Scratch cat 36"

[Jesse J]

As always, I thought of taking some shots before any sheeting, but then never did. I ran out of 1/8" balsa for tonight so had to stop (right now it kinda looks like the deathstar in the Empire Strikes Back). These are made from Shockerman's plans I have up on my website (http://jessej73.home.bresnan.net/jessej73.html)for free if anyone dares.

This will run twin Proboat motors on 4-6S each and CR x442 props. This ought to allow me to approach 60mph if not give it a big :hug1: !!

I will update progress as we go, and try to inspire others out there that have never built a scratch cat to give her a go. It gives you a whole new appreciation for the glass/gel coat hulls out there.

I am gonna see if I can get some resemblance of a Mystic out of this, need to round the sides, so stay tuned to see how it comes out.

[blackcat26]

Cool Jesse! I was thinking of a build like this in either the 36" or scale that one up to 45". You gonna glass over it or marine ply?

[Jesse J]

right now it is 3/32" ply formers with 1/8" balsa. I will then cf the inside tunnel and motor mounts and then glass the outside and probably deck with the heavier glass. I want it bullet proof rated for 80mph, even though I am shooting for 60ish.

Lemme know if you wanna scale up, I can help ya.

[shockerman80]

boat looks good i would probably fiberglass it if i were you. I have an updated design ive been working on of this boat that im currently at the same place as you with. ive relocated the steps raised the rear deck to give it a little more room inside and majorly changed the tunnel. I changed alot of this stuff so she runs alot better in rough water as i live on the shores of lake erie. Glass water is in short supply here unless i run in ponds.

[Jesse J]

that is great Alan, I would like to try this revised version once you get a prototype or two out in the waves. I am super happy with even this version - looks AND handling! I will be working with the transom area to approximate the more tapered Mystic design that I so love - the rear end is one of the most important parts for me!

Yes will be glassing the exterior - a buddy and I were talking about some motor hatches for the twinskies - need to be able to get in there and move around. At 36" there is A LOT more room to work with inside there now.

[shockerman80]

i am changing the rear to narrow it as well to replicate the mystic style.

[Jesse J]

Hey Alan (or anybody!), Do you have a good place to get/make the drives for this? Any less ridiculously expensive option would be interesting.

I am looking at the ones at MHZ and for $270 a pair I have a hard time selling a whole boat for just the drives on another... But, they are absolutely gorgeous...
http://www.mhzusa.com/images/m-1675_A_1.jpg


I am thinking of this rudder too ($115).
http://www.mhzusa.com/images/m-1675_R_1.jpg


AND a paint scheme of the Platinum Princess.
http://www.turbinemarine.com/images/platinum/plat_27.jpg

[blackcat26]

Hey Jesse, what about those from tough racing? They are the ones pictured in those plans...

[Jesse J]

ya, but they are still $118 each! unless you know of a better line on em...
http://www.toughracing.com/zc126d/images/liftstrut01.jpg
http://www.toughracing.com/zc126d/images/liftstrut02.jpg

they don't have any specs on em and the transom mount is larger footprint.

thanks for the idea, will keep it in mind.

[blackcat26]

I was actually thinking of these that you have recommended to me before. Not as cool but cheaper.

[Jesse J]

.............. well I have a pair of $25 ones that look pretty similar, but this is the "Platinum Princess" and if I have to sell a boat to have scale drives then I will. I see what you mean, and I appreciate the clarification bro. Also, if you notice the footprint is even bigger. I need to get the shafts to exit as close to the tunnel as possible. The farther apart, the more difficult the turning at speeds, or so I have found with the Twintruder.

[shockerman80]

i have speedmaster stingers in my 42 inch mti that work awesome and are pretty easy to adjust. ive also used the older sv27 stingers with good success on the 36" mti i built. All you need to do is make a box into the bottom of the hull for the higher parts. I really cant see spending that kind of money for drives on a model boat. If i ever built twins again i would without a doubt use the speedmaster stingers.

[Jesse J]

how do you adjust the speedmaster stingers with the overhang?

I can see using the SV27 stingers, maybe black ones or painting them black and making a fake support.

[shockerman80]

ask and ye shall receive. this is the way i do it. They are brass plumbing fittings with allen head set screws epoxied into the hull. its a tapered thread so that as you tighten down they seal themselves. Simple quick and easy.

