Apparition strut adjustment?

[airdrew99]

I am new to this forum. I've spent many hours on this site looking at discussions on motors, batteries, esc, props, etc. I have an apparition with a single Turnigy 3674 2200kv, 180A Turingy ESC, and two 4s 2650mah 45C batteries (parallel). The rudder is stock and still in the stock location (center). I recently got this 3674 motor installed and ran the boat. The original TFL 435 prop seemed too small. I had a TFL 440 that I installed and ran at 43.5 mph. The boat handled great with this prop. All components were cool to the touch. It had a very smooth ride at top speed. A few days ago I detounged and balanced the 440 prop and reinstalled. I made no adjustments at this time. I ran the boat yesterday and it seemed to chine walk (not sure if this is what it is called on a catamaran) around top speed. It only ran 40 mph. When it got close to top end, the boat seemed to rock side to side (water touching one sponson, then the other). I think the driveshaft is about even with the sponsons right now. I have the prop angle at neutral.

Do I just need to raise my strut up a little bit?
Also, where should my center of gravity be?

Also, I have ordered 2 more props from hobbyking.
Prop Metal CL-08A PRODUCT ID: HK-5B12x42
Prop Metal 12 x 48 - CL-08B PRODUCT ID: HK-5B12x48

Thank you for any input.

Drew

[kfxguy]

X642 prop detounged is what you need. Strut should be level or have a touch of positive prop angle. The strut should be about 2.5mm to 3mm below the ride pads. When setting flat on the table, the rear ride pads will not be touching the table. I have the cg written down at home, I'll post it later. The last apparition I did had a 2200kv motor on 4s with the prop mentioned above, it ran low 50's.

[airdrew99]

Is the red arrow in the picture pointing to the ride pad? I'm not quite sure what that is. Thank you for the input.

20150309_135313.jpg

[airdrew99]

Bump

[kfxguy]

The ride pads are what would sit flat on the table. The strut should keep the rear pad from touching the table. Should be 2mm - 3mm depending on prop size. You want just a touch of positive prop angle. Example...

[robbo1]

I have my strut set 3mm above sponson and neutral angle… what different characteristics or attitude would I see if I was to set it 2-3mm below sponson?

[airdrew99]

My ride pads aren't even close to touching the table. The driveshaft/strut hold the boat up off the table. I guess I would need to break loose the glue where the drive shaft exits the boat so I can re-position it.

[kfxguy]

I have my strut set 3mm above sponson and neutral angle… what different characteristics or attitude would I see if I was to set it 2-3mm below sponson?

The ideal strut position for a 45mm diameter prop is 2-3mm below (I'm referring to the bottom of the strut) below the sponsons. If it's higher then you don't have enough prop in the water costing you a good bit of speed.

[kfxguy]

My ride pads aren't even close to touching the table. The driveshaft/strut hold the boat up off the table. I guess I would need to break loose the glue where the drive shaft exits the boat so I can re-position it.

The ride pass should be 2-3mm off the table being help up by the strut bottom. You should not have to break anything loose to adjust is. Brass tube bends.

[airdrew99]

I ran the boat today with a detounged and balanced 440 prop and then tried a new balanced 440 prop. No matter where I set the strut, the boat's front end kept bouncing up and down when I got up to 30-40 mph. The water was smooth. Do I need to add some negative prop angle? I had it balanced around 30 to 35% from the back of the boat.

[kfxguy]

Post again this evening and ill post the cg you need. the post is to remind me.

[airdrew99]

Ok. Thanks.

[airdrew99]

Do you think getting the CG set will fix this problem (the front of the boat bouncing up and down over 30 mph)? Thank you for any input.

[kfxguy]

It should. Measure from the bottom rear edge (rear of boat) of the sponson (ride pad....what the boat rides on when on plane) Measure 8 7/8" and put a piece of masking tape in that area. Then with a marker make a mark at that exact 8 7/8" point. Put something under it right there whether it be a piece of round rod or angle iron....whatever you an use to let it teeter on. Move your batteries until you get the boat to balance on the thing it's teetering on. Mark the position with tape, marker etc. go drive it balanced like that. Report back.

[airdrew99]

Thanks for the information. I will definitely do it.