On Board with Mark Corke

SeaFire automatic fire extinguisher

 

 Of all the things that scare boat owners the most when they are far out at sea are sinking and fire. Sinking is probably at the top of the list but fire is no less of the threat, and indeed a fire even if you manage to put it out can lead to a sinking. The first line of defense when it comes to preventing a fire on board is to make sure that all systems are correctly installed and that there is nothing that can turn a small problem into a large one. The fact is that no single act alone will cause a fire aboard it is most often caused by a combination of risks or factors. A bad connection can lead to sparking or a short which causes a cable to overheat which ignites some oil or grease and this in turn sets the boat ablaze.

Should the worst happen then you need to slant the chances in your favor of putting a fire out. After all off shore the only place that you might have to retreat to is the life-raft which having spent some time in one in the past is not something that I personally want to repeat. The best fire extinguisher is probably a man in a panic with a bucket but after that it usually come down to fire extinguishers. Most boats often have a few of these around and there should be one in each cabin in a very visible and conspicuous location so that it can be grabbed and used in a hurry; speed is of the essence here.

 

But what if the fire is in the engine space? Because it is out of the way you may not even know that you have a fire down below until it is too late. Opening up the engine cover is often a bad idea as it allows additional oxygen to the fire and may cause a flare up. The ABYC recommend that the fire be tackle without opening the engine cover or on larger vessels the door to the engine room, Sensible advice as it maintains a physical barrier between you and the fire and restricts the amount of oxygen that can reach the flames and increase it's spread to the rest of the boat. Sailboat makers such as Beneteau thoughtfully include a fire port into the front of there engine boxes; a small plastic disc pops out allowing you to deploy the nozzle of a fire extinguisher through the hole. This is a very sensible approach but although effective is not the best solution. Top of the tree has got to be an automatic system. In their simplest form these work by sensing the engine room temperature which when it rises above a preset limit deploys an inert gas that deprives the engine room of oxygen thus putting out the fire. The gas used to be Halon but concerns about environmental impact have resulted in this being outlawed and new system use another gas called Heptaflouropropane however halon is still acceptable for existing systems. This means that if you purchase a boat that has a Halon system you can still go ahead and use the boat and the Halon is still acceptable it is just that if it ever has to be refilled it cannot be refilled with Halon; the same holds true for older refrigeration units that use halon as a refrigerant.

 

Installing an automatic fire extinguisher in the engine room is certainly within the capabilities of a competent DIY owner but it is necessary to do a little research first. I contacted Sea Fire who supplied me with the necessary parts to complete the installation that you see here but not before they had sent e a worksheet that asked some questions about the boat; engine size, location and most importantly the cubic capacity of the space that the system would protect.

 

In theory it would be possible to install an automatic extinguisher in the engine room without any extraneous connections. A vial which looks like the glass tube on a sprinkler head is at the top of the cylinder and this bursts at a temperature above normal engine room temperatures smothering the fire. In truth most owners will opt for a slightly more sophisticated system which is what I did. Connected to the top of the cylinder is a cable release, which with a handle next to the helm can be pulled and thus deploy the extinguishing agent manually. For many sailboat owners in particular that will be the extent of the system but I chose to go one further, the donor boat had a large electronically controlled engine and thus I installed and automatic shut down system. With this if the extinguisher is deployed either manually or automatically then a relay operates which shuts down the engine. On boats when the engine is shut down by pulling a handle then this stem will not work but larger or more modern engine have an electric solenoid to shut down the engine and it is for this type of installation that the auto shut down feature is designed for. Shutting down the engine if it is running ensures that the entinguishant will not be sucked into the engine and ejected out of the exhaust before it has the chance to do it's job and put the fire out.

 

 

Here's how I did it

 

 

 

1 Decide where the extinguisher is to go, in many cases the decision is made for you as there is not much space in the average engine room. Bear in mind however that you have to make connection to the top of the cylinder and dependent on the type of system that you have the cylinder may need to be mounted either horizontally or vertically but this will be made clear in the installation instructions.

 

2 Measure carefully then bolt the mounting bracket into position I had a nice clear space on the aft bulkhead which was just perfect. You may not be so lucky and you may have to re route cables or pipe work if it is in the way.

 

3 Mount the extinguisher as outlined in the instructions that come with it. The Sea Fire that I am mounting has stainless steel worm drive clips that pass through the bracket and around the cylinder. Make sure that they are tight.

