User Tag List
Results 16 to 30 of 273
Thread: Triple Monty Power on a Scarab.
-
08-15-2012, 11:22 PM #16
Kim,
I"m glad to see that your rig is almost ready for that speed that you've been wanting to achieve. I'll be following your progress. All the best.
MarcDrive it like you stole it!
1991 Allison GSE 1998 225 ProMax
-
08-15-2012, 11:44 PM #17
So what's the official record for carburated CC? And yes the 88 number has very much to do with the fountain.
True Viking
Scarab 34 SS with Triple OMC 4.0 V8's
-
08-16-2012, 12:25 AM #18
Last edited by Smoking Joe; 08-16-2012 at 02:04 AM.
Wellcraft Nova 230 XL, 300hp Johnson.
Seahawk 45 Sport Fisher, twin 306hp Volvo.
Steadcraft 28, Yanmar 300hp. Sold.
Markline 800, Volvo 300hp. Sold.
Haines Hunter V19, Volvo 170. Sold.
16ft 6in Figlass Sidewinder, 140 Suzuki. Sold.
-
08-16-2012, 12:47 AM #19
-
08-16-2012, 07:53 AM #20
Sorry... But I don't think you will be able to turn 29 Bravos. I run tripple labbed 26 bravos through 1.75 gears with 300's. At 6000 I am running 73 mph in my Fountain. 29 bravos are a ton of wheel, even for your 400 hp monty's. Mercury does make them in every pitch now. However, The odd sizes are custom and much more expensive. If you order a 29 bravo XS, it starts life as 28 that is then worked. IE. more cup, removed difuser ring, and large vent holes. The pitch on bravos is not same as three blade either. What I mean by that is, a 26 bravo really measures out to around 24 inches on the pitch guage. Mercury over rated the pitch on the bravos to try and keep the rpm and set up numbers the same for people spinning other mercury props. For example lets say someone is turning 25 Tempests and wants to switch to 24 bravos. Bravos are a great wheel and are my favorite wheel. But it takes gobbs of power to spin em. 15 1/4 diameter and 4 big blades make it very tough to turn. For big boats, the only other prop I like is the Hydromotive. Bravos like to run high, and you will need them very high to turn 29's. I would start with 26's and turn a few more rpms. I know your thinking optimistically, but I don't think you will turn those 29's to 6,500. If you can, you will be flying. Older center console scarabs also have older hull technology. They are not very fast. It used to take a total of 1600hp IO's to make a 34 scarab go 80-85mph. Now you can buy almost any sport boat with 1600 hp and it will run mid 90's. This is just my opinion and I dont know squat. The boat will still be awesome I did not mean to spoil your fun. Again, its just my opinion. Good luck. Can't wait to see you break Fountain's record.
Ps. Just something to think about, On my flats boat I can turn a 26 bravo to 6000 with 1.62 gears to 80 mph. I can turn a 3 blade 28 merc chopper to 6200 and I am running 85mph..... Just shows how much more power it takes to turn the bravoLast edited by native2; 08-16-2012 at 08:24 AM.
Cawley
-
08-16-2012, 09:46 AM #21
-
08-16-2012, 11:44 AM #22
The rule of thumb says 1gph per 10hp, so roughly 38gph per motor. I do have a Lowrance LMF-400 gauge in the boat, but the first of the fuel flow meters are just now on their way to me. When I did the testing with the LMF-200 temp unit I had before, I was only interested in cruise. I cringe to know what it burns WOT.
Keith-
-
08-16-2012, 12:42 PM #23
Ken over at ProGods has a speed calculator program that is amazingly accurate. If you give him your current info he can tell you almost exactly what it would take to get to 88mph. We used it on a 23 Donzi CC going from a single 250 to twin 200 and it was dead on. Also used it on a 23 Fountain like mine that went from a 225 Opti to a 300XS and it was dead on as well. Its actually the reason I didnt repower with a 300 when i had the chance. The difference was only about 4mph and it just didnt make sense on my fishing boat.
13' Biel tunnel AKA "Flight Risk"
13" Modified Yamaha V4 - 101 mph
21' Paramount
Mercury 300 Promax
-
08-16-2012, 12:47 PM #24
-
08-16-2012, 02:03 PM #25Junior Member
- Join Date
- Feb 2009
- Location
- Sarasota
- Posts
- 18
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
this is the calculator. http://continuouswave.com/cgi-bin/crouchcalc.pl
If you know the actual GPS speed you ran with different power, you can put your total weight, HP and speed in to calculate your "hull factor"
Then put in the "new" HP, and erase the old speed to calculate the theoretical speed you would get with the new HP.
Its only as accurate as the numbers you input.
We've used it on a few repowers and its normally pretty spot on.
Some numbers from some of the other 34 Scarabs I've seen with people on my forum. (and they vary quite a bit)
here is one that runs 60 with twin 250's http://www.propgods.com/forum/defaul...g=posts&t=1746
here is one that runs 50 with twin 250's http://www.propgods.com/forum/defaul...g=posts&t=1109
here is one that runs 47 with twin 275's http://www.propgods.com/forum/defaul...?g=posts&t=994
you said the hull weight was 5100 lbs. lets say with fuel people and motors its 8000 lbs. (play with the calculator and see the different results)
lets go with the guy claiming 60 MPH with 250's
That would give a hull factor of "240"
putting 900 HP on there, would give a top speed of 80.5 MPH
If you hit 80, I'd be impressed. I hope it goes 88, but I have a feeling it may be a little short of that.
-
08-16-2012, 02:14 PM #26
ken2, the way I read it is he putting 1200hp on it...
22' Activator w/ 250xs Merc Opti, back home again
-
08-16-2012, 02:26 PM #27
love the na sayers!
Bobby Pazos- Member Of The
BULL-FROG EYES DRAG RACE TEAM
Fellow-G-Man,
Sunshine Syndicate
2006 23' Action Marine 300 HP V8
2001 19' Action Marine White Power
1998 23' Concept CC (sold)
1999 17' Action Marine (sold)
1996 STV River Rocket (sold)
-
08-16-2012, 02:32 PM #28
Will look forward to seeing how it runs. I know my V8 loves fuel i go around 35-38 at 4k with a 23p 15.25 PT prop and if i switch to my trophy plus 24p that speed drops to 30-33mph same rpm. 24p fury prop was even worse.
Just a little Cat.
24 Twister V8 E-Rude (For Sale)
2008 Concept Sport Deck 2x 300X
-
08-16-2012, 02:34 PM #29Junior Member
- Join Date
- Feb 2009
- Location
- Sarasota
- Posts
- 18
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
Yea, if they are beefed up to 400 HP, maybe it will.
Using 1200 on the calculator show 92 MPH.
The question is, will that hull go 60 with twin 250s ?
I hope it hits 88
-
08-16-2012, 03:10 PM #30
I hope it does as well..
Cawley