DOES ANYONE KNOW HOW MUCH A 72" CAT WITH TWIN RZ254 RCMK'S,OR ZENOAH'S WEIGHS FULLY RIGGED.EXAMPLE MHZ CT03,MHZ MYSTIC C5000,CENTRAL HOBBIES MYSTIC.GOING TO WEIGH MY BOAT BUT WANT A BALLPARK WEIGHT TO GO BY??????

Hi Maddog.

(Please don't write in BIG LETTERS. It's like shouting, and not nessecary).

I can't answer your question about the weight.
But about engine: Why do you go for twin (small) engines, when you can get a single and more much more powerfull engine like a Blata? (Price should all together be about the same, but setting it up would for sure be less complicated).
Also I think that a 35 or 40 cc Blata would be the best for a boat that big if you really want it to run fast, and I think it's weight is less than fx a twin zenoah.
(The fantastic sound of a Blata not mentioned)
Just my humble opinion.

Cheers!

Woody

PS: As you maybe have guessed I bought a Blata for my own unfinished project.

When you don't provide a discription of your boat other than it's 72 inches long, with twin whatever engines, would be like me asking you "how high is up".

hello steve my boat is 72" long 19.5" wide an is a offshore cat design and triple stepped it is based off of a spectre cat which runs 165mph with twin illmoore v-10's.took some measurements from the boat at which i work and scaled every thing down .RC BOATS ARE NEW TO ME STARTED OFF WITH SUPERVEE 27 TWO YEARS AGO AND AM NOW HOOKED.ALSO I DID STATE MY ENGIES WERE RCMK RZ 254 REAR EHHAUST WITH 2" BAND PIPES

Maddog.

I think you should bring som pics or drawings showing your boat.
Also I think that you should not bother too much about the weight. If you want it to run really fast, you should go for the simple and most effecient solution: A big Blata or something equal to that with lots of hp and rpm. "Engine trains" of twin, triple or quadrouple Zens (or likely) are too costly, too complicated, will weigh too much, and will be difficult to maintain.
That's my advice: Go simple and go strong.
And again: Let's get pics or drawings.

Cheers!

Woody

Thanks for your response . I am new to this obsession love boats im a marine service tech and love fast boats . I went with these motors because of boats like the mystic c5000 I watched on you tube running these engines ,also wanted to know what my boat would run like with twin stock basic engines .iM LEARNING AS i GO COULD NOT AFFORD TO BUY A 1200 DOLLAR HULL FROM MHZUSA AT THE TIME SO I BUILT A PLUG THEN A MOULD AND NOW HAVE MY FIRST HULL ALMOST READY FOR THE WATER ILL POST SOME PICS SOON SO EVERYONE CAN SEE WHAT IM WORKIN WITH . SHE'S (MY BOAT )NOT YOUR ORDINARY SCRATCH BUILD . I USED MY 12 YEARS EXPERIENCE BUILDING BOATS AT SONIC,SPECTRE CAT,NOW KNOWN AS Frisini motorsports to assist me in designing and building. P.S. NOT THAT GREAT ON THE COMPUTER SO EXCUSE MY CAPITALISM.LOL

MADDOG, let's see if you get pictures of your boat up before Woody gets his up.

I know what his engine rails look like because I made them. The boat? Only time will tell.

Does anybody know if there is a class of races for large scale gas boat's ?72"long??If so any website,or info would be appreciated.THANKS

The biggest boat you can run in NAMBA is 60 inches.

ok got my 72" scratch build in the water for the first time. Ran the boat a few times still adjusting things my question is about next prop choice to improve slippage.According to prop calculator ive got 44-46% slippage.Cuurently running abc 2720/3 left and right getting 16,000 rpm only 21 mph.i think i need bigger diameter but less pitch to accommadate diameter .Twin single rcmk rear exhaust rz254(stock 16,500 or 17,000rpm to be expected) ,surface drives,boat rtr with fuel 47 lbs. yes i know shes a little heavy first one out of the mold next one will be lighter,"every boat you build something new is learned"hope i have included enough info .Please suggestions