 

4 The next step is to install the manual release cable. This is straight forward but bear in mind that it is stiff and very similar to a throttle or gear shift cable and as such will not bend in a tight radius. Cables are supplied in almost any length in foot increments so you have measure the run of the cable before ordering, an old piece of 6mm 1by 19 thick rigging wire is handy for this as it has the same bend characteristics as the release cable.

A . After deciding where the cable is to go install the plate for the manual release which should be near the helm. You also will need to drill a hole for the cable attachment but I was lucky and was able to use the plate to cover an unwanted extra hole where a gauge used to be mounted.

B. Instal the brass nut and shake proof washer before passing the end of cable through the hole.

C. Then install the other components on the other side; barrel nut, O ring,T handle, and safety clip.Connect up the other end of the cable to the cylinder which is retained by a spring clip. It is also worth noting that the cylinder has a safety pin in place which has to be removed but leave that until you have completed the installation to avoid a potential accidental discharge.

5 Use a hole saw to drill a mounting hole for the monitor panel.

 

6.The panel is passed through the hole and secured by a straddle clip on the back.

 

7. Wiring is likely to take the longest part of the job which must be neat and well ordered. The first job is to mount the relay/control box. I put mine behind the breaker panel. Use cable of the correct gauge Sea Fire recommend no smaller than 16 AWG.

8. The wiring is fairly easy to follow but requires connections from the top of the cylinder, a power feed from the vessels wiring and connections to the electrical engine shut down solenoid. If connecting up to the shut down solenoid be aware that the contacts will either be normally open or normally closed. You may need to to refer to the engine wiring diagram to identify your specific application and which wire you need to splice into.

9. Connect up the CAT 5 Ethernet cable between the monitor panel and control box.

9. Make the power connections to the fuse box which must be protected with the correct amperage fuse.

10. Don't forget to mark up the fuse for identification later.

11. Finally clip back the cables for a neat and orderly appearance.

 

With thanks to SeaFire, Brewers South Freeport and Matt Durkin 

Outboard water pump service

Ask around the average marina and the chances are that most outboard motor owners have no idea when the water pump was serviced on their engines, in fact some owners are not even aware that their engines have pumps at all! But a water pump is a very important part of any outboard, a pump that is blocked or working improperly will cause the engine to overheat which can lead to permanent damage to the motor. If you suspect that the engine is running hot it could be time for a water pump service. This basically consists, in most cases at least of replacing the water pump impeller, it's not a complicated job and the average DIYer is likely to have the necessary tools already. Don't try to do this with the boat in the water, either have the boat hauled if it's large or do it when it's on the trailer in the driveway that way you won't loose anything vital.

 The engine that we serviced was a 1996 115 hp Mercury hung on the back of a aluminum Starcraft of a similar vintage and the pictures refer to that but all outboards are very similar and although the pictures may not look exactly like what you have the sequence will be the same.

 I took the pictures as Adam Conte at Portside Marine in Danvers, MA serviced the pump. Working thoroughly and methodically he did the whole project in less than an hour so a competent owner should be able to do the job from start to finish in under two hours.

 Here's how to do it.

 

The first step is to drain the oil from the gearbox. Unscrew the drain plug with a large screwdriver and the oil will start to run out. Make sure that you place a suitable pan under the motor to catch all the old oil. Unscrew the upper oil level plug too which allows air into the gearbox and ensures that all the oil is evacuated. There are small washers under each screw head which often get stuck in the threads, if they do not come off with the screw you may have to pick them out with a small screwdriver or other tool. Let the oil drain as you move onto the next step.

 

Loosen and remove the nuts that hold the lower unit in place, almost all outboards have four nuts holding this in place. A socket will not fit so use a ring wrench to give good purchase on the nuts which will almost certainly be stiff to undo.

 The lower unit should now theoretically be free but in practice it almost invariably sticks and will need a few taps with a soft mallet. Do not hit the flange cavitation plates at the sides or they are sure to break, a few taps on the after end of the gearbox unit as shown here are acceptable however.

 Once a crack opens up the battle is won and you can insert a broad screwdriver and carefully pry it apart being very careful not to damage the castings of the mating surfaces.

 Lift the unit clear and place it on a suitable bench or jig designed for holding it. They service outboards everyday at Portside marine so had a proper jig on hand which is ideal but you may have to prop it upright in the corner of the garage, it works but is just not as convenient and you will be working at floor level.

 

With the unit clear of the top half of the outboard leg we can get to work on the pump proper. The first thing to do is to slide off the seal which sits atop the pump housing.

