Zelos 48 G electric conversion build

[fweasel]

Got a great deal on a stock Zelos 48 G last summer and thought I would take it to the big lake on our yearly vacation. All of my other boats were just too small and they never ran very well in the rougher water. Had my fill of messing with a gas boat after about 5 days. It ran close to 50mph on the stock prop, but was a real bear to turn at slower speeds and as an electric guy, I found it difficult to to keep it running. I knew that it was going to be converted to electric before I came back next summer. Before I left, we stripped it down, and put the 30CC Zenoah into my friend's Rockstar that had an under powered Chinese 26cc motor in it. It was almost a direct swap with only a few modifications because of the Bonzi clutch he runs. It really woke that boat up. Took a lot of sanding to get all of the old epoxy and oil stains out and make a good surface for the inlay to attach to. Luckily, this hull is huge compared to what I'm normally used to and there's plenty of room to work.

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[fweasel]

After the hull was prepped, I reinforced the seams around the entire perimeter with a bound strip of carbon fiber cloth. This particular hull was probably Proboat's best layup to date. It's incredibly stiff and sturdy. It didn't really need an inlay, but put one in anyways across the bottom of the hull mostly to start fresh cosmetically with the new build and hide some of the oil stains that soaked into the original fiber glass layers. I used a 2x2 3k carbon fiber cloth and West System resin/hardener. The canopy is super strong as is, so I chose not to put an inlay on it. That also keeps it GPS friendly for testing. I epoxied over the holes from the older auto bailers, the electric kill switch, cooling outlets, and original antenna location. I closed the vents in the canopy and the rear of the hull with small strips of carbon fiber cloth and epoxy. I still need to pour some epoxy and chopped fibers into the tips and across the bridge and cut out a 3mm carbon fiber stiffening plate for the rudder mount. I kept the original stuffing tube which made the decision about where to locate the motor mount a non-issue.

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[fweasel]

I mocked up the motor shaft mount angle using telescoping lengths of brass tube. Locked it into place, marked off the hull, and epoxied it in with G-Flex thickened with silica dyed black. Came out nice and there's plenty of surface area to support the weight of the TP5680 motor I'll be running.

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[fweasel]

I planned to re-use the 1/4 scale Spektrum servo that came with the boat, but it needed a new mount. I couldn't find a vertical mount for a 1/4 scale servo anywhere, so I sent a photo of the standard sized TFL mount I've used in the past to my friend Gabe Clegg at Stump Fabrication. He drew up a new, larger design and milled it from billet aluminum. Came out perfect, except he uses standard threads and I hate boats with a mix of standard and metric hardware. I drilled and retapped for M3 and broke two different taps while cutting new threads. So, he sent me two new crossbars with metric threads already cut, and I epoxied the whole thing in place. The stock flex cable had a square drive end and was welded to the propshaft by a blind seven year old with a torch. I had Mark Copley from M.Cop Racing in the UK make me a new cable with a custom length propshaft.

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[fweasel]

I broke in a set of vertical spacer blocks on my Sherline lathe this winter so I could turn down the 56mm water jacket. I needed to remove the cooling fins to make a flat surface so that I can epoxy a thin carbon fiber veneer around the center section. A completely cosmetic project, but it looks great and fun to be able to do it myself. Since the boat will run on 12S, I was able to place the ZTW 300A ESC in front of the motor and still keep the center of gravity in check. These are really nice ESC's, but they're huge. Still battling with the one in my SV43 build because I don't know where to mount it. I cut up an old TFL motor mount and used the carbon fiber side rails to make an ESC mount. I turned some aluminum spacers on the lathe to fit between the side of the ESC and the mounting rails. They got the job done, but I didn't like the silver color so I sleeved them with small sections of carbon fiber hollow tubing. Soldered on 8mm Castle bullet connectors for the motor wires and OSE 8mm anti-spark connectors on the battery cables.

