Looking to power a 28 inch catamaran

[Joejoe]

I have 28 inch graupner catamaran that I would like to repower.I would like to use a single new motor, mount and new esc.I use 2 nimh 8.4 volt batteries if these batteries are not correct I can upgrade them as well.looking for little more speed . My prop shaft is 4mm. I need a little help on getting the right equipment thanks .

[larryrose11]

You will likely end up with a entirely new power system, perhaps running gear as well.

Do you know what the hull is called? Is it an plastic hull or fiberglass? That makes a difference because of strength.
The search on the forum is your friend. Leverage what others have done before you.

[Joejoe]

It’s plastic hull the graupner systems catamaran

[Panchothedog]

Probably as soon as I give you my experienced advice someone will chime in with their opinions of how it will not work or how it is a bad idea as seems to have happened several times in the past. In the late 1980's and all through the 1990's I had and ran many Graupner boats. This was back in the brushed motor days and I ran them stock with graupner set ups as well as astro- flight motors and Ed Hughey twin motor set ups. Anything I could do to make them faster. Fast forward 15 years and I like every one else is running brushless motors and fiberglass hulls and just loving it. I converted some of my old plastic boats to brushless with varying degrees of both success and failure. Mostly failure,but by far the best one was my Graupner monster vee. The twin motor mount also came drilled to accept a single motor in the center as I believe your systems cat also does and all of the Graupner motor gears have an insert in them to get them down to 1/8th" to fit the old brushed motors. Pop out the insert and the gear is made for a 5mm shaft exactly what is on most all brushless motors. What I am trying to tell you is it is really simple. On mine I just bolted on a aqua craft 36x56 1800 kv motor and a 60 amp esc (same brand) and left everything else as it was from when I built it about 30years ago, steerable plastic out drive and all. On 4-s it was good for about 38 mph and on 5-S it would go around 45 mph.It also eventually tore itself up pretty badly but I knew that was in the cards and didn't do much to prevent it. Mostly running too fast late in the day when the water was too rough and the crashes became more than it could take. This should be a very easy conversion for you and if you don't get stupid or careless as I did it could be a fun project. Just keep in mind that plastic hulls are not nearly as strong as fiberglass hulls and the only thing weaker than a plastic hull is an OLD plastic hull. Best of luck.

[Joejoe]

Yes I see don’t put too much power to it and eventually get a fiberglass hull thank you.

[bogieboy]

Probably as soon as I give you my experienced advice someone will chime in with their opinions of how it will not work or how it is a bad idea as seems to have happened several times in the past. In the late 1980's and all through the 1990's I had and ran many Graupner boats. This was back in the brushed motor days and I ran them stock with graupner set ups as well as astro- flight motors and Ed Hughey twin motor set ups. Anything I could do to make them faster. Fast forward 15 years and I like every one else is running brushless motors and fiberglass hulls and just loving it. I converted some of my old plastic boats to brushless with varying degrees of both success and failure. Mostly failure,but by far the best one was my Graupner monster vee. The twin motor mount also came drilled to accept a single motor in the center as I believe your systems cat also does and all of the Graupner motor gears have an insert in them to get them down to 1/8th" to fit the old brushed motors. Pop out the insert and the gear is made for a 5mm shaft exactly what is on most all brushless motors. What I am trying to tell you is it is really simple. On mine I just bolted on a aqua craft 36x56 1800 kv motor and a 60 amp esc (same brand) and left everything else as it was from when I built it about 30years ago, steerable plastic out drive and all. On 4-s it was good for about 38 mph and on 5-S it would go around 45 mph.It also eventually tore itself up pretty badly but I knew that was in the cards and didn't do much to prevent it. Mostly running too fast late in the day when the water was too rough and the crashes became more than it could take. This should be a very easy conversion for you and if you don't get stupid or careless as I did it could be a fun project. Just keep in mind that plastic hulls are not nearly as strong as fiberglass hulls and the only thing weaker than a plastic hull is an OLD plastic hull. Best of luck.

very interesting.... i also have a Monster Vee, and as soon as i swapped out the pair of speed 600s for brushless, it went to pot... anything over 15mph or so was porpoise city...

[T.S.Davis]

Back around 2003 maybe, we had a guy running one on a geared brushless setup with 24 Nimh. Was insane.

You can get more speed than stock out of it but if you get too nutty the plastic will give out. A ton of fun to drive up to around low 40's. After that a good gust of wind, a blow over, and crunchy bits everywhere. I used to make them plastics myself. When we all went brushless I gave up on my plastics.

The Graupner Key West was super cool. Cheap n' fast. The Super Vee was a great race boat too. I might still have a Systems in the basement some where.

[Joejoe]

Thank you for the info I was looking to bring the boat back to life but now I see my limitations . I like the fact I have a few options.

[Panchothedog]

Bogieboy the key to and probably the only way to keep the boat from proposing uncontrollably is a HUGE pair of cavation plates. I think they made by graupner, I know I bought them from Hobby Lobby which I believe was the main distributor for graupner back then.I just measured them and they are 1 1/4" and 1 7 /8" long. Not that wide but pretty long by today's standards .They are made of plastic, hinged, with an adjustable turnbuckle. Very realistic looking and functional. If I wasn't such a technical klutz I would post a picture of them, but I don't even know how to take a picture much less post one. Kind of a weak spot for this old goat.

[T.S.Davis]

I can't remember what electronics came with the Systems. A cheap option for a scale....ish looking runner might be an old 700 brushed motor.

[ray schrauwen]

If you work the ride pads to get rid of the hook on the last one and sharpen the edges it goes a long way to stop the bouncing.

I ran one on 12 Nimh and a brushed 700 motor back when...

The original came with the option of single 700 motor drive or twin 550 motors geared to one shaft. The gearbox was very limited on what you could put in for power as gears would explode past 30,000 rpm etc...

[Panchothedog]

I'm sorry but I think you are wrong on the motor mount issue.The fact that you can run a large single motor ( 700 brushed or 36mm brushless) or run twin 550 brushed motors makes it pretty darn versitel in my book.I can't think of any others right off the top of my head that you can do that with. As I said in my first post I used an 1800 kv motor with both 4 and 5 S batteries and if the gears weren't original to the boat (1989) they were at least 25years old. The math says unloaded RPM way past 30K.I have no idea what my final under power RPM was and while the plastic hull didn't hold up so good the gears are OK.

[Joejoe]

Got it done now have to test it out.IMG_2422.jpgIMG_2423.jpgIMG_2427.jpgIMG_2424.jpg I installed a Leopard 3674 1400kv with 150 raider esc new motor mount I'm gonna try two 8.4 volt Nimh batteries first and maybe graduate to Lipo .

[ray schrauwen]

Looks great! Only one critique. You have a lot of flex shaft exposed that can whip easily and possibly knot up.

You are not spinning too many RPM's but keep an eye on it. The stuffing tube really should be longer.