Prop position of cat

[Blackmanba]

Hi :) , would you teach me basics of positioning a prop for a cat please. I have a 36" Aeromarine cat.

Should the centre of prop be above the bottom line of hull or align to it?
Should its end point bit upward like mono or straight to the bottom line?

I understand how it should be is heavily depending on water surface condition but I'd like to konw basic settings as starting point. Thank you.

[Blackmanba]

I tried it with the centre of prop about same as the bottom of the hull line and pointing straight backwords. It was stable but not particularly fast. Then I lifted the shaft about 10mm and setted the end to poit bit upwords. It got worse. :p I'll try the centre same to the bottom then point upwords next time.

[BoatDoc]

i don't know much about setting up cats, but i know you're going to have to fiddle with it quite a bit. here is a suggestion based on what i've seen other people do, try the prop at about 1/16"-1/8" above the bottoms of the sponsons. start with a flat angle. run it, check the ride angle, if it's flat give the prop about 2 degrees of up angle. that should get you in the ballpark.

[Blackmanba]

Thanks BoatDoc, great! Iwill try what you told me next time. I think I lifted prop too much at onece.

[Blackmanba]

Hi BoatDoc, I realized that I had set the end of drive shaft at over 1/2 inc above the bottoms of the sponsons with large up angle last time I run the cat. I guess the prop was almost completely out of water. That's why it only made bubbles but barely moved. I was thinking of lifting the bow of the cat only and totally forgot about relativeness of the prop position. :o It is set to less than 1/8 inc abobe and no lift up at the end now. I hope I can try it this weekend. Thank you again and I will post the result. :)

[NOS JOE]

Hi BoatDoc, I realized that I had set the end of drive shaft at over 1/2 inc above the bottoms of the sponsons with large up angle last time I run the cat. I guess the prop was almost completely out of water. That's why it only made bubbles but barely moved. I was thinking of lifting the bow of the cat only and totally forgot about relativeness of the prop position. :o It is set to less than 1/8 inc abobe and no lift up at the end now. I hope I can try it this weekend. Thank you again and I will post the result. :)
Blackmanba, What size prop are you using? I have the 3 of same cats running Picco 80s. I have tried many ways and found that by keeping it flat with the bottom of the hull works best for me. If it's too far down. way too much drag and no long a surface drive. If it's raise the prop too high it will run fine until the hull lift from the water and spin air until you slow down and the boat start sinking back into the water. there is about 1 1/2 -1 3/4 from water line to bottom of the hull depending on weight. If you get the front too high. it will flip when it gets too much air. That boat runs like it's on rail . Just my 2 cent. around what kind of speed are you getting? I have had good luck using The Prather's 275. Happy Boating

[TRIKDYA]

i have the same boat (im assuming you have the Team Believer being its 36").. I have the bottom of the strut level with the bottom of the hull with the strut flat (no angle). Runs pretty dry and gets the front up pretty good even on calm water. This is with a K&B 67 w/ P250 prop.

[Blackmanba]

Hi Boat Doc :), I could not try your suggestions last weekend due to terrible storm.

Hi NosJoe :), my prop is Octura X645 and the heart is an OPS .45 with an OPS pipe but no silencer. It runs nicely when the shaft is parallel to the bottom of sponsons at the same hight to them but the hull itself is also parallel to the water. It looks to me little bit too much drug. Then it does exactly what you described above when the shaft is lifted high up. Lots of babbles and no go. As BoatDoc said, I need to try settings in between. After I read suggestions from both of you, I think the Cat does not require lifting bow much up to get high speed. I have no idea about speed I'm getting, sorry. I'd like to purchase a GPS one day. Happy boating same to you.

Hi TRIKDYA :) , I purchased my hull locally(in Australia) and was told it was Aeromarine 36" cat with a clasic cowl. It looks same as you have other than the cowl. By now I guess my Cat is under power compare to yours or NosJos's. That could make me think my boat was running flat and not fast enough. I only compared my boat to others in RCBM photos. Many of cats were running bow up with huge rooster tail in pictures just like your cat.

By the way, the CG of this boat is about 1' from transom. Is this OK? Thanks for all your help.

[NOS JOE]

Hi Boat Doc :), I could not try your suggestions last weekend due to terrible storm.

