WELCOME TO RIVER DAVES PLACE

To Flop....or Not to Flop.

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
Ok...for all of you salty dawgs who have experience with Cats which have twins with high X's....whats your sequence to get 'em flopped over? My current boat (and 4th Cat) is a 28 Speedster with twins, XR/SSM 1.35 drives with -2 shorty (and now 1/2 spacers) running 34 labbed Max 5's. Also has a center tab. It's been an adventure learning how to coax it on plane. I'm about 80% successful now but if you miss the cue's you are toast...pray nobody is paying attention and start over. I've tried the "turn the wheel to the right, back and forth" deal once the nose lifts to move some air to the props, it can help but it's finicky and timing has to be spot on. PS...it takes a few seconds at 1/2 throttle to get it to the point where the props are about to break loose. If you're not ready when they break....it's 4K RPM and a class B shit-show going on. That said when you get it all just right it's like an Old Milwaukie beer commercial..."Doesn't get any better than that".

What's your Secret?
 

OldSchoolBoats

No longer "boatless".......
Joined
May 8, 2014
Messages
13,299
Reaction score
16,157
Are you burying your tab???

Have you tried a -1??




Sent from my SM-N960U using Tapatalk
 

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
Are you burying your tab???

Have you tried a -1??




Sent from my SM-N960U using Tapatalk
Yep - Tab and drives buried. Have not tried a -1 but even the 1/2" spacer scrubbed some top end, prefer not to lose any more if I can help it.
 

Wmc

The Mayor
Joined
Dec 20, 2007
Messages
4,151
Reaction score
2,224
Sounds like that's what you got. My 30 was the exact same drove me nuts. Props break loose boat starts to roll over, pull back throttles
 

Flying_Lavey

Dreaming of the lake
Joined
Feb 13, 2008
Messages
15,577
Reaction score
9,624
Yep - Tab and drives buried. Have not tried a -1 but even the 1/2" spacer scrubbed some top end, prefer not to lose any more if I can help it.
Don't bury the tab. When the bow rises it increases the negative angle to the point where it'll act as a water brake. I'd suggest neutral to slightly negative for the tab and drives tucked.

(Mind you, I have no experience in big power twin or single cats)

Sent from my LM-G710VM using Tapatalk
 

Singleton

Well-Known Member
Joined
Feb 5, 2008
Messages
11,470
Reaction score
9,965
Take it to Teague and have him play with the setup.
He should get it dialed in for you and then explain what needs to be done
 

lake p.a.l.

Well-Known Member
Joined
Jun 18, 2009
Messages
3,843
Reaction score
3,880
I truly wish I understood why some cats do this. I drove Bullys 28 Nordic a few weeks ago and tried to learn this "system" without great luck. I hope to learn something from this thread.
 
  • Like
Reactions: DWC

prosthogod

Well-Known Member
Joined
Jan 3, 2008
Messages
1,917
Reaction score
988
My 4 th cat. This is a 30ft magic septor twin670hp. switched from 5 blade maximas to 4 blade hinson. Incresed top speed by 5mph, and didn't effect coming out of the hole. 3k rpm and it rolls right over. It's for sale!
 

MotiV8

Member
Joined
Feb 12, 2019
Messages
24
Reaction score
22
Where is your prop shaft centerline in relation to the running surface? I assume since you're running 2" shorties (plus a 1/2" spacer) that it is above the bottom by about 1-3/4", but verifying that will help narrow down issues. Are you running on extension boxes?

Out of curiosity, what speeds have you been able to get and @ what RPM?
 

Boat Bling

Well-Known Member
Joined
May 20, 2014
Messages
1,158
Reaction score
1,324
Don't bury the tab. When the bow rises it increases the negative angle to the point where it'll act as a water brake. I'd suggest neutral to slightly negative for the tab and drives tucked.

(Mind you, I have no experience in big power twin or single cats)

Sent from my LM-G710VM using Tapatalk
I've got some hours behind the wheel of a 28' tall deck. Heavier layup but same bottom and likely similar setup. What Flying Lavey said was correct and made a big difference cutting plane time by 50%. Especially helpful when loaded down and seems to be much easier on the drives.

