On Board with Mark Corke

Oil samples - what can one sample tell you?

 

At the recent SAMS meeting and symposium in Halifax there was one session on oil sampling and what an oil sample could tell you. This was interesting to me as one of the things that I often get asked for when I do a survey is to take an oil sample. The trouble with oil samples is that there are so many variables; if the oil has just been put in the engine before the winter layup as it should be then all that an oil analysis is going to tell me is that the oil is new. If on the other hand the oil has been in the engine for several years and not been regularly changed then it will often show high levels of sulphur, water and other contaminates which is not necessarily the fault of the engine but more the fault of the owner who has not changed the oil as often as he or she should have. Then there are so many different formulations of oil that unless you know what was used in the engine you have no base line to work from.

Oil samples can be useful and to my mind the best method seems to be to test some fresh oil of the type used in the engine and get the raw data from that, then with fresh oil and filters on the engine test the oil after say 25 hours of running then compare these results with the base sample. If high levels of particulate are present then these will be spotted and it may provide an early warning that all is not well with the engine. If samples are taken at similar intervals each season and records kept then a fairly reliable and accurate picture can be drawn up over a number of years of the health of the engine. If samples are just taken willy nilly at no known hours since the last oil change then the results are pretty meaningless as oil that has been in the engine for one week and has ten hours on it will give completely different results to a sample that is taken at 250 hours the following year.

Diesel repower?

     

Duramax diesels are a familiar name on the roads of North America. Powering many trucks by Chevy and GMC the 6.6 liter engines have been proven over many years of service so it is exciting to note that there is now a marinised version available. What is interesting is that the overall dimensions are very similar to the gas GM Crusader engines and the information that I have seems to indicate that the diesels will be pretty much a straight replacement for the gasoline power plants. Two years ago Sweden Diesel signed an agreement with GM and started development of the engines which are to be sold in the USA through Performance Diesel out of Galveston Texas. The engine are available in four variations currently, a 350, 400, 450 and 500 hp versions. Another interesting point is that the diesel is actually 50 pounds lighter than the comparable gas version.  Also in the works but not as yet available is a version of the engine equipped with twin Lysholm superchargers called the TSC which would be a great replacement for boats that need a lot of get up and go such as the Cigarette style boats, Baja and so on. When you consider that the V8 575 supercharged gas version uses about one gallon every two minutes at wide open throttle there could be significant energy and operating cost savings after swapping over to the diesels.

Considering the amount of boats out there that use the Crusader engines I can see that these new diesels will be great not only as OEM fitments but also as repower units.

 

 

Propeller tip clearance

 

It is essential to have the correct amount of tip clearance between the end of the propeller blades and the hull. The recognised minimum clearance  should be between one sixth and one fifth of the total prop diameter. Therefore with a 16 inch blade like the one in the picture we should be looking for about a 2 and half inch clearance at least What there is in fact is so little room that it was impossible to get even the end of my pen between the underside of the hull and the blade tip. The way that a prop works is fairly complex and it creates lift and thus drives the boat forward. When the tip clearance is compromised two things happen; the first is that the water flow is interrupted and the blade will not be anything like as efficient and secondly the water is 'trapped' between the rotating prop and the hull. With each revolution this slap will be felt inside the boat as added vibration. The only way around this probelm in this particular case would be to either have a slightly longer shaft to move the prop away from the boat a little but even that I doubt would not be enough or secondly would be to go for a different prop of perhaps a smaller diameter but with a slightly increased pitch.

As a footnote the generally accepted practice is that the shaft should project no more than one and a half times it's diamter past the end of the cutless bearing.

 

 

Minn Kota

 

This is my Minn Kota riptide 40 electric outboard. In standard configuration the shaft between the top and bottom sections is too long for use on many boats. The clamp is adjustable and sure, you can raise and lower the outboard  to adjust the height or rather depth that the prop sits in the water but then for most dinghies and other small craft the handle is up too high. Unlike a conventional outboard where the engine is at the top and connects via bevel gears on the lower unit to the prop on electric outboards the motor connects directly to the prop with the motor encased in a waterproof submersible housing. The engine is heavy as it contains a lot of copper and the control head at the top is simply a rheostat control for forward and reverse, all very simple. Anyway the point is that by removing a few screws from the control head I was able to cut some 13 inches off the shaft  which both makes the top to bottom of the outboard more compact and also allows it to fit in a cockpit locker on the mother ship more readily. The shaft is in fact no more than a thick walled plastic conduit pipe which carries the cables from the speed controller to the engine and is easy to cut with a hacksaw. I am not sure what Minn Kota would say about the changes but the motor has worked flawlessly for the past 6 years since I got it.

Incidentally all the focus these days seems to be on the Torqueedo electric outboard undoubtedly a good motor but frankly I like the look of the Minn Kota better and instead of having to buy the very expensive special snap on batteries as you do with the Torqueedo you can use a 12 volt marine deep cycle battery which are far cheaper and available almost anywhere.