 

Unscrew the bolts that hold the pump housing in place. We needed an impact wrench as this pump had not been serviced for some time but a ring wrench will work in most cases. Avoid using an open ended wrench, if you round over the bolt heads you will have a bad day for sure.

 

Separate the housing and slide it up the shaft. You can see in this picture that the bottom plate is coming off with it. We need to remove this plate also so if it stays stuck in place you may need to pry it up very carefully.

 

All in all the pump was in pretty good shape, all the vanes on the impeller are intact. Note the old impeller on the right next to the new one on the left. The vanes should be straight, they develop a set to them after they have been in the pump for several months.

 

Before reinstalling the pump clean up all the mating surfaces to ensure that there will be no leaks. A sharp razor blade can be used to scrape off the larger bits of old gasket and sealant, then some fine emery paper will get rid of the remainder. Wipe down with some clean rags when you are finished. Everything should be clean and bright.

 

Wipe out the interior of the pump housing checking to make sure that there are no score marks or gouges, if there are water may leak past the vanes of the impeller and the pump will not work as efficiently as it should. If there is any doubt as to the condition of the housing then it should be replaced.

 

In addition to the impeller all the parts that are required for a routine service; gaskets, O rings and seals are included in the kit.

 

After cleaning up everything reassembly can start. Smear on a little gasket cement. Adam swears by Permatex Form a Gasket sealant liquid but any other proprietary brand should be fine.

 

Lower the gasket into position making sure all the holes line up. The gasket is asymmetrical so if something looks wrong you may have it upside down.  Next install the new bottom plate (shown) that comes in the pump kit, we used a little more gasket cement before dropping this on.

 

Install the smaller gasket which seals the joint between the top and bottom sections of the pump housing. This gasket has a neoprene bead built in so no cement is required or should be used.

Install the new key which sits in the flat on the shaft.

 

Then slide down the new impeller making sure that the key-way in the hub lines up with the key previously fitted.

 

 

A little glycerin or dish washing liquid makes getting the pump cover on that little bit easier and provides some lubrication for the second or two until the water gets into the pump and lubricates the vanes. Do no use oil or silicone which can attack the composition of the impeller and lead to premature failure.

 

Slide the housing down and ease it over the vanes as you twist the shaft in a clockwise direction with the other hand. This bends the blades and allows the body of the pump to sit fully down onto the base plate gasket.

 

Reinstall the bolts and tighten them till they are just snug.

 

Slide the new seal down over the shaft until it just rests against the pump housing.

 

A setting tool is included in the kit and this is pushed down on top of the seal and does double duty of spreading it out and ensuring that it is not compressed too much. With the seal thus set the compression tool is then removed.

 

Smear a little engine spline coupling grease onto the top of the drive shaft.

 

 

Then a little more on the gear shift coupler which should still be on the gear shift shaft inside the leg, it is a fairly loose push fit so it may have fallen off onto the floor if it is not where it ought to be.

 

Refill the gearbox with the correct oil. Note that contrary to what you might expect the oil is forced in from the bottom until it comes out of the upper level hole, then both screw plugs can be replaced with a new washer under each. Portside marine service lots of engine so that have a big tub of oil but the average DIY boater is more like to use the oil that comes in squeezable quart bottles but the technique is exactly the same.

 

Reinstall the lower unit onto the leg, it helps a great deal to have a helper rotate the engine by hand a little to get the splines to mesh. Then replace the nuts and washers that hold the two parts together, there are torque settings for these but Adam does them up so they are just snug. As long as you don't swing on the wrench it is difficult to over tighten these.

 

With everything back together the job is complete. We ran the engine in a barrel to make sure all was well. You can use muffs on the water pick up but the pressure of the hose tends to force the water into the engine, running it in a barrel ensures that the suck from the pump is correct. Note that there should be a healthy spout of water coming out from the telltale in the engine housing.

 

 

 

 

 

 

 

 

