Converting a gas outrigger to electric

[Glass Man]

Greetings all,
I'm a newcomer here,but a forty year R/Cer and currently run a 1/8 scale gas hydro.It's time for this aging guy to build an electric.I have an old rigger,natural finish and pretty light weight.40 inches long and 24 wide,5" tub(former gasser).Would it be worth electrifying this antique?Todays battery and motor prices make it a lot more attractive than back in the day.
I see motors for under a hundred bucks and a 220 amp ESC for 180 or so.I'd be happy turning laps
in the 60 plus mph range.1/4 flex shaft in boat now.
I started long before ARF's,so my first boats and planes were all kits.I'd build a rigger from a kit but I'd rather reuse this old bird if feasible.
Thanks for any and all info.
Paul

[Panchothedog]

Hello Glassman and welcome to the forum. I don't have a lot of experience with riggers or boats in the 40" range but I had been into nitro and brushed electric boats for about 30 years before getting into brushless boats 6 years ago.The power that's available from today brushless motors is amazing.You will be able to easily match or really exceed the same that you had in the boat before.I would think that some of the larger 40 mm or mid sized 56 mm motors would do you just fine.If your boat still has all of its running gear in it pay attention to the CG because that is one of the things that will change the most with the addition of the lipo batteries in converting a fuel powered boat to electric. Sounds like a neat and worthwhile prodgect. Keep us updated on how it's going.

[RaceMechaniX]

I would recommend against converting an existing gas rigger. With the position of the engine and stuffing tube in a gas boat, the mass tends to be too far forward when you put the motor, ESC and batteries in the front. So the front end plows and the back end blows as there is not enough tail weight.

You would be much better off building a new kit and starting with a reasonable power system instead of something to power a gas size rigger.

Zipkits and ML boatworks both have electric riggers available as kits which are known set-ups.
I would recommend trying either the JAE 21FE: https://zippkits.com/index.php?main_...roducts_id=649
or the ML RSG310 or RSX380 hulls: https://mlboatworksrc.com/shop?olsPa...-2-srs1&page=4

[Fluid]

I have built a bunch of FE riggers, although none quite as large as the OP’s. Tyler makes good points and starting anew increases the chances of success. But the OP wants to use his existing hull, and if he decides to do that then he should consider the hull a blank slate. That means that the stuffing tube and motor mount will have to move aft to allow the CG to be in the correct place. The most common FE rigger setup from the bow back is battery pack, ESC then the motor. The best procedure is to have these items in hand, place them in the hull and move them for and aft until the correct CG is achieved.

An FE rigger must be water tight, so a deck/hatch must be constructed to cover the equipment - and it must not leak.

The OP’s speed goal is quite low for a rigger that size, my JAE21 runs upper-70s and 12-second laps in oval trim - on 4S. If he stays in the 60s then he will increase his run time, decrease his amp draw, or reduce his costs. As in all things FE choose any two: speed, reliability or run time.



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[Glass Man]

Thanks for the input,it's all appreciated.
Fluid is right on about using the old hull,I'll have the gear to drop into a RSX 380 if I go new later.The hull weighs in at 4 lb 10 oz with rudder/strut,turn fin,shaft tube installed.If I have to relocate shaft,I'll shed some weight(thick fiberglass around bottom of hull at exit).I spoke to another member whose RSX380 weighs just over 9 LBS.RTR
I'm going to mock up motor,batts and esc with weights to see how close I can get to balancing the CG.Relocating the shaft isn't an issue.I'm removing 20 oz of fuel plus tank from the nose.Might batteries forward of the motor with esc in rear work?Wire length kept to a minimum.
My gas hydro runs in the mid sixties which keeps the blood pumping for the pond size.faster would be a bonus though.I hoped a 220 amp esc would handle 6 or 8s.Price jumps at 300 amp point.

[Panchothedog]

I think that you will find the order of placement that fluid mentions, ESC in between battery and motor simplefies installation as well keeps wires as short as possible. Just the shape of a rigger hull dictates that the components be placed in line as compared to a cat or mono where one has more hull width to work with and can move things around more easily.

[RaceMechaniX]

Assuming you use the existing stuffing tube location and mount the motor where the engine used to be you can try mounting an ESC alongside or even underneath the motor depending on which ESC you go with.
Depending on the lipos you choose you may be able to place the ESC on top of the batteries.

As Fluid mentioned, water tight is crucial and I always recommend stuffing flotation into any nook and cranny to improve buoyancy in case the cowl does come off.

[Glass Man]

After mocking up batts,motor,esc by size and weight and doing some CG homework,I'm going to give this old hull a shot.The balance looked very promising,I may get the shaft tube lower in the hull but it's all workable.
The existing shaft is 1/4",would I be wise to go to 3/16th?All of my existing props are around 70 mm,I see 60mm is more where I'll be with this setup.
I P.M.ed Sammyha and his ML Boatworks rigger weighs 9 lbs,I'm at 8 lbs without receiver and flexshaft so I seem to be pretty good weightwise.I'll start with 6S 5000 Mah and go from there.
I'm excited to work with these new age components.I appreciate the concerns about watertightness,my first build was a Dumas Hot Shot(original version)in the seventies.I've been keeping electronics dry for a long time.It can take some effort,but it is essential.