in board / out board

[Lynx]

It all depends on how it is set up. The factory way is to set up the Alt to only put out a small amout at idle and full amount at normal RPM's. You can get a device to change this although you may have warenty issues.

Most manuals will have a chart on this. Some motors do not like to be at idle much.

[Pericles]

Rickm505,

What would be the cost of fuel polishing or a day tank in comparison with running your diesels longer and using the fuel more quickly, so you always have fresh fuel in your tanks?

Just curious.

Pericles

[Tropic Cat]

At fuel usage of a pint an hour per engine at cruising speeds, it's just too many engines hours to make it practical to burn up the fuel as we use the boat on weekends. Also, running 2 diesels for 8 hours just to burn up 1 gallon of fuel in each fuel tank just doesn't seem practical from an engine 'wear and tear' standpoint. Notice I said 1 gallon. Common understanding is to keep fuel tanks full to minimize condensation, ie microbes growing at the fuel/water line in the tanks, especially here in the tropics. If I kept my tanks full, I'd have a real eco-disaster on my hands when I'd have to get rid of the old fuel.

I read a post on the boatdiesel forum where the fuel degredation problem was discussed. Apparently in recent years oil companies changed the oil distilling process to extract more usable fuel from each barrel of oil. This cracking process is more efficient yet the end product doesn't store as well as the old product, so it's a concern for all sailors with diesel engines.

From what I understand after a few months there are particles that begin to separate out of the fuel which rapidly clog filters. Add the age old problem of microbes in fuel tanks to the new particle problem and it really does become a rapid filter clogging issue. This has stimulated my interest in an onboard fuel polishing system.

[Pericles]

Rick,

In which case would these help?

Bugs in my fuel

Testing

Cyrus Energy fuel treatment products

Fuel Treatments - Force 4 Chandlery

Regards,

Pericles

[Tropic Cat]

My friend, been there done that.... or rather am doing that. Bugs in the fuel are treatable. Fuel that is designed to go bad over time is not.

[beau]

I am a advocate of Newer type outboards being suitable for cruising,
BUT only if the boat is properly designed for it. Your boat is NOT.
With what you are suggesting I would definitely go for an inboard diesel.

[Tropic Cat]

Beau, I'm curious. What boat is properly designed to operate an outboard with the same performance and efficiency as an inboard diesel in a cruising environment?

[beau]

Ok Rick, good question.
What I was trying to say is that it is no good putting the outboard out at the far stern of a boat that is designed to pivot at approx 2/3 of its waterline length, the prop will come out of the water and over rev. in large seas. The pivoting point of the boat has to be much further back like it is with a planning power boat, so that the props stay in the water.
There are many outboard powered Planning boats that are very safe in large seas. The problem is they use too much fuel to be suitable for cruising.
There is a schionning cat that sucessfully uses outboards.
My Trimaran with a wide stern is designed for outboard power either gasoline or Diesel (Yanmar)

My point in general terms is that outboard power has improved tremendously over the last ten years or so.
Four strokes are quiet, fuel efficient and very reliable with a much longer service life (if you buy Japanese)
They are also light weight and much cheaper than diesels and very very safe if set up properly.( In spite of rhe unrealiable,misinformed information that comes out of this forum sometimes)
Outboard ripped off the back of boats??? gasoline tanks blowing up for NO reason.???
Diesels are heavy, expensive, and are only reliable if run under load most of the time. (which does not happen with most sailing boats).
Most diesel motors I have had in Yachts had a dismal record of reliability because they were not used properly. (under load) Technology wise, they really have not improved either.
All that said, I am not in favour of gasoline inboard motors unless set up with Bilge blowers etc running continuously.

[bearphish]

i am lucky i have an inboard well on my new (old) boat. i really dig this arrangement, don't require a long shaft motor, and i have picked up on the "wheel barrow inner tube shaft seal" idea and is so far working like a charm. every once in a while i have to check and see if the inflated donut of an inner tube has not worked it's way out of place, but that is the extent of the maintanance. i may pull the motor and completely clean the shaft area of oil and grime where the tube resides, thereby helping to further keep the tube in place longer. this set up keeps the inboard well nice and dry, eliminating any fill up or splash-in of seawater into the well area. best idea i ever heard of. i know my old johnson approves!

[Tropic Cat]

When I was looking for my boat I had put diesels on the list of items to have based on reading forums like this one. I've had the boat two years now and can honestly say that if I had to do this over again I'd go in a different direction.

Beau makes a good point in that diesels are designed to run at load. Look at all the "my engine is broke" posts to see what diesel owners have to put up with.

In my way of thinking, it's difficult justifying paying double or triple for powering our boats with diesels just to end up with more problems than the less expensive option.

[Ex-Calif]

Inboard diesels provide convenient electrical power and when maintained properly are uber reliable. Broken diesel threads are usually very old diesels or poorly maintained ones.

The other dirty little secret is that those that got 'em use them more than they would like to admit. I admit to running the iron genny "lots and lots." Primarily because I can sail till the wind stops (nightfall usually) and then motor home. I could plan better but I don't need to and the last 45 minutes under power allow me to charge the batteries, have a cocktail and square away the boat for a hasty departure after we catch the hook.