Hi NosJoe :), my prop is Octura X645 and the heart is an OPS .45 with an OPS pipe but no silencer. It runs nicely when the shaft is parallel to the bottom of sponsons at the same hight to them but the hull itself is also parallel to the water. It looks to me little bit too much drug. Then it does exactly what you described above when the shaft is lifted high up. Lots of babbles and no go. As BoatDoc said, I need to try settings in between. After I read suggestions from both of you, I think the Cat does not require lifting bow much up to get high speed. I have no idea about speed I'm getting, sorry. I'd like to purchase a GPS one day. Happy boating same to you.

Hi TRIKDYA :) , I purchased my hull locally(in Australia) and was told it was Aeromarine 36" cat with a clasic cowl. It looks same as you have other than the cowl. By now I guess my Cat is under power compare to yours or NosJos's. That could make me think my boat was running flat and not fast enough. I only compared my boat to others in RCBM photos. Many of cats were running bow up with huge rooster tail in pictures just like your cat.

By the way, the CG of this boat is about 1' from transom. Is this OK? Thanks for all your help.

45 OPS might be a bit small for that boat, if it's the 36" Cat. a 67 OPS would be a great start. My problem is your statement about CG. How can the CG be an inch from transom? Are you sure? My boats CG is 13" from transom. At first I thought of the bow not lifting is that you used way too much 2 part mix foam.and with time suck up a bit of water. But when you said the CG is 1" from transom. what is the size of the boat . do you know the weight of the boat? Here is the specs for the cats. I don't know what size you have.
50” Popeyes Hull, 50" Beam:16 1/2" For .90/1.0 Nitro engines or 23-35cc Gas,
Jesse James Hull, 42" Beam:15" For .80/1.0 Nitro engines or 23-25cc Gas.
Team Believer Hull, 36" Beam:14 1/2" For .65/.80 Nitro engines or 23-35cc Gas. Hope the info help.

[Blackmanba]

Hi NosJoe, You misred what I wrote. I stated that the CG was 1' from the transom. ;) Not 1". (1' = 12" = 30cm). 1' is one foot. My boat is 36" long and it means 3' or three feet. I should've said that the CG was 12 inc or one foot from its transom first hand and sorry for confusion. I didn't mean to fool you. :) I forgot to mention that CG was measured less Rx batterys and with an half full tank. It should be about same CG point with Rx batt. in the radio box and a full tank. CG point moves little bit towards the transom as fuel used. Regards.

[TRIKDYA]

Hi TRIKDYA :) , I purchased my hull locally(in Australia) and was told it was Aeromarine 36" cat with a clasic cowl. It looks same as you have other than the cowl. By now I guess my Cat is under power compare to yours or NosJos's. That could make me think my boat was running flat and not fast enough. I only compared my boat to others in RCBM photos. Many of cats were running bow up with huge rooster tail in pictures just like your cat..

after seeing pics of the entire boat, you have the Sprint Cat (not the Team Believer like i have) which they say is for .40 to .80 size motors. Depending on how much the boat weighs, it probably is a bit underpowered with an OPS 45 in it. Id imagin you are probably getting low-mid 40's or so with it.

btw mine actually does not throw up a big rooster tail. Actually has a pretty low one.

[Blackmanba]

Thanks TRIKDYA, so it is called Sprint Cat. Good to konw. Hobby shop owner told me to use .45 size engine for it when I purchased this hull back then. I never knew it could go with upto .80 size engine. It used to be faster than my 50" Gas mono but I recently made the mono lots faster than used to. All the members here helped me a lot about how to set it better. Then I assumed I could make this Cat faster too. May be, it was already running fast as. I never thought it was bit under power. Anyway I will fiddle a little bit more as BoatDoc suggested me before. I'll accept as is unless anything makes any change in speed. Buying a new bigger engine for it is too much for me.

And sorry for misunderstanding of your boats splash but it looks hot and fast anyway. :cool:

[TRIKDYA]

hell it may move out just fine with the .45 in it... all that matters is you have fun running the boat, whether its going 40mph or 60+mph.

no problem.. was just stating it actually has a very low rooster tail. In that pic i was only a little over 1/2 throttle as ive had a wot bug to work out... which i believe i may have fixed now.

[Blackmanba]

G'day TRIKDYA, you are absolutely right. The time I spent looking for all bits and pieces, building them up, running it and fixing it gave me so much fun. And I am still having fun with it. Thanks mate.

Did you say "a little over 1/2 throttle"? You must have huge rooster tail by now no matters it's high or low. Happy boating. :)

[TRIKDYA]

Did you say "a little over 1/2 throttle"? You must have huge rooster tail by now no matters it's high or low. Happy boating. :)

yeah... its been wanting to die if i go WOT, which i believe i have solved after talkin to someone on JRCBD last night (low speed needle too lean)..so ive only been able to do half throttle and just over runs. GPS showed 37.2mph on the pass in that pic (again at just a bit over 1/2 throttle). Im hoping this weekend i will find that i fixed that issue and be able to hit the 50mph mark. The rooster tail is indeed pretty long, just very low.