Try setting tab to neutral then lift up as soon as boat planes out.

Interesting trick discovered at Powell. If props wont blow out and boat is just bogging along, trim up a bit to aerate the props and build some RPM.

If all that doesnt work, check out the max machine "whale tail", most speak very highly of it.

-Zack

Sent from my SM-G955U using Tapatalk
 

HGP3

Well-Known Member
Joined
Sep 5, 2018
Messages
1,827
Reaction score
2,325
I truly wish I understood why some cats do this. I drove Bullys 28 Nordic a few weeks ago and tried to learn this "system" without great luck. I hope to learn something from this thread.
Is this considered an issue, or just something you deal with? I would think if BHB's boat has this "issue", it must be something you just have to deal with? From what I've read on the forum, BHB seems to know about setup. I'm surprised his 28SS does this.
 

McKay

Well-Known Member
Joined
Jan 22, 2015
Messages
616
Reaction score
325
I slowly roll my boat over, I hold it to about 3K RPM's till it stops gaining speed then just a little more throttle and it will start to cavitate and roll over. When it cavitates I keep pulling back on the throttles and try to hold it at 4500 RPM and keep it under 5K and it will roll over in less than a couple seconds.
 

ONE-A-DAY

Well-Known Member
Joined
May 21, 2010
Messages
13,804
Reaction score
13,765
Yep - Tab and drives buried. Have not tried a -1 but even the 1/2" spacer scrubbed some top end, prefer not to lose any more if I can help it.
What has Kenny been suggesting? Are they trying to sort it out for you?
 

Sigus

Above the wet spot
Joined
Dec 20, 2007
Messages
814
Reaction score
456
If you are using max 5 I assume you have pulled all the plastic plugs to help with aireation.

Sent from my SM-G965U using Tapatalk
 

lake p.a.l.

Well-Known Member
Joined
Jun 18, 2009
Messages
3,843
Reaction score
3,880
Is this considered an issue, or just something you deal with? I would think if BHB's boat has this "issue", it must be something you just have to deal with? From what I've read on the forum, BHB seems to know about setup. I'm surprised his 28SS does this.
His 28 Nordic is absolutely DIALED in. I know a lot of center pod boats, I/O & outboard, single & twins, struggle to get on plane. I'm in NO way bashing, I love all boats, fast & slow.
This is just gonna be a thread I learn from.
 

HGP3

Well-Known Member
Joined
Sep 5, 2018
Messages
1,827
Reaction score
2,325
His 28 Nordic is absolutely DIALED in. I know a lot of center pod boats, I/O & outboard, single & twins, struggle to get on plane. I'm in NO way bashing, I love all boats, fast & slow.
This is just gonna be a thread I learn from.
For sure! I wasn't trying to make it sound like you were bashing. I'm learning as well. I was curious if this is just part of the program when owning a cat.
 
Last edited:

pkbullet

Well-Known Member
Joined
Jun 19, 2013
Messages
370
Reaction score
818
Not the same set up, buy my experience. First boat m29 565's center tab. Finally got to roll over consistent with five blades and drive plates, still a dog though. Second boat m31 860's no tab, first season pain in the ass people climbing under bow. Second season added areators and everything works fine except you have to be over 167 degrees because she is banging 5 grand to roll over. My neighbors mti rolls over like my MasterCraft, and pisses me off every time.
 

4czn10

Well-Known Member
Joined
Oct 28, 2012
Messages
230
Reaction score
121
i have the same problem. My 27 Ultra Shadow whippled 525 running scx drive 1.36(?) and a 26 bravo. I've tried the max machine "whale tail", and it made it worse for me. i do leave the tabs at neutral or a little bit down. i slowly take it up to 3500-3800 then a couple of s turns and it gets up in about 8-10 seconds with 2 adults. Of course if i have more passengers, i need to move some up to the open bow, and take it to 4000. if y'all tell me that's normal, then i will live with it. it's just a little frustration coming from vee hulls...
 