Fix a wobbly prop

I was changing the propeller on a boat today and I thought that this tip might come in handy for some readers. Inboard powered boats have a prop that sits on a tapered shaft and the the prop is then held on my a nut and lock nut. To prevent the prop slipping on the shaft there is a key and key way on the shaft. The shaft in nearly every case is stainless steel although there are some bronze shaft about but these are increasingly rare. The key is a square piece of bronze that sits into a machined slot on the tapered section of the shaft and then this in turn slides into a slot called a key way on the prop and it is this that makes sure that the prop turns when the shaft does and thus will not slip.  A fairly common problem is that if the key is a little too high for the key way the prop may not seat all the way onto the shaft and will therefore be eccentric to the shaft and although it may feel as though everything is OK problems will arise when the boat is launched and the boat is put in gear. A prop that is not seated onto the taper correctly will be out of balance and this will lead to vibration that can be felt through the whole boat, increased and rapid cutless bearing wear and a whole plethora of other problems. To avoid having these problems slide the prop onto the shaft so that it is snug onto the taper then using a sharpie pen or piece of masking tape mark the limit of where the prop comes to on the shaft; I used black sharpie pen and you can see that in the picture. Remove the prop put the key into place and slide the prop back on once more. If the prop does not go all the way to the mark there is a good chance that the key is too large and may need to be gently filed down to allow the prop to slide all the way home. Make sure however that you have the key the correct way round as they often appear square in section but in fact are not. You want to remove just enough and no more until the prop slides up to the mark. When this has been done put on and tighten the nut and lock-nut to complete the prop installation.

Outboard engine maintenance

 

Outboard motors with an external fuel should have at least two fuel filters, a small inline filter on the engine itself and a larger filter between the tank and the motor. Both must be changed at least once per year but many are not. Dirty fuel reaching the engine can block injectors and carburettor jets.

 

I like to write the date that I have changed the filters on the filters themselves with a sharpie to act
as a reminder of the date when they were changed.

 

 

If there is one thing that gets overlooked more than any other it has got to be the water pump impeller. Many owners entrust this work to a mechanic or boatyard as it can be a bit daunting for many as a DIY project. Both diesels and gas engines will have similar looking water pump impellers and I recommend that the impeller is changed at least every two years, more often if the boat is operated in silty water.

 

The engine oil, if it is a four stroke, should have been changed before the engine was stored for the winter. If it was not do it now. Changing the oil flushes out contaminants, water and other impurities that have collected during the off season. Sulfur deposits in the old oil combine with water and form sulphuric acid which is very corrosive to internal parts especially engines with aluminum blocks. Don't forget the transmission fluids which should be changed at the same time.

Clean all external parts of the engine. Remove the cover on outboards and wipe down the engine with clean rag then spray with a light coating of WD40 or some other rust inhibitor.

 

All electrical connections should be clean and bright. If there are any suspect connections, those with corrosion visible, frayed wires or wires that have simply been twisted together in the past repair them now. Poor connections increase resistance in the wires which can then overheat causing a fire.

 

Lubricate all control cables and control lines. Apply some waterproof grease to the throttle and gear
shift lever pivots and spray a light lubricant onto the movable parts of the cables both at the engine and the control shift at the helm station.

 

Make sure the batteries are fully charged and in the case of wet cell batteries ensure the electrolyte
is covering the plates. Top up with distilled water if necessary until the plates are just covered. Wipe the batteries down and make sure that connections are clean and tight. Keep then batteries charged up throughout the winter.

Fill the tanks with fresh fuel and add a little fuel stabilizer to absorb any moisture or algae which may be growing in the tank. Make sure that there are no fuel leaks and that all pipes and fuel hoses and hose clamps are in good condition.

 

Finally give the engine a good looking over and if you see something that is not right either get it fixed or fix it yourself provided you know what you are doing. Another tip that I learned many years ago is to keep a note in either the back of the boats log book or a note pad especially for the purpose of any problems as they occur with the engine. If the engine has a misfire at 3000 rpm make a note of it with the date and any other comments. That way when the time comes to take the engine in for service you will remember to mention it to the mechanic.

 

 

 

 

How to install a fuel polishing system

In a perfect world the fuel that you put into your diesel tank aboard the boat would be perfect, free of contaminants, water and dirt. But sadly the world is not ideal and fuel is often full of all sorts of stuff. One would think that fuel in a tank would be safe from further degradation but this is not so. As a tank heats up and cools down moisture laden air is drawn into the tank through the breather pipe where it condenses on the surface of the fuel then sinks to the bottom of the tank. This happens many time during the course of the year and often goes unnoticed by the average boat owner, the amounts of water may be small and either lie in the bottom of the tank below the level of the pick up tube or are mixed in the with the fuel through the natural movement of the boat where they are carried through to the engine  and burnt off as a natural part of the combustion process. Water is not the only thing that can prevent the engine from running properly, general dirt and poor quality fuel are all out to do the nasty on the engine.

 

A natural question to ask is why do cars and trucks have fuel polishing system. Basically it all boils down to the fact that cars are used frequently and the fuel rarely stays in the tank for more than a few days or a couple of weeks at the most. Fresh fuel is constantly added and there is little opportunity for it to degrade. Leave  a a car or truck with a half empty tank of fuel out in cold for a year and the chances are it will be very hard to start being afflicted by the very things that affect our boats.