[Blackmanba]

I hope you sort out your carb. issue and are able to hit the stick all the way up. Post another photo of your low and long rooster with full throttle if you have a chance to take a shot of it. Cool man. :cool:

[TRIKDYA]

ill definetely get more pics, and hopefully some video this time :)

[Blackmanba]

Hi guys there, as I was readimg the thread "Wild thing cog etc", I realised that my CG should've been 28%~30% as the boat was underpowerd. My CG is one foot, means about 33%. This must contribute to heavier bow. I don't think I can get my Cat going like TRIKDYA's Cat even I get prop position right. I mean boat attitude "bow up in the air". :(

Btw, yeh I'm waiting for your awesome video, :flame:

[TRIKDYA]

been a little while... fixed the throttle issue but the water being a bit choppy ended up only getting me this

http://www.youtube.com/watch?v=flcbXLjbVRM

[Blackmanba]

Dancing, dancing.... wops 180 safe landing rescue please

[TwistedLiquid]

Hi :) , would you teach me basics of positioning a prop for a cat please. I have a 36" Aeromarine cat.

Should the centre of prop be above the bottom line of hull or align to it?
Should its end point bit upward like mono or straight to the bottom line?

I understand how it should be is heavily depending on water surface condition but I'd like to konw basic settings as starting point. Thank you.

Hello, new here but I run cats....the idea set up for the cat you have is to have the strut flush with the rear sponson bottoms. This will cause you to pierce the surface and give you a good top speed. You can acomplish this by losing the strut and setting a flat edge from sponson to sponson and use the flat edge to push the strut up to become flush with the sponsons. If you more control of you cat I would go inline with the rudder and prop..this makes it more stable in ruff water..exspecially in turning.

[Blackmanba]

Hi TL, thanks for your advise. I unfortunately didn't have any chance of running my cats for a while and am still looking for my day of run to come. I will definitely try all suggestions and report results hopefully with photos.

By the way, I had a look on your homepage http://www.twistedliquidracing.com/
Cool :cool:

[TwistedLiquid]

Hi TL, thanks for your advise. I unfortunately didn't have any chance of running my cats for a while and am still looking for my day of run to come. I will definitely try all suggestions and report results hopefully with photos.

By the way, I had a look on your homepage http://www.twistedliquidracing.com/
Cool :cool:

Thanks for the LOOKS COOL words...we do have a Sport 20 we just hardwared..and the videos on the front page...it moves real well. Our turn fin, rudder and prop. We hardware the big boys boats all the time but we consintrate on RTR's mainly.

[TRIKDYA]

been awhile again.... finally got to get some clean runs in, here ya go blackmanba

sofar have GPS'd 51.3mph with a X455/3 prop & O'donnell 10%, pipe at just a little over 11". Might be able to get another 1-3mph with the pipe shorter and a little more lean.

http://www.rcuvideos.com/view_video.php?viewkey=c99f0e662c9177946c62

[Blackmanba]

Hi TRIKDYA, how are you? Yes it's been awhile and thanks for the video with good tune. Welldone mate. It seems you have bit more room to improve it faster. Go for it.

Contrary, I've been stuck since then but I will get my cats fly and post a photo or two though it will take a time.

Cheers

[TRIKDYA]

Hi TRIKDYA, how are you? Yes it's been awhile and thanks for the video with good tune. Welldone mate. It seems you have bit more room to improve it faster. Go for it.

Contrary, I've been stuck since then but I will get my cats fly and post a photo or two though it will take a time.

Cheers

Doin pretty good. I think once it starts to get really cold i might be able to get 53mph or so out of it... but im gonna be putting my OPS 65 in anyways, which should put me in the 55-58mph range (at least i hope).

Ive since decided to join the "Dark Side" and am getting a gasser. Buying the IMPBA District 2 champion Mono (Insane gen1 w/ zenoah 260). Really just getting it to be able to play when the water is too choppy for the cat, but i might just start racing as well since ill have a competitive boat. :)

[Blackmanba]

Be honest, I prefer a gas mono. It's much easier to run and handles rough conditions lots better.

I had hard time with my Cats while I blasted my 50" gas mono last time I was at local river. I controled my mono onboard a real boat and we kept going the river up and down for long distance long time side by side.

Show us photos and video of your new addition again please.