single/ or twin cruising

I just retired, now i'm wanting to buy a trawler for full time liveaboard, i know that 2 engines will be more $ , my queston is, if you have 2 engines , can you cruise on one at a time? thank you for any opinion.

Yes, maybe but it probably isn't worth it. Some twin engine transmissions and shaft logs can't handle being freewheeled with the engine shut down. You might save 20% on fuel but if yours is a transmission that can't handle it, don't do it. Even if your running gear can tolerate it you are probably talking about going from 3 NM/gal to 3.6 NM/gal at best.

David

Worrying about fuel consumption should be dependent on how many hours a year you plan to operate. If its well above 500 then you have to decide whether fuel conservation is worth the trouble and it does become a significant decision.

Less hours and it's almost not worth worrying about compared to just running the boat the way it was designed.

A properly rigged/engine single is probably your best bet if concerned....if not a long distance cruiser...then get whatever you want boatwise.

After my refit I did sea trials operating with one engine only or with both. I was surprised, initially, that for a given speed the fuel consumption was effectively identical: the single engine at higher rpm and load to give the same speed used the same fuel as running both engines. Not that surprising when you think about it: the fuel burn is the HP required to balance the hull resistance. Now, the idle prop will have some extra drag, but that effect was lost in the rounding/measurement accuracy. This was at a number of points between 5 and 8 knots.

So the only reason to run on one engine (other than a breakdown) is to go slower than is possible with twins, perhaps to really max out the range.

Twins do have an overhead for maintenance, as well as original install if you are doing that. But the extra maneuverability is worth it.

Twin engine vessels run on one engine are all over the map as far as increased efficiency.

Just because one vessel shows or doesn't show a significant change in fuel economy doesn't mean all vessels do/don't.

larry216,
If you're talk'in about the expense of fuel w twins just forget them. Get a single or a smaller boat or a twin w very small engines. I have seen a GB 36 w twin 55hp Yanmars (as an example).

Usually the trips you take ( miles) would not be worth the effort involved.

thank you, that was what I needed, I really enjoy reading the forum. hopefully we will be seeing you out there soon.

for me the biggest advantage of a single engine is reduced mechanical maintenance and the fact that the prop is protected by the keel

I would agree with Motion, My Chris Craft was very manuverable at slow speeds with the twins but maintenance was definately more expensive than a single. With a single and a bow thruster you have just as much manuverability and the benefits Motion spoke about. However tight quarters manuverability suffers on twins when one engine is out. At least you can get home though. Lots to weigh in deciding.

Kevin

Before making that or any other decision about boat choice, you have to know exactly how and where you are going to use the boat. Not what you dream of doing but what you will actually do. Then buy a boat to suit.

boatpoker said:

Before making that or any other decision about boat choice, you have to know exactly how and where you are going to use the boat. "Not what you dream of doing but what you will actually do." Then buy a boat to suit.

Click to expand...

It only took me 8 boats to understand that message. Great advice.