How to build a Hydro2 boat for racing?

[NativePaul]

There's a fair range of sizes, MHZ stealth, Rocker XL and H&M exess2 at 700-750mm going up to dr Psycho lui, mr Krabs and Lindenau Bathlett at 800-850mm.

We use nearly all the capacity often putting over 5000 back into a 5000 pack.

Props are around the 35mm region.

I have no idea about the speeds, we have only had 1 records weekend since LiPo were allowed and the records got lost somehow, yeah were that organised over here I have 2 certificates but no records. Take a look at this clip and decide for yourself, although its shot from the turn so its a little harder to tell the http://www.youtube.com/watch?v=MYw2I...e=channel_page

By all means try it, the kV is good and I'm sure it will be competitive, I haven't heard of anyone using the 14xx so I have no idea what there like although Brian's recommendation carries a lot of weight as he seems to be THE MAN and always has good advice, personally I would go for the 1512 1y though as I have heard the D winds are amp hogs (although I don't really get that or fully believe it surely the KV sets the amp draw and the way its wound to get the KV is an irrelevance?) but mostly because with Neu's extra efficiency over Feiago they don't have to be as big to produce the 1000W and the rotor is shorter giving it less inertia which lets it spool up quicker, like using a long 480 for hydro1 not a short 540.

The high KV winds do have the max efficiency higher than the lower KV motors of the same design but I have never seen the graph for Neu motors and would be intrigued to see what it looks like, I have a Lehner and its max efficiency is 93% at 90A which is over its rating, but the latter half of the graph is pretty flat so it doesn't drop below 90% until I get under 40A.

[simengj]

Okay,
i just cant dicide what motor im going to use...

it must be either the neu 1415 1,5d/1Y or the neu 1512 1y..
Sounds like a motor with 2800kv and a 35mm propp is the best!

But is it better to use a short motor or a long motor with less dia?

What kind of motor are the H2 champs running?
maby i shuld just spend some money and buy the best motor avalible.

[raptor347]

Thanks for the link!

If that's the course with the 60m straits and 15m diameter turns (is this correct?) I'd guess the speeds in the low-mid 50's. Those boats run very differently compared to what we run here.

That course looks alot like our old 1/10 mile oval straits with huge radius corners. Remember that I'm looking at this from an ocean and continent away. Just watching the boats run makes me think the lower kV turning a bigger prop may be a good alternative. If I were to build a boat for the class I'd go with the 1415/1Y in one of my spec riggers (or equal) and start with a 42x55 or H-4 and modify those blades to get the duration I needed. The bigger props generally handle rough conditions better. The high RPM setups certainly work as well, I'd just go at it differently. But what do I know. On my 2S sprint race rigger (27"), I went from a 37mm prop with a 5500kV motor to a 43mm prop and a 4400kV motor and picked up speed and improved handling. Depends a little on the size/design boat you want to run as well. Our spec boats are 750-850mm long.

How many laps does a competitive boat run in 5 minutes? How many cycles do you get out of a pack if you draw them down that low?

This is turning out to be one of the more interesting threads we've had in a while. I may have to build a boat up just to see what it will do.

[BILL OXIDEAN]

Thanks for the link!

If that's the course with the 60m straits and 15m diameter turns (is this correct?) I'd guess the speeds in the low-mid 50's. Those boats run very differently compared to what we run here.

That course looks alot like our old 1/10 mile oval straits with huge radius corners. Remember that I'm looking at this from an ocean and continent away. Just watching the boats run makes me think the lower kV turning a bigger prop may be a good alternative. If I were to build a boat for the class I'd go with the 1415/1Y in one of my spec riggers (or equal) and start with a 42x55 or H-4 and modify those blades to get the duration I needed. The bigger props generally handle rough conditions better. The high RPM setups certainly work as well, I'd just go at it differently. But what do I know. On my 2S sprint race rigger (27"), I went from a 37mm prop with a 5500kV motor to a 43mm prop and a 4400kV motor and picked up speed and improved handling. Depends a little on the size/design boat you want to run as well. Our spec boats are 750-850mm long.

How many laps does a competitive boat run in 5 minutes? How many cycles do you get out of a pack if you draw them down that low?

This is turning out to be one of the more interesting threads we've had in a while. I may have to build a boat up just to see what it will do.

Yeah man, what they're doing over there is an entirely different animal, and all the countries correspond except for us here in the US.

They're getting plenty speed, and tons of runtime on minimal Mah.. They run 1p for twice the duration we run on 2p but they're only like 5mph slower than us in oval trim throughout the classes

I've been wanting to race over there beceause my setups are mild here, but I believe would be pretty hot over there..

their boats are a bit smaller too.. a 23 inch mono can do awesome over there on 2s

I tell my teamates in Belgium that they'd have a hard time over here with the setups they run..

I'd love to see a couple of world classes besides Eco..

[raptor347]

They're getting plenty speed, and tons of runtime on minimal Mah.. They run 1p for twice the duration we run on 2p but they're only like 5mph slower than us in oval trim throughout the classes

Just very different forms of racing. You need more man power to run the NAVIGA style races just for lap counting and timing.

The Aussies run sprint races like we do but with a battery weight limit. A good 2P sprint boat should be significantly faster than a 1P endurance boat. My N2 hydro (2S2P, same battery weight as Hydro 2) runs in the low 70's and the 4S2P boat is running mid 80's. Those are radar speeds not GPS.