Tom Slick

Well-Known Member
Joined
Apr 8, 2008
Messages
804
Reaction score
847
Ok...for all of you salty dawgs who have experience with Cats which have twins with high X's....whats your sequence to get 'em flopped over? My current boat (and 4th Cat) is a 28 Speedster with twins, XR/SSM 1.35 drives with -2 shorty (and now 1/2 spacers) running 34 labbed Max 5's. Also has a center tab. It's been an adventure learning how to coax it on plane. I'm about 80% successful now but if you miss the cue's you are toast...pray nobody is paying attention and start over. I've tried the "turn the wheel to the right, back and forth" deal once the nose lifts to move some air to the props, it can help but it's finicky and timing has to be spot on. PS...it takes a few seconds at 1/2 throttle to get it to the point where the props are about to break loose. If you're not ready when they break....it's 4K RPM and a class B shit-show going on. That said when you get it all just right it's like an Old Milwaukie beer commercial..."Doesn't get any better than that".

What's your Secret?
I didn't see it posted, but what motors and horsepower does your boat have? And what is you current top speed?
 

CJ_Donahue

Well-Known Member
Joined
May 24, 2018
Messages
948
Reaction score
1,994
I have to be honest, when I read the title I hought this was going to be about Soccer or Basketball.... They are always flopping.
 

MK1MOD0

Well-Known Member
Joined
Jun 4, 2019
Messages
554
Reaction score
714
I had a 28 ft Advantage sportcat with twin 800’s , 135 sport masters and 36p bravos. It had a tab, but I soon learned to just leave it neutral. Dropping it just slowed down the process. I’d start rolling in the throttles, getting the boat moving forward then bring the motors up to about 2500 rpm until she rolled over and the props would spin up. At that point she was off. I did make sure all extra weight such as coolers,gear etc was all the way forward.
 

lake p.a.l.

Well-Known Member
Joined
Jun 18, 2009
Messages
3,843
Reaction score
3,880
For sure! I didn't mean to make it sound like you were bashing. I'm learning as well. I just was curious if this is just part of the program owning a cat.
Not all cats do it. I owned a 28 "cat" deck single BBC that wouldn't aerate prop at all to get on plane, even with crazy heavy loads of people. I owned a 25 Daytona BBC that would aerate the prop a lil getting on plane but never any issue. Currently own 308 Skater twin 300XS that aerates props a lil to get on plane but my 5 blade DeWalds can plane without aerating when boat is light.
Sorry, not trying to thread jack, just want to learn
 

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
Great stuff - Appreciate the replies. It has 600SCI's and Merc ITS boxes so has a little set-back as well. I have the plugs in the Max 5's but was told by a couple people that they do nothing if you don't have thru prop exhaust? I guess I should pull 1 out on each prop and just see what happens? There's like 3 per prop! I'll try backing off the tab next trip out as well and see what that does. Without measuring it I'd guesstimate that shaft centerline is around an inch below outside sponsons...plus or minus. I attempted to trim up a little when the nose was in the air and it wasn't quite ready to start building RPM...that was a "Thanks for playing and do it again". Maybe I'll try trimming up a little right from the start and see how that fares. Top speed thus far was 128 at 5850 with Kenny at the helm, assuming it was on fumes. Since then we have added the 1/2" spacer and dropped the center tab 1 notch which gives it more down leverage but also doesn't lift it completely out of play when its all the way up. With those changes my top thus far has been 122 but with 3 in the boat and a bunch of fuel.
 

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
What has Kenny been suggesting? Are they trying to sort it out for you?
They did the spacer and lowered the tab, if I couldn't live with it the next solution would have been to add more spacer which would also scrub more top end. I'm gettin' better at it so its not enough of a PITA to mess with more spacer...just hoping to rule out and tricks of the trade that I may be missing. LOVE the boat, just don't love getting it on plane. :)
 

GRADS

Nonessential Mod
Joined
Dec 19, 2007
Messages
17,092
Reaction score
19,199
I had a 2006 28' Daytona and had similar issues. I have to head out now but I will post my thoughts later after I read every post. I will say this, after skimming through and reading a few posts I was like :eek::eek:. No wonder you fuckers blow so many drives....keep it under 5000 rpm's to get on plane???:eek:
 

