New .21 outrigger

[Saugling]

To be clear:
Here is what I measured:

absolutely right...we are talking about the red line in your photo

For the beginning I would set it to about 8.5"

Which Carbon-Prop did you use for yout initial testings?

 

[MitjaJ]

>> Which Carbon-Prop did you use for yout initial testings?

42 mm, then tried the 45 mm but the rear end hopped too much.

Didn't do much testing since the hull got filled with water very soon and the

boat almost stopped - so I had to bring it to shore. I will file away the ears on

one 45 mm prop to see if it will reduce hopping.

I was thinking first to seal the holes on the sponson tubes and hull bottom-try if it

will stay dry - if not I will try the trick that Dan recommended.

 

[Saugling]

well...I never had hopping-problems with these graupner carbon props on any of my boats since these props are already low lifting ones.

try some rearshoes / sponsons to stabilize the tub's riding height.

maybe you need more / less weight on your prop.

is it possible that your turnfin is pulling the front of the boat down?

seal the holes with some tape - since you are running alone there shouldn't a problem.

did you "throw-in" your boat so it is already on plane from teh beginning on? or did you just put it in the water like many electric guys do it?

I ask this because I can not think of a reason why your tub is filling with water if the boat is on plane.

 

[MitjaJ]

I tried the "electric way" and the "flying start" - with the same result - the boat came on plane but after a while started slowing down. The turn fin is straigth - I will try to remove it to see if it helps.

Will put the reciver battery on the end to put more weight on the prop.

 

[Dan_Cousin]

I tried the "electric way" and the "flying start" - with the same result - the boat came on plane but after a while started slowing down. The turn fin is straigth - I will try to remove it to see if it helps. Will put the reciver battery on the end to put more weight on the prop.

When I've had hopping problems it was one of the follwing things.

1) rear sonson attack angles too high - tended to bounce in the corners

2) CG to far forward on the front sponsons - tended to titter totter on the front sponsons

3) Strut too deep

4) strut on too much of a downward angle

5) prop with too much lift.

6) Boat ride attitude way out of whack - boat fighting itself to stay straight.

First thing I'd try is taping some weight on the back end of the boat to see if it settles down. Keep adding weight until it gets heavy enough to weigh the boat down. If a reasonable amont of weight make the boat settle down, measure the CG with the weight and then move the radio gear (or anything else to try to get the CG to the same spot while adding a minimum amount of extra weight.

If not next thing would be to raise the strut so high it will bearly launch. Then gradually lower it to se how the boat reacts.

Make sure the strut angle is almost dead flat with the water line each time.

 

[MitjaJ]

Tested it today - runs fine - no hopping, no more water in the hull

Mods that I've done:

- moved the strut closer to the hull (still parallel to the hull)

- moved the RX battery to the rear of the boat

- put rubber washers on the sponson tubes (to close the oval holes)

- new custom made pipe (loud :huh: ) Javapipe

- replaced the teflon shaft liner with brass tube

- O.S. #8 glow plug

 

[Dan_Cousin]

Glad to hear it!

Have fun.

 

[Dr Hydro]

On my hydros I mount the turn fin 1/4 inch in front of the CG.

 

[MitjaJ]

Well I have some problems - the boat runs really well - the only problem I have is that the engine stalls a lot - It seems that air enters in the fuel pickup tube - I allways see bubbles at the carb when the engine dies. How to solve this problem ?

 

[crazykite]

Put some shock absorber under fuel tank. It has been useful with my car !

 

[lundahl]

Use a smaler tank betwenn the main tank and the carburator. The smaller thank will the allways be full so no air can get in to the fule line to the carb.

 

[MitjaJ]

I have solved my problem.

Emptied three tanks today without a problem.

All I did - used a felt clunk in the tank = No more stalling on the water.