General discussions - FAST RC boat

[LibertyMKiii]

Octura 1640 with some tip cup and a bit of increased camber roll creating a lower lift profile can be a killer prop. sharpened and balanced with heat treating prior to use is key.
In my many years of R/C boat racing, prop cupping / mods was a part of it. Having prop cupping ball jigs. dial indicator measurement fixtures & heat treat kiln etc to do so was part of the obsession.

Great fun .. but a Very very very deep rabbit hole to grasp all the specifics of the hobby & good for you diving in to figure it all out

Thats awesome!
I did buy a cupping rig and hammer setup, but didn't get as deep into it yet for a kiln.

 

[Notoriousone]

So i finally got my TFL Cheetah twin running right, here's a quick video of the test run last Saturday. Some slight strut adjustments and light sanding of the ride pads, and switch to 4219 props running inward was all it took to get it running well. It does big laps consistently at over 65mph and runs cool with nothing getting over 105 degrees. It has two 4074 SSS 2150kv motors with seaking 180's on SMC 5000mah HCL packs. Since it ran cool, next time out ill try some 4519 props

 

[LibertyMKiii]

So i finally got my TFL Cheetah twin running right, here's a quick video of the test run last Saturday. Some slight strut adjustments and light sanding of the ride pads, and switch to 4219 props running inward was all it took to get it running well. It does big laps consistently at over 65mph and runs cool with nothing getting over 105 degrees. It has two 4074 SSS 2150kv motors with seaking 180's on SMC 5000mah HCL packs. Since it ran cool, next time out ill try some 4519 props

That looks really good! That may be the sweet spot for this hull.
I worry that higher speeds are going to mean crashes if its already getting pretty shaky at this speed.

 

[Notoriousone]

That looks really good! That may be the sweet spot for this hull.
I worry that higher speeds are going to mean crashes if its already getting pretty shaky at this speed.

Your correct, this probably is the sweet spot. Conservatively speaking I would rather try a smaller prop like a 4319 or 4419 on it next, but both 43 and 44mm props are limited compared to 42 or 45mm sets for twin cats.. I can find some sets in those sizes but not the same profile that I would want. This boat ran 72mph with a set of 42mm high rake CNC props, but was on more of a knife edge handling wise, so for a oval boat like this I do prefer a little less top speed and more stability. If I can get more speed but still retain good handling and cool temps with the 4519's ill go with those, but if there are heat or stability issues ill stick with this setup, I'm pretty happy with how it runs now

 

[Big Kid]

In the TWIN set ups, are they counter rotating or the same rotation ?

 

[LibertyMKiii]

Your correct, this probably is the sweet spot. Conservatively speaking I would rather try a smaller prop like a 4319 or 4419 on it next, but both 43 and 44mm props are limited compared to 42 or 45mm sets for twin cats.. I can find some sets in those sizes but not the same profile that I would want. This boat ran 72mph with a set of 42mm high rake CNC props, but was on more of a knife edge handling wise, so for a oval boat like this I do prefer a little less top speed and more stability. If I can get more speed but still retain good handling and cool temps with the 4519's ill go with those, but if there are heat or stability issues ill stick with this setup, I'm pretty happy with how it runs now

Yeah man that boat has plenty of speed and handles great! Looks like lots of fun!!!
Keep us posted how the larger props work out for you.

 

[LibertyMKiii]

I managed to squeeze a ONYX 6600mAh 3s pack into the R4. I am a bit nervous having so much weight on the front but optimistic it will work out ok.
Planning to try it out after work today!

Those 7ga wires

 

[jkflow]

In the TWIN set ups, are they counter rotating or the same rotation ?

Always counter rotating. If they turn outwards you will be more stable in curves but loose a little top end speed, inward and you will flip a lot easier in turns but max top speed in straight. Maybe 1-2 mph difference, not worth it for bashing.

 

[FL-2100B]

So i finally got my TFL Cheetah twin running right, here's a quick video of the test run last Saturday. Some slight strut adjustments and light sanding of the ride pads, and switch to 4219 props running inward was all it took to get it running well. It does big laps consistently at over 65mph and runs cool with nothing getting over 105 degrees. It has two 4074 SSS 2150kv motors with seaking 180's on SMC 5000mah HCL packs. Since it ran cool, next time out ill try some 4519 props

Man thats awesome dude , good job .

