If you are not a member of a club or some similar potential self help group and regularly fish alone in situations where a tow back to shore may not be available if your outboard suddenly gives up the ghost, then carrying an auxiliary engine makes a lot of sense. Primary power outboards are highly reliable pieces of kit these days, providing of course they are looked after with regular salt flushing and servicing, and all the main manufacturers can justifiably hold their heads up in that respect. Apart from the occasional rogue, it's as they age or suffer long term neglect that problems usually start to kick in. But remember, this is equally applicable to an auxiliary, which for obvious reasons is going to get far less use and very likely far less maintenance. As a result, an occasionally used outboard is probably more likely to fail when called into operation than a primary power source.
Obviously there are ways of minimising this. Without doubt the best of these is to buy from new. Small outboards don't cost the earth and provide a much more comprehensive insurance than buying some old battered cheapie that has been gathering dampness in somebodies shed for years. You should also run the thing on a regular basis, which is best done in a tub of fresh water at home, because if you run it at sea it will still need to be fired up again back home to flush the salt from its cooling system. But without doubt the biggest concern expressed by potential auxiliary users has to be how big, or more to the point how small, and in that respect I have been impressed to say the least at how much push some of these smaller engines can deliver to a heavy planing boat.
When a planing boat is operating at low speed it becomes very thirsty, which in why having a paired 4-stroke main and an auxiliary a very good idea. At least that way you have fuel compatibility, because over a long distance with such a small engine you will need more than the volume of a small integral tank. Having done similar testing with small outboards in the past across a wide range of heavy planing hulls, it was anticipated that 4 horse power was probably going to be about right for the weight of a typical trailed boat, and as Suzuki had suggested their 4-stroke DF4 as a partner for the DF90 currently fitted as standard on our Warrior 170, that then is the model under the microscope here.
Simplicity and reliability are the key requirements in an emergency situation. For that reason, any backup must be easy to fire up, straight forward to operate, and capable of moving the boat in any prevailing conditions of wind and tide. Anything less would be worse than having no backup at all as it could well lead to a false sense of security. This then was the basis of the testing done here on the Suzuki DF4.
Start Up
The DF4 is fuelled by a gravity fed integral 1.5 litre tank. Simply turn on the external fuel switch below the base of the cowl, set the throttle to start position, apply the choke, and pull the cord. The choke can then be released. The one draw back here is that it cannot be fed directly from the main fuel tank line and would on a long journey have to be re-fuelled repeatedly by hand.
Operation
Forward and reverse are selected by a lever on the side. The steering offers 180 degree's of manoeuvrability. It can also be locked in the forward position with the throttle locked at full revs allowing you to effectively steer the boat with the steering wheel using the non functioning main engine as a rudder. This allows better weight distribution within the boat and makes for a much safer ride.
Power
Power is provided by a single cylinder OHV engine with a displacement of 138cc producing excellent low to mid range torque and good acceleration. Checking the performance with the GPS speed over ground facility, this had the boat running at a very creditable 4 mph. Now that might not sound like much, so picture yourself drifting helplessly further and further offshore at 4 mph in a lumpy sea. That should put it into better perspective. A very respectable speed for such a small engine moving all that weight of boat.
Something that is often overlooked when dealing with small fully self contained outboards is that they can also make a very good main power source for small boat fishing in sheltered inshore waters, or for low speed trolling with rapala lures. And just to illustrate the point that there isn't necessarily always a direct correlation between distance, water depth and quality of fishing, on the day of the test we pottered off no more that 600 yards, popped the anchor over and caught four species of fish including 18 plaice.
One final point worth making here as a general comment for all auxiliary outboards is transit security. On occasions, auxiliary outboards have been known to work loose and disappear from their pads while under way. It pays then to attach a safety lanyard just in case. An even better idea is to thread a ratchet strap behind the clamps, attaching the other end to a fixed point in the boat like a stern cleat, and ratchet the thing up tight. This will take any bounce out of the pad both on the road as well as on the water. When not in use, the auxiliary then travels in the lifted pad position with the engine itself tilted up out of the water. This both helps prevent the clamps working free in the first place and acts as a lanyard in case they ever do. Only when required for running is the ratchet relaxed, though still kept in place, to allow the pad and engine to be dropped to motoring height.
