I could use that prop info CR. Maybe a PM?Originally Posted by Cap'n Ron
Comparing a 300hp 350ci with a bravo 2 drive and a duoprop.
Also a 383ci with 50ft lb more of tq. With them two drives.
The tq of them engines is 350ft lbs and 400 ft lbs.
Looking for the best setup to scoot across the water faster at lower rpm with best mpg.
PM sent.
On my Shamrock I'm running 13x11 rh. I'm not real fast but I can tow some heavy schtuff. Have tow set up cause it used to be a Marina boat. My mpg is right up there. MDR to Catalina and back on less than 15 gals of diesel. When I run the fly I use one tank to get there and fish and the second tank to come in. Center displacement and a keel with a shaft drive.
I don't worry about out drives and lower units anymore.
What rpm at what cruise speed are you doing with that prop?
15 gals round trip to Catalina? You must be getting 3 mpg or better.
I was looking into diesels for my boat.
A 4 cyl diesel doesn't have the power to push my boat. Cost is 24k also.
A $32k 6 cyl diesel will not fit very good.
Would need 6" of more forward space. Fuel tank in the way.
Would also have to raise my engine hatch 4"
That im not willing to do. I like my flat decks.
Those engine prices are complete with drives.
A complete Merc 383ci efi is 13k All carb 383ci are pushing over 400hp.
All new small blocks with trans run near 13k.
Cutting corners could stay with my Alpha 1 outdrive.
Then replace smallblocks at 3k for rebuilt or 6k for new.
My boat needs to do 20 kts to get on plane.
Bravo 2 drives have huge props that are suppose to lift heavy fishing boats on plane faster.
Probably giving a nasty list condition. Trim Tab that out.
Bravo 3 duo props. are supposed to have 30% more forward thrust then a single prop.
Sounds like that gives more speed at lower rpms. Planeing sooner again?
Bravo 2 is a stronger unit.
Everybody seems to upgrade to duoprops. Ive been told the bravo 2 is better for my boat.
Very hard to get good accurate info out there.
Paying 11k to 19k more money for a diesel would take a long time to break even.
Diesel fuel cost about 1.00 per gal more then gas also.
Will have to live with burning more fuel per trip with the gas motor.
A engine/drive upgrade probably get me 1.8 mpg. if lucky 2.0 mpg.
Getting like 1.5 mpg now. 3400 rpm@19kts 16x14 prop 1.47 gear ratio.
Had a 15x17 prop. 3200rpm@21kts. Very nice. Broke a tooth on a pitted pinon gear.(Mechanic didn't change)
16x14 prop slower. But much easier on the outdrive.
On the computer again. No mtn bike ride at the beach today. Guess I should go finish installing my fresh water washdown.
Last edited by Tail Chaser; 05-31-2008 at 11:11 AM.
cruise it at 1900rpm 16 mph.....fast enough for me.
I just filled both tanks to the top. Taking xtra weight with me like when I'm fully loaded down for the fly. Gonna run my burn numbers back and forth and see if I'm not squeezing 4mpg or more.
Tanks are 25 usable. Pick-ups mounted way back in the tank. My bait bag is mounted on my port stern. I run the port side tank when I leave port. Coming back in I'm drawing off the starboard tank the ride stays nice and level. I don't play with the trim tabs that much port to starboard when running.
Yeah Diesel is a buck or more a gallon, but I'm getting way better than 1.6 per.
1900 rpm at cruise. Whats the redline on that Perkins?
The 4 cyls work great in 24' and smaller boats.
The Yanmar and Volvo diesel tech guys both told me I need 300hp.
Thats requires the 6cyl in line.
I need more ponys to play with.
My inflatable gets like 15mpg.
Thats good enough for me.
Got to take it out to the shoe.
Pinpoint exactly one kind of mpg I get.
Last edited by Tail Chaser; 05-31-2008 at 02:12 PM.
damn,now i know i dont want a bigger boat then my 13' whaler,,,3-4 gallons of gas a day...
You also dont have to worry about getting out there where..... Your going to scare yourself on them big waves either.
I keep my swim fins for economy
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