 

How a fuel polisher works

 

Basically a fuel polisher is no more than an extra set of filters through which the fuel is circulated thus removing most if not all of the contaminants. Obviously it is essential to have a good filtration system on the engine and this most often consists of a large primary  filter and secondary filter before the fuel reaches the injectors. The problem arises in that on most sailboats the engines are quite small and as we want to sail rather than motor the engine is used infrequently. In a sail boat with a modest 20 gallon tank it is not unusual for the majority of that fuel to remain in the tank for many years where it continues to degrade. All tanks have to be vented and during the warmth of the day the air in the tank expands, add to this the fact that the fuel returning from the engine via the injector return pipe is warm. At night when the temperature drops air is sucked in through the tank vent and condenses on the inside of the tank and the surface of the fuel where it drops to the bottom of the tank where it can be picked up by the pickup tube. Small amounts of dirt  and water will be filtered out by the engine filtration system but that only works when the engine is running. What is better is if there is system that filters the fuel on a regular basis when the engine is not running. Fuel polishers have been available on many large power yachts for many years but it is only that sailors have started to wake up to the fact that they may be a good idea on their boats too.

Filters are measured in microns, this has nothing whatever to do with the physical size of the filter but is the size of particulates that the filter will capture. Parker who make the very popular Racor range of filters offer filter sizes of 30, 10 and 2 micron. For most sailors the 10 micron size offers a good balance between adequate filtration and not becoming clogged readily. It is also worth mentioning that the average Racor filter is capable of filtering upwards of 50 gallons per hour which is far more than the total amount of diesel that we have in our tank.

 

In it's most basic form a fuel polisher is simply a pump and  a filter through which the fuel is drawn from the tank passed through a filter then back to the tank. Even a quite modest fuel polishing system is capable of processing 50 gallons per hour  and if run a couple of times per week will keep the fuel in tip top condition. Many fuel polishers incorporate some sort of automatic time switch which can be programmed to turn on and run the fuel through the filter even when the boat is left unattended. This can be a great option especially for boats they are laid up during the winter months it will mean that a battery will have to be left on board to supply power for the pump but power consumption for even a fairly large system is going to be less than 2 amps so it might be worth considering taking off the large boat batteries for winter storage and replacing it with a smaller cheaper battery from the local Auto Zone or Napa for the sole purpose of
running the polishing system pump, remember that you will need to periodically charge this battery though. There are two basic variations of installing  the system components and these are shown in the accompanying diagrams; either a dedicated fuel polishing loop or incorporating the fuel polisher into the feed to the engine. I think that with bigger engines it may be better to have the dedicated loop especially when the fuel tank supplies fuel to more than one source such as the propulsion engine and a generator. As I only have a small auxiliary engine I opted to install it into the fuel feed line. This has the added advantage of adding an additional filter into the line before the fuel feeds to the engine and allowed me to do away with my existing rather small primary filter which I incorporated into the fuel delivery line when I built the boat. Much more fuel is sucked up than can be used by the engine and this excess fuel passes through the polishing module and returns to the the tank by the return line. My tank is only 6 gallons when full and experience has shown that more than 10 gallons an hour passes through the filter with the engine running, thus a couple of hours under motor will pass all the fuel through the filter 3 times, more than ample to keep it in tip top condition.

 

I bought the Racor polishing kit which contains the filer, module, pipe and fittings for around $550 but if you want to add the timer then expect to add another $150 to that price.

 

Step by step to installation

 

Sit down and with a pencil and paper draw a plan of where you want to install the polishing filter, pump and any other components that you want to install in your system. This will help you decide pipe runs so that before cutting into your existing system you will have all the required parts, tools and accessories to hand. My system is simple and there are only two main bits, the filter and the pump. I installed these on the bulkhead inside a locker fairly close to the fuel tank. There is no reason why the fuel polisher has to be installed in the engine space and in fact there are lots of reasons for not doing so. Engine room space is often severely limited on many boats and installing another piece of hardware will make changing filters  that much harder. Also the filter needs to be installed vertically.

 

If teeing into existing cut the fuel lines with a set of cutters or a knife avoid using a saw as the swarf will get into the fuel and could find it's way to the injector pump which will not like it at all. You will need to cut into both the flow and return lines from the tank.

 

Install some nylon tee fittings and secure the pipes with stainless pipe clamps.