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[fweasel]

Finished up the battery series harness extension and routed the wires cleanly underneath the ESC. Today was battery tray day. I know I'll run a minimum of 2 6S packs, one in each sponson, wired in series for 12S. To maintain a CoG of about 30%, they needed to be placed nearly all the way rearward in the hull. I wanted the option to be able to run 12S2P for increased runtime in smoother water, which meant much larger trays. MBP made a set of lipo sleds that were almost the perfect size for this application. They're originally designed for a 185 MHZ or HPR sized cat, and probably the only two Steve at OSE has sold in quite awhile. I ripped down one side of each base plate on my band saw using a diamond crusted blade. I bought the blade over a year ago and misplaced the box. I just found it, so this was a good project to break it in. Man, cuts through composite material like butter with no chipping or wandering, but makes quite a mess. Built a few small stand-off supports for the inside rear corners of each sponson from carbon fiber plate scrap and epoxied them into the hull last night. I set the trays in place, masked off the edges, and glued them in place with black aquarium silicone. They're curing now which is why I took a break and put this build thread together. Lots of little details left, but it's getting close to be able to throw it in the water for sea trials!

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[Jesse J]

Beautiful work as always Ryan!! Glad to see you back at the work bench!

[fweasel]

Beautiful work as always Ryan!! Glad to see you back at the work bench!

Thank you sir. I hope my batteries are still good by the time I finish one of these projects

[Jesse J]

Just keep cycling.. just keep cycling..

[fweasel]

The world's prettiest Zelos 48G now has cooling lines. I don't like to see cooling hose running everywhere and this hull is too big to route it up under the hatch opening like I do on my smaller boats. So, I made hard lines out of 6mm carbon tube and attached them to the hull with pipe bus clamps I found at McMaster. I cut the clamps into sections of two and milled out the bottom to accept an M3 countersunk screw. Ran the lines right down the tunnel and it still looks clean. Still unsure on where I'm going to dump the water. I'd like it to be straight out the back, but because of the longer run times this setup can handle, they should probably be positioned so they create visible streams. I might use one of the old gas air vents on the rear deck to hide two brass outlets and send the water backwards, on a slight upward angle. I also need to run one more carbon tube to hide the extension harness for the ESC and the futaba temperature sensor wires and then it's ready for electronics testing.

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[fweasel]

Now I know why I left this step for last... filling the rear deck ventilation holes. It took a lot of random little pieces to get the hull propped up in a manner that made the ventilation openings parallel to the ground so that the epoxy would settle in place when poured from the inside. I left the expanded aluminum mesh in place that Proboat installed at the factory, figured it would only strengthen the epoxy. Not sure why the picture got rotated.

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[Jesse J]

Ryan, I like the ride attitude!!

[fweasel]

Ryan, I like the ride attitude!!

Ha, I actually got epoxy in my hair (COVID length haircut still) sticking my head inside trying to pour it in place.

[fweasel]

Finished up the last few details on the 48G. Ran an additional carbon tube to hide the ESC receiver wire and dressed all of the remaining wires in nylon loom. I ran the second cooling line to the rudder and installed a second aluminum fitting on the transom to match the one from the factory. Cut some foam pieces to fit in the rear corners of the hull and hollowed out a hole to hold the LiFe receiver pack. Ready to go!

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[fweasel]

Took my Zelos 48 out for the maiden two weeks ago. If the boat was 1/8" longer, it wouldn't fit in the trunk. Ran two sets of packs through it. First set was slow and easy, checking for cooling flow and leaks. Stopped after a few passes and measured temps. It all looked good. Sent it back out to stretch its legs, but it was too light in the nose. CG was set around 30% to start with. Made a few long passes. Flipped running into the wind. Got it back, flipped it over, and moved the 2nd set of packs forward a few inches for run #2. Sent it out, made one pass, then sounded like I lost the prop. Got it back to shore with the tug, popped the hatch, realized the collet slipped and the prop hit the rudder. No damage to the prop, a small nick in the rudder, but the collet was toast. First time I've ever had an issue with the H&M/LMT style collets.

When I got the boat back home, I swapped in a MBP collet that I had on my SV43 with the same motor. The cable had aluminum shavings in the winds, but did not appear damaged itself. Took the boat out again last weekend and ran two more sets of packs through the boat. The new MBP collet held fine. Ran 73mph at about 75% throttle. Got a little braver on the second set of batteries. Ran 80mph. Had more in it, but still needs more weight up front before I can run full throttle. The hull is so wide and tall, it packs a lot of air and is running at speeds way higher than it was originally intended.

I'd like to try one more setup to see if I can pull a Back to the Future run (88mph) on the GPS, but then it's time to find a smaller prop, maybe a 2114, that will cruise in the 60's. Built this to run on a big lake with large swells while on vacation.

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