twin engines for 20ft alaskan /lund

[carmichael]

currently running 115/2stroke yamaha would like to go to twin four strokes for safty reliabilitie and fuel economy. Use the boat for fishing, moose hunting and fairly long distance river travel/ie 2 hundred miles or more without refueling spots. Any suggestions on what combo would be best?

 

[Forktail]

Re: twin engines for 20ft alaskan /lund

Twin F50's.

 

[carmichael]

Re: twin engines for 20ft alaskan /lund

What brand and do you think the top end would remain the same

 

[Forktail]

Re: twin engines for 20ft alaskan /lund

You'll probably lose a little top end because of the added drag of twins and the extra weight. But she'll scoot along plenty fast.<br /><br />You could always go with twin F60's (that boat is rated for 125 HP), but you mentioned fuel economy, and the F60's sit on a bigger displacement engine and will burn a little bit more fuel than the F50's.<br /><br />The F50 and F60 are Yamaha brand. They will be, by far, the most popular and proven in Alaska and the Yukon where I assume you're running. No problems with parts or service. Suzuki's DF50 and DF60 are fuel injected and fine outboards too. But the DF50 is a 3-cylinder vs. Yamaha's 4 cylinder, and finding parts for the Suzuks around the Yukon can be tough.

 

[phatmanmike]

Re: twin engines for 20ft alaskan /lund

forktail.... you couldnt have said it better

 

[carmichael]

Re: twin engines for 20ft alaskan /lund

is thier any word on the street as to weather yamaha might make thier fiftys fuel injected next<br />year as that seams like the way togo?

 

[imported_esoxhunter]

Re: twin engines for 20ft alaskan /lund

Take a look at the E-TEC 60s.

 

[Silvertip]

Re: twin engines for 20ft alaskan /lund

I question the logic of twin anything as a replacement for an engine with double the HP. It is a known fact that an engine of any HP, 2 stroke or 4 stroke, carbed or FI will burn 10% of its rated HP per hour at WOT. So two 50 four strokes will burn 10 g/hr and the 115 Suzy will burn 11.5. The 115 Suzy will very likely get you to your destination faster than the twin 50's so the small difference in economy is made up be the increased drag of two legs in the water and possibly slightly increased weight. In addition, you have to run longer with the twin 50's (it simply takes longer) so there goes the economy. Go to the the Yamaha web site and look at performance tests for the single big motor (use Yamaha 115) and then compare that with two F50's. Since you do run long distances, why not one big engine and a kicker of about 15 - 20 HP for backup and slot trolling if needed. Just being the devil's advocate here and offering an alternative viewpoint. I run a fuel flow monitor and can attest to fuel economy figures. Mine agree with Yamaha and I run a Merc.

 

[dajohnson53]

Re: twin engines for 20ft alaskan /lund

I question the logic of twin anything as a replacement for an engine with double the HP. It is a known fact that an engine of any HP, 2 stroke or 4 stroke, carbed or FI will burn 10% of its rated HP per hour at WOT. So two 50 four strokes will burn 10 g/hr and the 115 Suzy will burn 11.5. The 115 Suzy will very likely get you to your destination faster than the twin 50's so the small difference in economy is made up be the increased drag of two legs in the water and possibly slightly increased weight. In addition, you have to run longer with the twin 50's (it simply takes longer) so there goes the economy. Go to the the Yamaha web site and look at performance tests for the single big motor (use Yamaha 115) and then compare that with two F50's. Since you do run long distances, why not one big engine and a kicker of about 15 - 20 HP for backup and slot trolling if needed. Just being the devil's advocate here and offering an alternative viewpoint. I run a fuel flow monitor and can attest to fuel economy figures. Mine agree with Yamaha and I run a Merc.

I agree with you totally about the fuel usage - gallons per hour are not the pertinent point, MPG is. One little nit to pick - the 10% figure is approximate (and does indeed hold true as an approximate figure). The 115 may burn 10 GPH or 12 or anything in between, still approximately 10%. Same goes for the 50's. Not important though, because the important factor is HOW FAR he goes on a gallon.

I'm also with you on the thought that the 115 is likely to be quite a bit more efficient in MPG than twins. But OP was looking for redundancy. For a lot of uses, your idea of the kicker is the way to go, but if you're doing river running in a largish boat, the kicker often/usually won't get you home upstream. BTDT

 

[Silvertip]

Re: twin engines for 20ft alaskan /lund

No -- MPG is definitely NOT the best measure of fuel economy for a boat, especially when comparing two or models, types, etc. How far you go on a gallon of fuel (MPG) is only relevent if you add the time factor and it is also relevent only for the boat being tested. You can test another totally different boat and get, for example, 10% less MPG. But the other boat may be 15% faster. So in the end, over a given distance, the boat with lesser MPG will get to its destination faster and hence burn the same or even less fuel. The key is flow rate over time, not volume over distance because speed is not included. Airlines use a similar method but they use pounds of fuel/hour which can be calculated into gallons/hour as well.