Re-Powering Weypago - Part 2 of 3
In the last edition I covered the main reasons behind my decision to re-power Weypago. Interestingly, in the August Boating New Zealand, is an article by Len Gilbert covering the exact same issue, albeit in a larger vessel, that was my major concern. That is that a Compass H28 with standard propeller aperture does not have sufficient room to swing a propeller large enough to efficiently absorb 18 horsepower plus. Therefore, similar performance and better efficiency can be achieved by down-sizing the engine to better reflect the capabilities of the propeller and the power requirements of the hull form. I also speculated that there might be other advantages such as reductions in weight and physical size for example. Well, I think I have chosen an engine that will deliver in these areas and several others as well.
It is the Lombardini LDW502M marine diesel engine, rating 13 hp at 3,600 r.p.m. at the propeller shaft. There are a lot of things I like about this engine, for example its physical size, especially the relationship of the engine mounts to propeller shaft, is only a little different to that of the old 2GM20 Yanmar, meaning the required installation modifications are pretty minimal. The Exhaust is on the other side, but this is only a matter of pushing the rubber hose over to its new location. The exhaust outlet diameters are the same. The throttle is in a similar location, the compressor and associated pulleys can go in the same place, so I will not have to de-commission the freezer for the installation. Likewise the oil filter is similarly located. And that’s where the similarities end.
THE ADVANTAGES:
Fresh water cooling:
The Lombardini is fresh water cooled via a heat exchanger on the port side of the engine. To me this is far better than sea water cooling. FW cooling is an optional extra on the Yanmar which, unfortunately, mine didn’t have. With the use of appropriate water treatment the whole cooling system will stay in much better condition.
Ancillary equipment:
The possibility of mounting the secondary fuel filter and stop/start solenoid remotely is very useful in that it will improve service access to both the filters and the raw water pump. Driven off the camshaft, the raw water pump is mounted on the upper rear of the engine. Remote mounting the fuel filter gives relatively easy access to the two allen head cap screws retaining the raw water pump, enabling easy removal for servicing.
Also, a sump pump with hose attachment via a banjo fitting, can be mounted in any convenient place for oil change purposes, quite an improvement on the old “stick it down the dip stick hole” method currently in use. It is also interesting to note that the fuel on/off solenoid has a manual over-ride making it easier to prime the fuel system.
Fuel injection system
One of the most delightful features of this engine is the fuel injection system. Many readers will have had the occasion to “bleed” their fuel systems, perhaps because they ran out of fuel, or perhaps had a damaged fuel line letting air into the system. It can be a bit of a messy, smelly business, and it can be a bit time consuming if you are not an expert. The Lombardini does not require bleeding as such.
Its overhead cam design incorporate “unit” type fuel pump injectors driven off the cam shaft. These devices serve the purpose of both high pressure pump and injector in one. The obvious benefit in this is the absence of a high pressure fuel pump which has to be maintained. But the second, and perhaps more important advantage, is that priming the fuel system is accomplished by simply turning on the key or using the fuel solenoid manual over-ride, and operating the fuel lift pump handily located on the starboard side of the engine near the top. Pumping for 30 seconds or less is all that is required to restore the system to operating condition after (say) running out of fuel. Imagine how handy this might be if you were in a tight spot! The pump circulates fuel past the injectors and then to a drain back to the tank. No fuel outside the system, no smelly hands! Starting
The Lombardini has a glow plug starting system which assures easy starting. My old Yanmar is a similar design in that it also has pre-combustion chambers but for some reason the manufacturers left out the glow plugs. It has always been inconsistent in starting, usually starting quite well when warm, but sometimes requiring a lot of throttle (over fuelling) when cold and needing quite a few turns as well! Which brings me to the next point, the Lombardini does not have a hand starting arrangement. Old salts will cringe at this, but you can’t have everything. Hand starting requires a heavy flywheel to give the require inertia, and with a heavy flywheel, you no longer have a light weight engine. There are other practical considerations. On her delivery voyage Weypago lost battery power. Use the hand start we told the skipper- impossible says he, the compressor gear is in the way! So much for that. In its time, the 2GM20 was considered a light weight diesel hence it does not have a large enough flywheel to give enough inertia for hand starting, so even if the was no compressor in the way, my mechanic tells me, it would be extremely difficult to get this engine to start by hand especially at sea. So the hand start, or lack thereof isn’t really an issue in my mind.
Weight
At 75Kgs the Lombardini is significantly lighter than the old engine, which is a bonus. This can lead one to wonder whether it is just a souped up version of some lower powered industrial engine, a common method of improving the power to weight ratio of pleasure craft engines. This takes us into the area of ratings which is a complex subject to say the least, so I will keep my comments brief. Broadly speaking, the greater the power taken from an engine, the shorter its life will be, hence different ratings for different applications. For example you may find an engine rated at 350hp pleasure boat use may only rate 185hp continuous for work boat applications.
For both situations the engines will be subject to unremitting load for the time they are operating, but the pleasure boat engine will do significantly fewer operating hours each year. A similar parallel exists between Automotive (intermittent load) engines and industrial engines which are subject to unremitting loads driving (say) pumps or generators. The automotive engine will have the higher rating because it is not subject to unremitting loads. It follows then that Automotive ratings would approximate pleasure boat ratings while the more conservatively rated industrial engines will be closer to continuous duty work boat ratings.
On enquiring regarding the industrial equivalent Lombardini engine I found that the ratings are the same, this is most definitely not a souped up industrial engine. Further inquiries revealed that in New Zealand , units of this engine family typically run over 5,000 hours between major overhauls and that 5,000 hours is the manufacturer’s recommended major overhaul interval. I am much comforted by this fact. It transpires that the weight saving is accomplished by better design and materials, not performance enhancement.
Gearbox
As luck would have it, the engine is available with a 2.6:1 reduction ratio gearbox. On referring the propulsion package and hull details to propeller maestro Dave Buchan of Nalder and Biddle in Nelson, we were able to establish that the existing propeller (14x8) should be a good match.
Engine mounts
The engine is sold with Polyflex mounts which I understand comply with Cat 1 requirements in the respect that if the rubber material fails and the boat is rolled, the mounts are designed in such a way that the engine will be held securely in place. It struck me that this is rather a thoughtful action on the part of the engine dealer.
Mike Holibar – “Weypago”
