Auxiliary Outboard Engines Guide

This is a quick guide to auxiliary engines, including who should have one, sizing, best practice and tips.

Should I have one?

The coast guard agency, RNLI etc. all recommend that where possible a boat should have one and with outboard brackets taking up to 20hp engines there is also really no excuse.  Obviously this though depends on where you are going to do your boating i.e. if it is inland loch, river or canal you are never going to be that far from the shore or help so though it would be useful, you are less likely to be in life threatening situation.

If however you are in coastal waters then your back up engine/ auxiliary outboard could well be a life saver let alone boat saver.

Look at it this way. If you main engine broke down and it was even if your auxiliary engine was badly sized, it would at least take you longer to hit the rocks, drift out to see etc i.e. it would have bought you time in a dangerous scenario.

What should it be able to do?

Fundamentally the auxiliary outboard is designed to get you out of trouble i.e. if you have travelled 15 miles up or down the coast, the outboard engine should be used to get you to the nearest port/ harbour/ place of safety.

Any other use for the engine is a bonus but do include i.e. trolling when fishing, tenders (depending on engine length) etc.

Sizing your engine

Obviously getting the right size of auxiliary outboard is vital for your safety and the easiest way to do this is simply to call us with as much of the following as possible:

  • Make and model of boat
  • Main engine size in HP including if it’s a 2 or 4 stroke
  • Approximate weight of equipment including fuel
  • How many people will be on the boat
  • Where you will be using the boat

Based on the above we can give you a few options to consider.

Using your auxiliary engine

First of all check that you have enough fuel (preferably in a separate from your main supply) to get you to safety. This might sound obvious, but many people still run out of fuel and hence keeping your auxiliary engines fuel supply separate is a good practice safety measure.

Start your engine before every trip as there is nothing worse than finding out that your auxiliary outboard also has a problem!

Make sure the engine is not dragging in the water when not being used.


When you change your backup engine it is a good idea to run it on your first trip out to confirm that it is the right size and to measure how much fuel it has used and hence you will have a good idea on how much you need to take on future outings.


Many outboard serving companies will offer a discount for servicing your main and auxiliary engine at the same time including us!

Auxiliary engines are often very easy to steal so please make sure it is secure and either taken with you or locked in your boat when you are not around.

Check that you have the right size bracket to take the weight of your backup engine as these vary a lot.

If you need more information on auxiliary engines or have other safety please call us on 01475 744555

Auxiliary Outboard Engines List

This table allows you to view by HP size, weight , warranty and RRP to help you make an informed choice of what engine is best suited to your requirements. Please note that RRP's only are shown and the price does not reflect any discounts or a trade in price for your outboard.

NOTES: We have also added the Tohatsu 6HP Sailpro outboard due to this engine having a few changes to a normal 6HP and is designed for heavy boats ie over 1000kg.

Tohatsu also are the only manufacturer to make an Ultra long shaft
HPWeight in KGLong shaft =L
Short shaft = S
Ultra long shaft = UL
Warranty Manufacture