The more I think about it, I think one of our spec hydros would make a pretty good Hydro 2 boat with a more efficent motor and some tuning. Not a world beater, but it would run pretty well.

[simengj]

There's a fair range of sizes, MHZ stealth, Rocker XL and H&M exess2 at 700-750mm going up to dr Psycho lui, mr Krabs and Lindenau Bathlett at 800-850mm.

We use nearly all the capacity often putting over 5000 back into a 5000 pack.

Props are around the 35mm region.

I have no idea about the speeds, we have only had 1 records weekend since LiPo were allowed and the records got lost somehow, yeah were that organised over here I have 2 certificates but no records. Take a look at this clip and decide for yourself, although its shot from the turn so its a little harder to tell the http://www.youtube.com/watch?v=MYw2I...e=channel_page

By all means try it, the kV is good and I'm sure it will be competitive, I haven't heard of anyone using the 14xx so I have no idea what there like although Brian's recommendation carries a lot of weight as he seems to be THE MAN and always has good advice, personally I would go for the 1512 1y though as I have heard the D winds are amp hogs (although I don't really get that or fully believe it surely the KV sets the amp draw and the way its wound to get the KV is an irrelevance?) but mostly because with Neu's extra efficiency over Feiago they don't have to be as big to produce the 1000W and the rotor is shorter giving it less inertia which lets it spool up quicker, like using a long 480 for hydro1 not a short 540.

The high KV winds do have the max efficiency higher than the lower KV motors of the same design but I have never seen the graph for Neu motors and would be intrigued to see what it looks like, I have a Lehner and its max efficiency is 93% at 90A which is over its rating, but the latter half of the graph is pretty flat so it doesn't drop below 90% until I get under 40A.

Could you pleas give me some specs on your settup?
propp, esc and motor?

Cant understand how you could get 5 min of runtime with neu 1415 1Y and 40mm propp, my fecalc says around 70 amps, 54 mph and 3,7 mins...
A 60 amp settup sems to be god for 5 min of runtime and 50mph if the fecalc is right.
This fecalc drives me nuts

Theory and practice are two diferent things, so the fecalc isnt entirely correct after all..

[NativePaul]

The course is 60m straights with 15m radius although the course in the vid I linked to is a touch short maybe 55m straights because the banks looked a little tight for the hydro2s and supermonos when it was put out full size.

I dont hold any faith in radar for our small composite targets, but if you do one of the europeans brought a 6xl powered rocker XL which is very fast but doesn't handle chop well that radared at 70mph, to our nats last year

I would say that over 20 laps is competitive as the fastest boat doesnt allways win, 25 laps is a good score and if you get close to 30 your on a winner if you can keep it up. this years winner got had 45 laps over 2 rounds and last years champ who was still the fastest lapper got only 5 laps.

I'm not racing H2 this year last year I used a 12L with a X640 and while it wasn't really fast enough for more than club racing it was still way too fast for my 25" hydro which last saw action with a 700 and 12 1700s, I have a 6XL for next year and am working on a 32" hydro with a lot less lift, I hope to be able to use a very well cut X637, but as always starting small and working up is the thing to do, a bit of an arse at this size though as under 37mm the props are 1/8th bore and the 37 is 3/16 I do have wires of both sizes though.

Fe Calc is a rough guide, usefull to tell that your not going to pull 300A from a setup your going for 30A with but not too accurate.

I'm not sure that endurance events take any more manpower, we have a caller/timekeeper that calls each boat as they pass the line and times how long after the time each boat crosses the line on their final lap, someone to count the laps, 2x buoy judges 1 at each end to note if anyone misses a buoy, and a race controller that calls any dead/slow/upside down boats or wildlife on the course etc, I've never seen a sprint race but would have thought you would need the same their just tied up for 5/6 minutes not 1min, it you have more than 10 peeps at an event there should be enough manpower, low attandance events generally have less boats per class and the caller/timekeeper can also do race control and the buoy judging can left to the honesty of the competitors.

With 2p and 30C giving 2 min runs (although I understand that you'll start melting things if you run for longer than the minute that your 5 laps take) there's the potential for 5 times our power for hydros or 6 times our power for monos you sure should be more than 5mph faster although I bet we would make a chunk of that back with our stepped monos, as I believe your not allowed steps over there except in offshore, speaking of which your offshore classes sound similar to what we run, in the UK we have a local class called supermono which we introduced to replace the mono3 class that naviga knocked on the head recently, its monos and cats, any motor/s 8s lipo max 1120g, 10s mill time 6minute race time, it sounds just like P offshore but with lower kv motors, I run 1200kv in my 36" cat unfortunately we don't allow parallel battery setups but if you had a twin with 4s1p per side it would fit our class.

NAMBA is the USofA's NAVIGA affiliated association so I'm expect they would be open to running a naviga class and having some decent representation at the worlds, I have heard that some Americans did go to a worlds a while back, but without any racing of the classes back home to practice and hone their settups they did rather poorly. Personally although I don't like monos I would like to see one of the mono classes pop up in the states as I guess over there you would have a more even split of stepped hulls and unstepped ones within the heat for a mono class whereas over here there almost all stepped which would make it interesting, and it would be super to see a demonstration heat of N2mono and mono1 I would find it fascinating to see a comparison between the little light stepped selfrighting mono1s and the big heavy unstepped N2s with huge power, it could be like when the you entered our touring car racing series in the 60s with your huge mustangs and chevy cameros fighting it out with our little lotus cortinas and mini coopers.

http://www.youtube.com/watch?v=gpFdHFQEY8s