30" Scratch Built Cat

[Jeff Wohlt]

I will have the same unit but will have a 3/16" shaft sleeve to run reular sized shafts. Should have them in about a week.

[lomdel]

I will have the same unit but will have a 3/16" shaft sleeve to run reular sized shafts. Should have them in about a week.

You talking about the Etti stinger, Jeff? If so at what price and would the mounting flange be the same size? The unit can be a bit longer though... Would you be able to supply them with 3/16" counter-rotating shafts assembled?

[Norman2]

30" Scratch Built Cat

YAY good job norman. can't wait to see her in the water!
J

Hi Jesse, lomodel,and rawson, Just completed the cats maiden voyage and I can't
be happier. The only adjustment I had to make is to lower the strut 1/8" and move
the batteries on both sides back 1". Moved down the strut because it had too much
cavitation when accelerating. Now she runs perfect and turns perfect. My friends GPS
clocked it at 34.2 mph with a 700 SC. Not the best but good enough for me. Used
an X447 and could probably go faster with a bigger prop. Now to start planning to
go brushless. Maybe a Feigao 580. Regards
Norman

[lomdel]

Glad to hear that Norm! I think a 580 would be a bit big for such a light hull. Rather try a XL...

On my build: I finished the sheeting and the lid (no cockpit yet) and she's a beauty!! I will post pics tomorrow. I want to ask; now what? Should I first apply a couple of coats of polyurethane exterior sealer with sanding in between and then a coat of sandable wood primer? Bondo? Should I then use automotive paint or any aerosol based paint? Is it neccesary to apply a coat of fibreglass & resin before the primer or not?

[Jesse J]

Great results Norman, 34 is a very scale speed and I bet it looks great on the water! Yes I agree with Lomdel, go XL, maybe 10 or 12XL on 4-5S. She ought to do 40s no prob.

Lomdel, I have a carpenters background so I like the polyurethane as a grain filler and hardener. I always do polyurethane then fiberglass, then sand the snot out of it and bondo any issue areas. Want that hull to be true. Then I always go for some primer and a sand to check for any places I missed with bondo and fix if necessary. Another coat of primer or two sanding between each - smooth as silk and all lines crisp. Thats where my perfection ends. I then go get my Krylon paints and use up a can or two on the hull. Automotive would be really nice if you have the set up. Depending on your glassing skills, mine suck, you may glass after you paint, since it will be pretty much clear.

Then you are done! Get vids! You to Norman!!! Great thread guys, I am really glad you did parallel posts, worked out real nice.

[Norman2]

30"scratch built cat

Hi Jesse and Lomodel,
I finished mine just as Jesse explained. I used Duplicolor Auto Spray and it
worked fine. There are a lot of colors but Krylon Enamel is just as good and
dries faster. Jesse, I am still using NIMH cells as I know nothing of lipos and
have many matched 4600 MAH packs. I think I will use them and try to learn
something about Lipos unless you think that I should do that now. Regards
and again thanks for your help. Rawson Reyes is also trying to build the same
cat so I sent him my two files to help him out. Hope this was OK. Regards
Norman
ps. I do not have a video camera and I am trying to get a friend to video it for me.

[Jesse J]

Well, my personal opinion is this: don't buy any more NIMHs as 2S lipos are $40 a pack. The only start up expense is the charger ($130). I would recommend a gadget that tells you exactly how much capacity is left in the cell (a gas guage) and that is about $100 - BUT you don't need to learn anything except that you need to use the capacity guage. you will eventually develop a sense for how long your packs will last with a given set up. ALSO you get way more power output from lipos than the NIMHs. My dad is in the same boat, he wants more batteries but doesn't know lipos. I gave him the same advice. for about $300 you are set up with charger a pair of batts and the capacity gadget - plus you get much more life out of lipos. I can look up some links if you decide to go this route.

I was given permission from the creator of those plans to distribute freely, so do so! Cheers Norman and can't wait to see your beauty makin roost!
J

[Simon.O.]

Shortened quote

Well, my personal opinion is this: don't buy any more NIMHs as 2S lipos are $40 a pack. ALSO you get way more power output from lipos than the NIMHs.

If I can add anything to this thread it is to agree with Jesse on the Lipo thing.
I agonised for a long time over BL motors and then even more on Lipos.
I read so much about Lipos blowing up that I scared myself out of using them.

Then I got some. Well fark me the difference between Lipo and Nimh is like the difference between Stock brushed and BL motors.

My boats went nuts on the new power and I love it !!!

