Rigger Help - Making a Tub

[capnswanny]

Hey guys,

I'm just starting out in the FE boating...but I'm quickly becoming addicted. I picked up my first real project at the Hobby show in Monroe a couple months back. It's Dumas Hawk 3.5 that was setup for nitro when I got it. I pulled the tank filled in holes, sleeved the shaft to 1/4, built a cover and turn fin, etc. I have the COG balance at the turn fin. I'm running the UL-1 motor, AQ 60A ESC, 4S, 45mm prop, .150/3/16 flex.
I've run it a few times and as a first timer I was really pleased that it moved quick...
Here's a video with the rear sponsons still on, it was skipping a bit:

http://www.youtube.com/watch?v=DHlEhjrHy3w&context=C466a0e0ADvjVQa1PpcFPN7LRkU4kE6S924-cSotmuUFXNypEgAA0=

Last night I pulled the rear sponsons and ran it today, hoping that losing the drag would help but it REALLY skips a lot:

http://www.youtube.com/watch?v=1oBr8e7zOWE&context=C496e53fADvjVQa1PpcFPN7LRkU4kE6eydSmOD_A1a5zHuglCIuMs=

I'm thinking I need to build a tub under/around the prop shaft. All I was told this weekend by my FE mentors was to copy the line of the sposon I removed and build a tub around the shaft. I'm unsure how wide and deep the tub should be. I also am unsure of the final placement/trim of the prop which precludes building a tub that goes right to the bottom of the prop shaft...it may need to move up or down.

I plan to build using 1/16" plywood. Any advise would sure be appreciated.

Thanks in advance!

Corey

[Chuck E Cheese]

most of the ones i have built are around 3/4" wide. when i made scratch built tubs i would experiment by tapeing the "ski" on in different widths and do short runs making notes on the lift provided. some of the smaller/ heavier boats liked them around 13/16ths. i would guess that 3/4 would be a good starting point and use the prop to add lift if needed. you can also double the sides with 1/16th ply to widen it once it is allready on the tub..

[carlcisneros]

ok here we go.

first off, put the rear sponsons back on the boat where they originally were located.
Your water pick up is a good idea BUT, make it SHORTER and angle it so that the tube end is behind the prop so that
it will get water forced into it by the prop.

What prop are you running on it? by the looks of it, the strut needs to be flattened JUST A TAD to get the hopping taken out.

I have ran the Hawk for quite a few years (nitro version) and have had a great time racing them.

you have a good boat there all it needs is a bit of tweeking is all.

main thing is what prop are you running on it.

[capnswanny]

Thanks for the advice I will start with 3/4"'and work from there, how deep do you go with it. It would seem that of you go too deep you'd end up shadowing the prop. Is the rule of thumb to go as shallow as possible?

[capnswanny]

In the 2nd video I'm running the 5$ 45mm Graupner... I haven't bit the bullet on the high dollar prop yet. In the first video it is a M445 that my buddy let me try. Honestly the differences between the two props (when I still had the sponsons on) were very minute. I can put the sponsons back on (looks cooler anyway :)) but I'm not sure what you mean by flatten the strut. I have tried adjusting the height and angle of the strut to not much avail....should I work on getting that dialed in better? Thanks for your help!

[carlcisneros]

the m445 is a good prop to use as well as a x445.
these are very easy props to get to work with.

put the pick up tube in back of the prop in around the 2-3 o'clock position
and about 1/2 inch in back of the prop. you will get pleanty of forced water thru the cooling
system and as a side benifit, you will LOSE the drag caused by the
pick up tube being stuck in the water BELOW the boat. also, the tubing is also
slowing down the boat where you have it now.

flattening the strut, meaning take the angle out of it and set it so that it is level with the bottom of the tub setting on a flat surface.

[capnswanny]

Thanks, I will make the adjustment to the pickup, I think I read a couple threads on using hte prop wash to force the cooling.

Looks like I need to get into the real prop business. I've been dragging my feet on the prop business as I'm operating on a tight budget and I try to get the most bang for my buck. I think I'll get a balancer and and pick up a couple props.

Thanks!
Corey