scratch build: micro cat

[Jesse J]

this build is based on the same plans that I have made a 24" and 29" cat from (see my albums), thought it was time to try a competitor for the micro c cat. This one will be 15" with 14" of wet hull. It is 4" wide and not a whole lot of room inside. This is why I am going slowly on the sheeting. Probably mount up all hardware before sheeting just to know what problems to avoid and what I may need to modify.

I am using 1/16" ply for frame (pics below) and 1/32" for sheeting. I will have to design my own hatch from 1/32" sheeting and insulation foam as I have for all my scratch builds. I will use Joe Solinger's micro rudder and scratch made strut for the .098" cable running down a 1/8" K&S stuffing tube. (pics to come, JB weld is curing at the moment.)

I was thinking of using this Venom 380 bl motor (3980KV) and the Mystery 30A esc on 2S lipo. Anybody see a problem with this motor/esc combo? I have waterproofed and cooled the controller and maybe even add watercooling to mister motor, might not need it though.

[Eyekandyboats]

i have the same esc for on my my planes.
don't let a drop of water even with in 2 feet of that esc or it wont work.
trust me.
even in a plane if it is a humid day it will just cogg and not do a thing

[Jesse J]

I totally coated it in 3m Dp270 Clear Epoxy, so I am hoping it should be good.

[Jim Bob]

If that is a 20mm motor I think you will not be impressed with that motor(not big enough). It will more than likely run hot and not perform well. The ESC should be fine though.

[Jesse J]

Yes, Jim Bob, it is the 20mm you are warning against. OK, I have a Mystery outrunner I got with the ESC that I can use. My brother gave me that one, maybe I save it for the glider.

So, on this little guy, I am now wondering just how far back I should have the prop and if I should try to mount the rudder directly behind it or off set.

[Jesse J]

Updates:
skinned bottom and sides, opened up interior to make room for electronics, made strut, prepped Mystery controller.

[Jesse J]

updates continued.

I am now going with the mystery outrunner, and although Dr. Jet mentioned cats need a bigger motor, I am thinking I can keep weight dowwwwwwn on this lil guy and might be ok. I am now contemplating a strudder. Will post predicted weight soon, still gotta install stuffing tube.

How important do you guys think it is to have the rudder inline with the prop? and how much distance is minimum if one is to go that route?

[Jesse J]

almost ready for paint!

So my computer crashed last week and I just now have substitute for update posting. Since, I have added two splash rails and a chine. I just like the looks of a chine. I also installed stuffing tube and motor mount screws. I test fit everything probably 50 times and it will be tight. I filled the front cavities as well as the transom overhang. I have probably 5 thin coats of Minwax polyurethane on so far and will be painting soon. I had to go with a large hatch to be able to feed wires through the framing.

[Jesse J]

Forethought, actually just plain physics, lead me to mount the motor pretty far forward and have stuffing tube exit forward as well (needed room for battery). this means I have lots of room to play with strut depths and angles as I can bend the stuffing tube to just the right position. I went with 5/32 K&S to allow the .098 flex have a little more room than the 1/8" I was originally planning on. Consequences will include greater tendency to leak water up through this larger gap - better goop my tube

Next is to epoxy the cowling and finish the hatch. I have shaped a piece of insulation board, but the scale version won't allow the motor to stick up as far as it currently does, so I will have to add a spacer and position it farther forward than I would have liked. It ought to come out pretty cool though.

[Avanti]

got any pics of the bottom
this boat is looking good keep the pics coming
I might have to get back at the manx here shortly
there are quite a few of us building micro cats
the 30a mystery will be fine I've used them in a few different micros on the water

[Jesse J]

Yes, bottom. I knew somebody would want to see the most important part... I will post some soon. I have since primed her, so the only proof she is wood is the interior view.

[Norman2]

Catamaran

Hi Jesse J. Where did you get the plans. Thanks for your help.
Norman2

[Jesse J]

Plans, I got them from LoneWolf - I am not exactly sure who designed them, but he sent me a pdf and I have made all scales, except big and that will be next.

as for pics, here are some of the canopy, I am actually happy with how it looks. had to make it taller in front than scale, but this way the outrunner can do his bizness. I designed the side and top view in a drafting program then paper-glued them to that foam insulation board and went to the bandsaw. To get a smooth finish, it took 3 coats of epoxy (just the cheap regular Ace Hardware stuff). I taped the hatch in place to try to approximate the double curve of the deck and with hatch tape should be fine.

[Jesse J]

as for the bottom, I went with the plans except I removed the two steps figuring this scale wouldn't miss em. I did add two splash rails as per the plans and kept the lines sharp and smooth. The hull got several coats of polyurethane and then a couple light primer coats. It is water tight and will need a maiden voyage soon.

[Avanti]

nice work, I like your lifting strakes. the spray rail on the side looks cool too.
I did the steps in mine but no strakes, I might add some.