FUEL AND BILGE PUMPING SYSTEMS
When I first refitted the boat, I built this bilge system:
All sink and shower drains went into the Atwood sump box with it's own 750 GPH pump that could also serve as an additional emergency bilge pump by popping off the top. The whole system worked great but a few problems became apparent after the first season. The sump is huge. It was almost impossible to reach the equipment at the bottom or clean out the sump box. The wide flat bottom of the sump, nearly half the total keel length, is a weak point in these boats with only 1/2 to 3/4 inches of fiberglass to resist pounding if grounded in a swell. The huge amount of space above the pumping equipment was also pretty much useless for anything else.
Strider's original fuel system was also terrible to fill. The deck fill plate is located right at the edge of the transom so any overflow is hard to keep out of the water. As soon as the tank was more than about 80% full, the sloshing caused by slightest motion of the boat would shoot fuel back up the fill pipe due to trapped air in the tank and the typically small diameter vent line.
The 2QM20 Yamaha diesel engine in the boat has the return line running to the engine mounted fuel filter instead of back to the tank so there was an unused fitting shown above in the right corner. The solution to the filling problem, as well as the need for a sounding tube to supplement the inaccurate gauge, was this:
Late in the summer of 2007, I replaced the original elbow for the vent with a 4 way cross fitting and moved the elbow across the tank with a hose connection. Both corners of the tank are now vented and air displaced by sloshing can short circuit front to back and side to side without pressurizing the fill line. A short length of pipe with a ball valve was screwed into the top of the cross. This serves both as a sounding tube and also as an auxiliary vent when filling. The sounding tube comes up under a hatch in the seat locker and I wrap an oil spill pad around the tube. If I should overfill the tank, the first sign will be a spurt at this inboard point instead of down the transom and into the water. Refueling has been stress free since this modification.
In the winter of 2008, I had this 12 gallon aluminum tank constructed with 1/4" inch plate bottom and 3/16" sides and top.
The tank was inserted into the bilge through the floor hatch with the top flange removed for clearnace and set on a sandwich of fiberglass, cement, and plywood with resin poured around the lower couple inches. This will make a very strong structure together with the aluminum tank bottom. The top cover flange was then epoxied and screwed down to the top. The space between the sides and the keel was filled with foam and top bonded to the hull with a flange of epoxy and fiberglass. The aft part of the keel should now be nearly as strong as the forward part with the ballast.
Here is the general arrangement of the tank and bilge pumping arrangements:
I had originally planned to relocate the Atwood hotel drain sump box to the space shown by the dotted lines but that is very useful bilge space, especially when working on tank connections. It couldn't go on top of the tank because of the obstruction of the tank hoses and it needs to be cleaned fairly often. So...
The pump from the Atwood unit, which has it's own integral float switch, went where indicated by "A". This pump uses a small diameter line so will not suffer backflow recycling or or need a troublesome and unreliable check valve. Behind the Atwood is a smaller sump for the manual bilge pump in the cockpit which is used for stripping out the bilge.
The two 1100 GPH Rule bilge pumps and their float switches go on top of the tank. Their function now will just be to deal with a major water influx that endangers the boat. The straighter hose run will maximize their capacity and they will probably never operate except for testing. They will also back up the Atwood in case of a leak while the boat is unattended.
After living with the Atwood sump for three seasons, I have never noticed
any objectionable odor when I removed the top so I don't think dumping all the grey water in the aft sump will
be a problem. The Sump pump float would jam occasionally due to crud build up but this seems to be mostly from
grease and small food scraps that go down the sink. A
removable plastic strainer basket fits over the end of the sink drain hose and will be cleaned out occasionally. The Sahara pump the Atwood uses also has a third wire that I ran to an existing panel breaker switch to force it on if the float switch does jam.
The fuel oil tank installed:
(Fiberglass tab damaged during tank insertion yet to be repaired)
There is still room for a couple of six packs in there. Maine water keeps beer at just about the maximum drinkable temperature when the ice runs out.
Below are the new bilge pumps mounted on the tank top. These are the "Save the Boat" pumps and will seldom run except during tests. Keeping them high and dry most of the time will extend their life. The last set, which were always sitting in 3/4" of water, only lasted three seasons.
I would have used solid state bilge switches with no moving parts but I already had these. Except for testing occasionally, they will almost never operate so wire fatigue and other problems endemic to the type should not be an issue.
Here are the expected performance numbers with the additional 12 gallons based on trials from last summer and keeping 4 gallons reserve.
The extra fuel capacity will come in handy on the planned long trips to Canada but a primary benifit of all this work will be moving 12 gallons of fuel 7 feet forward and and 4 feet down in a boat that is a bit on the tender side and little stern heavy with last years addition of the Cape Horn windvane gear. During periods when I'm mostly daysailing, and apt to have more guests in the cockpit, I can use just the bilge tank and have a stiffer and better trimming boat.
