pair of large motors

[Bande1]

Not exactly sure about your references but a capable 45" hull like HPR06 or Mystic 114 will easily push 100mph with a twin 4070 setup on 6S each? I have hardly any experiences with gas engines and I'd agree to your claims about cost and runtime but a promod gas engine pushing 8.5kW and outperforming a twin FE setup with 4070's is not something I'd take serious to say politely.

maybe OP should elaborate more on which hull he wants to use and what speeds he wants to achieve

care to find me a video of an electric boat lapping "over 100mph"?

There's 750w in 1 horsepower. Here is a gas engine making 11.3kw.

IMAG001.jpg

[ManuelW]

care to find me a video of an electric boat lapping "over 100mph"?

There's 750w in 1 horsepower. Here is a gas engine making 11.3kw.

[ATTACH=CONFIG]180686[/ATTACH]

8.5hp is 6.2kW and not 11.3kW. And I was referring to straight line speed.

[Bande1]

8.5hp is 6.2kW and not 11.3kW. And I was referring to straight line speed.

8,500 / 750 = 11.33

I know you were referring to straight line speed when you were quoting my post that said "lapping speed" 3 times.

Quickdraw engines have a 119mph SAW speed record.

[fweasel]

Quickdraw engines have a 119mph SAW speed record.

and there's 1 or 2 electric records faster than that...

[Alfa Spirit]

If you want inexpensive motors look at ROCKET, 1250kV with 2 x 8S setup will be fine.

https://fr.aliexpress.com/item/1005007207651175.html?spm=a2g0o.productlist.main.1.68100yL30yL3J5&algo_pvid=da91a022-5cae-4db6-a602-740242c017d4&algo_exp_id=da91a022-5cae-4db6-a602-740242c017d4-0&pdp_ext_f=%7B%22order%22%3A%22125%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21EUR%2156.01%2152.69%21%21%21429.84%21404.38%21%40211b615317421666635396909e99f4%2112000039925015529%21sea%21FR%21127316132%21X&curPageLogUid=A1RoN2mwJIdc&utparam-url=scene%3Asearch%7Cquery_from%3A

[larryrose11]

You are not racing, so the racing rules don't apply.
Going with a 12S setup will be much better than a 6s for sure. Half the amps to supply for the same power, less heat too.
You will have plenty of room, so small water pumps may be in order since you want to push the system hard.
Twins put less strain on the system than a large single.
Upgrade the water fittings if you can to help with coolant flow.
Run the motors near their max voltage, and use small props with a low pitch to keep the loading low. Start with small, cnc 1.4 pitch props and work your way up.

[vvviivvv]

12s in a 47" boat is a lot...

with 12S in a 60" cat im over 125mph.

Better to go 6-8s/ side utilize XLX2's and happy days.

12S / side is also a lot of lipos in a 47" boat. i wouldn't be able to fit 12S in my 45" cat, 8s / side is already tight.

[Bande1]

and there's 1 or 2 electric records faster than that...

its like 162mph, nitro is a close 157mph. That's because electric is allowed way more power @ well over 20kw or 30+HP. The rule structure allows FE pretty much open power (unlimited current) where as nitro and gas are highly restricted. If they allowed sport 20's a .91 engine you'd see nitro around 200mph.

[vvviivvv]

Actually for a electric boat circa 2017 the two way average is around 195mph with a peak over 204mph...

Twin cats have averaged over 170mph already...

[Ken Haines]

a promod 30 will get you around high 60's

Bande1
I am a very experienced Open Electric Mono racer, just recently started racing a GX-2 Mono.
We finished up last Saturday testing props using a radar gun and high 60's just is not a reality.
Very low 60's at best, and we were one of if not the fastest boat at the Miami race on Sunday.
Stating that a Zenoah is faster than an electric is just not true even with my Roger Pane 29.5
my Electric 8s lipo mono is faster. A twin is also faster than a single in electric racing especally if the
Namba capacity limits do not apply. Manuel Wenny is highly experienced European SAW racer
his information here is spot on. Heat can also be an issue and I would recommend using 6 pole
vice 4 pole motors. Tp does use 6 pole in their 56mm motors, so using a 5650 could be an option
The new Tenshock 40mm motors are 6 pole as well. The Electric setups done properly are
definitely more expensive, and admittedly a bit less reliable and do offer less run time. However
boasting that a GX-2 motor is faster is simply wrong in properly done electric setups as witnessed
in many of the Open class races which allow up to 10s lipo.