ozzie-crawl

just brought another boat tring to find some info if anyone has got or seen one. it is called a apparition and is 32" long fiber glass hull (36 if u include the rudder assembly ) 9.5" wide and has a 2950kv motor that is 2" long and about 1.5" in diamater. iam hopeing to run it on 4 and 5 cell lipos does anyone now if a 120 amp speedy will do the job.thanks scott

kahnen

I don't know what boat/motor it is but going by the numbers I'd say your motor is to hot for a 4s (43,660 rpms) or a 5s (54,575 rpms) setup. You should try to stay under 30,000 rpms unless your running SAW racing or you don't care if you blow stuff up every few runs. With that motor KV, a 3s (32,745 rpm) lipo would be a better choice, though pushing the limits still. The motor KV is an odd "size" for boats. Not enough for a 2s and to much for a 3s.

ozzie-crawl

okay thanks kahnen. any suggestions on motor esc lipos for a 40-50 mph boat

kahnen

Since I've not hit 40-50mph range yet myself, I will offer my suggestion and with tweaking and tuning hopfully you can get your goal.

A good read from those with more experience.
http://forums.offshoreelectrics.com/...read.php?t=271

Use a XL sized motor(75mm long) in a KV range of 1200-1800

Run 4s on the high side of that KV range or 5s on the low side of the KV range.

Controller needs to be able to handle 4s or 5s and atleast 100 amps continuous.

This post in that thread I linked above actually has some nice builds in it and exact items used, might offer some insight. My suggestion look pretty close to what they have done.
http://forums.offshoreelectrics.com/...8&postcount=12

CadillacDTS2001

that motor is WAY to hot for 4 or 5 S lipo.
that is a a good 2s or 3s motor. 2s 6XL is great for a large N2 mono

ozzie-crawl

thanks for the info and the link its got just what i needed the reason i was thinking 4-5 cells lipo was my mates boat (wich is smaller ) runs a 3800 kv motor on 3-5 cells and has even had afew goes at 6 cells but at 6 cells was uncontrolable. we havent speed tested it yet but judging by our other boats on 5 cells it must be doing over 60 mph. thanks scott

ozzie-crawl

just in case anyone wants to know ran the boat to day on 3 cells ran rather well then tryed 4 cells and it went really good nice speed will try 5 cells next as on 4 cells the esc didnt even get to 100 deg. motor was about 85. batteries were still cool. have a small video will post link when i get it goes up on u tube only short run as i had radio problems

rclaw

I have this cat too. It came with a small motor which burnt after two runs. I am now running it on ETTI 125 esc with 2p2s and 2p3s 5000mah lipos in series.

785boats

Hi Gang.
Well I dropped an 8XL in the Cat & gave it a run today with a GPS going along for the ride.
The reading was 81.1 klm/hr. That's 50.4 mph.
The prop was a Grim Racer 40 x 52 - 3 blade.
Batteries were 2 x Himodel 2s 5350mah 25c packs in series.
All temps were good after 5 laps but one problem. It still won't turn at full speed.
I've had this problem even with the Aquacraft SV27 motor in it.
The rudder has very little effect until the speed is washed off & then with very little movement of the rudder it hooks violently & spins out. It doesn't flip just spins out.
Any ideas on how to remedy this problem?
My best Guess is to move the rudder to beside the prop & get it out of the prop wash.
Two questions on this though.

1) Should it move to the left or the right of the prop? I've read somewhere that the rudder creates a certain amount of lift in a turn & that if it is on the left of the prop it can lift the left sponson slightly & help the cat around the right hand corner on an oval course. But a lot of photos I see have the rudder on the right hand side of the prop like the accepted practice on a mono.

2) Should the leading edge of the rudder blade be level with the leading edge of the prop or in front or behind?

Any help would be appreciated as I 'm in uncharted waters when it comes to setups on a cat. I've searched the forums but can't find a difinitive answer to these posers.

I am quite pleased about the speed though.

rclaw.
What motor are you running in the cat now?

