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Friends34 CV thinking of repowering soon. Maybe 2/350 yams instead of 3/275 V rats

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Friends34 CV thinking of repowering soon. Maybe 2/350 yams instead of 3/275 V rats

Old 07-25-2011, 05:52 PM
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Bly
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Default Friends34 CV thinking of repowering soon. Maybe 2/350 yams instead of 3/275 V rats

We usually to and from the canyons at anywhere from 30 MPH or more to a usual 42 to 45 MPH return. 70 miles each way. We are both a little older and wiser. So yes they are slow speeds for most. We have our backs still tho. Also the 34 Sea V get about about 1.2 MPG at 40 MPH. What do you think a pair of Yam 350s will get MPG at 40 MPH and what RPM? His warrantee only has 1 more year and the boat is perfect for the needs.
Old 07-25-2011, 06:49 PM
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Originally Posted by Bly View Post
We usually to and from the canyons at anywhere from 30 MPH or more to a usual 42 to 45 MPH return. 70 miles each way. We are both a little older and wiser. So yes they are slow speeds for most. We have our backs still tho. Also the 34 Sea V get about about 1.2 MPG at 40 MPH. What do you think a pair of Yam 350s will get MPG at 40 MPH and what RPM? His warrantee only has 1 more year and the boat is perfect for the needs.


I have a new 34 cv with 300 Vrats and find the performance excellent with superb fuel economy. Rev4's get me at about 52 WOT light. Yam 350's will not trim up all the way if you stay in water. ie lower still in water.
Old 07-25-2011, 07:06 PM
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Repower with trip 300s if repowering. Twin 350s will be more expensive with rigging remounting dash configuration. 300s unbolt unplug and reverse the process ur done.
Old 07-25-2011, 07:07 PM
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Originally Posted by bradv View Post
Repower with trip 300s if repowering. Twin 350s will be more expensive with rigging remounting dash configuration. 300s unbolt unplug and reverse the process ur done.

Good idea and less costly than Yams!
Old 07-25-2011, 07:24 PM
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Jay, a friend of mine took delivery of his 34 with twin 350s this spring. Let me know if your friend wants to contact him
Old 07-25-2011, 07:36 PM
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I agree with brad, repower with trip 300 mercs. Can usually find them at good prices, plug and play repower pretty much after you get them on. I don't think you will gain much in efficency and if you lose a motor for some reason you can come back on plane.
Old 07-25-2011, 07:48 PM
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One of my friends has a 34 sea vee with twin 350s and he gets mid to high 50's light and low 50's loaded. Hes been real happy with the performance and I believe he is planning on ordering another one with the same setup in the near future
Old 07-25-2011, 07:50 PM
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All have pointed out good points, If you have the gen 1 vrats and you get the new 300's fuel burn will be even better.

Don't know much about the rigging and personally I like twin's vs trips on that boat, but with that trip loosing a motor and being able to get home up in the NE , that to me is a peace of mind.
Old 07-26-2011, 04:25 AM
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Default Thanks Billy and JyamahaR. I thought I explained my self pretty good to the others

Originally Posted by tunatango123 View Post
Jay, a friend of mine took delivery of his 34 with twin 350s this spring. Let me know if your friend wants to contact him
that recommended trips again and even more power???? that we dont use the top speed we have now w trip 275s? that we were leaning towards twins instead. Mostly for simplicity. Two non super charged engines instead of trips. As far as dash work or glass work? No problem I will handle that. I am leaning yam because of service. The marina he has been using let him down on the shift recall. They ran out of parts and ignored his request to repair it early when he got notice in the spring . They fixed many other newer ones that hardly use their boats but ignored him because he is a nice guy. It still has not been fixed???? I say switch to yamaha because we have a local 30+ year best service dealer in the area. It is more about local service and a different marina. Thanks billy for the offer. I think I still got your cel number. We are still just tossing the Idea around. He was going to sell the boat to get new power and I suggested the engine swap instead. Billy If you get a chance ask your friend about his fuel burn at around 40 MPH? The top speeds are more then enough that you stated. Infact billy dont you have twin 350 yams on your YF36? wowI am slow? How is your beautiful 36 doing? Did you bloody the decks many times yet. We have been doing good w the YF tuna. sunday was un real. Left dock at 5 returned in the dock by 4 in after noon w 5 YF. 120 ft of water down here. We got No blue fin down here this year tho.
Old 07-26-2011, 06:58 AM
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Just because you have 900 hp doesnt mean you have to use it all for top end. The biggest thing i have noticed is if you do canyon runs i assume you are quite heavy so 3 props in the water is going to give you better slip numbers than twins. Putting 3 engines on the back will make you go faster but will also allow you to cruise without pushing the motors as hard as you want and then can also get you home on 2. trip 300s will put you about 52k and you can probably sell your 275s for 20k. Or you can buy twin 350s redo all your rigging and probably be over 60k. If you really have that hard of time with your merc mechanic id look for someone else. I have kicked the idea around about switching to trip 350 yamis or twin 350s etc but theres no way to get the numbers to work not to mention the added weight and the prop selection of the 350s have never been enough to impress me when there are such good 300 options now.
Old 07-26-2011, 10:59 AM
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I doubt you will see a big difference in fuel burn at 4k rpm between twin F350's and trip V300's - both will be @ 30gph. Not sure what speeds you will get w/ the V300's, but figure add @ 5mph to the top end, and pretty similar cruise speeds as the 275's, but w/ better fuel burn (maybe squeek out a little better burn if you can move up a pitch, or add some cup?).

Service aside, it seems like plugging in trip V300's would be simpler, better safety back-up, and better performance (slip & response). That said, if starting from scratch, twin F350's seem like a great match for this hull.

Here's a good post:
http://www.thehulltruth.com/boating-...-34-twins.html

& some specific #'s from it:

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I have an '08 34 Sea Vee with F350's.....great set-up for that boat. Light load top end is 61mph, loaded is about 57mph. Cruise at 4000 rpm's/38-39mph getting 1.3-1.4mpg.

From another thread as well:

At 4200 rpm she runs 32-33 knots burning 30gph for almost exactly 1.25 mpg. This is repeatable real world performance loaded for a canyon run in honest 2-3' seas. With a more moderate load or really flat seas, I'll get close to 1.4mpg at the same 4200rpm. In bad seas (honest 4-5's), I'll slow down to 20-22 knots and efficiency will suffer -- maybe 1-1.1mpg. The boat can handle the rough water better than I can.

Top end was 61mph light and before bottom paint. Loaded for bear and with bottom paint she won't do more than about 57mph, but if top speed was my highest priority I would have went with a stepped hull.
Old 07-26-2011, 11:29 AM
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I have run a 34 CV with twin 350's and loved the set up for that hull. The weight is not an issue on the hull and the fuel burn at cruise of 33 knots is around 30 gph. I just repowered my 38 Fountain with twin 350's and love the set up. I am getting around 1.2 overall trip and hope to get better with my new props. To me there is no need for trips on that boat! And its not like having mercs, Yamaha 350's don't break down. LOL!
Old 07-26-2011, 01:21 PM
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bradv- X10, He nailed it in my opinion.

I would stay with trip's, just for the fact, If/when I had to "run", I could.

I would have trip 300's and just lower my RPM's when I am running. When I loaded my boat, I figured that I added 5,000 lbs to it. If I could keep my RPM's down to 3,800 to 4,200. It would save on the fuel in the long run.

Ice
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and then add about 5 or 6 tuna in the 150 lb range

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