 

[LibertyMKiii]

What speed do you all think it went? Fast for 3s for sure!

Some idiot didn't put the GPS inside the boat

 

[Big Kid]

63 mph ... WAG

 

[LibertyMKiii]

I knew it was probably 70+ but really happy to see 80 mph today!!!
Pretty crazy for 3s with a tiny tp3630cm motor!

The clean run is at 1:50
Sadly the real speed is away from the camera and mostly all you see is the prop spray.

 

[LibertyMKiii]

The 39" Seaducer is almost ready.

Today I added some neochrome vinyl on the top. It. Changes between green, yellow, and orange

 

[Big Kid]

The 39" Seaducer is almost ready.

Today I added some neochrome vinyl on the top. It. Changes between green, yellow, and orange
View attachment 358030

When Jerry first came out with his design we called them Sea-Dunkers .. Fast as heck but would unexpectedly submarine time to time.
These current Ducers looks somewhat similar to the Microburst monos of 15-20 years ago.

Very nice

 

[LibertyMKiii]

When Jerry first came out with his design we called them Sea-Dunkers .. Fast as heck but would unexpectedly submarine time to time.
These current Ducers looks somewhat similar to the Microburst monos of 15-20 years ago.

Very nice

And probably more of a problem with the open hull gas setups. At least sealed up FE setups should float

 

[Big Kid]

And probably more of a problem with the open hull gas setups. At least sealed up FE setups should float

Jerry's early hulls had a huge amount of Deck crown front to rear having an Air tunnel / trough down the middle of bow.
They were NITRO engine hulls & as I recall 2 sizes, a little one @ 28-30" for .21 cu in class and a @ 36-38" for the .45 & .67 class engines.
It was several years before he came out with the GAS class hull that was as i recall @ 45" long.
All were Run as Surface drive having drive shaft exit in bottom of V at transom, NO trim tabs were used. Ride attitude by Strut angle and prop lift tweaks.

Spent many a day racing against them in .21 & .45 nitro class's and in later years Gas class ... but never wished to own one due to there wretched handling traits in spite there wicked speed.

In the early 90's TWINCRAFT was king of the Mono's, then Calvin Motley came out with the CALCRAFT & Twincraft went out of fashion within just a few years.
CALCRAFT also made 3 sizes being in the same class applications. 27" / 39" / 45" as I recall. Out of Canada mid 90's came the MicroBurst which as well had 3 hull sizes.
INSANE & STRIKER also made very competitive Monos in that @ time line.

Personally still have my 39" Calcraft that was run as a .45 as well .67 nitro rig. I won the NAMBA 1997 Nationals in Manteca Ca in "C Mono" ( .67's nitro ) with it as well setting the 6 lap National record the same year in Fremonts Kaiser cove.
Also have my 47" Microburst mono gasser out in the race trailer along with some misc others.

Yea the Racing boats hit a nerve !!! Spent @ 20 years neck deep racing within Namba District 9 and at times with District 19 guys out of So cal.

GREAT TIMES !!!!!

 

[LibertyMKiii]

Jerry's early hulls had a huge amount of Deck crown front to rear having an Air tunnel / trough down the middle of bow.
They were NITRO engine hulls & as I recall 2 sizes, a little one @ 28-30" for .21 cu in class and a @ 36-38" for the .45 & .67 class engines.
It was several years before he came out with the GAS class hull that was as i recall @ 45" long.
All were Run as Surface drive having drive shaft exit in bottom of V at transom, NO trim tabs were used. Ride attitude by Strut angle and prop lift tweaks.

Spent many a day racing against them in .21 & .45 nitro class's and in later years Gas class ... but never wished to own one due to there wretched handling traits in spite there wicked speed.

In the early 90's TWINCRAFT was king of the Mono's, then Calvin Motley came out with the CALCRAFT & Twincraft went out of fashion within just a few years.
CALCRAFT also made 3 sizes being in the same class applications. 27" / 39" / 45" as I recall. Out of Canada mid 90's came the MicroBurst which as well had 3 hull sizes.
INSANE & STRIKER also made very competitive Monos in that @ time line.

Personally still have my 39" Calcraft that was run as a .45 as well .67 nitro rig. I won the NAMBA 1997 Nationals in Manteca Ca in "C Mono" ( .67's nitro ) with it as well setting the 6 lap National record the same year in Fremonts Kaiser cove.
Also have my 47" Microburst mono gasser out in the race trailer along with some misc others.