The schematic for the new fuel system which includes a fuel polishing and transfer pump and filter set:
This looks like a very complex system but, if you trace just the supply system (black lines), you will see that it is simply my current gravity fed system with the new tank tee'd into the supply line and tanks selected by the valves at the tanks.
The major addition to the system is the polishing / transfer system with a high capacity Shelco filter. This system will be running any time the engine is on, constantly recirculating and filtering fuel from the tank currently in use. The same valves used to select the tank to fill can also direct the output from the polishing / transfer system to move fuel from tank to tank. This pump will normally be connected to the engine electrical system going on and off with the engine key but there is a switch to either shut it down or run from battery power when the engine is off.
Normally, combined vents are not a good idea but I decided to violate the rule in this case. If the fuel quantities are misjudged during a transfer, fuel will simply recirculate instead of being pumped out the vent. The result will be a little extra fuel filtration instead of a spill and possible fine.
The Priming-Boost Pump will normally be off when gravity feeding from the main tank if the polishing system is not running. First trials on shore indicate that this pump will need to be on when the polishing system is operating to compensate for the suction of the polishing / transfer pump. This pump will also need to be on when drawing from the bilge tank.
Emergency procedures will be very simple when the polishing system pump is on, which will be the usual operating mode. Just turn the magenta valve (Painted red in the actual installation). This will let some of the flow from the polishing system into the engine supply. The pressure will be regulated by the continuing flow back to the tank limiting pressure at the engine to just a bit over the normal pressure head. The boost pump can then be shut off, the F1 filter isolated out of the system and the element changed.
In the event that the mechanical engine driven pump fails or the secondary filter mounted on the engine starts to load up, the valve above the pump can be gradually closed to bring pressure at the engine up to the full PSI of the polishing pump. This would be a last ditch operation to be undertaken only if continued power was necessary to keep the vessel from going aground.
Here is the new fuel oil fill manifold installed at arms length through the small hatch in the cockpit seat locker. The elbow in the top of the tank was frozen in place despite weeks of soaking in Silikroil and I couldn't turn it with the maximum force I dared subject the aluminum tank to. This forced some compromises and the final critical clearance was just 1/4"! It also made using straight ball valves from the hardware store rather than waiting for a 3 way valve to arrive an easy decision. The 3 way and its elbows would have taken up a lot more room in this orientation.
The fill can just be seen coming in from the transom at the upper left. A cross fitting goes down to the valve and line to the auxiliary tank in the bilge and straight through to the main tank. The return line from the transfer / polishing pump and filter come in from the right to the top of the cross.
The fuel system with all components concentrated in an easily accessible space. The polishing / transfer pump and filter are on the left:
The line from the main tank comes in from under the longitudinal just ahead of the port engine bed and continues on to the lower left of the picture. The "Tee" in the line which is just visible below the orange isolation valves for the Racor filter goes up to another large "Tee" with a valve under the blue Shelco filter. Detail below:
The line up from the tank supply line comes up on the right. The line to the left goes to the primary FO pump and Racor filter. The valve is for isolating the Polishing / Transfer system and the line running out of the picture to the upper right goes directly to the Shelco Filter.
Here is the primary FO pump and filtering system:
The red valve is an emergency supply from the polishing system. As long as the polishing / transfer pump is running, which will usually be the case, simply turning this valve will send fuel directly to the engine bypassing the Racor filter and primary FO pump. The Racor can then be isolated and the element changed.
Here are the FO pump switches easily reachable through a lift hatch in the companionway step:
The push button is for bleeding the FO system. "Auto" means the pump goes on whenever the engine electrical system is on. The line running from the Walbro FO Polishig / Transfer pump goes to the "Tee" and valve at the upper left and then continues on to the fill manifold. Closing this valve gradually will increase the pressure to the engine supply when the red emergency valve is open. Closing it completely will divert all flow from the polishing / transfer system directly to the engine supply. The line loops up out of the picture at the top and then is visible again running down behind the pump.
With temperatures in low 50's, the system pumps fuel from the bilge to main tank at 16 GPH and 26 GPH going downhill. Polishing circulation rates should be a little better and warmer summer temperatures should improve flow a little more. Each tank can be turned over a little under an hour which is a good rate for filtering.
The system is now complete and fully functional so "Strider" could go back in the water with just a coat of bottom paint. It's nice to have her back to that point again.
I've just totaled up all the receipts for this project and the cost comes to a bit over $2,500, something people who think they can get a boat cheaper by building one should think about. This doesn't include the cost of the new bilge pumps which I accounted for separately as equipment replacement.
Back to Winter Projects
Back to Strider Home Page