[shockerman80]

some more pics of the same setup

[Jesse J]

thanks man, but I am not seeing it, could you maybe add a sketch? not sure what kind of plumbing fitting you are using, and how it works.

thanks again for sharing. Oh, and I don't see many boats photographed in bed...

[shockerman80]

here hope this helps. i believe i used a 1/8 npt allen pipe plug and a 1/8 Straight NPT Brass Lock Nut to make it. I believe that what it was its been a long time since ive done it just make sure that the pipe plug tightens into the nut. The allen pipe plug shouldnt just thread all the way through. Just cut the hole in the bottom of the boat for the diameter of the lock nut hole. epoxy the nut to the top instant adjustment hole.

[Jesse J]

ok, re-evaluate. hardware will be as follows:

If I can figure out how the Shockerman has the struts adjustable, twin Speedmasters (maybe painted black) and an $18 rudder from OFE store:
http://www.offshoreelectrics.com/prodimages/ose-80055-rudder-3.JPG


for the cost of just the rudder I was looking at, I can get all the hardware... until I get a real job and make some real money and get a real hull.

[shockerman80]

if you want to adjust it just remove the pipe plug and insert the allen key into the top of the speedmaster hardware.

[Jesse J]

So all the NPT stuff is just to seal off the hull, I think I am seeing it now! removing the pipe plug will allow a hole through the hull and into the un-altered speedmaster hardware... thanks dude, I think I can handle that. Especially since I have still to sheet the top of the hull, can make this allowance. Cool, done deal. I will show pics for your approval once installed.

[shockerman80]

i actually made my fit inside the hatch area on my boat so that you dont see it when the boats running. The mti has a slightly longer hatch.

[Jesse J]

ya, that got me thinking to make the hatch on mine large enough or to have another small hatch just for that. Once you get the attitude right, you typically don't mess with it much. thanks again, now to the hardware store.

[Jesse J]

After a little more thought and even less free cash, I am thinking of making up my own ... need to replicate as close as possible the scale ones. Here is what I am gonna make:

http://www.turbinemarine.com/images/platinum/Picture-019.jpg

http://www.turbinemarine.com/images/platinum/plat_23.jpg

[Jesse J]

Here is my idea.. any thoughts? Any good ways to make the strut brace adjustable?

[Jesse J]

Had some fun with the two part foam - my first time. Did the cat and Cyklon simultaneously. Here are some shots of the updates. CF ed the back half of the tunnel, finished the base and sides of the hull and gooped her up with 4lb foam. She is solid as a brick chit house.

Worked on the rear some, got her tapered and ready for the mounts for the struts.

Gonna do the Proboat motor/esc on each side for now, leaving tons of room in the tunnel and rear sponsons for battery placement. She's gettin heavy... probably gonna tip 10+ lbs with a pair of 6S batts.

http://i298.photobucket.com/albums/mm272/wolfmanfotos/boats/36%20inch%20cat%20build/IMG_7995.jpg?t=1295222703

http://i298.photobucket.com/albums/mm272/wolfmanfotos/boats/36%20inch%20cat%20build/IMG_8004.jpg?t=1295222703

http://i298.photobucket.com/albums/mm272/wolfmanfotos/boats/36%20inch%20cat%20build/IMG_7997.jpg?t=1295222703

http://i298.photobucket.com/albums/mm272/wolfmanfotos/boats/36%20inch%20cat%20build/IMG_7998.jpg?t=1295222703

http://i298.photobucket.com/albums/mm272/wolfmanfotos/boats/36%20inch%20cat%20build/IMG_7999.jpg?t=1295222703

[LarrysDrifter]

Looking good.Oughta be solid as a brick.

[Jesse J]

Anybody recognize these struts? I give you a hint: Steve just got em in stock and they are less than $25.

I just flipped em around and viaola, I have my scale struts at nonscale costs. Still working on the support bracket.... The new rudders are awesome, I love em.

Goin with wire drives - how do you like the motor mount idea?

[blackcat26]

Ha sv stingers! Very creative between those and the motor mounts!