 

Ensure that the pipe is suitable for fuel use.

Bolt the filter in a convenient position remembering that you will have to get the top off later to change the filter element, also you will need access to the bottom of the glass bowl to drain off any water that separates out.

 

Note that the filter is marked in and out for flow coming in and clean fuel going out.

 

Next install the polishing module which can be close to the filter. Leave the cover tapes in place to prevent contaminates getting inside until you are ready to connect up the pipes.

 

You will need brass NPT fittings to to screw into the module and filter. Use Teflon tape to seal the threads but keep it back from the ends so bits don't  find their way into the fuel.

 

Nip up the fittings up but don't over tighten.

 

Everything connected up.  The pipe coming out of the top of the module goes back to the tank as the return. The pipe on the right is the suction pipe the pipe to the left goes to the engine.

 

 

 Additional notes

Some installations use copper. Don't cut these with a hack saw instead usea pipe cutter for a neater job which is less likely to distort the pipe.

 

Slide on the clamping nut

 

Then slip the brass ferule inside the pipe

 

Push the pipe into the fitting and then tighten with the correct size wrench.

 

The neat completed joint.

 

Finally double check all hose connections  to ensure that there are no air leaks. Although this is not directly part of the fuel delivery system to the engine leaks on the vacuum side of the pump will mean that air can find it's way into the fuel system when the polisher is not running.

Connect up the electrical connections which merely consists of connecting up to a spare breaker. If installing a timer the wiring will be a little more complicated but I just had to run a couple of wires to a spare breaker at the chart table so I can run the polisher at a time of my choosing.

Outboard fouling prevention

 

This past year I have been carrying out a test of Interlux Trilux 33 anti fouling paint for out-drives and outboards. I prepared the surface as outlined in the manufacturers instructions which I followed to the letter; sanding the new outboard with 80 grit paper, wiping the surface with the correct solvent and so on. The pictures speak for themselves I feel and are of brackets for 250 hp Yamaha outboards of the same vintage. One is the outboard bracket of an untreated outboard and the other is coated with Trilux 33. I am impressed but it seems others have been less so. A quick trawl of the internet shows that same users have reported poor results from Trilux but this has certainly not been my experience. My guess is, although I cannot be certain that the correct preparatory work was not carried out on the metal prior to application. Although it is somewhat hard to take abrasive paper to a brand shiny new outboard bracket this step cannot be skipped or done improperly if things are to go well. Outboard brackets are somewhat fiddly and have many nooks and crannies and I spent at least a couple of hours on each bracket before I felt I was ready to apply the coating. Application is straightforward once the rubbing down has been done but you do need to mask off the surrounding area well and if applying it outdoors do it on a windless day, I still have a few spots on the back of my pick up where the wind blew it.

 

 

With Trilux 33

 

and without.

Suzuki DF300AP

I have been itching to bring news of the all new DF300AP from Suzuki ever since it was unveiled to the press some time back but as they wanted to make a big announcement at the Miami boat show we were banned from releasing information to the public until now. The new motor which is currently only available as a 300hp model addresses the age old problem of counter rotating props. Until now if you had twin or triple engines on the back of the boat you had to buy at least one standard engine and another with a left hand rotating propeller. A left handed rotating engine has typically been $800 dollars more for two reasons; the manufacturers make a lot less of them and secondly the lower unit internal gearing was slightly more complex than the standard unit. With the new engine Suzuki have addressed all these problems and now the 300AP can be simply be user updated to rotate in either direction. Of course the engine does not rotate in the other direction, what happens is that essentailly the forward and reverse pinion gears are used in a different sequence. This change is acheived electronically and by simply removing the small plug connected to the wiring harness under the cowling the motor becomes a left hand turn when the shift is placed into forward gear. All the judges at the Miami innovation awards,of which I was one thought it brilliant and a deversevedly just winner of one of this years awards. The first question that anyone seeing the engine for the first time usually asked is why no one has come up with this before. This apears to be a home run for Suzuki, dealers will now only have to stock one engine which will make their inventory controls cheaper and simpler and there should be a cost savings to the customer as the only extra charge is that a left handed prop which is still slightly more expensive than standard rotation. Looking to the long term when a pair of engines get sold on the second hand market it is always the standard rotation that gets sold first and the left hand engine is more difficult to sell and is often sold at a lesser price even though it was more expensive when intially purchased. In the pictures avove you can see the small tag on the plug that is pulled to convert a the engine from left to right operation and vice versa. Brilliant!

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.