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Performance #s 34 Yellowfin w/twin Yamaha 300's

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Performance #s 34 Yellowfin w/twin Yamaha 300's

Old 08-04-2011, 03:20 PM
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Default Performance #s 34 Yellowfin w/twin Yamaha 300's

Does anyone have performance numbers running a 34 Yellowfin with twin Yamaha 300 four strokes. Also what shaft length, 25's or 30"s.
thanks
Old 08-05-2011, 10:13 PM
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Hey i dont think anyone as of now has run that set up, but it should top out just under 60 light. The 32 with f300's does 61 light, and with f350's does 67 light. With f350's the 34 reaches 64 mph(best ive heard of so far). The f300's and f350's are always a 4-6 mph difference depending on props, centers etc.
My dream cc is the 32 yellowfin with f350's but the f300's will definitely be a more economical setup without sacrificing much speed, but IMO its hard to beat those big v8's.
Hope this helps!
Old 08-06-2011, 06:35 AM
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Go to yellow fin. com
Old 08-06-2011, 06:56 AM
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I have this setup. My boat is an 05 that I repowered last year with the 300's.
VERY happy with the boat and motors. I was offshore yesterday kinda lite with 150 gallons fuel 200lbs ice and 3 guys/gear and my boat cruised at 40-42 mph getting between 1.4-1.5 mpg.
When you slow down to 34-36 mph it will stay at 1.6 mpg. Send me a pm and I can answer any specific questions.

EDIT: sorry that I did not see the yamaha in original question. I am running twin 300 Verados.
Old 08-06-2011, 08:38 AM
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Originally Posted by Extractor View Post
I have this setup. My boat is an 05 that I repowered last year with the 300's.
VERY happy with the boat and motors. I was offshore yesterday kinda lite with 150 gallons fuel 200lbs ice and 3 guys/gear and my boat cruised at 40-42 mph getting between 1.4-1.5 mpg.
When you slow down to 34-36 mph it will stay at 1.6 mpg. Send me a pm and I can answer any specific questions.

EDIT: sorry that I did not see the yamaha in original question. I am running twin 300 Verados.

What's your top speed?
Old 08-06-2011, 10:23 AM
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read John Brownlee's article with 2x275 Verados.
i would think it should within 10 % of one another.

http://www.yellowfinyachts.com/os34.html

http://www.yellowfinyachts.com/os29.html
click on 34



Bonus question what is 557 in the US Navy .
Who do you think built it,what engines and numbers.
What material was used for the hull.
This one had some new fangle electronics installed?RADAR

http://www.navsource.org/archives/12/05557.htm

http://www.pt-boat.com/packard/packard.html

Last edited by conehead39; 08-06-2011 at 01:39 PM.
Old 08-06-2011, 07:09 PM
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Originally Posted by MakoMyDay View Post
What's your top speed?
My top speed with the 275's and 19 mirages was 52 and with the 300's and the 19 Rev 4's is 55.(medium load....don't care about top end with FULL load) This boat is usually outfitted from the factory with the 21's but I frequently tuna fish/bahamas and run heavy with 360 gal of fuel and full load of crew/gear so the 19's serve me better. Could probably get a little more top end from the 21's but I am more concerned with getting on plane and midrange fuel economy for long trips.
Old 08-07-2011, 04:41 AM
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Low to mid 50s sound about right for twin 300s on a 34. If you go light a lot of the time its fine. If u load it down 350s for the larger diameter prop or trips would be better.
Old 08-08-2011, 12:22 AM
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Originally Posted by bradv View Post
Low to mid 50s sound about right for twin 300s on a 34. If you go light a lot of the time its fine. If u load it down 350s for the larger diameter prop or trips would be better.
second the 350's. They may be the quietest outboards I have ever driven. Id say quieter than my f150 and f250's. They have massive torque but yes as we all know they are economical...until you go over 4500 rpm. Then she starts to chug. I wanna say 4k rpm will give you a 40mph cruise at 26 gph or maybe better depending on load. 5k rpm your burning over 40 and hour and 6k your burning near 70. I say wake up bright and early and cruise. I think if you get the f300's you will regret it when you really load her down heavy.
Ive never been a fan of having more than 2 outboards but i guess trips could be nice for redundancy.
My advice, get those big bad v8's. Great motors. You will forget that they are idling.

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