[ls1fst98]

looking good! like the turned around sv struts, very creative thinking there! id love to get plans for something in the 35-38" range and run twin t600 outrunners and capable of some rougher waters., an idea for the vertical brackets, maybe find some square tube to fit over the strut and notch it so you can raise or lower the strut

[Jesse J]

Square tube... I like! I can send you a copy of these - scaled to 36" in PDF or if you have Canvas drafting program, I can send you the raw files and you can play with them. Actually, the PDF file is openable in many different vector drafting programs...

[ls1fst98]

sweet, PDF works, we have a laser cutter at my buddys work and he can work with that. greatly appreciated!

[OldMann]

Hallo Jesse J
...propellers used in this application are not good. You need a propeller rotation on the left and a right.

[Jesse J]

copy that. those were two sitting around that happened to be 42mms. I have my CR props on the way from Egneg, so rest assured - props will be opposing directions. thanks for pointing that out, I figured more would have said something about it.

[Jesse J]

So ponds thaw = back to work

got drives in (.078" wire), struts mounted, cooling tubes in and bottom ready for testing. Went with slightly staggered rear ride pads and tried a little negative camber on the inner front sponsons.

two coats of west systems seems to do it - no glass. still need to get the top deck coated and the hatch done. I formed the cowl out of construction foam and did glass that - you never know. Once upper deck is done, I won't have much room to play like I do now. All areas covered in these shots are full of foam, so I don't think there is much risk of sinking - unless somebody stands on it.

struts are starting out pretty much straight - adjust as necessary. Rudder is not impressing me with size... so it might get upgraded. Went with two Proboat motors and Swordfish 120s. Will spin x442 CR props prepped by Egneg.

[tiqueman]

Thats lookin real good Jesse. Cant wait to see it run.

[Jesse J]

Thanks dude,
anyone who has huffed sawdust for weeks/months on end will appreciate what has gone into this one... Simon has been a big inspiration with his design-oriented builds and lacquered balsa look, as well as others out there with a half inch of sawdust on everything int he shop. If it stops snowing, I might get her out in the next few days - electronically she is ready. Just need to get the hatch done and she will be sportin roost.

[dana]

nice work jesse :thumbup1: looks like youve stepped it up a bit on this one:banana: man you love those proboat motors dont ya? hehe cant wait to see video!

[Jesse J]

thanks for the compliments guys.

video is uploaded. (http://www.youtube.com/watch?v=c8rxTqmPDLU)
Overall, she is very stable, turns good - I even pushed one turn and she kinda skidded around it not hinting of flipping. Has a ways to go to get speeds up towards 60, but I think the hull design is success - I like how she rides. Might want to raise struts a tad.

couple issues:
1) she ended up pretty bow heavy... everything as far back as possible and I barely make 33%. I am tempted to add some ballast to the rear.
2) rudder might be too small? she hooks pretty sharp. Could be partially due to negative angle on inside of front sponsons too forward COG?

Funny thing is that my Intruder 38" twin did very similar thing - and had a big rudder.
Maybe just a function of twin cats? or running too wet?

[tiqueman]

:popcorn2:

[Jesse J]

So after copious amounts of west systems (two coats per side) and a fair bit of bondo, she is water - ready.

The hatch was quite time consuming. I ended up using 1/8" bass wood sheet, curved to match the deck and then heavy (6oz) glass and more west systems on the bottom. More in a rush than anything, I added the white styrene to water proof the top for the test runs.

for the cowl, I traced the outline (top and side view) of the cowl on the platinum princess and scaled this to my build size. I then attached these printouts to blocks of insulation board and went to the band saw. After some 80 grit sandpaper and some elbow grease, I got it shaped pretty good. then I west systems'd with heavy glass and then coated a second time for a better finish.

To make a sturdy closure, I have a couple hooks in the front then down in back with the cowl locks (from OSE - the small ones). I also want to tape for extra strength and water proofedness, so I built up a ledge around the cowl. After some bondo and another layer of west systems, we are starting to get there.

Once I am happy with performance and looks, we will paint. For now, I added some adhesive monokote for a bit of color.

[DV8ion]

The boat looks good :smile: I know you found a set of drives already, but I thought these looked pretty good.
http://www.horracing.com/product_info.php?products_id=441&osCsid=nmosjsi51ieal2b0bnnslnjvn1

[Jesse J]

Thanks for that link.. eh! those could very easily be on my next twinskies. BUT, this build was kinda meant to be "lets see what I can do on a budget" build. I know the next one will be an HPR or something sexy like that (once I start making some real money).