Compression tests

 
One of the old chestnuts that I get asked for over and over again as a surveyor is for a compression test on a gasoline engine. Truth is there are times that a compression test is worthwhile as it can detect problems within an engine and will tell if a particular cylinder is not performing as it should. I carry a compression tester of the type shown above in my truck and how it works is this. Once the engine has been run up to normal operating temperature the spark plugs are removed and the hose for the compression tester is screwed into each plug hole in turn. The engine is then spun over and the reading is recorded and written down for each cylinder. It is basically a comparative test and what we are looking for is a significantly lower reading in one cylinder compared to the others. The reason that it has to be performed on a warm engine is that an engine that is cold will give disproportionate readings which will be higher than a engine which has reached normal operating temperatures. These tests are easy to do and is all fine and dandy on an outboard or an inboard like an atomic 4 where the plugs are easy to get to it becomes more of a problem on a large V 8 engine.

 

 

This is is a prime example of a pair of 525 V8 supercharged mercruisers in a Fountain 38 that are crammed in so tight that the two inboard exhaust risers are almost touching. These engines run hot and getting the spark plugs out after the engines have been run for 30 minutes or so is a job that I do not like to do. Apart from the fact that it is easy to get your hands burned, getting the plugs out is long job that requires the dexterity of a skilled octopus. They are hard to reach, then when you do get them out you have to screw in the compression hose adaptor one cylinder at a time and there are of course 16 chances to burn your fingers even if you can actually reach the plug hole in the first place. It is a long job that takes a great deal of patience and time and is likely to take as long as surveying the rest of the boat combined and the buyer who was requesting the compression test on this particular boat could not understand why I wanted to charge $500 just for comprssion test in addition to the survey fee.

But these engines had just over 100 hours on them which is nothing in terms of their potential life and a compression test was unlikely to reveal anything startling with the engines so new. Think of it this way; a Honda 90 hp outboard uses the same base engine as fitted into the Honda FIT car. If you walked into a car dealership and asked for a compression test the dealer would probably think you nuts. Typically you could easily expect the car to do 150, 000 miles. At an average speed over the life time of the car of say 30 mile per hour that equates to FIVE THOUSAND hours of engine run time so why boat buyers ask routinely for compression checks on engines that are otherwise running fine and have 100 hours on them which is equal for the average motorist of a couple of months driving is beyond me. I have seen commercial boats with these same Honda outboards with 2000 hours on them still going strong.

Incidentally you may be interested to know as a footnote that the engines in the Fountain shown above ran great, when the superchargers really did their stuff as the rev counter reached 3,000 rpm the boat was touching 70 mph and sucking up fuel at the rate of 2 gallons per minute!

 

Fuel filter indicator

 
I have recently just completed a story for Sail magazine on fuel polishing systems. One of the issues with any fuel filtration system is that you never know exactly when the filters need replacing or are restricted in some way. One method is to install a drag gauge into the system which will show just how much 'suck' there is in the vacuum side of the pump, the greater the drag, the higher the reading and thus more the fuel fuel flow and filters are clogged. It is a great system but comes at a price and complications which many recreational boat owners can do without. A simpler solution is the fuel flow service indicator from Racor. Essentially this simple but effective bit of kit is teed into the fuel line on the vacuum side of the line between the filter and the pump. As the vacuum increases a yellow disc is sucked down in the clear bowl. While the disc is in the green sector all is well but as the pump has to suck harder as the fuel filter becomes blocked it enters the red sector indicating the need for a filter change. I should add that the disc stays at the highest setting achieved even after the engine is shut down so it is possible to monitor the performance of the filters even when the engine is off and cold. Once filters have been changed the operator merely has to press the button on the top of the unit and the disc resets. The cost is a very sensible $60 and can be had from West Marine and other such suppliers.

Honda outboards

 
I like Honda outboards. Honda make some good products and as a volume car manufacturer it makes sense to use their experience in that direction when it comes to powering a boat. For instance the engine for the 90 hp model is basically the engine used in the FIT, Honda's best selling car globally. This engine has numbers in the millions now so they should know what they are doing. But what Ifound strange at this years Miami boat show was all the razzmatazz sounding the engine that you see above.  Not due for release to the public until the fall Honda sent me a press release that was very coy and did not divulge much only to say that I should come to the booth at the appointed time.  I apparently was  not the only journalist there a whole slew had turn up for the unveiling which turned out to be frankly disappointing. The black cover was whipped off and revealed the engine that you see.  Everyone present was expecting something new and exciting and all we got was this the only visible difference is the black grills in the cover. Of course it is what is under the hood that matters and the press materials said that the engine had VTEC (Variable Valve Timing and Electronic Control) which is not new and has been used on Honda engines for the past eight years.  Interesting as a new engine may be this was a let down and I feel that Honda thought that they ought to have some sort of 'exciting press event' as they have for the past few years. This was most definitely not it.

