Engines

Yorkshirelad

Active Member
Oct 21, 2017
132
Stratford
Boat Info
340 Searay 86
454 Mercruisers with v drives
Ray-marine radar and gps
Engines
454 mercruisers
Hi Guys,
Just a question as I’m new to power boating, would you run on the one engine when putting along slow or use the two 454’s just asking.
Cheers Rob
 
Welcome Rob. Not sure if your '86 340 has crossover cooling for the shafts like the newer 340's or not, but if it doesn't you'll want to run both engines. Your shaft seals are cooled via raw water and the shaft on the non running engine will rotate underway. This will heat and quickly wear away the shaft seal on that engine.

Anyway, this thread goes into it more in detail : http://www.clubsearay.com/index.php?threads/cruising-on-one-engine-only.13646/
 
I have Tides dripless shaft seals with crossover cooling lines. I also have Garmin GFS10 flow meters so I can run a comparison. If gas prices keep climbing it may something to consider doing when safe to do so.
 
Welcome Rob. Not sure if your '86 340 has crossover cooling for the shafts like the newer 340's or not, but if it doesn't you'll want to run both engines. Your shaft seals are cooled via raw water and the shaft on the non running engine will rotate underway. This will heat and quickly wear away the shaft seal on that engine.

Anyway, this thread goes into it more in detail : http://www.clubsearay.com/index.php?threads/cruising-on-one-engine-only.13646/
Thanks Mike I will check it out!
 
Crossover cooling is not universally safe for unlimited operation. THey can back feed and cause problems. Just be aware of how they are implemented on your specific boat and use accordingly.

Mark
 
I would err on always having both engines on, and ready. What do they burn at slow speed? Mine burn 1g/hour each, maybe 1.5, even so, turning off one saves me only 6$ each hour in FL. And I’m assuming my boat goes at the same speed with 1 vs 2 running, which it doesn’t.
 
From a safety standpoint, I would never voluntarily turn off one of my engines just to save fuel. Consider maintenance and resale value also. You would have to constantly be checking to see which engine has more hours and try to even it out because trying to sell a boat with one engine with much higher hours would be a big red flag in a survey. For maintenance, those tasks are typically timed by the hours on each engine. Would you want to have to do an oil change on one engine and then the other a few months later? It doesn't seem practical. The last factor you should consider is maneuverability. A boat with two engines is meant to run with two engines and steering will be affected by only running one engine.
 
From a safety standpoint, I would never voluntarily turn off one of my engines just to save fuel. Consider maintenance and resale value also. You would have to constantly be checking to see which engine has more hours and try to even it out because trying to sell a boat with one engine with much higher hours would be a big red flag in a survey. For maintenance, those tasks are typically timed by the hours on each engine. Would you want to have to do an oil change on one engine and then the other a few months later? It doesn't seem practical. The last factor you should consider is maneuverability. A boat with two engines is meant to run with two engines and steering will be affected by only running one engine.
This!
 
I'm pretty sure you'll get same or better fuel economy on two engines at 8-10 MPH than one engine at 6-8 MPH. I tried on a Pursuit 28 with two Yamaha outboards a long time ago.
 

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