[Jacked1]

The boat looks awesome!! :thumbup1: I am deff going (to try) to make a woodie this summer when I get some time.

You could try kicking the bottom of the rudder forward a little to push the bottom of the boat down in the turns some.

[Jesse J]

Thanks for the compliment and seeing the end product - rather than the present aesthetics.

Well, my Speedmaster 21 rudder came in yesterday's noontime mail delivery - and after 4 hours of revamping (modifications and decisions, many of which did not make it to the final setup...) I got her mounted up. During the process, I noticed the low profile servo didn't have satisfactory torque, so I replaced it with higher torque laying down (Hitec 485 HB).

The good news (:sarcasm1:): it started snowing just as I got her buttoned up... now its 29F and 4" of snow... WTF???

Anybody have any good ideas about what to do with the water pickup? I have thru-hull pickups that are sufficient... now can either plug or do something fun with water spout...

[Meniscus]

Jesse, are you running 4s2p?

[Boaterguy]

if you put a vaporizer/boiler in there, run the steam over the prop to reduce cavitation, it works with engine exhaust, I don't know about steam, you could even try it with water just to add a little pressure behind the blades

[Jesse J]

Jesse, are you running 4s2p?

4S1P - I think the batteries are bunk; Nanotech 4000mah 45-90c (ya right!). Test yesterday failed... extra ride pads peeled off and lost a wire drive/prop! speeds didn't even break 30mph... :ThumbsDown01:

Now going with 45mm CF props and epoxied ride pad (so now all ride pads are same depth). I tipped up the props a tad too. If the snow storm is short lived, might get back out this afternoon for another test.

video on the way.

not sure what to make of the vaporizer idea... haven't ever heard of it. please explain more.

[Meniscus]

Jesse, you need to consider running 4s2p. With twin, you're experiencing voltage sag. If you switch to 2p, you should be jamming on plane much better. I wouldn't run 5s or 6s until you get up on plane better.

[Boaterguy]

on full size race boats, the exhaust from the engine is run over the prop in order to reduce cavitation, theres an article on it somewhere, but I forget the site. I was thinking if you boiled water, it would be similar enough to the exhaust, and could also be run over the props. Less cavitation = more speed.

[Jesse J]

Jesse, you need to consider running 4s2p. With twin, you're experiencing voltage sag. If you switch to 2p, you should be jamming on plane much better. I wouldn't run 5s or 6s until you get up on plane better.

if you mean how many packs are in the boat: 2 4S packs, even though each motor only sees one 4s pack, so if that is technically 4S2P then yes.

ran again today.... 28mph on 4S still, but the 45mm CF props... 10mph below what you had calculated. I am wondering if the hull is too heavy - Dad might have rightly named her the "spruce goose"...

Here is video from yesterday (http://www.youtube.com/watch?v=cxn7LcPnZfw). Today she did get a little looser, but still slower than expected. Any reason to not try the 51mm CF props if I stay on 4S?

[Meniscus]

If the hull is too heavy with foam, then you risk pulling some heavy amps. You mentioned it was nearly 10 lbs. ready to run. Is that a guess?

If it is indeed that heavy, it may be too much. In any case, I don't have experience pushing heavier hulls. Perhaps someone else has more experience with more weight could chime in.

[Jesse J]

so you are saying you are a lightweight? I will need to weigh her accurately, might not be that much. Ran today and on 6S2P....... 44mph. somethin aint right...

[Meniscus]

Yes, I'm a lightweight. And you said you have the timing at 15 percent?

[Jesse J]

ya, 7lbs w/o batts, reprogrammed swordies to hi timing. will try on 45 props and if timing is back to where it should be, then will go back to 442 props. Then to throw the data loggers in and see that both are working the same amount.

[Simon.O.]

If it is any help at all, I ran 42 props on mine for a while and had the struts here there and everywhere and could not get the Cat to fly even with some not to clever rpms. :eek:
I fitted the 45's and got the results !:rockon2:

[Boaterguy]

Try to lower the stinger a little bit, it seems to be running pretty dry

[sambini]

What would be a good size sinlge motor for the single drive version?

Thanks