MotiV8

Member
Joined
Feb 12, 2019
Messages
24
Reaction score
22
Great stuff - Appreciate the replies. It has 600SCI's and Merc ITS boxes so has a little set-back as well. I have the plugs in the Max 5's but was told by a couple people that they do nothing if you don't have thru prop exhaust? I guess I should pull 1 out on each prop and just see what happens? There's like 3 per prop! I'll try backing off the tab next trip out as well and see what that does. Without measuring it I'd guesstimate that shaft centerline is around an inch below outside sponsons...plus or minus. I attempted to trim up a little when the nose was in the air and it wasn't quite ready to start building RPM...that was a "Thanks for playing and do it again". Maybe I'll try trimming up a little right from the start and see how that fares. Top speed thus far was 128 at 5850 with Kenny at the helm, assuming it was on fumes. Since then we have added the 1/2" spacer and dropped the center tab 1 notch which gives it more down leverage but also doesn't lift it completely out of play when its all the way up. With those changes my top thus far has been 122 but with 3 in the boat and a bunch of fuel.
Correct, without thru prop exhaust, pulling those plugs will not do anything for aeration. 122 with people and fuel seems pretty good to me. I notice a few mph loss with just a few extra people in my daytona. Wish I could help more with your planing issues, but as I'm pretty far under propped right now I usually roll over right around 2500 rpm, regardless of where the tab is set (but with drives fully tucked).
 

02HoWaRd26

Well-Known Member
Joined
Dec 19, 2007
Messages
5,679
Reaction score
9,900
I may have missed it, but what about swapping props, if your running inward flip to outward, seems like a 5 minute swap, then flip levers backwards for a run, if it helps awesome if not swap back. Seems simple enough to test.
 

pkbullet

Well-Known Member
Joined
Jun 19, 2013
Messages
370
Reaction score
818
As some had mentioned about using the center tab, my experience was that with smaller pitch four blade props they would aerate too early. If I put 32 four blades on, I could not use the tab. With 33 5 blades it helped. The drive plates made the biggest difference.
fullsizeoutput_166.jpeg
 

Teague_JR

Well-Known Member
Joined
Jun 7, 2018
Messages
85
Reaction score
219
As some had mentioned about using the center tab, my experience was that with smaller pitch four blade props they would aerate too early. If I put 32 four blades on, I could not use the tab. With 33 5 blades it helped. The drive plates made the biggest difference.
I agree with this setup. Try the larger cavitation plates. All the DCB F29's with 525's or 565's have them... You might even be able to remove the spacers if they work well enough. With our 28 Speedster with INDY drives, center tab all the way down helped reduce planing time and RPM required to plane...

JT
 

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
So...Update. I've now tried 36P labbed B1's (it hated those until the boat got over 70mph, lots of vibration and had to lean hard on them to flop) then went to the 15-1/4" Max 5 34P labs - those are 1/4 larger diameter than my originals. These seem to be the best bet thus far. New trick to NOT blow out the props...feather it up to around 2K, then as the props start to get loose keep 'em at around 2500-2700 RPM and it will slowly gain enough speed to drop over....takes about half a football field to do it but it's at least consistent. The Max 5's seem to be the ticket on this boat...pretty good slip numbers on the top +/- 8% and 127mph at 5600'ish. This boat is VERY trim sensitive....from all the way negative (0 on gauge) you can get to around 1.5 to 2 on the gauge and at that point you have a mile long rooster tail and the slip numbers are horrid. Seems to like virtually no roost on the top end and about level on the trim. If you just tap and I mean tap the trim button at speed the boat immediately reacts. Assuming this is a function of a taller X dim...Looked again and the centerline of propshafts is about even to 1/2 above bottom of sponsons. Still learning but getting better.
 

THE Cat Sass

Well-Known Member
Joined
Mar 7, 2018
Messages
88
Reaction score
158
PS....Tab absolutely must be totally buried. Its not having any part of a non-buried tab at the flop!
 
Top