Hor Apparition 32 too Heavy Low at back, Need Advice

[Drax21]

Hi any advice would be great to lifting the hull out of the water a little. I have a video of its first run, its very unstable on corners and dives at one point in the vid.
Specs are
32 inch Hull bought from Astec Models
2 Feigao 7XL (heavy)
2 200Amp Himodel ESCs with Special Water coolingDSC_0731.jpgDSC_0730.jpg
2 Counter Rotating Threaded Flex Cables
2 X442 Props
Running in 4s 2 2s batteries connected in series at both ends

VIDEO http://www.youtube.com/watch?v=c2vIaSP7ZrQ&hd=1

[Boaterguy]

move components forward, that'll lift the boat up more.

[Drax21]

The Motors as well?

[Lockk]

Well I think if you look at most of the catamaran builds on here you would see that the motors are moved to the back of the boat keeping the drive cables
short as you can. I have a 32" cat and from the back of the hatch opening to the face of the motor is 4.5". My batteries go up into the sponsons towards the
bow, with the batteries located so close to the transom as you have them a lot of weight is to the back and my guess is your CG is not at 30%.

Bottom line to much weight to the back of the boat is causing the problem and from the picture you don't have much room to move the batteries but first see if you can get the batteries as far forward as you can if it doesn't help, then one solution is to refit the motors and batteries into a location that gets your CG at
30% from transom to bow.

The problem will only get worse if you go to say twin 4s batteries in paralell to get more tun time.

A lot of smart guys on here and they may come up with a better solution so hang in there.

[Lockk]

move components forward, that'll lift the boat up more.

This is the Readers Digest version but I'm afraid it's correct.

[Fluid]

Where is the balance point from the back of the sponson transoms, not from the rudder mount? It doesn't look that bad to me in the video, the boat is not flying the bow and it gets on plane quickly. If you would run in an oval instead of all over the place it would be easier to tell how it is running. You need to hold full throttle for longer to tell how it runs at speed.

These boats to not corner well unless you have a deep rudder, how about a photo of the transom from the side? How are the struts set, how deep and at what angle relative to the boat sitting flat on a table?


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[LarrysDrifter]

This is my opinion based on my experience with a twin 32:
Your motors are too far forward, preventing the batteries being placed in front of them. Since the motors are already mounted, I would run the batteries on the tunnel floor and test. Or, another option you can do even before moving the main packs is to move the esc's forward as well as the reciever pack. Your placement of components seems backwards to me. That doesn't mean it won't work though. Move some things around and let us know how it runs.

[Drax21]

DSC_0736.jpgDSC_0737.jpgDSC_0739.jpgDSC_0740.jpg

I will move a few things around. Thanks for all your help so far.

[Drax21]

OK just sealing the prop shafts. I didn't set this boat up, I bought it off a Guy on ebay. Turns most of the inlets and shafts were not sealed so ended up with quite a bit of water in my boat. I have added a few pics so you can see the struts rudder etc. Will add a video to show how low it sits in the water with the Lipos in.

[Drax21]

Ok everything should be sealed nicely now. There was even a small hole by the struts! all sealed. Will test it for leaks in the bath and will take a pic showing how it sits with lipos in. They should be able to be moved forward about 8cm from the back. I believe this to be the cheaper Chinese version which mean thinner fiberglass and less buoyancy. I just talked to a guy who only has one motor and he said he added extra float to the back with noodle?? Will run it some time this week if no more problems arise.

[Drax21]

Here are the pictures as promised, I took 2 without Lipos in and I would say that is the height I want then I took 2 with Lipos and back end sinks right down. I need to give the Hull some lift, any ideas?DSC_0741.jpgDSC_0742.jpgDSC_0743.jpgDSC_0744.jpg
I did move things around but Esc has to stay where it is(too high for anywhere else) and motors I am def not moving unless absolutely necessary. All Lipos more forward caused dipping at front.
Thanks

[Fluid]

I believe this to be the cheaper Chinese version which mean thinner fiberglass and less buoyancy. I just talked to a guy who only has one motor and he said he added extra float to the back with noodle?? I need to give the Hull some lift...

You (and maybe 'the guy') are confused and worrying about the wrong things. Thinner fiberglass has nothing to do with buoyancy. He added foam pool noodles to the inside of the boat to keep it from sinking if the hull is breached. Don't worry 'how you want it to look', who cares if the stern is underwater at rest? What matters is how the boat runs, and in the first video it did not look bad at all. (These boats will hook easily if you slow down too much while trying to make a tight turn and have too shallow of a rudder - and yours is not deep enough.)

Where is the CG (balance point)? This is what matters, not where the motors are mounted. Your little boat is heavy with those large XL motors, packs and ESCs. The CG should be about 3" behind the front of the hatch opening...but based on the video, where it is now may not be so bad. If you want to move the CG forward, put one pack in front of a motor, not both, an easy fix if needed.

Really, stop worrying about how the cat looks at rest and spend your time and effort tuning it to RUN. Otherwise, you might as well just rip all the guts out and make it a display model. That would be too bad because with your current setup you should see 50s easily with plenty of performance and run time.


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[Drax21]

OK many thanks for your replies, you know your stuff so I will take it to the lake by Fri. Will upload a vid if I get some nice speeds.