Yea the Racing boats hit a nerve !!! Spent @ 20 years neck deep racing within Namba District 9 and at times with District 19 guys out of So cal.

GREAT TIMES !!!!!

Lots of experience and knowledge gained racing competitively for 20 years. Glad to have you here! (you can point out the things I am doing wrong LOL)

It is a shame the boat hobby is not as big as the RC car side. Boats are a ton of fun and can be challenging which makes it interesting.
Getting them balanced just right and riding at their best takes quite a bit of testing and adjustment.

I wish some of those brands you mentioned were still around but the quantities sold just does not pay the bills or the owners are now part of the "silent engines" list.

Most people these days only know the plastic Traxxas and ProBoat brands because hobby shops don't push boats like they do cars. TFL seems pretty good and bridges the gap to the racing level fiberglass boats. I noticed many sellers are now exclusively on Facebook, but I don't get on that site.

I have been tempted to build a dual prop large fountain mono. There is a builder in Germany that looks to be the go to guy for those hulls.

 

[Big Kid]

Lots of experience and knowledge gained racing competitively for 20 years. Glad to have you here! (you can point out the things I am doing wrong LOL)

It is a shame the boat hobby is not as big as the RC car side. Boats are a ton of fun and can be challenging which makes it interesting.
Getting them balanced just right and riding at their best takes quite a bit of testing and adjustment.

I wish some of those brands you mentioned were still around but the quantities sold just does not pay the bills or the owners are now part of the "silent engines" list.

Most people these days only know the plastic Traxxas and ProBoat brands because hobby shops don't push boats like they do cars. TFL seems pretty good and bridges the gap to the racing level fiberglass boats. I noticed many sellers are now exclusively on Facebook, but I don't get on that site.

I have been tempted to build a dual prop large fountain mono. There is a builder in Germany that looks to be the go to guy for those hulls.

I'l make a point of digging into my Small Boat Prop box and see if I have any @ spec/size props that your running.
I do know there should be a few ABC H4 & H7's in there from my .21 outrigger dayz

You running on 3/16" ( .187") prop shaft ?
Wire drive or cable ( .150 or .187" )?

 

[LibertyMKiii]

I'l make a point of digging into my Small Boat Prop box and see if I have any @ spec/size props that your running.
I do know there should be a few ABC H4 & H7's in there from my .21 outrigger dayz

You running on 3/16" ( .187") prop shaft ?
Wire drive or cable ( .150 or .187" )?

Everything I run is 3/16" flex cable. I have a good collection of props currently. About 6 from Chris Hoffman (heat treated).

I have the H7 abc and a nice range of rigger props 1817, 1819, 1823 and the 1917,1921, 1925
For now its just a matter of getting to the pond and seeing what the hull likes.

I have a few Octura I plan to start this mono hull with. X445 x447 and x645. I also purchased some ABC 2014 and 2214 props to try with a lower KV motor to see if larger diameter can help. The Dasbota x645 is the prop I took the 42" mono hull to 90mph on 6s with. That prop is very good!

 

[Big Kid]

Sounds like you have a good handle on it !!
At one time stashed away within 3 prop boxes were give or take 80+ props going from 37mm to 80mm. Pitch ratios from 1.4 to 2.2"

Yea those are some really HIGH pitch ratio props & surprised the cavitation even allows getting up on plane
12 years out of sight or mind .. Found 1 of the double stack "Gasser" prop boxes ... About 50 props in this box alone $$$$$

Everything I run is 3/16" flex cable. I have a good collection of props currently. About 6 from Chris Hoffman (heat treated).

I have the H7 abc and a nice range of rigger props 1817, 1819, 1823 and the 1917,1921, 1925
For now its just a matter of getting to the pond and seeing what the hull likes.

I have a few Octura I plan to start this mono hull with. X445 x447 and x645. I also purchased some ABC 2014 and 2214 props to try with a lower KV motor to see if larger diameter can help. The Dasbota x645 is the prop I took the 42" mono hull to 90mph on 6s with. That prop is very good!

PROP SHOP UK or VOODO Props make some great offerings as well.
If your mono build is surface drive ( Transom exit ) run 3 blades in the 1.4 to 1.6 pitch ratios