Why do twin engine boats never have the same amount of hours?

[ranger58sb]

Originally Posted by Goosebumps

Also catamarans power or sail should be operated under one engine when calm seas, little current or head wind.

Just a flag on this for those whose twin-engine boats should not routinely be operated under only one engine. Gear issues could be an example. Check with manufacturers, first.

(Our gears are OK for free wheeling at our trolling speeds of ~2.5 kts per manufacturer, but not at higher speeds.)

-Chris

[b_mac]

Thanks Gents

[rwidman]

Originally Posted by Zoid

Some prefer to keep a difference in hours between the engines to space out the maintenance required. Easier to service one engine at a time rather than have both to do at the same time.

Do you do that?

It makes no sense to me. If you have to get out all the tools and equipment and buy the supplies (and dispose of the old fluids and filters), it would make more sense to me to do it all at one tine and be done with it.

[Goosebumps]

Originally Posted by ranger42c

Just a flag on this for those whose twin-engine boats should not routinely be operated under only one engine. Gear issues could be an example. Check with manufacturers, first.

(Our gears are OK for free wheeling at our trolling speeds of ~2.5 kts per manufacturer, but not at higher speeds.)

-Chris

Are you saying that if we sail fadter than 2.5knots we got to run both engines?

Indedd always better to check the properties and limits of your yacht's twin engine setup.


Sent from my iPad using Cruisers Sailing Forum

[ranger58sb]

Originally Posted by Goosebumps

Are you saying that if we sail fadter than 2.5knots we got to run both engines?

Indedd always better to check the properties and limits of your yacht's twin engine setup.

No, not at all... necessarily.

Just useful to check with your gear manufacturer about whether freewheeling is OK or not... given potential issues with lube (in some gears) when the prop's turning but the engine isn't running.

-Chris

[svfraidknot]

CALM SEAS FAVORABLE TIDE LITTLE WIND running BOTH MOTORS AROUND 1600 RPMS I CAN MAINTAIN A SPEED OF 5.8 KNOTS as high as 6.2 .. mine is a very heavy boat 42 solaris ,, 1978 so very heavy construction ,, one motor same rpm 3.9 to 4.8 3/4 gal per hr each motor ,, i ran once 2200 rpms for an hour my speed increased little but i was in some heavier seas unusual circumstances ,, does this seem normal for a boat this size ????50 hp yanmars less than 1000 hours each original motors ..

[smj]

Originally Posted by Goosebumps

Very good point. Also catamarans power or sail should be operated under one engine when calm seas, little current or head wind. Often speed difference under these circumstances between using 1 or 2 engines is only 1 or 2 knots, but fuel consumption will be double with 2. Displacement trawlers can operate under 1 engine power but at lower speed as the autopilot wouldnt be able to cope with high power from either port or starboard. On catamarans autopilot copes better.

I agree with you Goosebumps

[ranger58sb]

Originally Posted by svfraidknot

CALM SEAS FAVORABLE TIDE LITTLE WIND running BOTH MOTORS AROUND 1600 RPMS I CAN MAINTAIN A SPEED OF 5.8 KNOTS as high as 6.2 .. mine is a very heavy boat 42 solaris ,, 1978 so very heavy construction ,, one motor same rpm 3.9 to 4.8 3/4 gal per hr each motor ,, i ran once 2200 rpms for an hour my speed increased little but i was in some heavier seas unusual circumstances ,, does this seem normal for a boat this size ????50 hp yanmars less than 1000 hours each original motors ..

You might consider starting a new thread -- with a useful title -- for that question. Folks who might be able to answer it best might not be reading this one...

-Chris

[Tellie]

On Cats out of charter (If you are looking at used cats) guaranteed one engine has many hours more that the other. Charterers just run one engine to charge their batteries at anchor. If there is a holding plate in the fridge charged with an engine driven compressor as well, the difference may be in the thousands of hours depending on the age of the boat.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

[Stu Jackson]

OK, I'll bite:

for the OP: why do you think they should be the same?

[b_mac]

I just assumed you would always run both, therefore they should be relatively the same. Reading about the hot water etc makes sense to me. Also about engine replacement, didnt think of that one. I appreciate the response folks!

[belizesailor]

Originally Posted by Tellie

On Cats out of charter (If you are looking at used cats) guaranteed one engine has many hours more that the other. Charterers just run one engine to charge their batteries at anchor. If there is a holding plate in the fridge charged with an engine driven compressor as well, the difference may be in the thousands of hours depending on the age of the boat.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

Another good point, engine driven reefer and/or water maker.

[Seymore]

Originally Posted by b_mac

Hey, been noticing on twin engine cruisers, when I look at the engine hour meter, one engine always has more hours? Why is this? Why would one engine be favored over another?

When you make a turn, the outer engine runs farther.

[belizesailor]

Originally Posted by Seymore

When you make a turn, the outer engine runs farther.

Hour meters measure run time not distance. Hours run would still be the same.

[rwidman]

Originally Posted by Seymore

When you make a turn, the outer engine runs farther.

So that side of the boat is actually running faster than the other side.