The most import decisions to make are:
1. What is the maximum HP (horse power) and outboard weight your boat can take (this information is available on the identification plate on the transom of your boat)?
2. What shaft length fits the transom on your boat?
3. What weight is the outboard and will you be able to man-handle it?
If you are completely new to boating and are looking to buy an outboard for your boat you’ll need to know what all this new terminology means. One of the biggest and most costly mistakes made is not knowing which length of ‘leg’ or shaft outboard you require to suit your boat. This particularly applies if you are buying second hand as often the seller is as confused as you are!
Below is a guide to an outboards layout
- outboard layout
Mounting it too high can result in the propeller not being fully submerged in the water causing it to draw in air (cavitation) resulting in loss of drive/momentum and loss of steering. This can also cause the engine to overheat as the water intake will suck air instead of the cooling water required, resulting in engine damage!!
Mounting it too low can cause extra drag with loss of speed and heavier steering.
The diagram below gives you the measurement you need to take to fit the correct length of shaft to your boat. If the correct height cannot be achieved with the bracket sitting onto the transom you can do a bit of ‘fine tuning’ by using a ‘packing piece’ placed under the clamp bracket to raise it.
- transom height
For example a Tohatsu 15hp or 20hp 4 stroke outboard weighs 52kg but a 2 stroke 15hp or 20hp outboard weighs 39kg however sales of new 2 strokes for ‘pleasure use’ ceased in December 2006 so you’ll be shopping for a used second hand 2 stroke outboard if you want one or consider a 10hp 4 stroke instead at 38kg.
Hope this helps and happy hunting.
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