I will never buy a sub-c pack of Ni.. cells again.
I have a lot of worn and old cells now that are fine for my Crawler, that will go Lipo when I get new ones for my boats.

[Norman2]

30" scratch built cat

Well, my personal opinion is this: don't buy any more NIMHs as 2S lipos are $40 a pack. The only start up expense is the charger ($130). I would recommend a gadget that tells you exactly how much capacity is left in the cell (a gas guage) and that is about $100 - BUT you don't need to learn anything except that you need to use the capacity guage. you will eventually develop a sense for how long your packs will last with a given set up. ALSO you get way more power output from lipos than the NIMHs. My dad is in the same boat, he wants more batteries but doesn't know lipos. I gave him the same advice. for about $300 you are set up with charger a pair of batts and the capacity gadget - plus you get much more life out of lipos. I can look up some links if you decide to go this route.

I was given permission from the creator of those plans to distribute freely, so do so! Cheers Norman and can't wait to see your beauty makin roost!
J

Ok Jesse, I am going to follow yours and Simons thing on Lipos. Now what is a 2S?
I would like to know what is the Lipo equivalent of my 7.2 volt 4600 MAH 6 cell NIMH
packs. Are they the same size as the packs I have so they can fit in my boats.
Do they have Dean Plugs. And help me out with this balancing thing. As soon
as I get the info I will start ordering the stuff. Thanks
Norman

[Jesse J]

Norman, 2S means 2 cells, you will use them in the same way you use the 6cell packs. These packs have two Lipo cells in series 3.7 V each for total of 7.4V and a much higher power dump. Here are some of the packs I was talking about. Get a pair of these (they come with Deans):

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7653&Product_Name=Rhino_4900mAh_2S1P_20C_Lipoly_Pack

This is the charger I have been recommended several times and will be getting next:
http://www.offshoreelectrics.com/pro...-eos0606i-acdc
This has the balancing inside and solves all problems. Click on download manual for the specs on the charger

Here is a really handy and I think fundamental gadget:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6232&Product_Name=Cellmeter_8_for_Lithium_Polymer_Packs

I think this should get you started. The cell meter measures percentages as well as actual values. It gives you the amount left in the pack based on no more than 80% usage. I usually leave 30%-40% still on there just to be sure I am treating them well.

I know the start up cost is daunting, more than $300, but after that, you are spending same amount for lipos as for NIMHs.

Hope this helps!

[Norman2]

30" scratch built cat

Hi Jesse and lomodel
Some more photos with mufflers installed. Now need to order the scoops from
MHZ and I am then going brushless and lipos. Regards
Norman

[Norman2]

30" scratch built cat

Norman, 2S means 2 cells, you will use them in the same way you use the 6cell packs. These packs have two Lipo cells in series 3.7 V each for total of 7.4V and a much higher power dump. Here are some of the packs I was talking about. Get a pair of these (they come with Deans):

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7653&Product_Name=Rhino_4900mAh_2S1P_20C_Lipoly_Pack

This is the charger I have been recommended several times and will be getting next:
http://www.offshoreelectrics.com/pro...-eos0606i-acdc
This has the balancing inside and solves all problems. Click on download manual for the specs on the charger

Here is a really handy and I think fundamental gadget:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6232&Product_Name=Cellmeter_8_for_Lithium_Polymer_Packs

I think this should get you started. The cell meter measures percentages as well as actual values. It gives you the amount left in the pack based on no more than 80% usage. I usually leave 30%-40% still on there just to be sure I am treating them well.

I know the start up cost is daunting, more than $300, but after that, you are spending same amount for lipos as for NIMHs.

Hope this helps!

Jesse, Thanks, wil be ordering tomorrow. Will use the NIMH packs in my cars.
regards
Norman

[lomdel]

Norm, I would suggest buying 2x 4S 5000mah 25C packs and a Feigao 540 10XL motor. Then you can run it in a 4S2P parallel configuration giving you 10000mah worth of runtime and enough oomph to the motor.

On my build front, here is the latest pics. Will start finishing now. How do you like that sexy rear end ! The cockpit braces are just there to show the profile.

[Norman2]

30"scratch built cat

Hi lomodel. Wow, that boat is looking great and I agree that is a very sexy
transom design. Why didn't I think of that LOL. What paint scheme are you
planning? You are almost done with beatifull work. Regards
Norman

[Jesse J]

Great job Lomdel, yes I will be incorporating that design in my next balsa cat! Lookin real good!