A Fun End of Season Project

I don't have much time left before winter shuts down work on the boat, so I'm trying to make the most of it before it gets too cold.  It may seem like I'm randomly picking projects to cross off the list, but I do actually have a plan (subject to change of course).  I'm trying to work from the bottom up in most cases but have found that certain projects (like the wiring and plumbing) logically should be done before others. 

Now that I have both the wiring and plumbing completed (mostly), my next step is to start prepping for the engine install.  Originally, I was going to put the engine back in this fall, but I decided that keeping it in my heated shop until spring makes more sense. First of all, I won't have to winterize it and second, I can run it every few weeks or so during the winter to keep it happy.  

With that decision made, there were a few things I'd like to take care of before winter and the one that made the most sense was to get a start on the engine install and get the fuel system fully ready to go.  I had done a bit of work on it over the summer by running the fuel fill hose through the compartment where the water pump is now housed, but not much more. 

Most of the prep work to install the new tank was done for me other than getting the bilge painted (I did this last fall).  I basically had to plop it in place and bolt it down.  The original tank was held in place by a single wood bracket that spanned across the tank and mounted on a plywood 'rib' that was glassed into the hull.  I decided that was a little bit sketchy given the fact that 37 gallons (new tank size) of diesel weighs more that 250 pounds and even though the tank is wedged in pretty nicely, I don't think that wood bracket and the floorboards screwed down would hold it in place if something major happened (a knockdown or outright roll).  So I purchased some 2x2" aluminum L channel, cut a 2 foot section to through bolt to the forward rib.  Because the fuel fill and vent access the tank from the aft end, I cut 2 smaller pieces of L channel and through bolted them to the aft rib on either side of where the hoses run on top of the tank.

Next up, I spent a stupid amount of time fiddling with npt fittings to make sure they fit the fuel line and return (I ordered marine grade A1-15 fuel hose for both the fuel line and return).  The previous owner had planned on installing a dedicated fuel polishing system that he could run on demand that routed to a separate fuel water separator and had 2 extra tank ports installed. It's good idea, but I'm going to hold off on that and do it once the boat has been in the water.  In the meantime, I capped off those tank ports.  The fuel feed line I added an aluminum shutoff valve (3/8" npt male to 3/8" barbed hose end) onto the 3/8" npt aluminum elbow. For the return line I installed a 3/8"npt male to 1/4" barbed brass elbow.  I wanted to use aluminum (to avoid galvanic corrosion), but I couldn't find a fitting in aluminum that had the low profile clearance I need because the tank is within 2.5" of floorboards once installed.  I'll keep an eye on that, but I should note that I used permatex fuel grade sealant on all the connections, so that should effectively separate the dissimilar metals.

Finally, my son and I thought it would be fun to incorporate arduino devices on the boat, and the fuel gauge seemed like a perfect first project.  The tank came with a resistive fuel sender that is essentially a float mounted to a potentiometer.  When the tank fills up, the float rises with the fuel level and the resistance changes as the float moves toward the top. Knowing that arduino devices are very good at taking signal input I could use a python program and a OLED screen to convert the values to a 0-100% scale and print it out on the screen.  

I didn't want anything complicated that would require running more wire (I'm done with that) and decided to use battery power and a momentary switch to take the reading and then turn off.  The amount of battery consumption is so small that it would take quite a long time to run out of juice.  I bought an 'arduino nano every' board, a tiny OLED display, and a momentary switch for about $25 total and got to work.  It will be mounted on top of the fuel tank below one of the removable floorboards on the centerline of the boat.  In all the boats I've owned over the years my fuel gauge was always a grimy wooden stick and compared to that this will be quite the luxury.

We wired up the circuit on a breadboard and wrote a simple program to convert the incoming values into a 0-100 scale. My son added code for a small graph to show the level visually as well.  Once we had it working, I designed and 3d printed a simple box to house the electronics and after a few tries (my son thinks I'm terrible at prototyping) we were able to fit everything in and got it installed.  It certainly looks homemade, but it was a fun project and enjoyed working on it with my son.