 

 

 

 

Engine over heating problems

 

 I took this picture the other week and thought that you might be interested to see it. It shows one of the cylinder heads from a V 6 two stroke outboard. I can't remember which model but it is one of the engines that has a separate tank for two stroke oil and another for the gas. It seems that the owner was using this engine and reported a sudden and complete loss of power before the engine seized up completely. Further investigation and questioning revealed that there was nothing wrong with the motor before the catastrophic failure but further probing revealed that the owner had filled up the gas tank but had not thought to check the level in the separate oil tank. So as you might expect the engine was starved of lubricating oil and the seizure failling very soon after. Operator error was entirely to blame which resulted in the replacement of the entire power head on this motor. What is interesting about this picture however is that the number 1 cylinder is on the left of the photo and has suffered the most damage as it ran out of oil first while the number 3 on the right is relatively unharmed being lower down when the engine is in the normal upright position.

 

Here is a close up of the piston in it's bore of the number one cylinder and as you can see the piston has started to melt, the crown is completely gone and the top piston ring which has fractured in several places is exposed. All this damage and expense because the boat owner forgot to check the oil. If you have a boat with separate oil and fuel tanks then I say top off the oil each and every time that you fill up with gas.

 

 

Here is another instance of operator error. This water pump body is from an engine with only 3 hours on it, basically brand new. The water intake was blocked by seaweed on the outboard leg and the owner just kept right on going without paying any attention to the temperature gauge which I later checked and found to be working. The engine got so hot that I has completely melted the water pump housing. The impeller too was toast, there was substantial damage to the engine which left the boat owner with a bill for $8000 for repairs.

 

 

Ethanol limits set to increase

 

I mentioned about a year ago that many boaters were experiencing problems with gasoline containing ethanol, well things are about to get a little more interesting. Earlier this past week the EPA  waived a restriction limiting gasoline to having a limit of 10% ethanol by volume and increased the limit to 15%. To be clear this does not mean that your local marina will suddenly start selling fuel with a 15% ethanol rating, what it does mean is that gas stations and other retailers are now allowed to sell  E15 for cars and light trucks built after 2007 which are designed to be E15 compliant. The problems with ethanol based fuels and gasoline containing ethanol is that the ethanol itself acts as a detergent and loosens dirt, can soften the inside of fuel lines leading to blocked injectors and carburettors, gumming up of valves and other parts inside the engine. Ethanol can also soften fiberglass tanks which in turn can lead to leaking thus causing a fire and explosion hazard aboard. It should also be noted that experts claim that ethanol has a shelf life of approximately six weeks after which time it starts to separate away from the gasoline, otherwise known as phase separation. It is also hygroscopic meaning that it readily absorbs moisture of which there is plenty around the boat. This mixture then sinks to the bottom of the tank and the low octane gasoline sits on top. As fuel is always drawn from the bottom of the tank the moisture saturated ethanol is sucked up by the fuel pump where it either causes poor engine performance of the engine refuses to start at all!

None of these problems are issues to the avaerage car or light truck, the fuel tank is topped up often and fuel does not sit long enough to cause phase separation. Hoses and other parts are designed to meet the latest regulations and handle E15 fuels without problems. Boats on the other hand often sit for long periods between outings and the fuel may be many months old, just the reverse of what is required to get peak performance from the engine additionally many of us have boats that were designed and  built long before ethanol was even heard of.                             

In surveying boats one of the major issues that I come across is old hoses which do not comply with current  standards. All hoses should be marked B1-15 if they are to be safe from ethanol based fuels. Old hoses will degrade and they will block up your engine so changing the hoses could be  smart thing to do over the winter layup to avoid problems in the spring. One final point is that opinion seems to be divided on whether it is better to store the boat with empty of full tanks. My advice is drain the tanks if you can, use the gas in the car or truck. If the boat is large then it seems best to top up the tank to almost full then add some sort of fuel stabilizer.

 

Hybrid power

 

There has been lot of discussion lately about alternative power for both sail and power boats. One of the options that has been getting a lot of press is the hybrid power system. Essentially it consists of a diesel engine connected to an electric motor. This gives the boat operator the option of running the boat via the diesel directly, the electric motor directly or a combination of the two. There is a lot more to it than that but in a nut shell that's it.

Hybrids have been held up as the boaters answer to saving the planet, I'm all for ecology and taking care of our surroundings but in my view the use of a hybrid power plant in a recreational boat is white elephant. Of all the boats that I survey many of them have well below 1000 hours on the engine and often much less. In the grand scheme of things 1000 hours equates to about you driving 4000 miles in your car which is hardly anything. When you factor in the additional cost of the hybrid, the additional wiring etc etc it makes no sense at all.  Plus it is a sad fact of life that most boat engines wear out not through use but from under use as they rarely reach optimum temperature. Also most boats are over powered. M advice is to buy a smaller motor use it wisely and often and it will repay in lasting longer and still use less diesel than even a modest hybrid unit.