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Hey guys, new to the forum. Glad to see a resource like this out there...Been away from boating for a while and ready to get back into it.
I don't want to open up the single versus twin debate. I'm well aware of those pros and cons... but haven't really found an answer to my question. I'm shopping for a used 22 - 26 foot boat. With this economy there seems to be lots to choose from and have already come across the same boat in different engine configs. For example: twin 150's or single 225 also twin 150's or single 250.
I know the total horsepower figures aren't the same but I'm wondering how to calculate the difference in total gph for these configurations. Any ideas?
it also depends on the specific boat. Some boats just run better with one or the other. But a heavy boat with a single 225 may actually burn more gas than the same boat with twin 150s. An engine that is working hard burns a lot of fuel.
There is more to consider than just GPH. You will defenitly burn more fuel with twins in comparison to single if you have the right set up for the boat.Meaning if you set your boat up with the right horsepower for each setup. but you also have to figure in the cost of maintanence such as when you change spark plugs instead of six its twelve instead of one water pump change its two.I do all maintence and repairs that I can handle on mine but whatever I do its double the parts.if you pay a mechanic its also double the labor.
Good luck on your decision
I was talking to a local fisherman last summer and he uses both motors (150 Yamaha 4 strokes) to get on plane and then cuts one motor and tilts it up. Said it was saving him $$$ daily.....anyone ever hear of such a thing? He said that he couldn't plane on just one but once on plane it would stay on plane at 3/4 throttle with the one.
Seems like even though it might save fuel it would be hard on the one motor but then again the other motor is seeing no wear...............
my knowledge is that like with like for HP you loose about 30% from a twin due to the drag of the second drive, props etc
so I would think you would spend 30% more fuel in a twin set up, more or less, obviously with less the HP you might spend less but this as stated by others before depens how much stressed would be the engine to plane and your normal cruising speed
then with twin you have the safety factor which IMO is priceless really, especially if you venture offshore
The guy who gets the boat up on a plane with two and cuts back to a single, is more than likely lugging that single engine, and will have decreased life span of the engine. I would not do that to save a little bit of fuel.
Figure 14 hp per gallon per hour for a gas engine.
If it is a big heavy boat, or you want the twins for redundancy--then go with twins. For a smaller and lighter boat I think that the single is more economical.
if you are worry about fuel for boating. try blow boating instead. wind is FREE!
now if you simply want to know the fuel comsumption. Assumming same boat, same load, same cruise speed and lastly same HP. Very important keyword here. "SAME". Becuase twin will have another lower unit to drag. It will be less efficent. Period.
So a single will win in the fuel efficency - given the senario of "SAME" above. That doesn't go without saying that twin may perform better - more propeller in the water.
Now on the other hand. Say if you went twin. Instead of having the "same" HP as the single setup. You get twin with more HP than the single setup. Becuase this extra HP can overcome the drag of the lowerunit(s). Your fuel economy may be similar or sometime exceeds the fuel economy of the single. This is why some quad boat with lots of HP have similar fuel curve as some triple and some twin. The motor"s" have so much HP combine - they are bearly working in push the boat - yielding good fuel consumption.
Thanks for the feedback guys. Between your responses and checking some outboard manufacturer's data sheets (trying to compare similar boats with similar weights with both single and twin), I think I have the info I was looking for. Just needed a well educated guess. For the boats I'm looking at, which weigh about 4000 lbs dry, twin 150's might get slightly less MPG then a single 225....then again depending on what kind of use they might do better or be same...but I think it would be close (ie. twins would not cut efficiency in half). Not just looking at dollars and cents, but range too...and how this will all fit into my buying decision.
Thanks for the feedback guys. Between your responses and checking some outboard manufacturer's data sheets (trying to compare similar boats with similar weights with both single and twin), I think I have the info I was looking for. Just needed a well educated guess. For the boats I'm looking at, which weigh about 4000 lbs dry, twin 150's might get slightly less MPG then a single 225....then again depending on what kind of use they might do better or be same...but I think it would be close (ie. twins would not cut efficiency in half). Not just looking at dollars and cents, but range too...and how this will all fit into my buying decision.
Thanks again-
IMHO - for any boat that sports that engine class. Zuke 175 would be the motor of choice. Not that I am bias toward Zuke. I am not. I am all for HP to weight ratio. Zuke 175 wins in that weight class. Anything less is shorting yourself of what's available to you.
If you let dollars and cents to the leading - you will end up with a large single. Singe are typically cheaper upfront cost, cheaper to maintain, and most of the time cheaper to run.
As for range. You can always install a larger tank or get some bladder for those one time trip. OTOH if you are always taking long trip. Consider a larger boat. There is a reason why larger boat have bigger tanks. Not becuase they drink more. But becuase they typically can handle larger seas - hence going out farther.
single or twin - fuel economy
