation of the prop, the very first thing a student learns to do in preflight is to drain the water out each and every time you start the bloody engine. In my mind, this is a case where safety supercedes the law. Look at the law and ask yourself whose butt is on the line.

Being a belt and suspenders man I would design the system aviation fashion with one sump for each tank and a final sump prior to engine access. It’s cheap