Best regards.
Paul.

rclaw

Paul,
I am running a Feigao 9XL in the cat. You may want to try Octura X442 or X642. I'm running x642, and mine turns on a dime. I got helps from the guys on OSE when i was setting up mine. Try this link.
http://forums.offshoreelectrics.com/...ead.php?t=5487

SV27dayton

Yea,
I agree you should play with props and also the CG of the boat before you move the rudder. I'd also even consider adding turn fins. I hate seeing turn fins on a cat b/c they really shouldn't need them but in the end they may solve your problem with few side effects. Moving the rudder may not solve the problem. There are pleanty of people running the rudder behind the prop. I intend to. I have the same power system going in my 27" balsa cat so I'm excited to hear yours went so fast initally. Good stuff.

ozzie-crawl

hi paul left you a bit of a answer on o.s.e. mainly concerning the steering rod flex. i found with mine at speed it was flexing back and forth. with mine i run a 7xl does anyone else find there boat having a lot of tourqe roll
cheers scott

785boats

Hi guys.
Thanks for all the info. I finally put it to good use yesterday.
Hi Scott. Saw your post on the 'Prince' thread & thought I'd answer it here.
I dropped the strut a bit , changed the prop to an X642, added a small hooked turn fin at the rear of the right side sponson, & removed the wedge that I'd installed under the rear of the tunnel.
It now takes the bends at 3/4 pace. If I try it at full noise the arc is too wide. Hitting the rocks at 50mph probably won't look too pretty. I'll change the linkage on the rudder to give it a bit more throw & see how that goes, but I think it might need a wider rudder blade from what I've been reading elsewhere.
Guess who's a happy little sailor.
Thanks again everyone.
Paul.

ozzie-crawl

good to hear your getting it sorted paul if i can get some more batteries soon i will make a trip up to see how mine goes around your course. havent gotten to far with the twin motor cat as the aussie dollar isnt to good at the moment but dont think thats going to change any time soon so may just have to pay the higher prices so i can get it going
cheers scott

785boats

Hi Scott. It would be good to see you up here again to have a bit of a run. Just a reminder though, that we are restricted to 4s max by the Entertainment Centre.
The dollar value has put a hold on a lot of projects around the place.
I've got an X640 now so I'll sharpen & balance that this week & give it a go on Saturday.
See ya.
Paul.

ozzie-crawl

thanks for that paul i run 4s but geoff has been running 6s. order some new batteries today so hopeing to make it up there soon
cheers scott

ozzie-crawl

got a chance this weekend to do some work to my twin cat, motor mounts and stuffer tubes in ready for glassing.

785boats

Looking good Scot.
Trevor, from our club, kindly took a video of the cat today so I thought I'd share. 8XL, 4s Lipo, X640 prop.

[link]http://www.youtube.com/watch?v=po3I_GMW47E[/link]

Great fun.
All the best.
Paul.

ozzie-crawl

looks to be running real nice paul what size batteries you running
scott

785boats

Scott.
They are Hi Model 2s 5350mah 25c . Still using the Hi Model 200A ESC too.
Paul.

ozzie-crawl

thanks paul . i orded a new set of batteries for the mono last week going to run 2 2s in series and drop the weight of the boat by 500 grams and use the 4s 3700s in the twin motor cat and then get some batteries for the single motor cat looking at a 2-2s setup and take a bit of wieght out of the hull as both batteries wiegh 820 grams
scott

Gerwin Brommer

Scott,

with the motor so far to the front, where do you place the cells ?
Why not motors close to the back, and cells in front of the motors ??????

785boats

Gerwin.
I think your question is for Scott (ozzie crawl.) That's his boat with the twin drives.
Take it away Scotty.
Cheers.
Paul.

Gerwin Brommer

oops, edited my previous post.
Thanks Paul.

ozzie-crawl

hi gerwin. the reason i put motors up front was to get my c.o.g rite. if i put motors to the back and batteries up front the c.o.g would have been to far forward, any way here is some pics